At my wits' end with oil leaks

[LongbowFoSho]

'02 Tahoe 4WD w/ 240k on the clock. A pretty massive leak. It needs around a quart every two weeks.

So far I've replaced:

- Oil sending unit
- Intake manifold gaskets
- Valley cover gaskets
- Valve cover gaskets

All of those were visibly leaking except for the valve covers, so I was hopeful. I decided to go ahead and replace those while I had everything else out of the way.

Absolutely zero improvement from these repairs. The more I look underneath this thing, the more oil I find and I swear to GOD the leaks are getting worse. The only good news is that the oil pressure remains constant. It was fluctuating between 30 at idle and 80 under a load when I bought it, but now it stays pretty damn steady between 55-60, so at least something seems to have improved.

Anyways, back to my Tahole. I've done a lot of reading on these things and the only culprits left seem to be either the oil pan gasket or the rear main. Based on the pictures below, I'm just going to go ahead and assume that it's both.

Any other leak-causing, engineering abortions that I might have missed?

 

[iamdub]

Judging by the oil inside the bellhousing, I'd say you at least have a rear main leak. Judging by the amount everywhere else, I'd say oil pan gasket. After those, there's nothing else left to leak oil.

 

[Erickk120]

Judging by the oil inside the bellhousing, I'd say you at least have a rear main leak. Judging by the amount everywhere else, I'd say oil pan gasket. After those, there's nothing else left to leak oil.

x2

 

[LongbowFoSho]

I also have a disappearing coolant problem. It tells me low coolant every week. No visible leaks anywhere. I have a verrrrry bad feeling.

 

[WTTAHOE]

I had a similar situation with my 04 Tahoe. I replaced the oil pan gasket and valve cover gaskets chasing a leak. I eventually realized my leak was on the right side of the timing chain cover. The oil was not visible in the cracks and crevices until it ran down/back and leaked around the pan. It has been three months since I replaced the timing chain gasket and no more leaks. Looking back the oil pan gasket needed to be replaced as it was a contributor to the leaks, valve covers were probably OK all along. Good luck because it is frustrating!

Sent from my SM-G955U using Tapatalk

 

[adriver]

I also have a disappearing coolant problem. It tells me low coolant every week. No visible leaks anywhere. I have a verrrrry bad feeling.

It could be something as simple as a radiator cap, and could be as costly as new heads. Search "coolant" or "coolant loss". This thread is about oil. After you search and read up on it, you should post a new thread, or slim chance on bringing up an old one that is more in depth but you need a little more help with.

EDIT: Just realized you started this thread.. I still stand by my comment as the two are not related, other than somebody let maintenance go.

 

[eohat]

I had a similar problem on my ’02 Silverado w/215k miles. The leak was fixed by replacing the oil pan gasket. The old gasket was leaking at the rear, which made it look like it might be the rear main seal. I stuck a telescopic inspection mirror in the bell housing along with a light and was able to rule out the rear seal being bad. You can also use an inexpensive USB inspection camera attached to your phone to look inside the bell housing too.

 

[adriver]

You can get those cameras for less than $10. Helps with a lot of things around the house too.

 

[LongbowFoSho]

I actually have a Harbor Freight snake camera. I'll shove that up there and look while I do the oil pan gasket.

 

[LongbowFoSho]

nm

 

[swathdiver]

Well, maybe it's time to yank the motor and put new rings and bearings and gaskets in it? Oil pressure supposed to be that high on those years? Maybe that 80 pound pressure blew out all those seals and gaskets?

 

[CountryBoy19]

If you're pulling the pan, you should probably do the problematic pick-up o-ring while in there. Cheap part, pain to replace bc you have to pull the pan, so do it while the pan is already off.

 

[Bill Hayes]

I had a 2007 Z71 that had a leaking rear main. Changed the rear main seal and the pan started leaking. Then I found the PCV valve is built in to the driver side valve cover. It was stopped up. Changed the valve cover and the oil leak stopped. Hook a hose to the fitting on the rear of the driver side valve cover. You should be able to blow through it. If it is stopped up, this will cause a leak.

 

[mattt]

There are 2 other possible problematic areas that I am aware of. First one is rear cover gasket. It's on the back side(trans end) of the block, and can leak independently of the rear main seal. Another one to check is the crank position sensor which is apparently above the starter.

I have an '04 Tahoe with 281k on it and I'm in the same predicament with oil leaks. Needless to say my undercarriage is "rust proofed" with all the oil spray from driving with an oil leak.

In regards to your coolant loss, you may have compromised head gaskets, or the dreaded and all too common Castech cracked head. Castech is the manufacturer of cylinder head castings for GM and they made junk head castings that crack with time. Once cracked, the coolant leaks into the oil and causes lots of problems. Plenty of online reading for Castech heads. For a temporary fix of coolant loss, you may consider Bars Leaks additive. I dropped a bottle in my 04 until I can find a replacement drop in engine, or come up with a plan of action to freshen up my existing 5.3.

I am at the point where I think the only way to take care of the multitude of problems that afflicts high mileage 5.3's is to remove the engine from the vehicle and address everything at once. Anyone found a way to effectively fix all the 5.3 issues without breaking the back and the bank attempting to do it in the Tahoe Suburban Silverado Sierra?

 

[mattt]

I had a 2007 Z71 that had a leaking rear main. Changed the rear main seal and the pan started leaking. Then I found the PCV valve is built in to the driver side valve cover. It was stopped up. Changed the valve cover and the oil leak stopped. Hook a hose to the fitting on the rear of the driver side valve cover. You should be able to blow through it. If it is stopped up, this will cause a leak.

I have checked that on mine. I can blow thru it, but not easily. I know that is a metered(choked down) orifice, but how much resistance should there be at the PCV when checking it by blowing thru it?

 

[HiHoeSilver]

I have checked that on mine. I can blow thru it, but not easily. I know that is a metered(choked down) orifice, but how much resistance should there be at the PCV when checking it by blowing thru it?

I have read about drilling it out larger. We did it to my buddies wifes enclave. It solved a milkshake intake issue.

 

[latvius]

As for the coolant leak mine was doing the same and it ended up being the heater core plastic connector. It only dripped when vehicle was running and dripped down on the coil pack then the exhaust manifold so nothing ended up on the driveway. Only way I found it was by observing it while vehicle was warmed up and running.