I discovered that the rear of my intake manifold was leaking oil down the back of the motor, so I pulled the intake and replaced the gaskets. I used Fel-Pro gaskets, along with copper gasket spray. The manifold was torqued down according to spec. I did it "by the book," as they say.

Now, my exhaust billows steam when the engine's running. It emptied about a cup of coolant within ten minutes. With the radiator cap removed, it'll bubble/spray coolant when I rev up the motor. There's no coolant in the oil.

The car surges now at idle, but it always surged a little bit. The car never idled perfectly smooth, but it was extremely close. A few years ago it was overheated well past 260 degrees, with no adverse affects (at the time).

Since I only touched the intake, logic tells me that I goofed the intake manifold installation. However, it's entirely possible that a head gasket could fail -- it would just be a coincidence. Is there a definite way to tell if it's the intake or the head gasket?

 

A head gasket is below the exhaust ports, so I don't know how coolant could get up there to burn off the exhaust. Do your heater hoses go over the exhaust manifold? Maybe they are leaking. Look at the end of the hoses that connect to the heater core. Thats right above the manifold and could be leaking.

 

Thanks for the response, Air_Adam. I should have clarified where, exactly, the steam is coming from. It's coming out of the tailpipes, so I know it's invovled in the combustion process. I just don't know if coolant is leaking into the intake charge via the intake manifold, or into the cylinder itself via the head gasket.

 

It's pretty near impossible for an intake gasket to leak combustion into the coolant but not the oil. Look at an intake gasket, find the exhaust and coolant ports, imagine how stuff could get out of one and into the other without either escaping onto the exterior of the engine or getting into the oil, and figure out for yourself how unlikely that would be.

I'd be inclined guess you need head gaskets.... or you have a cracked head. In either case, the heads need to come off and visit the machine shop. If you don't see a fornicated head gasket, then prepare to buy a head; and even if there is a bad gasket, get them pressure checked anyway, just for safety.

 

RB83L69, your logic makes perfect sense. I talked to a machine shop today, and they'll do a thorough check of the heads for $25 each.

When I checked the coolant bottle this morning, the waterline was about an inch lower than it was last night. I bet that overheating episode a few years ago finally caught up with me, via the head gasket.