1999 Grand Prix GTP oil leak

truc0011 · 04-09-2008, 11:05 AM

Hello all,

I have developed a new oil leak and I'm not sure where it is coming from. At first I thought it was the rear main (although it was replace 15K miles ago) because I see oil drips forming on the flywheel inspection cover, but I can't find any other visible leaks (besides oily residue on the underbody). Then I noticed a burning smell coming from the car so when I looked under it I saw the catalytic converter smoking. Upon closer look it looks like motor oil driped down from it. Not very much but a few drops were present. I might be dealing with multiple leaks here but I though I would see if anybody had any similar problems.

BTW it has 91,xxx miles on it.

Thanks!

BNaylor · 04-09-2008, 06:06 PM

Oil leaks are common and yes many of us get them. Especially with your mileage and if no gaskets or seals were ever replaced. It could be valve cover gaskets, oil pan gasket, crank harmonic balancer seal, rear main seal, oil filter seal, or even the oil pressure pressure sending unit. The best thing to do is a closer inspection to find the source(s) by jacking it up or put it on a lift. Also, remove the plastic cover at the bellhousing to double check the rear seal is not leaking again. You'll see oil all over the flywheel.

truc0011 · 04-09-2008, 07:56 PM

Quote:

Originally Posted by BNaylor

Oil leaks are common and yes many of us get them. Especially with your mileage and if no gaskets or seals were ever replaced. It could be valve cover gaskets, oil pan gasket, crank harmonic balancer seal, rear main seal, oil filter seal, or even the oil pressure pressure sending unit. The best thing to do is a closer inspection to find the source(s) by jacking it up or put it on a lift. Also, remove the plastic cover at the bellhousing to double check the rear seal is not leaking again. You'll see oil all over the flywheel.

I've done valve covers, lower intake, oil pan and rear main gaskets and the thing still leaks. The dealer did all the work under extended warranty. On all my other vehicles I've done all the work and none of them leak. I don't think dealers use the correct torque and precision that a person would on their own vehicle. I've worked at many dealers over the years and I have never seen a mechanic use a torque wrench.

BNaylor · 04-10-2008, 09:16 AM

I think you addressed the issue. If you want the job done right best to do it yourself and yes I would highly recommend using a torque wrench. Unless the oil loss is excessive take your time and go back over what was replaced or not replaced and see where the source is.

truc0011 · 04-10-2008, 09:33 AM

Quote:

Originally Posted by BNaylor

I think you addressed the issue. If you want the job done right best to do it yourself and yes I would highly recommend using a torque wrench. Unless the oil loss is excessive take your time and go back over what was replaced or not replaced and see where the source is.

I looked the car over last night when it was dark out using a trouble light. I have had success using that approach before. I still can't find the source of the leak, it must be the rear main. Like I said before the inspection cover is wet, there is oil dripping from the starter, it is on the bolts on the back side (towards the firewall) of the oil pan and if I look up the back side of the engine block I see oil all the way up the block, even on the frost plugs and all over the oil level sensor but I verified that the rear vavle cover is not leaking, I could visibly see it when I followed the exaust pipe up to the manifold. When I look at this area from the top of the engine the only oil I can see is a trickle from where the transmission meets the engine block. The head gasket looks fine too, its strange! I'll do some more research, maybe a closer look of if there is oil on the flywheel, but I assume I'll have to pull the tranny and fix the rear main. I did a tranny on my Montana and it wasn't very fun but if I have someone fix this for me I've lost all faith that they will do a good job. No more extended warranties for me.

BNaylor · 04-10-2008, 09:49 AM

Sounds like a good plan to me and it sure sounds like part of your problem is a reoccurring rear main seal. Definitely remove the plastic cover on the bellhousing. I recall two 10 mm bolts holding it on. Bad part is the autotransaxle and torque convertor does have to be removed if it is the rear main seal to replace it. What brand and weight engine oil are you using? Maybe using a high mileage engine oil with the seal conditioners will help in the interim.

truc0011 · 04-10-2008, 10:00 AM

Quote:

Originally Posted by BNaylor

Sounds like a good plan to me and it sure sounds like part of your problem is a reoccurring rear main seal. Definitely remove the plastic cover on the bellhousing. I recall two 10 mm bolts holding it on. Bad part is the autotransaxle and torque convertor does have to be removed if it is the rear main seal to replace it. What brand and weight engine oil are you using? Maybe using a high mileage engine oil with the seal conditioners will help in the interim.

I use Quaker 10w30, I guess I'd rather fix the problem than try to mask it for awhile.

birar · 05-30-2008, 06:07 PM

2 be positive before u rip the trans out cuz its a bitch go 2 napa and buy some infared dye put it into ur oil and shine a black lite around where u think its leaking after u have cleaned the area wit brake clean it will also help 2 see the dye if u use yellow tinted saftey glasses i have found all the most minor leaks wit that setup it realy works good.

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