OK Guys,

My '99 Z34 has over 201,000 miles on it and I've never had the upper or lower intake manifolds removed! In the past when I would notice a slow loss of coolant in the recovery tank, I would throw in some Bars Leaks and the loss would stop. I've gotten away with this for over 15 years.

I know I'm living on borrowed time and I would like to replace all. I know the stock LIM and UIM are both plastic and I have found one LIM option that is aluminum but it is well over $400. Dorman claims they have a "re-designed" Lower (plastic) AND upper intake manifold that will eliminate the dreaded leaks. Of course the price is a lot lower (than the aluminum).

Also, what gaskets do you guys recommend for the installation?

 

The redesigned Dorman will eliminate warpage and prevent fatigue/failure of the manifold around the EGR. Both Felpro and McCord make metal gaskets that will eliminate the coolant leakage.

 

The LIM isn't plastic, it's aluminum. The UIM is plastic though and you're correct, they do tend to warp. The cheapest route to go would be to look for a Dorman UIM in a junkyard put that on your Monte. You can also do an aluminum UIM swap from a Series III 3800, but it takes a little bit of work to do.


And I also recommend the aluminum LIM gasket. It's much better then the factory gasket.

 

I replaced the UIM on my '03 Impala back when I had it with the Dorman plastic UIM. Worked just fine. IMO unless you have some specific reason to switch to aluminum (ie you want to polish it first, etc)- I'd just stick with plastic.

 

reuse your LIM and replace the LIM gaskets with revised aluminum gaskets. replace the UIM with a revised dorman one and replace the UIM gasket also.

all LIM are aluminum and dorman never made an aluminum LIM. only reason to need to convert to a aluminum UIM is if your running a crazy amount of boost from a turbo or you want to polish it.

 

Turbo, Thanks for that. For some reason I thought my original LIM was plastic.

Ok, I'll just reuse it and get a new Dorman UIM, recommended gaskets and I'll be good to go. Thanks all for your input.

Andy
'99 Z34

 

Felpro Gasket.

 

All I use is gm gaskets. People have used felpro and like them but I won't do it.

 

Thanks guys for all your info. I have a Dorman UIM and gasket kit coming from Rockauto. I've worked on my cars for a long time (I'm 57). From what I've seen on YouTube I think this job will go pretty smooth.

Andy
'99 Z34

 

Hey, I just thought of another question. Since new I've stuck with Dex-cool because, well, that's what the car came with. Do you guys use it or the old green stuff?