Remember my Tahoe?

[Camino LS6]

It's been hibernating in the barn for a few months now due to a massive oil leak. I've been enjoying driving the wagon, so I haven't done anything about it until a few weeks ago.

I filled it up with oil and moved it over a clean part of the floor to try to locate the leak. Now I have run it and let it sit in the same spot for most of a month.

Guess what?

No freakin leak!

How the hell does that happen?

The entire font undercarriage is soaked with oil from when this happened, yet now it doesn't leak.

Have to get to the bottom of this.

[Robert Hall]

Interesting...any idea *where* the oil leak was coming from (oil pan gasket, front main seal, etc?).

I've seen something like this happen before..my '87 Mustang GT had a leak around the oil pan gasket when I had in Colorado, I had to add a quart every 2000 miles or so. But after moving it back to Ohio, no leak. I think it had to do w/ moving from a very dry climate to a damp one. But what you are seeing is stranger, as you haven't moved your Blazer.

[Camino LS6]

That's just it, I'm trying to find the source and fix it, but the whole underside is oil-covered. Now the damn thing won't leak so I can find the problem.

[Robert Hall]

That's just it, I'm trying to find the source and fix it, but the whole underside is oil-covered. Now the damn thing won't leak so I can find the problem.

Hmmm...maybe try cleaning off as much of the oil on the underside and then paint a light color on the suspension, bottom of the engine, etc and then let it run for a while or drive it some (is it drivable)? I did this to track down an oil leak w/ my Bronco years ago..sprayed the suspension, engine bottom, etc w/ gray primer.

[Camino LS6]

Not a bad thought.

I think I'll run it until it gets warm, and see if that get the leak going again.

I just don't see how a leak that big could just stop - very odd.

[daves87rs]

Give it a rough drive( Not too bad though!) and the leak will show itself.

[Camino LS6]

I think I'm going to go get some high-octane coffee and see if I can figure this out.

[daves87rs]

I think I'm going to go get some high-octane coffee and see if I can figure this out.

[NINETY EIGHT REGENCY]

That is really strange and odd. I hope you find the leak. There is a leak, but where?

[Blake Noble]

The Camaro did the same thing, actually. The leak wasn't as big as yours sounds, though.

I would try something similar to Moltar's suggestion. You could probably avoid using the paint, just wash the undercarriage off, drive it a bit, come back home and see where the oil leak could be coming from. Check all of the common suspect places like the drain plug, oil pan, valve covers, etc., first.

[Drew Dowdell]

coat the underside with gunk, hose off, repeat till clean.

The leak will show itself

[Camino LS6]

Drove it, checked it, drove it again, checked it again - nothing.

It refuses to leak.

I do have a theory of sorts though.

This was a Dexcool vehicle originally, and some of what seems to be oil might be Dexcool sputem. The radiator was recently replaced before I bought the truck, and I think one of the tanks may have been cracked during the install. Now, the engine oil cooler runs through that tank as well, so that may be part of the problem. Once it gets good and hot, I think the crack opens up and sprays coolant and/or oil all over the place. My short drives didn't reproduce the condition, but that's the only theory I have right now.

The truck has other, separate, issues that are related. The exhaust is often full of water vapor, so I think it may need intake gaskets. I have all but ruled out a head gasket problem.

So a cooling system overhaul may be in the cards, and while I'm at it I'll see what I can do about the mess the previous owner made of the HVAC system.

I'd love to pinpoint/reproduce the massive leak first though.

EDIT: That, and a good pressure washing.

Edited September 22, 2010 by Camino LS6

[A Horse With No Name]

Glad to hear your enjoying the wagon...and the deckscool thing sounds legit...

[daves87rs]

Glad to hear your enjoying the wagon...and the deckscool thing sounds legit...

True....

[caddycruiser]

Quote I grew up with, always scoffed at, and still heard frequently from dad until he got his Subaru..."GM's...they fix themselves."

Apparently so.

[Camino LS6]

Drove it again today - no drama.

But I still want to get to the bottom of the mystery.

[NOS2006]

Hmm, that's strange. I hate problems like that. I'm having the same problem with my Dodge, except electrical and not oil. It runs like $h!, wants to die... then suddenly when I want to test the voltage while it's dying out, it magically works. Jump on the road, and the fun starts all over again

[Camino LS6]

Yeah, chasing phantoms gets old fast.

[NOS2006]

Especially ongoing ones. Effin' sucks hard.

Think of the bright side... you at least have a backup vehicle when yours dies down. haha

[Camino LS6]

Absolutely!

I'd feel naked without at least one backup. I just can't exist without a car available at all times.