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Does anyone know where this leak is coming from? I can smell it at stop lights after racing around. I can even smell it after driving normal sometimes. Smoke comes out from under car of course and also through fresh air vents. I have to add oil pretty often to keep it full. I have already had a shop change the temp sensor and they said it was fixed but no go. I also had a new clutch put in and they checked main seal and cover and said that it was dry. Oil pan very wet. Exhaust pipe next to oil filter wet. See pics. Please please advise.
I had the same issue. Only smell when stopped and some smoke from under the hood when no wind parked in the garage. I had just replaced my oil sending unit with a Delco and I didn't have that issue before that. I have strong oil pressure and it ended up being the sending unit with oil leaking out the top and down the back of the engine on to the exhaust.
Does anyone know where this leak is coming from? I can smell it at stop lights after racing around. I can even smell it after driving normal sometimes. Smoke comes out from under car of course and also through fresh air vents. I have to add oil pretty often to keep it full. I have already had a shop change the temp sensor and they said it was fixed but no go. I also had a new clutch put in and they checked main seal and cover and said that it was dry. Oil pan very wet. Exhaust pipe next to oil filter wet. See pics. Please please advise.
I see oil on the drain plug too. i had the same issue with oil like that, come to find out my oil drain plug seal was worn out because I degreased the entire bottom of the pan before my oil change and drove it around, I found oil coming off the plug. that oil went everywhere even though I never saw any drip on my driveway. i replaced the plug with a new one and no more oil. its a thought and might save you from hours of troubleshooting.
degrease the bottom and take it out for a drive and when you come back check the oil drain plug for any seepage.
Well, so far we put her on a lift, brake cleaned everything, changed oil and filter as well as the drain plug. We also looked at the pressure switch behind the manifold and it is not leaking at all. Definitely doesn't look like the front main seal either. So we took it for an hour ride and put it back up on the lift and it is again soaked. So I was looking at some older pics that I took of the pan all wet from a couple months back and noticed that the pan is only half wet! Can you guys tell me if this pan looks cracked to you? I am thinking that the small car dealership that I bought it from used a floor jack on it when he changed the A/C belt tensioner (And left a few rusty tools under the hood as well as never put the belt back on! It was there but not on the pulley!). Also, can I just buy the lower pan if it is cracked?
Here is another pic that I took when I got home from cleaning it all up and changing the drain plug. I just reached under the car with my cell phone to take the pic. Again, as you can see, it's only half wet and always ends up all over the oil filter and exhaust pipe right behind it but only on the driver's side and burns.
SCRUB off that area so its OIL FREE and let it sit over night. If its cracked, there should be some signs if oil seep at that suspect crack area.
The GOOD NEWS: If it is cracked, you only have to change that lower part of the oil pan which is VERY EASY and they are easy and inexpensive to get new or used.
I had an issues that cause the entire underside of the engine and body to get oil covered. It turned out to be a bad harmonic balancer seal and sealing surface. Clean off the area around the front cover and harmonic dampener. See if there is any signs of oil there after driving it a short time. IF,, the seal is good, there will be NO oil at the seal or dampener.
Bill
Last edited by Bill Curlee; 04-20-2018 at 03:04 PM.
Thanks for the reply Bill. I spent this whole morning diagnosing with dye in the oil because come to find out, there was no sign of a crack in the lower pan. It only looked that way in the picture. I figured what the heck and drove out to the Chevy dealer to buy the lower gasket and meticulously replaced it and then went for a highway ride, came back to see exactly the same thing. Definitely nothing around the harmonic balancer or front main seal. It sure looks like the lower pan gasket is still leaking but I refuse to believe it now. If you inspect the pics below, it seems it might just be coming from the upper oil pan gasket and traveling down and settling in the lower pans gasket's groove from all the wind turbulence
. The funny part is, I can't seem to get it to leak at all on the lift even after revving it and waiting for almost an hour!
IF,,,,,,,,,,, It were my car, I would re-tighten the UPPER PAN BOLTS to the OEM Spec and see if that takes care of the issue. Clean it after tightening and reinspect.
Last edited by Bill Curlee; 04-21-2018 at 12:41 PM.
Yes, I have retightened the upper pan bolts but not to specs. I did get a quarter turn out of them, however. I will look up the torque specs and give it a shot. Also, this is the 3rd oil filter and oil change during all of my leak searching adventures (probably within the last 500 miles). I thought for sure I would be able to find the leak with the dye in the oil but it is still baffling me! I am beginning to wonder if the only reason it seems to leak when I am driving is that of the oil sloshing around in cornering or something to that effect? I also thought maybe it was the filter surface where the filter gasket seals against and purposely removed the filter again yesterday to inspect but it looks and feels perfectly smooth with no residue of any kind on the surface. I really hoped that I could see the very start of the leak by revving it over and over sending the car up and down on the lift like maybe 6 or 7 times! I gave up on that and took it for a highway ride for only 2 exits to come back and find the start of a real mess with it already burning off the exhaust. I still have the dye in the oil and will definitely not give up!
I did purchase that exact housing with a new gasket that the temp sensor screws into on the advice of my credible mechanic a couple weeks ago. When we installed it, we had changed the oil and filter at the same time only to find out that the housing was cast incorrectly and was slightly warped and/or had a weird groove in it of some type which caused the oil to spray all over the engine in an upward direction as we all watched about 3 quarts of oil slowly emerge from the bottom of the lift. Of course, we shut the car off immediately! What a mess! And it only made my oil leak search much worse! We ended up putting the old one back on but it is still possible that the old one is cracked or something. I spoke with the mechanic again today to see if we can continue the quest and he suggested getting another housing and gasket just to be absolutely positive about that piece in particular. I am thinking about putting a very small camera (that records to a microSD card) on the area and try to spot the start of the leak in that way. I guess it might be worth a shot.
UPDATE: I had my Corvette garage mechanics replace the temp sensor housing again with brand new even though the Chevy dealer wouldn't take it back as a defective piece unbelievably. I also had them replace the pressure sensor by removing the manifold/plenum and at that time they noticed a leak under the knock sensor cover plate. They replaced the gasket and pressure sensor both at the same time. They were sure that was it. It was not. It still leaks. In fact today it smelled badly in 88 degree weather with the A/C on fresh air and a couple times I saw smoke coming out from under the front of the car. I think its time to try and mount that camera under there. I cleaned it spotless last night on the lift thinking it was residue from the day before they replaced the pressure sensor and knock cover plate gasket. I am sure it's a mess again down there. This mystery leak is very persistent.
Have you considered the rear cover plate and seal. They make a very similar mess (ask me how I know) and I have read that they leak due to a casting problem with the plate. They are cheap but expensive to replace if you don't DIY. Good luck in your search I know the mess and smell are irritating and embarrassing.
Have you considered the rear cover plate and seal. They make a very similar mess (ask me how I know) and I have read that they leak due to a casting problem with the plate. They are cheap but expensive to replace if you don't DIY. Good luck in your search I know the mess and smell are irritating and embarrassing.
I just had the same guys do my clutch, flywheel, throwout and external bleeder at the beginning of March. I supplied them with a new rear main seal and cover as well, because they knew I was in search of this same leak. They didn't want to disturb the seal or cover since it was not leaking. He said it was so nice and dry in there that there was no need. I agree that there can't be too many more places for it to be leaking. I'm also starting to look closer at the front seal and the harmonic balancer as Bill has stated. I'm thinking that the oil quite possibly is blowing from the front to the back along the bottom of the oil pan. I mean, forget gravity at any speed! I had it on the lift again this evening yet again cleaning oil from everywhere, trying to see something that I might have missed. I guess my biggest problem now is that I can't see the harmonic balancer that well at all, at least from the bottom. How would I even begin to see the very front of the oil pan where the harmonic balancer might be leaking? Or even clean the back side of it? Should I be looking for a lea
k from the top? I have access to my friend's garage 24/7 with a lift and can diagnose until dawn if needed. I just need more of your expert advice / possible clues! I gotta fix this. I don't even care so much about the cost anymore. Thanks for all your advise so far. Here's tonights pic....
04-11-2018, 10:08 AM
Where is my leak coming from?
Theres NOT much left that could be leaking.
