Diagnosis and Repair of Your Oil Leaks


Imperial Homepage -> Repair ->Engine -> Leaks

Question from Roy (440):

I have been looking at the oil pump section of the FSM and I would like to get some clarification about what is not written in the FSM. The oil pump comes after the engine removal section of the FSM, but I can't see any reason why it can't be removed from the engine in the car, am I correct? Next from the picture, the shaft is pinned to the distributor gear and is slipped in from the distributor side, so it can't accidentally slip out when the oil pump is removed, correct? I just don't want any surprises!


From Peter:

The oil pump *can* be removed from the engine while the engine is in the car (at least on a 70 Imp). Access to the mounting bolts isn't terribly easy, though, and you'll probably have to remove the motor mount bolts and jack up the motor a bit. Also, the oil pump input shaft housing protrudes into the block about 2 or 3" (going on memory here) and is o-ringed. You'll need that clearance below the pump to lower it enough to get the input shaft housing out of the block. I recall rotating the pump housing (after removing the filter) to find a position where I could remove the pump. Regarding the pump drive shaft... The gear is pressed onto the end of the shaft, not pinned. The result is the same, though. The shaft rides in a bushing pressed into the block and will not drop out when you remove the pump. The distributor must be removed to remove the pump drive shaft. If you intend to remove the shaft (which isn't necessary to replace the oil pump), follow FSM procedures for positioning the crankshaft. Otherwise the distributor rotor will probably be out of whack following reassembly and your carburetor will turn into a flamethrower!

From Mark:

Yep, the pump can be removed with the engine in the car without too much difficulty. ESPECIALLY in an Imperial. The external oil pump is one of the more elegant design aspects of the big-block MoPars. (And is shared with all the MoPar in-line sixes and eights.) And, like Peter wrote, that shaft is not going to come out, unless you remove the distributor and pull it out from the top.

Question from Roger (440):

Where is the oil pump located on the engine ? Is it possible to get an electric oil pump for the 440 so you can lubricate the engine before starting?


From Mark:

On big-block MoPars, the oil pump is mounted outside of the crankcase, on the left (driver's) side, low and just behind the timing cover. It's where the oil filter spins onto. (And, I believe, helps contribute to quick filter re-filling when replaced. This helps extend engine life.) Most other engines made in the world have the oil pump mounted on a main bearing, inside the crankcase. The benefits of an outside oil pump include ease of service or replacement. There're rarely any clearance issues should one decide to install a high volume unit. In fact, MoPar used to supply a kit to modify the existing pumps, and many guys I know would install the kit without even removing the pump from the block! Try THAT on a Chevy! 

I've never heard of an electric oil pump, though it wouldn't surprise me to learn of one. I've seen a couple of pre-oiler systems, mostly at the autocross course for those cars that pull so much g-forces through the quick turns that all the oil has sloshed out of the pan or has been pumped up into the upper block faster than it can flow back into the oil pan. Basically, it's a cylinder that's capped on one end with a spring-loaded piston on the other. Oil comes through a valve into the sealed end, pressing the piston against the spring. At a determined drop in oil pressure, the valve opens up, and allows the piston to push the oil back out of the cylinder into the oil system. I've seen a couple of these systems set up so that the driver can trip the valve from the dash before starting the engine, thus allowing it to start with oil pressure already present.

From Steve:

The oil pump on B(361,383 and 400) and RB (RB=413,426 and 440) is located in front of the drivers-side motor mount and is kind of square looking. The oil filter actually screws onto the oil pump. The pressure relief spring is located under a large nut that is at the rear of the pump and faces the motor mount. A far as I know....there is no electric one available and it's value would be negligible as far as I am concerned. It has also been mentioned that the oil pumps are the "weakness" with these engines. I would have to say that it isn't so even though the oil pump relief spring stuck on my '73(three) Imp on it's trip home on the day that I bought the car and needed to be towed home. It came unstuck as I was driving the car into the garage to replace the pump but I replaced the pump anyway. It is much easier to change than the Chevy or Ford pumps since it is externally mounted.

Question from Bob (440):

I have '67 Imperial convertible. The oil pressure gauge reads about a quarter ways inside the left side of the safe operating level. I suppose this is an acceptable reading but it flirts with the edge of the low line after long runs.  What kind of readings are some of you other members getting? I was considering a motor flush for a possible restricted oil screen.


From Steve:

I would first suspect the gauge is not correct or replace the sending unit before suspecting that you have engine problems. If you are guessing the oil pump pickup tube screen is clogged, most likely the most thorough way to solve this problem is to drop the oil pan and clean out the screen and the pan. <--my .02cents Motor flushes might dislodge more varnish and sludge and clog the screen even more. You did not mention if you are getting a "low" reading when hot and at idle. An oil pump story: When I first bought my '73(which has been dead for some time now) the oil pressure dropped to "zero" on it's first ride to my house. The lifters started ticking and I started to hear "low end" knocks, so I shut it off and had it towed home...knowing full well that the gauge was NOT lying. I bought an oil pump which is easy to install since it is "external". I briefly started the car up just to get it in the garage and all of the sudden it had lots of oil pressure. I replaced the pump anyway and disassembled the old one only to find worn rotors/shafts and semi-stuck pressure sleeve and spring. The problem never surfaced again with the new pump. (end story, food 4 thought) Also, I neatly installed a small, quality (Auto Meter), mechanical oil pressure gauge neatly under my recent '75 Imps dash along with other gauges(H20 temp, volts, vacuum, and trans-oil temp.) The gauge reads about 65+psi when on high idle when cold...and about 25 when hot and idling in gear. '75's unfortunately don't have a factory oil pressure gauge..only a light. (thumbs down goes here) I use Castrol 10W-40.

Follow-up from Bob:

I kind of played with the wire connection on the top of the sending unit and it was kind of loose. Don't know if that could be a factor, but the readout is a little higher now. First day start idle is almost in the center of the the readout, hot idle dips down to about 25% of the readout towards the low end. Still in the acceptable range but it just seems like it should be higher. I stared running red line 20-50 a few weeks ago. Could have something to do with it also. I'll switch oil again before I do anything mechanical. On the 75 imp with the dummy light, how low does the oil pressure have to go before the light comes on? Also does anyone know the difference between a high volume oil pump a high pressure oil pump, and the standard unit? It seems self explanatory but I wasn't sure.

I was told by a parts store guy that you must raise the engine block up slightly to install and I imagine remove the oil pump. Is this correct, and thanks for the clarification on the oil pump types. As I said before I'm going to change my oil from red line 20-50 to something more nominal and see what happens before I make any mechanical moves. I know the redline is super thick at start up and runs a little different.

Reply from Steve:

Your oil pump is located on the left (driver's) side of the engine directly in front of the motor mount. If you don't have 3 or 4 inches of space between the pump and the frame...then you will have to disconnect the motor mount on that side and jack up the engine to have enough clearance to slide the pump out. If you decide to do this, be careful to watch the cooling fan as it will come close to the shroud. When I did it on my '73 many years ago, I also disconnected the throttle and kickdown linkage so that it wouldn't get bent. No big deal. As far as changing the relief spring in the pump...the cap/nut faces rearward towards the motor mount. You'll need about 2 inches of space to change the spring. How many miles are on your Imp anyway. Did you change the sending unit?

From Mikey:

And for standard, hi pressure and hi volume pumps: the difference between standard and hi pressure is the relief spring, the factory used a 55 PSI spring for standard. A high volume pump moves more oil by volume than a standard one, but not necessarily at a higher pressure. The general rule of 10 PSI per 1000 rpm is usable for most engines, so standard pressures should be fine. as a final note on the pumps, the pump will move a set amount of oil per revolution of the pump, its the clearances between the shafts and bearings in the engine and the viscosity of the oil that determine the pressure. If an engine is well within its limits of bearing clearances ( main, rod, rod side and cam ) then your oil pressures should be adequate. Usually changing from a 10-30 to a 10-40 ( for example ) won't make a huge difference.

From Peter:

The oil pump cover on my 70 LeBaron had a hairline crack and, therefore, an annoying drip. I replaced the pump with a new standard pump and *did* have to raise the engine. The pump has a cylindrical protrusion that is about 1" in diameter and 2 or 3" long to house and support the pump rotor shaft. You have to drop the pump down far enough to get the protrusion out of the block.

Question from Mike (440):

I have a '67 Crown that runs good, does not smoke, but if I take it on a long drive, it leaves a film of wet clean oil on the rear bumper and the rear of the car, any ideas of what would cause that?


From Bill:

Just a suggestion, you might have a small oil leak in the engine or tranny that is blowing back as you drive. It may be collecting at the rear where the turbulence are.

From Paul:

This is caused by an oil leak. Anything that is leaking that much would reveal itself to you by having a low oil level, and would require frequent replenishment.

In my experience, this has been usually either a transmission cooler line that has developed a leak, or a power steering pump/hose problem. Engine oil leaks will do the same thing, but since you stated that your car doesn't use oil, I am assuming that you are checking that often.

What ever it is should leave a spot or two (maybe more) on the floor of your parking spot, but some of these leaks are worse under operating pressure.

From Steve:

You have a leak somewhere. The wind picks up the dripping oil and deposits it on the back of the car for you. Good luck finding the source!

From Demetrios:

Usually the oil in the rear bumper is an indication of worn out rings and excessive oil consumption. People said about oil leaks, but the engine is in the very front. If the oil leak is bad enough to wet the rear bumper, the whole floor pan would be all covered with a thick oil film as well, I would expect.

How much oil is this engine consuming? Do you ever have fouled plugs? Finally, put your finger in the exhaust pipe(s). Does it feel greesy and oily? If its full of dry carbon, that would be normal. But if its greasy, I think your engine is using too much oil, and its probably the piston rings.

Follow-up from Paul:

I have had this happen several times when it had nothing to do with the engine itself. A couple of times it has.

In my case it was once the power steering pump, and the other time it happened badly, it was a transmission cooler line.

On the car where the problem was the engine, the car had so much "blow-by" that the crankcase was pressurized and pushing oil out the filler cap. It was then running down the engine and getting caught in the air currents, carrying it to the back of the car. That is where it gathered and made a big mess. Looking under the car did not seem to reveal anything out of the ordinary, except the spot where the oil was actually dripping from.

It doesn't take a "chassis bath" of oil for this to happen.

If you run your finger over the film, you should be able to tell if the oil is red, or black. I am thinking that it was said that the engine was NOT consuming motor oil.

From Rob:

My '65 convertible had a bad pinion seal that dripped occasionally on local driving, but on the highway it caused an oily streak under the differential and caused oil film on the rear lower bumper from the turbulance of wind going under the car & out the back. That was the only leak under the car. New seal cured it.

From William:

It doesn't take much oil at all to collect back there. All it takes is a few drops getting exposure to the air going under the body as the car is in motion. Might not be enough to have drips either.

If it was from oily exhaust from the engine, it'd be putting out a smoke cloud (i.e. fogging mosquitoes!) that was noticeable AND might get you reported to the air quality board in some states. Not to mention fouling out spark plugs, I suspect.

From Rich:

I had the same problem with oil spots and a oily film on the rear bumper of my '59 Ford wagon. It's oil from the motor leaking or it could be transmission fluid leaking. It's cause by an up draft coming from under the car when driving. On my wagon it even gets on the rear window at highway speed. The motor on that car is now being rebuilt which will stop the problem.

Question from Mike (440):

My 1970 Imp needs to have the engine pulled because of a blocked oil  passages..... ( at least that's what he says ) ... The problem is , there is VERY little oil pressure... He pulled the pan and cleaned up the oil screen and drop tube... ( which was plugged up too ) and still low oil pressure... His guess was the oil passage around the cam area..  Does that sound right ?  


From  Pete:

Here's a little info that you may find useful. I've rebuilt several engines and always make a tool for "pre-oiling" the engine prior to the first startup. For Chrysler engines I obtained a spare 440 distributor and oil pump drive shaft. The oil pump drive shaft has a hex drive at one end (it fits into the oil pump) and a big gear at the other end (it meshes with a gear cut into the front end of the camshaft). I took a bench grinder and ground all the teeth off the oil pump drive shaft. Then I stripped the distributor down to the housing and shaft (advance weights, points plate, & points cam all removed). These modified parts are then installed in the engine temporarily and I hook up a 1/2" drill to the top of the "distributor." Presto! I can run the drill to pressurize the entire oil system without running the engine. I usually do this before I install the intake manifold to verify that all the lifters are getting oil, but you don't have to. If you pull the valve covers you can also verify that the rocker shaft tubes are getting oil. On an engine with some sort of oiling problem, this setup allows you to add engine cleaner or kerosene or whatever solvent you want to the crankcase and loosen up/flush out the system without worrying about piston scuffing or bearing wipeout. You just drain the solvent and change the filter, then add fresh oil and a new filter and run the pump again for a bit to make sure that everything gets a good shot of oil before you reinstall a good oil pump drive shaft and distributor. You can also hook up a real oil pressure gauge and know what pressure will exist before you ever turn the key.

From PEN:

Before you pull out your engine, consider that a low oil pressure reading can come from one or more of the following: a faulty oil pressure sending unit, a wrong dipstick, diluted oil, the oil pump pressure relief valve stuck open, a cracked, loose, or bent oil pump suction tube, a clogged oil filter, or least likely worn engine bearings. Your mechanic said that the oil pump screen and suction tube were clogged, but with what? And if that were true, how could that "what" have made it up, through the filter, into the cam passages? If you really have very low oil pressure, then your engine will produce a great deal of noise just running. The lifters would produce such a racket that you would shut it down after a matter of seconds. On the other hand, and some may dispute me on this, if your engine runs and you get no lifter noise, then you are getting at least enough oil pressure to protect and run the engine. There is something, in my opinion, that just doesn't add up in what your mechanic has told you.

Follow-up from Mike (Car also has noisy lifters):

Well the lifters do make noise... So I do have legitimate low pressure to the top end... What worries me is it seems to be on both sides... Don't know that for sure... The rest of the motor is getting oil.... Even have oil up to the rocker covers. (?) I'm looking into other possibilities... 

Reply from Kne:

Some other possible reasons for noisy hydraulic lifters: Oil too low. Oil too high. Oil too thin....I hope you are not using the same water-thin oils that are being used in new cars. Oil too old. ("prolonged use of oil") Oil pump relief valve stuck. Air entering oil pump. (Oil screen/pick-up too high, leak in suction tube, loose oil pump cover.) Water or gas in oil. (especially anti-freeze) I would suggest an oil change before doing anything, and see how it sounds with fresh oil. If you just have an oil light or electric gauge, it may not be giving a true picture of what your oil pressure is actually doing. If so hook up a temporary gauge.

From Steve:

I'd sure try a high volume oil pump first. Unless the engine was terribly neglected, I doubt the passages are just plugged. I've seen some bad machining that caused low pressure (I'll share the details with those interested) but if the engine made it to 105K miles, she should continue to run for a long time. Big Mopars don't need a lot of pressure to be happy, just a good supply of oil. 10 PSI at idle is a little scary to see, but enough for the 440. I drove a 383 for years with real low oil pressure, and the crank in my 451 had an oil passage drilled right out into space... the 440 lived a long life before that! A good rule of thumb is 10 PSI per 1000 RPM. If the rockers aren't clacking at idle, keep a fresh supply of oil in the crankcase and enjoy driving the old girl!

From Norm:

Try the oil pump.  They are notorious for failing.

From Rolland:

It has to be extremely rare to have the oil passages plug up and not have any oil pressure. I have never heard of this. I would replace the oil pump, the sending unit, and check the rod and main bearings before pulling the engine. Were the rod and main bearings looked at when the pan was off?

Follow-up from Mike:

The rod and mains look good and are getting oil... He says there is a passage to the top end that's plugged... I guess it sounds ok, but I'm thinking their must be some way to clean that out short of a rebuild...

Question from Ben (413):

I am thinking about replacing the stock oil pump on my 64' Imperial (413 c.i.d.) with a new Mopar Performance hi-volume model. The engine has about 83,000 miles on it and runs great though the oil pressure is a little slow on the rise after being started. My question being, will it cause my engine any harm to use a hi-volume pump in place of a stock unit?  I'm looking to better protect the engine and have been told not to use the hi-volume model for fear of bearing damage. It this correct or a load of B.S. ???? 


From Mark:

I think a high volume oil pump is a GREAT idea on most all engines. I can't think of one drawback. (Other than the extra expense and the trouble it takes to install.) I've had one on a '66 Plymouth with a 383 since the rebuild about 13-years ago now, and that engine now has over 115,000 miles, and doesn't use a drop of oil. I installed it specifically to have as much oil pressure as soon after a cold start as possible. As most anyone who's been around the mechanical side of gasoline engines knows, study after study shows that something like 75% of all engine wear occurs in the first minute of initial, cold start up. And I've installed high volume pumps on a whole bunch of other engines, most non-MoPar, foreign and domestic, to no ill effect what-so-ever. What CAN cause trouble are high PRESSURE oil pumps, and I think this is where people who advise against high volume oil pumps get confused. A high pressure pump can pump oil in such a way as to damage the low end and cam bearings. Unless an engine has been designed for one, do NOT get a high pressure pump. In my opinion and experience, Ben, a high volume oil pump would most certainly solve your slow-to-rise oil pressure problem. (Though, also know that the oil pressure gauges on these cars aren't the most responsive....)

From Pete:

Maximum engine oil pressure is limited by the pressure relief valve in the pump. If engine bearing clearances are correct, installing a high volume pump (with the same rating pressure relief valve as the original pump) will simply cause more oil to dump directly back into the oil pan (or pump inlet) instead of flowing through oil passages. Pressure won't be affected. No bearing damage will occur. If engine bearing clearances are excessive, a high volume oil pump will force oil into the oil passages faster than it leaks out of the bearings. So, a high volume oil pump can be used as a Band Aid for a worn engine. Unfortunately, there's a down side. Oil leaking from worn connecting rod and main bearings will be thrown onto the cylinder walls faster than the oil control rings can wipe it away. High oil consumption will result. Bearing material is relatively soft and CAN be damaged by prolonged, excessive pressure. So much oil flows through the bearing/crank interface that it carries away bearing material. This can be caused by someone shimming the stock pressure relief spring or replacing it with a stiffer one. I once put a 400 engine in a Firebird for someone (he supplied the engine). Unbeknownst to me, he had installed a few flat washers behind the pump pressure relief valve spring to boost oil pressure. Boost it, it did! When I fired the engine for the first time the oil pressure gauge spun all the way around. Then, when I revved the engine, the oil filter literally exploded. What a mess! I wouldn't worry too much about a slow-to-rise oil pressure gauge. After all, on any Chrysler big block, the sender/switch is about as far away from the pump as you can get. Oil reaches the crank and cam long before it gets to the sender/switch.

From Leo:

Mopar Performance has a high pressure relief spring part #P4286571, which delivers up to 70 PSI with your existing pump. You can order it from your Mopar dealer.

From Mikey:

In all my engines I use hi volume pumps. Its the clearance in the bearings versus the amount (volume) of oil that the pump can push that gives you the pressure anyway. I believe the stock relief valve rating is about 55 PSI, Mopar Performance has a higher rated one also. One thing I have noticed, I have very little variation between cold and hot oil PSI as a result of this, and the pressure always comes up quickly on initial startup.

Question from Rob:

My oil pressure gage is slow to come up to its normal position.  Prior to having my oil changed last week, the needle would immediately and steadily move from the left to near extreme right when I start the engine. This has been so for the 2 yrs I have driven the car. Now the needle 'sluggishly' comes to lower side of half way and the slowly moves to the position I have observed as normal when I start the car. The performance is similar to extreme cold engine starts (-30C).  The first thing that comes to mind is defective filter. The place I  had my oil changed recently changed brand names (to Fram, I think), has anyone had or heard of a defective filter? The second thing is too heavy an oil for the temp, but this seems unlikely as the temp is still just above freezing ... hardly enough to 'thicken' oil ... and the oil is supplied from a 500 gal drum stored inside. The sending unit? Weak oil pump?


From Dick:

I am not personally familiar with 66's, but if it has an electrical gauge, the indicator should move up the dial in slow, pulsating surges, perhaps 1/4 of the way to its steady state position with each surge, which should occur about once per second. This is the gauge regulator doing its job, and is normal. If it used to fly up scale immediately, it is either not an electrical gauge and you had very thin oil, or there was something wrong. A slow reaction is pretty normal, even for the other type of gauge, which I call "mechanical", even though it is more properly called hydraulic, I guess. In any case, see if your gauge sender has a wire on it. If so it is electrical. If it has a tiny tubing on it, it is mechanical. Others on the list with a 66 will probably jump in here with the answer to this. Not knowing what part of the country you are in, I cannot comment on the oil you are using, but consult your owner's manual, don't trust the guys in the Quickee-Lube places. If the oil pressure is actually in the normal range when the car is thoroughly warmed up, there is nothing wrong with your oil pump, or anything else mechanically. I cannot fathom why a Fram or other name brand filter would be causing this problem, but I suppose if it is draining dry between starts, it could cause a slow rise of oil pressure. It would be wise to change the filter again, just to eliminate it as a cause. They only cost a few bucks, and you might save yourself a lot of unnecessary wear on startup if you got the one in a million that has a bad check valve.

From Bob:

A defective filter is a possibility. Somewhere I've got tests of oil filters, which included disassembly to check construction and there were surprising differences between them. I recall Fram was not on the top of the list.

From Norm:

This is the way all of the ones I have owned (10) have operated . If there is a problem, the filter could be involved as could be a dirty and/or erratically operating filter bypass spring in the oil pump. This sometimes responds to a " technical tap".

Question from Mark:

I had my car up on a rack, and while the guy was doing the transmission work, I think I found a leak.  It appears to be leaking from a bolt that holds the oil pump onto the block - at least it is back there near where the pump connects to the block. (There's the filter, then a curved pipe looking thing with a plate on it with about 4 or 5 bolts.)  OKAY, the question is: is there a gasket there?  Could it be as simple a matter as tightening that bolt???  Is there any way I can avoid replacing the whole dang pump?  Anybody have experience with leaks here?


From Richard:

Pull the pump and replace the gasket yourself. Three bolts hold the pump to the motor and replacing this gasket is only marginally tougher than replacing a fuel pump gasket. 

The first rule of chasing oil leaks is start from the top-front of the motor and work down and back. The second rule is start w/ a clean motor. I like Gunk brand engine cleaner and degreaser products. With enough cans, patience, rags, and a garden hose, you can get your motor and surrounding areas very clean and dry. A pressure washer helps. Repeated applications are generally required. If you've had nasty leaks for long periods of time you'll also have a ton of road dirt stuck to the oil. In this case, scrapping some of the thicker spots w/ a putty knife is helpful. Once you get the old stuff off, it's a lot easier to see where the leaks are actually coming from. This is especially true w/ the front of the motor as the fan and pulleys tends to blow things around. It wouldn't surprise me if you're oil pump leak was actually a valve cover leak running down the front of the block. One last thought: oil and rubber don't mix. While degreasing, inspect your radiator hoses, power steering hoses and motor mounts. If they've been soaked in oil for any period of time, replace them.

From Bob:

Yes there are two different gaskets in there. The first gasket is between the block and the pump assembly and the second is between the two pump rotor housing halves. If the leak is the pump to block gasket you have to take the pump off anyway and if it is the housing halves gasket you have to take the pump apart anyway. If you buy a replacement pump you will get the gaskets with the pump and have a new pump to boot. 35 to 45 dollars for a new pump. Up to you but if you have to pull the pump anyhow.....

Question from Mike:

What's a "windage tray"? And why is it called that?

Reply from Joe:

A windage tray is used in engines that are used for hard acceleration like in racing. Windage trays are positioned between the oil pan and the block, they help keep the oil in the pan so the mains, throws and the oil pump pick-up have oil to pump. When high RPM, hard launching cars leave the line the oil is sloshed backwards and whipped up into the block by the crankshaft, so the oil is not available for the oil pump to pick it up.....not a good thing at 6,000 RPM.

Question from Zan (413):

 My engine is making some bad noises and I have low oil pressure.  Any ideas what the problem is?


From Brad:

Low or unsteady oil pressure unaccompanied by overheating and nasty noises, is most probably due to an electrical fault. Check the pressure directly with a gauge. If you don't have one try replacing the sending unit. My '66's gauge would inadvertently drop to zero and then back up to "normal". I checked the wiring and then the sending unit. The sending unit turned out to be my problem. Try turning the body of the sending unit by hand. If it turns, it's bad and will at some points ground the circuit. A $12 replacement will prove if it's at fault.

From Denis:

This happened to my LeBaron, and I ended up replacing the oil pump which is easy accessible, and not to difficult to install. Good oil pressure now.

Question from Cory (413):

When I got my 65 LeBaron it had 10 year old oil in it so I bought some engine flush, flushed the engine and then added 10w30 Mobil 1 full synthetic(6 quarts right?) After doing all that I've notice that my oil pressure is lower than I'd like so I have decided to install a new oil pump since they are so easy to get at (no pulling the pan). Should I go with a stock pump, a High Volume pump, or a High Pressure pump? 


From Bill:

If you feel you must replace the pump, then just go with a stock one, unless you're spending weekends at the drag strip.

From Joe:

I have a high volume, not high pressure. It also acts as a coolant to run a lot of oil through her. I also run an oil cooler because of living in Palm Desert. I run 2 trans coolers. On the Imperial gage, I have the needle about 7/8 pressure from left to right. It was about half before. You only need about 10 pounds oil pressure for every 1 thousand RPM's anyway. I started using Mobil 1 13 years ago because till I learned how to lower the pumps of my engines here in the desert, I needed to stop my engines from cooking the oils that are called the conventional oils. They would fry around the heads and deposit a filmy black burnt substance there. Now, my engines are as clean as when they were new even after 125,000 miles. I change it every 5 thousand on the 5, 10, 15 20 thousand scale.  I use it also in my 525 Horsepower 69 Daytona. This 69 engine now has 83,000 miles as of last week. I asked the engine shop if we should pull and freshen it up, as I have driven it up to 180 MPH and they asked if the oil consumption has changed and it has not since new. The smog device sucks out some of the oil at high rpm, but no smoke or smell exists. They said leave it alone for now.

Question from Jack (318):

The basic facts:

81 Imperial 

85K+ miles 

New Timing chain 

New 4bbl Carter 

non original exhaust, no cat, no resonator 

I just had a bunch of work done on the car; and am driving around the city for the first time since I got it. It came with an aftermarket mechanical oil pressure and temp gauge. Now after I picked it up, and fed it a can of CD-2 to quell the nasty lifter noise, I have a chugga chugga sound when I accelerate. As if one cylinder isn't firing, or valves aren't closing??? It idles quietly, but the chugging sound is quite un-Imperial-esque.  Check exhaust manifolds for loose bolts? It still does feel like it's missing sometimes (I'm installing new plug wires, and doing a compression check this weekend) 

Oil Pressure> almost 0 on the gauge when warmed up , in gear, foot on brake. It goes up over 50 when just started, and seems to run at least 10psi per 1000rpm when at speed, but scary low at idle when warm . (I spend as little time as possible there!) The options seem to be: install new gauge to be sure of readings.. (like the mechanical/flex hose thing suggested in the archive) new oil/ filter, (was just changed, but with the CD-2 (detergent/clogged filter?) and put in synthetic? new oil/filter, and put in straight 30 wt ? 50 wt? Drop the pan, and make sure all of the ex timing gear nylon isn't blocking the screen? new oil pump? Drop in a new 440 crate engine? (ok, just a thought....) There don't seem to be any audible signs of engine distress, (loud valves, bearing knocks, etc...) so far.. The temp gauge reads a consistent 260 degrees, but it reads 190 when dead cold, so I figure that's just old funky gauge stuff. Any thoughts much appreciated. Could I have caused any damage, driving the 100 some miles when the timing chain slipped?


From Matt:

The low oil pressure is probably due to excessive wear. Although in my experience the cam bearings are not a Mopar weak spot.( Maybe a GM problem with their notorious butter camshafts). On a 360 in a 79 New Yorker I had, the problem was worn connecting rod and main bearings. The chugga problem and the suspected miss at idle seem to me to be lo compression symptoms. Possibly a burnt exhaust valve. The compression test is definitely recommended. The temp gauge irregularities may be due to the sender. Does the after market gauge hook up to the factory sender? If it does ,this could be the problem. The Imperial used a different sender than other cars due to the digital dash I believe. I've heard of this being a problem with engine swaps in these cars. 

From Kerry:

Some thoughts. First, regarding the Chugga... Does it sound off when you put it in gear, stand on the brake, and give it some gas, or only when driving? If you can get the noise to repeat when not moving, have someone help you and stand beside the car with the hood up and pinpoint where the noise is coming from. Exhaust leaks have many different sounds. The 4' piece of hose trick that Dick B mentioned works quite well. Second, regarding the oil pressure. My friend, I think your engine is about worn out. Of course, pick up another oil gauge and check to be sure but what I expect you will find is what you already saw. What this means is that some bearings (1 or more, probably more) have excess clearance. Or perhaps a weak oil pump. Blockage will normally show low pressure all the time. Solutions, several and none that good. I frequently run straight NON detergent 50 Vavoline Racing oil in my low oil pressure or oil burning cars. Makes them hard to start but the increased viscosity seems to increase oil pressure. I'd probably try 30 or 40 weight first. There are also some "molasses" like oil additives which increase oil viscosity but I would trust Vavoline more. Final solution is a bottom end rebuild.  

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