Burning oil from leak

[ponkotsu]

Just want to get some second opinion on this. I just bought a 2000 5.0 Mountaineer with 140k miles. Engine and tranny are very strong and run great. The engine oil is clean and really seems to have been well maintained. I get whiffs of oil smoke in the cabin. It's very noticeable outside the car particularly if the hood is opened. Strange thing is, I never have even a drop of oil on the ground. As for oil consumption, I haven't got enough miles on it to know how much I'm losing

So I took it to the local repair shop for a look, and to check out everything else. They tell me the problem is either a main seal or oil pan. I guess that's possible, but it seems odd that I never get a single drop on the ground. Seems more likely that its a valve cover gasket and it's leaking directly on the exhaust header.

Anyone out there ever have a leaking main or pan and not have anything on the ground?

 

[kkg1280fl]

Sounds like a valve cover gasket to me! I've got the same issue with my 91 XLT.

 

[n2epv]

The rear main seal leaks on my '97 Mounty V8, about a quart every 1000 mi. This is easy to see, just get under the truck and look up - the back of the engine and bottom of the transmission bellhousing stay wet with oil on my truck. I have a dirt driveway, so oil leaks aren't so obvious - I'm not sure if it does leave oil on the ground.

I agree with kkg1280fl, if you are smelling burnt oil, it's likely valve cover gaskets since there is no exhaust component near the pan gasket or rear main seal. On the other hand, oil leaking from a valve cover gasket doesn't have to travel far to get on the exhaust. And a single drop of oil now and then will make quite a stink.

 

[SoNic67]

+1 for valve cover.

 

[ponkotsu]

The cat has a little oil on it, but not smoking. I think I'll try snugging up the valve cover screws first. Changing out valve cover gaskets isn't that big of a job...

 

[ponkotsu]

Took a close look. Exhaust manifolds are dry near the valve cover. No visible smoke...

Not sure what I'm looking at under the vehivle. But there is a casing or pan directly over the cat that is very wet. :-(

 

[ponkotsu]

This is driving me nuts! Crawled under the truck last night. Couldn't see any indication of oil dripping from behind the engine onto the cat. If it was a main seal, I should easily be able to see oil dripping from the drain hole on the bottom of the bell housing sheet metal cover. There is however a little seepage around the pan gasket. There is also evidence of old leakage down the back of the bell housing cover. Its very small and not enough to actually drip. So I cranked on the pan bolts a little. Got maybe a half turn out of them. Took for a test drive and still had oil smell. Looked under the car, and no evidence of oil on the cat.

So even though the exhaust manifolds look dry, I have to assume the problem is from there. That would more easily explain smoke in the cabin. I never quite believed that smoke from the cat could get into the cabin at 50mph. Smoke from the exhaust manifold could though.

So today's project is new valve cover gaskets I think...

 

[L2rocku2]

This is driving me nuts! Crawled under the truck last night. Couldn't see any indication of oil dripping from behind the engine onto the cat. If it was a main seal, I should easily be able to see oil dripping from the drain hole on the bottom of the bell housing sheet metal cover. There is however a little seepage around the pan gasket. There is also evidence of old leakage down the back of the bell housing cover. Its very small and not enough to actually drip. So I cranked on the pan bolts a little. Got maybe a half turn out of them. Took for a test drive and still had oil smell. Looked under the car, and no evidence of oil on the cat.

So even though the exhaust manifolds look dry, I have to assume the problem is from there. That would more easily explain smoke in the cabin. I never quite believed that smoke from the cat could get into the cabin at 50mph. Smoke from the exhaust manifold could though.

So today's project is new valve cover gaskets I think...

Hey Ponkotsu. I too have been dealing with the constant burning oil smell!! I have a 2000 5.0 awd eddie bauer and i'm replacing the rear oil main seal today!! Just came online to double check a few things before I begin. The constant smell of burning oil has been driving me nuts!! If it's the rear oil main seal that's leaking, it usually only leaks when the engine is running. When I slid under to find out what was leaking, I saw the motor oil (not tranny fluid in my case) was dripping onto the exhaust crossover pipe @ the cat!! No wonder I never found any oil spots in my driveway, it was being burned away by the hot exhaust and would stop leaking when the engine was off and before the exhaust cooled enough not to burn it away. I wish it was as simple as a valve cover leak, but not in my case Time to get to it, burnin daylight lol.

Good luck with yours and hopefully it is just a leaking valve cover for you!!

 

[ponkotsu]

Hey Ponkotsu. I too have been dealing with the constant burning oil smell!! I have a 2000 5.0 awd eddie bauer and i'm replacing the rear oil main seal today!! Just came online to double check a few things before I begin. The constant smell of burning oil has been driving me nuts!! If it's the rear oil main seal that's leaking, it usually only leaks when the engine is running. When I slid under to find out what was leaking, I saw the motor oil (not tranny fluid in my case) was dripping onto the exhaust crossover pipe @ the cat!! No wonder I never found any oil spots in my driveway, it was being burned away by the hot exhaust and would stop leaking when the engine was off and before the exhaust cooled enough not to burn it away. I wish it was as simple as a valve cover leak, but not in my case Time to get to it, burnin daylight lol.

Good luck with yours and hopefully it is just a leaking valve cover for you!!

I thought mine was the rear main, so I put in some Bars Leak's. Seemed to help, but didn't stop. Someone suggested it was valve cover gaskets. They didn't look bad, but I changed them anyway. That seemed to fix it.

I had the constant oil burning smell also, even at highway speed. So if you think about it logically, there's no way you can smell the smoke on the cat at hiway speed. Only way is for it to come in through the cowl vent. I figure it was burning on the exhaust manifold and coming in from the hood.

I also had a really stinky heater core or evaporator that was confusing the issue. I still get the early morning stink (Doesn't really smell like a typical stinky heater core), but it's not so bad now.

It's still really a bit of a mystery what it was. Most likely a combination of all of the above.

I'd highly recommend you change out the valve cover gaskets before the rear main, unless you are absolutely sure it's the rear main. It's not really wasted effort, because even if they don't leak now, they probably will eventually. If you use the top level silicone gaskets, they likely will never leak as long as you own the truck. And it gives you a good chance to check for leaks in the PCV, EGR and intake while you are in there.

PS: the other thing I did was to clean the heck out of everything with engine cleaner so I could really see it. That's when I determined that the oil seemed to be dripping down the back of the engine. It's really impossible to see unless you have one of those pin hole cameras, and even then I doubt it.

 

[Turdle]

I wonder if the PCV valve might be clogged, and causing oil to puddle up and run down from the PCV hole in the lower intake--dead center all the way back.

 

[L2rocku2]

I've made it up to just the tranny left to slide out, then the rear main seal. Decided to take a break before doing the tranny Yes, i'm very sure that it's the rear main seal that's leaking and causing the constant burning oil smell. Besides watching the oil drip from the front of the trans, I did check the valve covers, every inch, and there isn't any leak or seepage what so ever. I did a complete tune up just a few months ago and one of the items I replaced was the pcv valve and all of the vacuum hoses. Oh how I wish it could have been anything but the rear seal!!! Not an easy job by any means!!