Thread: LIM cracked?

I had leaking intake gaskets when I bought the car as he said it was overheating and that he had replaced the water pump but that it didn't fix it. I replaced the radiator, installed a new thermostat (since it didn't have one) new radiator hoses, GM intake gaskets and a new SC gasket along with new valve cover gaskets. All of the surfaces were cleaned properly and torqued to spec. But... while trying to purge the air out of the system, I keep getting a surge of air in the coolant. If I rev up the engine I can see it forcing the coolant into the overflow bottle. Not to mention I still don't have any heat. Also I get fluid in the pocket in the LIM closest to the thermostat. I inspected the LIM when it was off but I'm starting to think that it has a crack and the forced induction it forcing air into the coolant. That or the gaskets aren't sealing it off. Any one have any ideas? This thing is killing me! I just want to get it running properly so I can sell it.

1997 GTP w/ bone stock L67. The SC has been rebuilt by the previous owner but not ported.

I've got a cylinder pressure gauge. What else do I need? I should also add that it doesn't leak coolant into the oil, and it doesn't burn coolant either. It just builds serious pressure in the cooling system.

Oh boy. I was hoping for anything but that.

But I am still confused as to how a head gasket would allow fluid to leak out on top of the LIM. It appears to be either coming out one of the bolts or through a hair line crack. Because the water bubbles like a leaky tire but I can't tell exactly where they are coming from.

I've tried a different cap on the radiator. With the hood popped and looking at the overflow bottle, if I rev up the engine you can see a surge of water come rushing into the overflow bottle. It's like turning on a faucet.

Ponder all you want Bill! That's the nice thing about having two of these cars side by side in the driveway. I can steal parts from one to test small issues on the other. I might add that when I bought the car, there was evidence (orange residue) all over the overflow bottle by the intake and where it was coming out the radiator cap. The original overflow bottle's diptube was down in the tank so it couldn't recover coolant. I installed the later version on the strut mount so I could install a CAI if I wanted to so it looks to have had this problem a while.

Ordered all the parts to do change the head gaskets this weekend. I just hope it stops raining by then.

My car overheated one time because of my lim gasket and I cracked a head lol, that was fun. Replace lim and head gaskets and see what happens just dont reuse the head bolts

I bought ARP bolts for the rockers when I changed the lifters so I only need new head bolts. The only thing that seems like it will suck are the exhaust manifolds. Any advice on getting them off the heads?

OK. Update time. I took it all apart down to the block. Both head gaskets appeared to be fine but the brand new GM intake gasket had a tear in one of the water ports. The car now has the following "NEW" parts...

radiator, water pump, 180 Deg. thermostat, radiator hoses, coolant elbow, head gaskets, intake gaskets, SC gasket w/ o-rings, radiator cap and updated coolant bottle. I inspected everything while it was off looking for cracks of any kind and found nothing but that intake gasket. Also what is the best way to get ALL of the air out of the system? It ran for like 5 minutes, the temp gauge never moved, there was NO heat coming from the vents and the bleeder screw on the thermostat was open and pouring water out and I wasn't getting any air. It acts like it's not able to circulate water or push the air to the top. Do I need to take the heater core hoses off and pre-fill them with coolant? After it cooled down for a few minutes, I opened the radiator cap slowly and a huge rush of coolant was forced into the overflow bottle from the built up pressure. I imagine, it's trapped air getting hot and expanding therefore building pressure with no where to go. Also while the car was torn down I forced clean water through the block and heater core and they flow free. Any help would be great. I'm starting to hate these damn things.

Thanks for the help Scottydoggs! I got all of the air out that way and it is finally running cool. Now on to the next issue with this thing.