07 Tahoe/Oil leak in the front

[ukrkoz]

I have a strange oil leak
07 Tahoe, 5.3L, 4WD, 170K.
I know, the answer is - find out where it leaks from but, maybe there's some previous knowledge on this.
Tahoe will drip a silver dollar sized oil stain ONLY when sitting on the incline, nose up, and after drive. Leak is approximately where the front pulleys are.
There is NO DRIP when on level or on decline, nose down. I checked many times, parking on dry concrete in garage at work. Bone dry.
Visual inspection from the engine outside in the front does not show anything special, pretty much, normal oil dusting for the age and mileage.
I had it up on the lift for oil changes and other repairs and the only drips I can see are coming from the engine REAR. Few weeks ago I tracked it down to the bad valve cover gaskets and had them replaced.
I'll put contrast dye into oil next but, maybe someone already had something like this. Not really losing oil excessively, I may add maybe half a qrt in several thousand miles.
It's literally ONLY after drive and inclined. Not a drop when level or declined.

 

[B-train]

Is it following the air deflector or skid plate and dropping oil from a leaking oil cooler line? They have crimped fittings right in that area. Pull that piece down, or look from the top with a light. Maybe that's the culprit?

 

[ukrkoz]

I got dye into oil and PS fluid, just in case. I'll get it up on the lift tomorrow am, while it's still dark, and scope everything. Whatever I can see or shine light at from the top, is bone dry.

 

[ukrkoz]

OK, nothing. Which is good news per se. Front main seal is not leaking. Found no leaks on anything else in the front. Just regular dirty underbelly.
The ONLY fluid I found is about 1/4'' drop of coolant under the expansion canister, right about in the middle. Can't really get my hand under without removing air box. No signs of coolant leak there from the top. New cap. All coolant hoses dry and not swollen.
But that's it.
More so, it rained yesterday and, by about 4 o'clock, there was no sign left from the stain on the asphalt.
No idea. Coolant drip? Truck does slowly loose coolant. Slowly.

 

[B-train]

Weird. I think you'll have to give er some more run time and see I the dye shows you anything. Was there any witness marks on the pan, bolt heads, etc that could possibly lead you to a leak?

I wonder if you could drive it and then park it comically inclined on purpose right away to see if you can duplicate it easier and then track it down?

 

[ukrkoz]

So just came back from about 40 mile drive+30min idling, patching son's Tesla tire.
Said - dye is good, cardboard is better.
Had it under for about 30 min.
Nothing. Prestine.

To be honest, that's quite phenomenal for a car with 170K on it.

So can coolant leave an oil looking stain on wet asphalt - that will be, later, flushed with rain away? Coolant is oily. I mean - had 2 stains yesterday, no sign of them today. Delivery trucks don't go, where I park, my Tahoe is the only vehicle there.

 

[ukrkoz]

Found it.
So there are 2 leaks

1 in the front is coolant. Apparently, radiator is leaking, I could not get good look because of the fan shroud.

That wans of wires, if you go all the way to the right, as it's attached right underneath the shroud, has several wet spots like thios on it. Reason I know its coolant is I had dye in coolant before and it shines in UV light. Plus, it feels light to touch.

2nd leak is coming from the engine block somewhere above the oil filter.

Whatever the circled piece is - it seeps down along its side. My bet is head gasket, as I had valve cover gaskets done about 1.5 month ago and, engine had that side head removed to replace lifters and, in the process, they broke one of the bolts and had to pull the engine out to fix it. How well - who knows. So it trickles down along that side and onto the flywheel belly


I'll just prolly let it be. No big deal to add some coolant once a month or so, maybe a cup. Oil level does not drop significantly, I really don't even add oil between changes and I change about every 5K. Too much work for me. Maybe replace radiator, if I'll find mech reasonable enough. Maybe will DIY summer time. I'm coming out of COVID, it's no fun 3rd week in a row, no desire to mess with such job right now.

 

[Dustin Jackson]

Hey buddy that part above the oil filter is the oil cooler block off plate. It has a gasket that can leak so make sure that isn't the culprit.

Shame more work wasn't able to be done on the motor while it was out of the vehicle. Perfect time to reseal and gasket the motor.

 

[89Suburban]

They make an aftermarket billet plate with an oring that replaces that. I just put one on mine a few weeks ago.

 

[ukrkoz]

How hard is it to get to? I can get Tahoe up on the lift.