One Quart Over filled = Smoke

#41

ctbimmer wrote:

PMS = Parked M20 Syndrome.

Happens every winter.:laugh:

#42

I dont consistantly do anything with my oil but change it…I think I add to 1/2 qt over…

The smoke may be coming from worn rings too much pressure in the crankcase…or the valve stem seals as CB mentioned…maybe the 1 qt over no smoke test may be an indication of a tight engine??

Al

#43

It’s got to be rings or valve seals. Nothing else lets oil into the combustion chamber, right? And even over filled, if there were no leaks in rings or seals you wouldn’t have smoke. Unless of course it was something hitting the exhaust.

Try that Valvoline MaxLife synthetic. If it’s valve seals that might help. I had a Miata that smoked like crazy. I used that oil and it quit smoking in just a few hundred miles. It was poorly maintained before I bought it and the seals were not lubricated well from extended oil changes. Also maybe a Seafoam treatment may get some old carbon off the stems and seals, but make sure you drain and refill after doing it. Maybe twice.

There, stayed on topic.

#44

Thanks for all the info guys, sorry I kicked up a shi* storm.

I just did a Seafoam thru the vacuum of the FPR(then ran it for about 30 miles, no smoke), then did a compression check and changed the sparkplugs and oil change. This is when I overfilled the Oil and it started smoking.

I thought that somehow some of the seafoam was still in the system, but it smoked for a few days. I then remembered that I got smoke last time I overfilled this car. I drained a few onces of oil out and instantly no smoke.

I did notice that cylinder #4 did leak down a bit. (could see the pressure dropping on the gauge). 145psi then drop to ~133psi after 30-60sec. It did this a few times.

#45

Indicates to me possibly a broken ring. Leak down should not move once pressure is established. Do you run a crank scraper? Chuck

#46

Chuck, I dont run a crank scraper as of yet. It is on the build sheet/to do list

#47

Leak down could indicate leakage through a valve seal also, I think.

Ranger did extensive leakdown tests recently and had it down to a science. He should be able to offer some comments, if he dares!:laugh:

#48

Leak down through a valve seal will be considerably slower than indicated, but still possible. You could pull the valve cover and squirt trans fluid around those valves to verify. However, since it only happens when over filled, I lean toward the oil ring since there is no scraper to limit movement up the right side of the block. I’m afraid its time for a motor. Chuck

#49

drumbeater wrote:

[quote]Leak down could indicate leakage through a valve seal also, I think.

Ranger did extensive leakdown tests recently and had it down to a science. He should be able to offer some comments, if he dares!:laugh:[/quote]

Chuck’s one of the masters here, I’m just poking around trying to understand things.

That being said…normally a wet leakdown test (DIY on my website) can give you info on where (valves or rings) the compression problem is, but that might not work with the broken ring theory that Chuck suggested. A table spoon of oil spurted into the combustion chamber (wet leakdown) might not seal the rings if the ring is busted. When you spurt oil into the combustion chamber, most of it just creates a pool in the center of the piston. It’s easily possible that not that much of the oil goes down to the rings and seals it.

My ideas would be…

1)Do a compression test. If all the cylinders are pretty close, that could mean that a broken ring is less likely.

2)Do a dry and wet leakdown test. See if you find anything interesting. Easy stuff, you could do all this in 2hrs.

3)Fill it a qt high and ignore the smoke. I mean who reallly cares if it smokes a bit? The bigger question is…is it ok on power? Run it against other E30’s and try to identify if your car is down on power.

Best case, you never really figure out what the problem is, but the engine is reasonably strong. Worst case, a ring is indeed hosed, but even that is not that big of a deal. Pull the head and oil pan. Unfasten the conrod bearing and push the piston up. Replace the broken ring and put the piston back in. You could do this in a day easy. If you know anyone coming to a SE event, I’ll bring my engine lift to them. It’s not a hoist, it’s an rig the size of an 6’ 2X6" that sits on the edges of the fender and will lift the engine a couple inches. That will allow you to get the oil pan off and pump out easily.