3100 V6 Lower Intake Manifold

Hey guys, actually have two friends that have 3100's with blown lower intakes. Neither one of them are too smart with cars, and didn't realize the gaskets were blown and kept driving. Now both of them came to me complaining of a noisy motor pretty much within the same week. I listened to the cars and both seem to have a very noisy valvetrain clatter. I was just wondering if these motors are toast or if they can just get new gaskets and a fresh change of oil, and be OK. I guess I've never had a 3100 make so much noise so I'm a little apprehensive to do the LIM job for either of them for fear that the clatter wont go away, and I'll be sitting on a pissed off friend who refuses to pay me becuase the motor "Still makes noise!!!". What should I tell them?

The 3100 has pushrods which are not lined up with each other and are splayed to the side of the lifter. Hard to describe without seeing it, but they're not all lined up parallel and in the same plane as the L36 or GM 350 V8 designs.

I actually think the top of the gasket has round looped "keepers" or "guides" for the pushrods (that is integrated into the gasket)...so there may be some contact there if pieces have broken loose...IMHO possibly the source of the extra noise. Memory is kinda going fuzzy there on the details, though :)

A good manual would probably have a picture of the basic design of the gasket and the pushrod layout...unfortunately I don't have one.

Your right again crazyhorst! The pushrods dont line up parallal on the 3100. I've done a bunch of these 3100 LIM's before, just havn't had any make this much noise. I'm aware the 3100 makes a little valvetrain clatter on initial startup, but these cars are WAY beyond a little clatter due to the amount of coolant being pumped thorugh the motor instead of oil. I was wondering if the lifters are toast now (and possibly a rod bearing) as coolant/water is not meant to lubricate.

I see your point...the lifters could be gummed to the point where they didn't "pump up" appropriately because of the coolant contamination.

And that's what they are....a closely fitted device that pumps up quickly and leaks down slowly.

I also see the conundrum...personally I think I'd risk it and be reasonably confident the oil flow would clear out the gum, if I was working on my own vehicle. The penalty for being wrong of course would be to do the job twice, my own labor would be essentially free, though...but if doing this for a paying customer, they'd want it done once.

If they are good friends you could present them with the conundrum and have them make the decision, if they are not good friends, I'd replace all the lifters as a matter of doing the job correctly.