Wednesday, November 23, 2016

GMT400: 5.7 Vortec Intake Gasket Failure

It's gone now, but a few weeks ago I picked up a 98 GMC Yukon for a couple hundred bucks that was draining it's coolant into the oil. Figured what the heck, it's cheap enough - I'll do a quick top end rebuild and have a 4x4 to drive around in snow.

Well it wasn't the head gaskets, but the notorious plastic intake gasket failure that caused the milky oil. 227k miles on what seem to be original gaskets and terrible coolant.

The rest of the gasket that's far away from the coolant passages maintained it's integrity, but everything that was in relative contact with coolant, turned into mush. Haven't seen any pictures of this on the web, so here they are.

This is where these 5.7 Vortec motors have problems with intake gaskets.  

Can see where the gasket broke and had water seeping into the oil galley. Felpro makes a metal/rubber gasket set for these that is essentially invincible. Torque everything to spec and you have a bulletproof 5.7 Vortec.

Truck didn't overheat, no bubbling coolant, etc. So I was confident it wasn't a head gasket. Put everything together and no more coolant loss. Life is good.

Then I sold the truck. lol


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