Engine Coolant Puddles On Intake Manifold

[The Mindless Philosopher]

2001 Boss Hoss ZZ4 350:

Several times I have noticed small engine coolant puddles forming on top of my intake manifold, around the studs that attach to the upper engine mount plates. Coolant had also bled onto the front of the block and down the length of the cylinder heads to the rear of the block.

Thinking coolant was seeping up from the cylinder head water jackets and oozing past the threads on what I thought were loosening studs/bolts, I removed them and applied silicone sealer. The problem continued.

I had begun to wonder whether my intake manifold was warped or the gasket(s) damaged/worn.

After browsing the Internet and running across a few similar conversations, I decided to focus my search on the cylinder heads (L94 in my case). After finding photo's of the same heads, I removed one of the valve covers and peeked through one of the manufactured holes in the cylinder head wall that opens up into the lifter valley. I discovered the upper engine mount studs do not run through any water jackets, but instead hang in open space beneath the cylinder head/intake manifold mating surface, in the lifter valley. The studs on the rear of the engine mount (#9 and #11 on the front of the manifold, in a standard SBC 350 torque sequence) clear the pushrods on cylinders #1 and #2 by roughly 1/16 (.0625) inch (about 2mm), if not a hair more.

So...

Gooping up the bolts with sealant to stop coolant from bleeding up and out was a waste of time. Applying sealant to keep coolant from seeping down into the block would be a better idea, but still not really necessary. The puddling coolant was coming from some other high pressure source.

Upon re-installation of the engine mount studs and the valve cover, I started the engine, twisted the throttle a handful of times, and allowed the engine temperature to climb to about 200* F (93* C) at idle, then shut her down, waited a few minutes, and checked for leaks. Sure enough, the ooze was originating from the base of the water neck, and easing down each side of the manifold into the recessed areas that house the engine mount studs. Time to put a better seal around the base of the water neck.

[V8Bikers]

Good find! Are you talking about the thermostat housing? If so, are you going to try a new gasket and sealer or just a gasket? In my experience a gasket worked good unless there was some warpage.

[The Mindless Philosopher]

Yep. Exactly that. I had originally used the wafer-thin gasket that came with it (replacement thermostat housing). It apparently didn't do the trick. Using silicone gasket maker this time around.