View Full Version : Calling all Engine Experts

04-04-2006, 08:03 PM
First off, this is regarding my Yukon's engine, but since it's the same block as in many of our MC's (and it's my tow vehicle) maybe I can get away with it??

The intake manifold gasket began leaking out the left front corner a couple months ago. Never lost that much coolant - a couple cups tops. Finally changed the gaskets this weekend. For giggles I pulled valve covers and was shocked by the difference in color between left and right banks. Being a "shade tree mechanic" I can't figure out what is causing this. I tried rubbing some of the color off with degreaser, but no go...seemed more like varnish than rust. Head gasket, intake gasket, whatever, you'd think it would be affect both sides. Any clues? Should I park it until I figure out what's causing this? Seems to run just fine. Thanks in advance for any help you can provide-

04-04-2006, 09:43 PM
just a thought, but was the wierd color on the side with the pcv valve on it? the vacuum could be sucking stuff into that side? if that is not it, then I got nothin....

04-04-2006, 10:16 PM
Thanks redmike - yes it is the side with the pvc valve. I guess another question is if that's what's causing it, will it eventually cause engine damage; or am I cool continuing to drive? Any way to fix/prevent?

04-05-2006, 03:47 AM
:twocents: if you had a water leak all of the water vapor would end up on that side.....not sure if I'm right, but from what you have said that is what I think, I wouldn't worry about a little discoloration if all else is good!

dog paw
04-05-2006, 11:10 AM
That is a sore point on that engine. 6 cyl's also. We do several a week. Like Mike said the PCV is drawing moisture out that side Thats not uncommon to see even if your intake had not failed. Man you shound see some of the snot buckets people keep running LOL! Anti freeze will make short work of main bearings :eek: Some of the older Vortecs had trouble with the heater outlet corroding away and leaking also. You might check yours. The replacements are stainless instead of the aluminium.

04-05-2006, 12:16 PM
Thanks for the replies redmike and dog paw. I'm not surprised there was someone on here that worked specifically on those motors. That's why I figured I'd wing it out there. Yeah, that is the 2nd set of intake gaskets I've put in it. Other than having to take off so much stuff, I don't mind spending a Saturday or Sunday doing it. I've heard that intake gaskets, fuel pumps, and alternators will give you problems on those engines...all of which I've replaced at least once. Other than that it's been a bullet-proof engine. Now has 185K miles on it. Sounds like as long as I keep the anti-freeze out of the crank bearings I'm OK. ;)