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CV Axle or Oil Cooler?

Hey all,

I own a 99 Subaru Forester, which has about 50K miles on it. I recently had a road trip from TX to CA. In the middle of the trip near AZ, I smelled a burning smell coming from under the hood. I took it to a mechanic(NAPA network member) and he said that my CV axle was torn and all the grease was spilling out and falling on the exhaust and that was causing the burning smell. I got the CV axle replaced from him. He said he couldn’t clean the grease completely, so the smell might last a little bit but it would go off in a while, once all the grease was burnt.

Then I drove it to CA. Could smell the burning still, (strength of smell was reduced though), but I took the mechanic’s word and thought it would go away eventually. Came to CA and had an oil change done because of the long trip. In a few days there was a knocking sound from the car, whenever I accelerated from a stop. Took it to another mechanic in CA (NAPA network member), and he said that the CV axle was damaged and that it was causing the knocking sound and he would replace it since it was under warranty. Now , its been about 2 weeks since I got the CV axle replaced, the knocking is gone, but the burning smell came back stronger again. Opened the hood and saw that there was oil/grease in the same location as in AZ. Took it to the mechanic in CA, and he says its an oil leak from the oil cooler gasket. It needs to be resealed. Then we need an oil change and a coolant flush. I am wondering if the first mechanic did not make a proper diagnosis. Is the CV axle near the oil cooler gasket? Could leak from one be mistaken for another?

Thanks for reading my story and thanks in advance for the reply.

You needed repair 1, too bad twice, and I might think the first mechanic took care of the obvious and might have missed the oil cooler gasket, and the gasket became more apparent after the CV repair. The torn CV boot was the most obvious source and I think you have been dealt with fairly.

Does your Forester have a manual transmission or an automatic, and does it have the turbo-charged engine?

It’s unusual for CV joint boots to fail at 50K miles. Not impossible, but unusual. The grease that leaks from a torn CV joint boot, however, is quite different from either engine oil or transmission fluid, and a mechanic should not mistake one for the other.

Normally the outer CV joint boots fail before the inner ones, and the grease deposits itself all over the inside of the front wheel, tire, and suspension parts. If an inner boot tore it could certainly throw grease onto the exhaust system.

I didn’t think Subaru engines had external oil coolers, but I’m not sure about the turbo cars. Automatic transmissions have external coolers, however, which are integral with the radiator.

I’m trying to tie the need for an oil change and coolant flush with this oil leak, but so far I’m having a hard time.

Can you be more specific about what’s leaking?

Thx mcparadise and waterboy.

mcparadise: To answer your qn : I have an automatic transmission.
I asked the second mechanic why he would need a coolant flush, and he said that when they fix the gasket, they would have to open the coolant system, and oil would mix with the coolant and contaminate it, so we would need coolant flush and an oil change.
Btw, I opened the hood once to see if I could spot any leak before I took it to the mechanic and I could see a brownish oily substance next to the CV axle , so I thought may be the CV axle conked up again… but it doesnt seem so.

I am a total car newbie…just know to drive :). The other car I have is a trusty Toyota Corolla …with no issues so far…so really appreciate you helping me out!

Can you see the route the oil would have to take to get onto a part of the exaust manifold?

Are you getting any oil spots under the car when parked? (I am trying to get a idea on the severity of the leak)

Thx oldschool.
Not getting any oil spots when parked.
Can you see the route the oil would have to take to get onto a part of the exaust manifold? Am not sure how to look for this.

Is it dangerous to drive the car with an oil leak?

You say no oil on the ground and the route the oil would have to take is not obvious,my conclusion is the oil leak is very minor.

I would get a professional engine clean up (I hesitate to say steam clean)some one who can clean up what is smelling/smoking and go from there).

Check oil daily until this issue is resolved,postpone oil cooler job until after engine clean up and the have it done only if they can show you the path the oil is taking to get on the manifold,be skeptical.

Oil dripping on the boot could cause the boot to fail, and a small amount of oil mixed in with a lot of CV axle grease would go unnoticed. Kudos to the CA mechanic for finding the root cause.

If the replacement axle was a “remanufactured” axle, I would urge you to replace it with a new axle, either OEM or new EMPI brand axle. I have had very poor luck with remans.

If the original boot failure was the inside boot on the passenger side that’s a common complaint and it’s quite possible that you may have had more than one fault causing the smell.

The car is 10 years old and at that age (mileage is irrelevant) any seal or gasket on the car can be prone to a leak at any time. True of any car as rubber will harden and deteriorate due to age and heat.

Anytime something on an engine is disassembled and there is a possibility of coolant mixing with engine oil the the oil/filter should always be changed.
Coolant flush? That could be debateble but if the coolant has never been flushed then this would be good time to do it. Flushing the coolant ever so often is recommended and beneficial for any car.