Diagnosis and Repair for Imperial Oil Burning Problems 


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Question from Remco (392):

My 392 is smoking lika a steam train I think the small rubber caps that are on the valve stems are gone. Can I replace these without having to remove the cylinder head?


From Julian:

White smoke is coolant, blue is oil and black is gas.

From Demetrios:

If its the valve stem seals, usually the car smokes a lot at startup. Also, in the summer, the condition is usually aggrevated.

I have heard that by pumping compressed air in the cylinder, you can prevent the valves from falling when you remove the springs and retainer. If so, you can replace the stems with the heads on. I can't see why this cannot apply for a 392.

Follow-up from Michael:

This isn't really conclusive and probably more often is a sign of worn rings. The usual manifestation is that the engine starts up ok, but as soon as the RPM is raised much above idle, the smoke starts rolling out, the reason being that the cold, worn rings are unable to seal against the oil sprayed on the cylinder walls when the engine speed is raised. The smoke tends to subside to some degree as the engine warms up and the rings and piston expand into the cylinder. A somewhat better quick check of the valve stem seals is to drive the car until the engine is warmed up, then let it idle for a fairly long period, say 3-4 minutes. This challenges the stem seals with high intake manifold vacuum, but does not tax the rings so much since there is relatively little oil being applied to the cylinder walls at idle. Now step smartly on the gas and drive away. If you are being followed by a smokescreen worthy of James Bond, it's a safe bet the valve stem seals are shot. Remember that all these external check are just indicators, and that often, the stem seals and piston rings are BOTH worn

From Kerry:

The air tool that hold the valves up works great. I've done this procedure on several cars.

However, before you go to this trouble, make sure it's the valve seals. If the smoke is worse at start up and goes away, it is probably the valve stem seals. New ones will help. If it smokes all the time, it's probably something else. Smoke color will tell you what. Black is fuel, blue is oil, white is water. If it smokes blue all the time, you have oil rings worn or broken. Probably worn out. Compression checks will give you a clue as to the state of the engine as USUALLY worn oil rings are accompanied by worn compression rings with corresponding lower compression.

From DeVere:

Yes, there is a handheld tool that will compress the valve spring so you can get the "keepers" out to remove the spring and seal. You will need to have the piston at top dead center, and compressed air bleed into the cylinder from the spark plug hole or a piece of rope stuffed in the cylinder to keep the valve from falling into the cylinder while you work on it. Remember to remove any burrs or "mushrooming" on the end of the valve stem to not tear up your new seals. The tool grabs the lower part of the valve spring, has a hand wheel you turn to compress the spring and will keep it compressed while you remove it. You must be sure the piston is exactly at top dead center, or the compressed air will push it down, you do not need a lot of P. S. I. of air, just keep the valve from falling. (65 Imperial). (afterthought, if the valve rockers are off, and the whole side would be, you do not need the piston at t. d. c. it will not matter, just watch the fan, if the air moves the piston, and turns it quickly to the bottom.)

Question from Bill (413):

While out test driving my Imperial today I noticed smoke coming in the car from under the dash board, and up through the vent onto the windshield, and also out of the outside vents by the wipers. I have seen this happen before, after the car had not been driven for a while, and figured it's just stuff burning off the block and exhaust and coming through the firewall. Today however it was prolonged, and even started to cloud up the windshield. I pulled over and looked under the dash, and then in the engine compartment, but could find nothing. It must be in the area of the outside vent between the firewall. Any ideas what this might be? The only thing that I could figure is maybe the heater unit.


From Phil:

Uh oh, it sounds like your heater core has given up the ghost. Coolant won't evaporate from the windshield like regular water vapor and can be a real pain when driving. You may want to check for a coolant-antifreeze smell. Keep an eye on your coolant level in the radiator and for wet floors under your heater unit! And if anyone has a good source for heater cores, now would probably be a good time to speak up!

From Bill:

If it's a white vapor and coming out of the defrost openings, it is probably a bad heater core. If it is a burning smell you better check your wiring.

From Dick:

You have a bad heater core, the vapor is coming out the defroster vents and condensing on the cold glass. Disconnect and block off the hoses to your heater system until you get a chance to have the heater recored.

Any radiator shop can put a new core in your heater, but he needs the old core to swap the end tanks and fittings. Just block off the hoses, take out the old core, and take it to a radiator shop. It will cost under $100.

From Neal:

I had my heater core removed by a local readiator shop in summer 2001. They sent it out for a rebuild by Old Air Products in Fort Worth. Their web site is www.oldairproducts.com; 4615 Martin St., Fort Worth, TX 76119;
817/531-2665. It took about 2 or 3 weeks, I think, and the price was fairly reasonable, though I don't remember how much. The heater core was dribbling on the floorboard, so I had it done before it got worse. It's been fine since.

From Bob:

You may want to check the passenger side floor just under the dash. My experience on leaking heater cores always swamped the carpet and if left in that condition too long, well you know what happens. Look up the part number for the core , it may be a common one for Chryslers if your lucky. Then when you take the old one out, you can put the new one back in and be done with the problem.

Question from Luis (440):

Recently purchased 1968 convertible but have not had the time and weather problems to work on her much since I got her. She starts up great but the white smoke and the fumes are killing us in my house through my closed garage door. I had a 1969 at one time and I don't remember it smoking like that. Could that be a bad sign? I would like to do a compression test on the engine how much would you think it would cost at a service station or can i do it myself. I know some thing about doing a compression test but don't the proper procedure. How does a compression tester cost?


From Stu:

I picked up a compression tester at Auto Zone for 25 bucks. White smoke does sound like you have bad rings to me...

From Demetrios:

As an easy test, try disconnecting the brake booster line. If the smoke goes away, you may have a bad booster that sucks brake fluid.

A worn engine normally pours out blew smoke, and this is a condition that develops gradually.

From Rob:

As a general rule:

blue smoke is oil (rings/valve guides)
black smoke is gas (too rich/bad mixture)
white smoke is water/coolant.

When a car is smoking white check the head gasket. This is a common problem with 2.2 turbo mopars. It's not generally much of a problem with small and big blocks Mopars. Take the radiator cap off and start the car, look in and see if there are bubblers in the coolant. If there are it's probably your head gasket.

From Bob:

White smoke is usually water. Seems you may have a blown head gasket, cracked head, or block. A compression check is not expensive, check with a few of your local mechanics on cost.

From Willliam:

NAPA has a "block check" kit that includes fluid that you draw the vapors from the radiator coolant through to check for combustion gasses in the coolant. I think the one we bought last week was about $50.00 for the kit. A definitive test.

Other than what's already been mentioned . . . Check and adjust the coolant level. Run the engine until it's good and hot (even drive it instead of letting it idle), and the temperature has stabilized for about 15 minutes or so (in a place that you can let it run that long and not kill somebody/something!), then make sure the radiator is pressured up as it would normally be. Then, turn the engine off and let it sit for about a day. The next step (after everything's cooled down) would be to check the dipstick for condensate or milkiness in the oil color. Then check the coolant level in the radiator to see if it's where it was previously. Finally, get out the spark plug sockets and such and take the plugs out of their respective cylinders. They should all be dry of condensate and have the same insulator coloration (or at least pretty close). Oil-fouled plugs would have the typically oily deposits on their insulators. If ! any one or pair of adjacent cylinders are different, that might be where things are not what they need to be. If you don't mind making a potential mess, with the plugs out you could spin the motor over and see if any "foreign" liquid comes out of the spark plug holes.

This procedure might take the longest to do, but would be the least expensive (a new set of plugs?). Using the block check fluid would be quicker, but more expensive.

From Joe:

I have seen the modulator valve mounted on top of the transmission go bad and throw out white smoke..Are you loosing tranny fluid without any sign of leakage?

Follow-up from Steve:

A leaking vacuum modulator on the transmission can very well cause white smoke. The only problem here is that the Chrysler TorqueFlite does not use a modulator. I would guess there is a antifreeze leaking issue or a slight possibility of a brake booster leak.

From Joe:

I have to agree with Bob. The first thing I check when I'm told a car is blowing white smoke is if its low or lossing coolant. White smoke is almost always Steam! check compression if your lucky it'll just be a head gasked, (low compression on to ajoining cylinders ussually indicated aburned through gasket)Low compression on just one cylinder could indicate a gasket blown to outside (rare) cracked head ussually 'tween valve (most common ara for heads to crack)or a cracked cylinder. This last failure will, however usually be accomanied by milky oil (water in oil)or bubbles (lots of 'em,) in radiator as cumbustion gasses are force into the water jacket). Odds are if the enginge hasn't overheated to warp the head or froze to crack the block it a head gasket or cracker head.

From Rich:

Another thing you may want to check if the spark plugs are firing. I had a simular problem once before with the white smoke, and when I pulled the plugs out one wasn't firing. It was wet with n gas. Bad plug was causing the problem. Change the plug, and problem was gone.

Follow-up question from Luis:

I got my car back (back Window replaced) and the white smoke was gone after it was warmed up still but had strong fumes. I think it first happens when it cold and after it's seems to be fine just with stong fumes. I checked some of the the signs you guys told me to check, oil was fine and the radiator and the engine started and really sounded pretty good. Maybe the problem is when I start and it is cold?

Reply from Rob:

Sometimes it is hard to tell exactly what color smoke you're dealing with. Does it smell like gas? From what you are saying, it sounds like it might just be a choke problem having the car run rich. Knock wood. It's a much nicer adjustment to deal with than rings or head gaskets.

Reply from Demetrios:

Try removing the brake booster hose. See if the smoke goes away.

Reply from David:

Combination of white smoke and strong fumes sounds like incomplete combustion to me. White smoke is not always engine water/coolant, can be an indicator of lean mixture or even steam from condensation in the exhaust, especially if the car has been sitting a while. Steam would no longer be present once all condensation has boiled off. Strong fumes from clear exhaust indicates something is coming out of your tailpipe that would not be present if proper combustion were occurring.

Question from Bryan (440):

I have a '67 Imperial Coupe that has a miss; the number three cylinder fouls the sparkplug quickly and thoroughly. The car smokes and it  appears to derive from that cylinder only.  The car exhibits another odd characteristic: upon startup, a water/oil  (carbon?) mixture splats onto the concrete from the tail pipe. It is a fair  amount of water mixed with a black soot-like stuff. Does anyone know why  this is happening?


From Joe:

I had a problem with fouling plugs also, turns out the valve stem umbrellas (seals) were gone from years of heat they turn hard and crumble off the valves. The new seals cost about $25 for the good ones with wire reinforcing. A good Mopar mechanic can replace rhe seals by charging each cylinder with compressed air and releasing the valve spring keepers to expose the seals and replace them without removing the heads. Worked wonders on my car.

From Frank:

When an engine sits idle for a while (not used at all) the valve seals almost always dry out and crack up. Engine oil then can run down the valve stems and burn in the combustion chamber. The piston rings can also seize in place, either: by rusting to the cylinder wall so that their sealing edges, when broken free by starting, don't seal anymore; or by the rings seizing in place in their piston grooves so that they don't expand outward to seal. When this happens to the lowest ring, the oil control ring, the engine will burn oil. Ring problems require a bottom end job. Assuming that the compression is good you can replace the valve seals yourself. You don't have to take the car to a mechanic to do this job. I've done it, most recently on a '76 New Yorker. Get the best quality seals that you're auto parts guy has. (Shop around to get a quality name brand.) Tools required: Compression tester, cylinder leakage tester or spark plug adapter fitting (something that you can use to put compressed air into the cylinder); air compressor; torque wrench; valve spring compressor; common 3/8 ratchet set. You don't need a monster air compressor, the volume of air flow is quite low, but the pressure is pretty high. I used my own valve spring compressor which was nothing more than a U shaped rod, bent to fit under a dowel bolted in place of the rocker arm. The U-rod hooked under the dowel and I could press down on the closed part of the U while removing the spring keepers. Worked better than the commercial tool, which I thought was a pain in the butt to use. (For a small guy, I have large fingers and this tool gave more room to work than the tool I bought. 

1) Pull rocker arm covers. Remove old gasket material. 

2) Remove rocker arm. Mark the front/back end of the arm and the locations of each bolt. 

3) Remove and mark each push rod. They must go back into their original positions. Mark also Top & Bottom 

4) Remove spark plugs 

5) Thread the fitting into a plug hole, connect the air line and pressurize to about 100 PSI 

6) Using the spring compressor press down on the washer above the spring. You may need to use a small screw driver to remove the keeper from the top of the valve stem. (The keeper looks like a cone cut in half along its longitudinal axis.) 

7) Remove the spring assembly. 

8) Remove the old seal. It may be broken, remove all the pieces you can. 

9) Install the new seal. The intake and exhaust valve seals are different! 

10) Replace spring assembly 

11) Compress spring with tool and re-install keeper. 

12) Repeat 6-11 for the other valve on the cylinder 

13) Release air pressure from the cylinder and remove air fitting 

14) Repeat 5-13 for each of the other 7 cylinders 

15) Reinstall push rods - observe original positions 

16) Reinstall rocker arm - observe original positions 

17) Reinstall valve covers with new gaskets. Don't use sealer since it can break off and migrate through the engine. Tighten carefully to just snug down the cover against the gasket. Over-tightening ensures leaks! 

18) Reinstall plugs. (Since they're out and cheap, might as well put in new ones.) If you are a belt-and-suspenders kind of guy, you can turn the engine so that the piston of the cylinder you are working on is at TDC, preventing the valve from falling into the engine. I don't think that this is necessary since these engines have BIG valves, about 2" in diameter, which at 100 PSI of pressure means that there is about 300 pounds of force holding the valve closed. If you need to put anywhere near that much force into doing this, you're doing something wrong. [ Closing force (pounds) = Pi * r ^ 2 * PSI ] First time I did this it took probably about 3-4 hours. Now about half of that.

Question from Steve (440):

Here is problem that I would appreciate some thoughts in: What causes an engine to blow blue smoke when first started up in the morning, but ONLY after the oil has been changed? The car is driven 3,000 miles between oil changes with almost no oil consumption, but right after the oil is changed, it will smoke for the first few mornings, and heavily, mind you...then clear up. Then it will be fine till I change the oil again. I thought the valve seals might be bad, but why would it do it only after the oil is changed and only for 5 or 6 cold-starts?? <---This one has me stumped. Oh, the cyl-head oil drain-back holes are clear too.


From Dick:

Only thing I can think of is that when you refill the engine, you are pouring 5 or 6 quarts into one valve cover pretty quickly, thus you are really drowning that side's rocker area with oil. Maybe it takes a few hours of running to get that all drained off the valve stems etc, and to get back to normal oiling in there. Sounds like it does need valve stem seals.

From Ron:

Dick's diagnosis of valve stem seals is probably correct (most become hard and brittle early), but once smoking on start up begins it continues at every cold start up until the seals are replaced. There is another problem I have seen over the years in Chrysler (and other) V8's and it fits these symptoms perfectly, small usually harmless cracks which form around the exhaust cross ports and the high side of an exhaust port around the seat area. These are very small cracks but when cold they get large enough for oil to pass thru, and as explained when changing oil a lot more oil is in the rocker area of the head that usual. This oil seeps into the exhaust port areas and will smoke for quite a while. As this oil was never seen on the dip stick no consumption is seen. When the engine warms up the head expands and seals these "hairline cracks" up and little problems occur. I know of engines run like this for years that got no worse, (I ran my motor home with a 360 like that for 25K) and usually get rebuilt/scraped for other reasons. One word of caution however, watch the coolant system, any overheating from pump/radiator/t-stat or whatever usually makes those hairline cracks expand and grow longer.

From Joe:

May I suggest that you take both valve covers off to see if they are all crudded up with buildup around the valve springs. You might have the drains plugged up also and the new oil is the only time the upper valve train is getting oil. There might be a plugged up upward oil passage or something of this nature. So, just for safety sake, take off the valve cover you put the oil in.

Question from Tony (413):

My 413 emits a light but steady amount of whitish smoke from the breather cap and vent tube when the engine is warm. Oil pressure is good and the compression readings on all cylinders are excellent (between 120 and 130 psi). The engine runs sweet and smooth but this car ('61) has no emission controls whatsoever. Is this smoking normal for an engine of this type? If not does anyone have an idea what might be causing it?


From Kne:

This sounds like normal "blow-by" to me, which is a small amount of combustion gasses that get by the cylinder rings. This is normal for all engines, but obviously a new engine would have the least amount. Normally not seen these days because an engine with a PCV system (positive crankcase ventilation) draws these gasses into the intake manifold, into the engine and out the tail pipe, so you don't see them. Or, in other words, if you disconnect the PCV on an engine you will see the "vapors" rise from the valve cover breather. This is normal. We had a discussion not too long ago about setting up a PCV system on engines that don't have them. It's a good idea, constantly scavenging the blow-by out of the crank case keeps a lot of moisture and other combustion by-products from mixing with the oil. It's a good thing. I even have my '48 and '49 Flatheads "P-C-V'd". So....no, you don't "have a problem", but if you put a PCV system on you engine it would be more happy and healthy. Of course, the cleaner oil and crankcase, and less water floating around in your engine won't be "original".

From Carmine:

Not that the PCV is a bad idea, but I don't think you should have enough blow-by to actually SEE it pumping out. My '61 has about 78,000 original miles (I'd guess, who really knows for sure?). I don't notice any measurable amount of smoke around the breather (no PCV on mine either). Certainly not at idle. And I know it will drink a little oil on the freeway. It used about a quart going from Detroit, MI to Auburn, IN back in '97. But then again, it pushed it real hard, doing a steady 80+ for many miles on deserted pre-dawn freeways.   It doesn't use much in town. BTW, worn oil-control rings won't show on a compression test. Only the top two rings are for compression, the bottom rings are simply to "scrape" the cylinder walls of oil. Yours might be worn. Try removing the oil filler cap and putting you hand over it. If you can really feel the "blow-by" pumping, and you hand gets oily pretty fast, you're oil-control rings are shot. It isn't the end of the world if you don't drive the car that much, but it should probably have a re-build. Just be sure to check your oil often.

From Mikey:

Are you sure it isn't just condensation that is being evaporated, it takes a bit to really warm one of these up, you have to get the oil up to temp for awhile to get all the moisture out, but I'd agree with Carmine - especially if its running good otherwise. When you really start to see smoke, especially the blue kind then its time to spend a few bucks.

Question from Roger:

What color smoke indicates a car is burning oil?


From Brad:

Black smoke: Too much fuel 

White smoke: Water vapor 

Bluish, whitish. blackish smoke, accompanied by nasty smell: Oil burner

From Steve:

I wouldn't worry too much about the black smoke. The choke was probably stuck on or the fouled plug on that cylinder is causing fuel to be passed into the exhaust and then burned, causing the black smoke. How old is the gas??? Did the oil pressure go up to an acceptable level after start-up?? Hopefully someone has thought enough of her to change her oil....especially since she has a fouled plug which is causing that cylinder to be "washed down" with gas. And if the choke is stuck on, the oil will be diluted with gas that much faster due to blow-by passed the piston rings.

From Kerry:

The black smoke is unburnt gas, probably from the missing cylinder. If the mileage is near correct, it is probably just a fouled plug or spark plug wire. Oil smoke is blue.

Question from Mark (413):

My '59 Imperial is having a problem with smoking. Once the engine warms there is a steady stream of smoke wafting up from the oil filler on the driver side. If you put your hand over the hole then the smoke will eventually start coming out the ventilation tube on the passenger side. Sometimes when you stop a cloud of light smoke will drift out from under the car and then sometimes there isn't a hint of smoke. This smoke seems to be coming from inside the engine and out the oil fill and / or the vent tube though it can be hard to tell with the engine running and the fan blowing things around the way it does. I have owned cars with blow by problems before... One so bad that if you pulled the oil fill cap off with the engine running you would get a face full of oil. This one just doesn't seem like that to me.... If you block one side it takes a minute for the smoke to start drifting out the other side and there seems to be no pressure behind it. The car runs and idles perfectly with the exception of some pinging under light load. This engine was not started for 35 years. The guy that got it going says he took weeks to do it by putting oil in all the cylinders and letting it sit then turning the engine about and inch and repeating until he made it all the way around. The car only has 32k on it. So here are my thoughts on what could be causing the problems.... 

1. She just needs to run for a while... We have only put a couple hundred miles on it since it was restarted. 

2. The rings are toast. Engine needs to be pulled, block honed, and new rings installed. 

3. The heads are getting to hot and burning off oil. I am thinking the heads are getting hot from impaired coolant flow caused by the rust that built up in the system over all the idle years. The pinging is what is making me think this. Anyone have other ideas?  Is there any practical way to add a PCV valve to suck up the smoke? I would have already tried, but the only vacuum source would be from the brake booster line and I hate to add on to that critical circuit.


From  Arran:

Is there any indication other then the smoke that the engine is overheating? Did you have the radiator flushed out before putting the car on the road? Sometimes radiators can get plugged up from sitting too long but still work well enough not to wreck the engine. Did you put new valve cover gaskets on the engine when you were trying to get it back on the road? Maybe oil is slowly leaking through one of these onto the exhaust manifold because the gasket dried up or wasn't seated properly. I know I'm not an expert but sometimes its the small things that you overlook that stump you.

 Follow-up from Steve:

The radiator was redone. The water is not overheating, but there was a lot of rust in the system so I am worried that some places may be stopped up and overheating.

From Kerry:

Could be stuck rings that may free up when you drive it a while. Could be a cracked ring or just plain worn but with low mileage I doubt it. One think you could do is replace your vent caps with the kind that have a hose output. You can then connect both the hoses to a carburetor port like PVC valves are today. The smoke will be pulled into the carburetor and reburned. Might work as a short term workaround.

From PEN:

When an engine that has not run for 35 years is restarted, the old oil will have oxidized and turned into shellac on the interior engine surfaces. The rings will no longer be seated, and the rubber valve guide seals will probably have crumbled upon restart. Thus the big blow-by, and the smoke, as heat causes sludge and tar to evaporate from the interior of the engine, and that mixes with combustion gas. The best solution is a complete disassembly and cleaning of the engine parts. Until then, I would use only non-detergent oil. Detergent oil will loosen up floaters which can drift and clog up oil passages leading to the complete failure of the engine. Non-detergent oil will probably help the smoke problem, but it should be used only to keep the car mobile while arrangements are made to pull and rebuild the engine. Until then, I would drive the car gently, and only when necessary.

Question from Leo (318):

Lately I have been noticing a rather large amount of blue smoke emitting from the exhaust of my 90K "83. upon startup. Nothing after running for a few seconds. I haven't had that problem since all three of my 78 NYB (400 C.I.) had leaky valve seals. It is possible that could be the same problem with my '83? 


From Carmine:

Yes, you probably have leaky valves.

From Paul:

Most likely it's a problem in the top end (valve guides or seals). I would guess that the seals are worn. After 20 years of the engine heat cycling these little suckers turn to stone (just like dried out windshield wiper blades). They can be replaced cheaply (usually about $40 including gaskets) and WITHOUT removing the cylinder heads from the engine. Some skill is required to do the job, but it's not that hard. The cylinders just need to be pressurized while you remove the valve spring retainers. I actually use a hose from my compression tester (remove the schrader valve) and hook it up to my air compressor (make sure the air compressor is regulated and turned down to about 30-40psi or you'll just blow out your engines other oil seals).

Or you could simply change to a thicker oil and live with it. Typically the seals will only cause smoke at start up, whereas the guides will cause smoke under high vacuum conditions (i.e.decelerating).

I've done seals on numerous vehicles and have been 99% satisfied with the improvement it made. No need to tear apart an good running engine if you don't have to.

This page last updated June 27, 2004.  Send us your feedback, and come join the Imperial Mailing List - Online Car Club