Hi guys,

I have a new problem on my LT1. Last friday a lot of smoke suddenly came from underneath the car. That happened on the highway just after accelerating from 60 MPH to 80...There was so much smoke I felt like a blue angels during an airshow...As this was white smoke I believe this is due to an oil leak somewhere.
I then pulled off and looked for the leak...All I could see was this smoke coming from the undercarriage without being able to identify where was the leak located. I just could see that the underneath of the car was a little greasy behind the transmission. After leaving the car for 4 hours (I pulled of at a restaurant )I could notice a small stain of oil (about 1 inch of diameter).
Do you have an idea of where than can be coming from?
Any input welcome
Thx

 

White smoke indicates coolant rather than oil which is usually described as blue. How is the coolant level?

 

Hi Dudule,
Been there done that! Although I'm not saying that the situation that I had is exactly the same as yours; here's something to think about...
Presuming you're running an 700R4 automatic, my guess is that it was not coolant in your combustion process but actually transmission fluid hitting your hot exhaust from the outside. If this is the case, you now have to narrow down where the fluid came from. Consider the following possible sources:
1. Transmission was recently filled with fluid and possibly overfilled. There is a vent on the top side where an overfilled 700R4 will spill out.

2. You have a leak at either the front or rear seal, due to wear and tear and old age. I'd be guessing more likely at the front where the pressure is.

Of course, if you're not running an automatic - you can disregard!

 

Hi Pletzvet,

Your input is very interestint regarding 2 points:
-Yes I have a 700R4 and
- Yes it's been filled recently,

I'd even say more:I had this stuff happening twice after the transmission was filled whereas it didn't occur before...So the overfill is a possibility.

I have then 2 questions:
-How do I check it's overfilled and
-If so, how do I go back to the normal amount of oil?

I'm kinda concerned about this cause I am not confident when oil burns, this could lead to a fire...

 

Oil, coolant, and transmission fluid all have different and distinct smells. You can check the tranny fluid be getting the engine to normal temps and run it through all the gears at a stop. While the engine is still running pull the dipstick and see where the mark is. You may have to repeat to get a more accurate line. To remove the fluid you can unscrew the tranny line that goes into the radiator and drain, but only what is needed.

 

I agree with RRT on how to make sure your reading on the dipstick is accurate (presuming that you are using an OEM dipstick). Hope you find that the fluid level is overfilled - it's a cheap fix!
Good luck.

 

I did check the trans fluid level as you told me to do and it doesn't seem to be overfilled...the level is within the "cold" range (I let the engine run till it reached 140°F).
But what surprises me is that when I removed the car from its parking location, in order to check where the leak could come from, I could see some oil on the floor (not a lot) but there was no evident leak source.
It was like the underneath of the car, the floor was greasy but you couldn't tell where the leak was located...

 

And what about engine oil?
May this smoke coming from engine oil dripping on the exhaust somehow?
I've checked my engine oil level and I noticed that I have too much oil...
It is not in the operating range but far beyond.
Can I remove the excess?
Thx

 

What does the smoke smell like? If your tranny fluid level is full then I would move on to the oil. You will need to drain some of the oil out if it is overfilled (can cause engine damage). Just get the car on ramps and remove the plug until you think it is enough or just go ahead and change the oil and filter so you know it is just right. While you under there use a flashlight and look for an area where oil might be running down from. The LT1 (and L98 for that matter) seem to get a notrious oil leak around the intake manifold. Both my 86 and 95 have had this leak and both were on the rear on the manifold. I never saw smoke though, but it is hard to tell you what it is... unless you can find a place on the car were you see some type of fluid.

 

The rear bumper of the car is actually all covered with a thin layer of oil(or tranny fluid) and it's black. As the tranny fluid is red I would tell its oil...am I right?

 

This concerns me a LOT, when you say way over full, how much higher than the mark are we talking about here? And do you have any idea how it got this way, or how long it's been this way? Both coolant and fuel can end up in the oilpan and cause it to be over full, but there should have been a lot of other symptoms to go with either of these conditions. Yeah, you can remove the excess, but
I suggest you look real close at it when it starts draining out the oil pan drain plug hole, looking for antifreeze, and smell the oil for evidence of fuel contamination.

 

, strongly.

 

Here is a picture of my oil level


What are the other symptoms you are talking about?
Except the smoke effect I have no symptoms...

 

Do you mean the inside (underside) or outer surface of the rear bumper? If the outer surface of the rear bumper has oil on it I would suspect it is coming through the exhaust

That would likely be due to some significant blow-by.

 

No, the entire rear bumper is covered with oil. This is due to the same phenomenon that happened when you drive on a wet road.
Because of the cloud of smoke that was trailing behind my car some oil has stayed on the rear bumper.

 

Yeah, that looks pretty high. Doesn't look like there's any water in it though, which is a good sign. Now does it smell like oil, or does it smell like it might have gas in it? Who did the last oil change? If you did, how many qrt's of oil did you put in? If not, who knows what they put in it? First thing I would do is drain it back down to a normal level (hell, depending on how many miles are on it, you might want to just go ahead and change it, starting over from scratch so you know exactly how much is in there) and if oil pressure is normal (gas would thin it out and lower oil pressure. Takes a lot to lower it to zero, but if you dump a gallon or two in it, it will go drop to zero. The Navy did this to my race car once!), go ahead and drive it and see if it does it again with a normal oil level. Have you dipped your finger in the little puddles the car is leaving and determined it's definitly motor oil? Also, the oil pan isn't damaged, is it? I have a 1993 Camaro that the previous owner's son took on a little offroad excursion one day, bending the crap out of the pan, and everything seemed normal until I headed up a REALLY steep drive way one day (about 35 degrees for about 50 yards), and the oil all ran to the back of the pan and a little slopped out onto the exhaust, leaving a huge cloud of smoke! I thought the car was on fire, took me a while to figure out what had happened. I would have never known, cause the car didn't really seem to be using / leaking any oil up to that point. This isn't the most likely culprit in your case, but if it's never done it before, I gotta belive it's somehow related to the abnormally high oil level. I'm out of here for the day, but it sounds like you should be safe to drive the car and see what it's doing. I'll check back in the morning and see what you came up with.

 

Just noticed your in France, my stepson was just in Paris, he's backpacking Europe for his summer vacation this year. Think their headed to Amsterdam right now, he has an uncle there.

 

How did the oil get that high? Did you check it with the engine on or off?

 

I checked the oil with the engine off...But a bit warm, I made it run an hour before I checked.

I didn't put the oil myself in, but the guy who did it is somebody I trust, he has taken car of the car for the past 5 years.
Yesterday I checked if there was oil in the coolant reservoir and there wasn't so I believe there is no water in the oil either.
I am gonna remove the excess today and see what happened thereafter when driving. We'll see...

 

So when the car sits overnight or over a few hours what level on the stick does it come up at then?