Oil leak

[Bikeboy80]

I know this is a tough question to ask without seeing it but here goes...
I noticed a slow oil leak showing up at the back of the oil pan and am trying to narrow down possible locations that it could be coming from. I know the oil pan gasket could be one place but could there be a likely place higher up? I don't see any thing on the sides of the engine around or above the exhaust manifolds. Could it be coming from the top of the block between the heads?

I'm just trying to get an idea of Likely places before I start pulling thing apart.

Thanks

 

[big_b_in_PA]

Sorry to say, but its almost likely your rear main seal. I just did mine when I rebuilt my tranny, mine wasn't leaking, but I figured since I was there.... Anyway, my last Tahoe had a rear main seal leak like crazy. There wasnt any fluid on the torque converter, and I knew it was not the intake gasket.

Check around your oil filter, and if you have oil cooler lines, check them out as well.


Good luck with your search.

 

[ATL]

i agree with rear main, but to get a better idea, lay a clean piece of cardboard under the truck overnight. thatll help narrow down the location, and what type of fluid it is. dirty trans fluid looks just like oil when its dripped all over concrete

 

[fire730]

There is a plate that houses the rear main seal. I've changed a few of those gaskets. I've changed the rear main seal at the same time but the seals were never leaking. The leak was from the cover gasket.

 

[Bikeboy80]

i agree with rear main, but to get a better idea, lay a clean piece of cardboard under the truck overnight. thatll help narrow down the location, and what type of fluid it is. dirty trans fluid looks just like oil when its dripped all over concrete

It is such a slow leak right now it won't actually drip, it hangs right on the oil drain bolt.

I know the leaks can be very deceiving. I had some spotting on the driveway last year an I would have sworn to you it was the trans leaking! It actually ended Up being the water pump on its way out and was leaking coolant from the weap hole, hitting the skid plate and running to the back and dripping on to the ground.

 

[afpj]

check the flywheel area through that big peep hole in the bell housing. The round metal cover just snaps off. If the inside is dry, you can "almost" rule out rear main seal or rear cover. In no particular order, common oil leak areas include valve covers, oil pressure sending unit, Intake manifold "valley" cover gasket, oil filter housing, oil pan, rear main and rear engine cover. Somewhere in the tech section was a nice write up on this subject, http://www.tahoeyukonforum.com/forum/showthread.php?t=34764.

Hope that helps.

 

[Bikeboy80]

Thanks, I will take a look in the bell housing.

As I was reading the thread that was linked, my worst fear was brought up. Chasing an infamous leak and replacing every gasket on an engine with 150k on it. Also if I have to disconnect the trans should I be doing a full service and/or rebuild on it. I just don't want it to become a giant can of worms, that I might have been better off leaving alone and occasionally just adding oil to make up for the leak?

 

[dorisk]

Yeah it's usually the main seal, but just put cardboard under it and you'll find out where it is.

 

[M3PO]

It is such a slow leak right now it won't actually drip, it hangs right on the oil drain bolt.

I

A leak is a leak and nothing fixes itself, but if you can slide clean cardboard under your truck and it wont leave one drop overnight, I wouldn't worry about it. I would just keep an eye on it, when you change your oil.

 

[Bikeboy80]

A leak is a leak and nothing fixes itself, but if you can slide clean cardboard under your truck and it wont leave one drop overnight, I wouldn't worry about it. I would just keep an eye on it, when you change your oil.

I get it, I do know that where I park it in the drive way there are no spots of anything. I will keep any eye on it, thanks.

 

[M3PO]

I get it, I do know that where I park it in the drive way there are no spots of anything. I will keep any eye on it, thanks.

I can appreciate taking care of the vehicle, I have a couple friends that give me trouble about doing routine maintenance. In this case, just know it might be a problem and keep an eye out. I hope not, but you never know if someone will steal your truck, total it out, etc, for one reason or another it is gone and you took the transmission out to replace a leak that any other person would never even notice.

 

[NC_John]

check the flywheel area through that big peep hole in the bell housing. The round metal cover just snaps off. If the inside is dry, you can "almost" rule out rear main seal or rear cover. In no particular order, common oil leak areas include valve covers, oil pressure sending unit, Intake manifold "valley" cover gasket, oil filter housing, oil pan, rear main and rear engine cover. Somewhere in the tech section was a nice write up on this subject, http://www.tahoeyukonforum.com/forum/showthread.php?t=34764.

Hope that helps.

The inside of my bellhousing was dry and it was the rear main and/or rear cover gasket. I had two mechanics look at it and they couldn't tell where it was coming from. Its a ***** to diagnose.

I changed my oil pan gasket first, then the intake set (removed the intake to check the oil pressure sensor seal), then finally the valve covers. Still leaked. Ended up pulling the transmission on Christmas Eve and changed the rear seal/gasket set. Hasn't leaked a single drop since then (15K miles). The only seal I've not changed on the engine is the front main and that is a piece of cake compared to the rear. Might do that one if and when I have to do the water pump. I was lucky that I'm able to do everything myself so it only costs me time and parts. That would suck to have to pay shop rates while they figure out what is leaking.

 

[fire730]

Glad you got it fixed

If you think that was a pain try doing it on a C5 Corvette. Now that's fun. Lol

 

[NC_John]

Glad you got it fixed

If you think that was a pain try doing it on a C5 Corvette. Now that's fun. Lol

Mine was easy- just time consuming. 2WD truck, borrowed a friends lift in his shop. Really couldn't have been easier (except for fighting with reinstallation of the tranny cooler line clips and the dipstick tube)..... These trucks are remarkably easy to work on.

Yeah, doing that job on a vette.... good luck to ya!

 

[fire730]

A lift is a must. Working together a buddy and I can pull a 2wd tranny in 45 minutes.

Now the Vette was a different story. The rear tires are the first thing you take off.

 

[electro]

I can appreciate taking care of the vehicle, I have a couple friends that give me trouble about doing routine maintenance. In this case, just know it might be a problem and keep an eye out. I hope not, but you never know if someone will steal your truck, total it out, etc, for one reason or another it is gone and you took the transmission out to replace a leak that any other person would never even notice.

So sad, but true.