Lower Intake Manifold Cracking....A Common Problem?

[radman3120]

Last summer I had a coolant problem on my 93 Z34 where the car would pour antifreeze at startup but stop once warm It turned out that my lower intake manifold was cracked and that its expansion once the car was warm was enough to seal the leak. I replaced the LIM with a junkyard one from either a '93 or '94.

It just started behaving exactly the same again!!!!! After one or two cold starts my low coolant light is on but once i get the car warm and refill it i can drive for hours with no problems. I havent heard of this but was it a common problem on these engines? Is there anything special i should do when i replace the LIM this time? Would it be worth it to spend the $300-$400 for a brand new one (the j/y one was $75)? Should i just throw in some aluma-seal and see what happens? Any input is appreciated. Thanks - Patrick

[SappySE107]

Check your gaskets and the heads. Id say something isn't flush and its putting stress on the lower intake. Where does it crack exactly? This is the first time ive heard of it cracking.

[radman3120]

I haven't had it apart for the 2nd time yet but here is a picture of where it was cracked the first time. The crack is by the coolant temp sensor. There is a weld mark where it was cracked b/c we thought about trying to weld it if we couldnt find a j/y part. The crack ran in the lengthwise direction.


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[series8217]

Mine is glued up right there. Probably cracked for the previous owner.
Blue Shift cracked that part trying to remove the quick connect fitting.
Probably pretty common..

[radman3120]

Everything around it looks good and flush so the only thing that would make sense for making it crack is the quik-connect. But i think we only have a hose coming off of that because the auto parts store was out of them when we installed the curent intake. IIRC it didnt come with a quik-connect on it and the one in my original intake would not come out. I havent gotten it apart to see if the new crack is in the same place or not (EDIT: from the dripping it looks to be the same place) because i have finals all week at school. I gues thats something i will have to do as soon as i get home.

Do you guys think this is a fluke or that it will keep happening?

Do you guys think i should just get another junkyard manifold or get a new one from GM? Would it be worth anything to port just the lower intake while i have it off and how hard is it to do?

[germ]

get a jy intake

dont use the thread tape and dont overtighten.

its happened to me on a 3100 lower before. now i just use a touch of grey rtv around the threads and tighten till its snug.