My 87 GL costs more in oil to drive than gas. It is somehow leaking onto the catalidic converter and burning off at an incredible rate. I am unable to see a trail of oil leaking to it and was hoping someone could give me some hints as to where to begin. I am a decent car repairsmen when I know what is wrong with the car but am not good at diagnosing. Thank you for your time.

Drop the Y pipe / cat and take a look. Could be a number of places back under there...

Sounds like your passenger side cylinder head may be leaking. Do you see any green coolant leaking with the oil? You may just need to retorque your heads. If you look around this site you will see a procedure for fabricating the special socket needed for this job. I did it a few months ago and it wasn't too bad.

you need to start from the outside of the motor (valve covers and work inward. oil leaks from valve covers, cam carriers and head gaskets can all end up on the exhaust and burn off.

 

oil leaks tend to flow from the "outside" to the inside of these motors. if it's leaking at the heads...the valve covers won't be oily. but if it's leaking at the valve covers the underside of the motor from the valve to the heads could have oil on it. so that's why you work you're way in. if the valve covers are clean then they are not leaking....

 

nice to clean the motor underneath good to get the old oil, grease and dirt out of your way. start first on the far passengers and drivers side of the motor (the "outside"). you'll see a valve cover on each end, check that juncture for leakage. if it drips on the crossmember, at the rear corner of the gasket it can leak on the cross member and run down towards the exhaust (but so can other leaks). or pull the covers and inspect or replace the valve covers. a really bad leak at the valve covers will often be cause by an actual crack in the gasket which you can see if you pull the valve cover.

 

if this all checks out then move to the next mating surface going towards the inner part of the motor. this will be the cam carrier and you should find some indications of a sealant application. all the other gaskets/ seals are formed, this one is a sealant application and made by gasket sealer. if there's a leak here then it's the cam carrier that's leaking.

 

if it's leaking at the next mating surface past the cam carrier then the head gasket is the next thing to check. these can and do leak oil without leaking any coolant. seen it myself and drove one for like 30 - 50,000 miles like that and it never failed.

 

after that you have oil pan and rear main oil seal to check. rear main seal is covered and requires engine or transmission removal to replace or even see it.

forgot to mention - check those valve gaskets very well as they often fail and leak alot. and they are very cheap and easy to fix. most other oil leaks are quite labor intensive or expensive (if you pay someone else to do it) compared to the valve cover gaskets.

I was out there trying to find the leak and there was definately no trail of oil going to the catyltic converter but it smokes like a campfire. I took a cloth on every path the oil could take to get to my exhaust but there was definately no trail, it wasn't even damp anywhere. When I accelerate under load it shoots more smoke out the back than I have ever seen come out of a car, maybe a 30 foot cloud of smoke comes out.

So its not leaking externally onto the outside of the cat; but rather shooting oil out the exhuast and vaporizing it on the hot exhaust parts?

First off, is it a Turbo? I had the same problem. I replaced the Oil Pump Seals, the Cam Seals the Crank shaft seals. I also found oil leaking from beneath the turbo, there is a tube that carries oil I think to cool of the turbo not sure. Anyways the car does not leak any 10W out of it now. It was leaking like a siv. My car is leaking 90W from the differential though. This is getting onto the Cat and smoking. I think that is the only thing causing it to smoke. I hope. I will watch this thread to see if you figure out you figure out your problem. It took about $100 and about 12hours for me to replace of of the abpve mentioned seals the water pump and the timing belts. I know I am slower than most. It was well worth it.

It is not a turbo. I will be replacing all those seals you said in time, unfortuantely I wont be able to get started for 2 weeks due to a broken wrist. Thank you for the help and I will let everyone know what I find out when I rip into her.

Just be sure to keep the oil full In the mean time maybe someone could do a compression test and leak down test for you? Might give you some insight before you even buy any parts.

 

Good luck.