The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support Kiggly Racing
Please Support STM Tuned

2G Smoke from the tailpipe at idle

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

shinzon

15+ Year Contributor
350
72
Sep 11, 2006
St. Petersburg, Florida
Fix one thing, another thing breaks....

I've been noticing what appears to be white smoke coming from my tailpipe if I leave the '96 idling for a few minutes.

White smoke would suggest coolant, but as far as I can tell it doesn't smell like anti-freeze, and since this is Florida and it's already in the 80s, it's not condensation. I drained and replaced the coolant, and the oil, and I see zero evidence of the two mingling. I'm also not noticing the coolant level dropping as much as one would expect if it were burning off.

I'm going to do a compression test this evening.

So where does that leave me? If it's actually coolant, I guess it could be coming from the Turbo--it's from a '91 and has never been rebuilt. I recently replaced the FLAV gasket, so maybe is leaking in through the throttle body?

Any advice?

One thing I'm going to check is the PCV valve. Obviously wouldn't cause coolant to burn, but I replaced it with a cheap parts store valve, and when I recently did a BLT I noticed significant amounts of air coming from the breather port on the valve cover. Maybe it's actually oil?
 
Last edited:
I swapped on an OEM Evo123 PCV valve I had laying around onto the car, and I got the results of the compression test. Average of three measurements, taken with a hot engine, and the throttle wide open:

1 179
2 179
3 182
4 182

Virtually unchanged from when I last did a compression test back in October. It's looking like this smoke issue is not a head gasket failure.

If it is coolant, that basically leaves the turbo, right?

Anyone else have any ideas?
 
I don't think it's the turbo after all. I evidently have a leak in my exhaust manifold gasket on cylinder 4, because I noticed white smoke coming from that area at idle. I assume turbo issues would present themselves post-turbo, not from inside the combustion chamber/inside the head.

With the good compression numbers, and the smoke seemingly coming from the combustion chamber, even though it's white, the smoke must actually be oil. If it's oil, then it's probably the valve seals, right?

You could try to pressure test the cooling system if you suspect a coolant leak.
Good idea; I'll see if I can rent/buy a coolant system tester.
Check your 02 sensor...

Funny you should say that. I literally just got back in from logging a cruise and noticed that my front o2 is occasionally dropping out to 0v for a few seconds...
 
Last edited:
The only way to tell color of smoke is at night with the flash light in the tail pipe. Otherwise it could be watching the car to see where and when it smokes

Easiest way to check is to remove the exhaust manifold. If the manifold is wet with oil, or the exhaust holes in the head are wet with oil, it's your valve seals

Also FYI, those numbers are skewed because you probably are burning oil, so those are your wet compression numbers. Dry with no leaks I would expect a higher mileage motor to be in the 150-160 range

You must be logged in to view this image or video.
 
if you are BLTing at the turbo and you're getting air out the valve cover then your turbo seal is a possibility as well. Air will go past the center cartridge down the oil drain and into the motor. I'm sure a new engine and new turbo will fix this smoking issue you're having ;)
 
The only way to tell color of smoke is at night with the flash light in the tail pipe. Otherwise it could be watching the car to see where and when it smokes

Easiest way to check is to remove the exhaust manifold. If the manifold is wet with oil, or the exhaust holes in the head are wet with oil, it's your valve seals

Also FYI, those numbers are skewed because you probably are burning oil, so those are your wet compression numbers. Dry with no leaks I would expect a higher mileage motor to be in the 150-160 range

You must be logged in to view this image or video.
Interesting point; I had been wondering why compression was so high on a 155k motor that has never had any major surgery.

To test this theory I did another compression test, engine hot, wide open throttle, with a cap of oil in each cylinder.

Results:
1: 180dry/182wet
2: 179dry/185wet
3: 181dry/182wet
4: 182dry/185wet

The minimal difference between "wet" and "dry" would seem to suggest that you're right, and there's oil entering the cylinder and my dry numbers are in effect "wet" readings.

I also have a bore scope and took a peek into my cylinders. I noticed some carbon build up on top of the pistons, but nothing obviously terrible.

Here's what the spark plugs look like (L-R 4,3,2,1):
You must be logged in to view this image or video.

Plugs have about 4 months and 3k miles on them.

if you are BLTing at the turbo and you're getting air out the valve cover then your turbo seal is a possibility as well. Air will go past the center cartridge down the oil drain and into the motor. I'm sure a new engine and new turbo will fix this smoking issue you're having ;)

No! I love my seven-bolt. ;)

I do have a freshly rebuilt E316g on my bench, and I see, at minimum, at valve job in this motor's future.

I've never done a leakdown test, but I'm going to rent a tool and see what that comes up with.
 
Last edited:
Yeah the results speak for

All of my valve seals for the intake were bad except cylinder 2, so I was getting skewed results.

I could remove a spark plug immediately after the car was smoking and I could watch smoke come out of the plug holes it was so bad

For reference my 14b pushes boost into the oil pan. If you test for boost leak at the compressor inlet you can hear the oil gurgle back into the pan. If you test into the system through a boost line it holds pressure.

My 14b pushes air into the crank case building boost, makes a great hiss out of the oil cap too over 10psi. Doesn't smoke tho

So yeah, a bad turbo could cause smoking on the exhaust housing but it wouldn't show up in compression numbers like that. Unless of course your turbo pressurizes the crank case and causes your valve stem seals to leak in the first place Lol. When my car got hot it would smoke worse than Cheech and Chong, hilarious to smoke out the McDonald's drive through sitting on the torque converter building boost

You must be logged in to view this image or video.
 
Last edited:
Valve stem seals are a tedious job, but if you've tacked a timing belt or two it is not any trickier than setting timing. And what's better than having another dsm specialty tool in your tool box LOL

You must be logged in to view this image or video.
You must be logged in to view this image or video.
You must be logged in to view this image or video.
 
Valve stem seals are a tedious job, but if you've tacked a timing belt or two it is not any trickier than setting timing. And what's better than having another dsm specialty tool in your tool box LOL

You must be logged in to view this image or video.
You must be logged in to view this image or video.
You must be logged in to view this image or video.

Ah, very interesting. I wasn't aware it was feasible to do valve seals with the head on the engine. My '97 will probably get that treatment as it's blowing blue smoke after sitting overnight, and I don't feel like pulling the head off it. What's going on with the string?

Not sure what I'm going to do with the '96. Even if the headgasket seems fine, it would probably be best to replace it before I start throwing 15 more lbs of boost at it later in the year, and I'm going to have both the hot and cold sides off the engine to do upgrades... might as well go the rest of the way. I also broke an exhaust manifold stud on #4 last time I had the turbo and manifold off the car ('08?), so it may just be best to take the head to a machine shop and let them sort it out.
 
The valve spring retainer is held In place by tension from the spring. Since it's been in place for so long the retainer is pretty lodged into the keeper

So you need to put pressure against the valve so the spring can compress without pushing down on the valve

Sometimes you can use compressed air to hold up the valve, sometimes they are so stuck you need to wedge something in there to prevent the valve from being wedged into the piston

Using air to hold the valve works most of the time, however to do it at a leisurely pace without stressing about the piston rotating the crank, or overpowering the air pressure pushing on the spring, you use nylon rope in the cylinder

So you feed the nylon rope into the cylinder, then rotate the crank to push the piston up as far as it can go to press against the valve.

Technically the rope is just a formality, but I would prefer to limit metal on metal contact, the valve could rest against the piston at top of the compression for the piston, but it seemed dicey
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top