Need help!

[blown69nova]

Here is my situation: I'm running a 383 sbc with 8:1 comp., TFS 195cc heads, forged bottom end, etc, etc. with a procharger d1sc making 15+ psi of boost.
I only have 500 or so miles on it, mostly tuning and working out bugs. I was having cooling problem running an electric fan so I put a mech. fan on it and now it runs between 160-200 deg. prob. solved.
I am using an Edelbrock Victor w/p that leaked water out of the rear plate on the pump above 3000 rpm or so last year. I replaced the gasket and it seems to be ok there.
My problem now is the gaskets between the block and the water pump are BLOWING out at high rpm! I replaced the gaskets the other day using RTV on both sides of the gaskets and they blew out again.
My block is a 1999 (vortech) out of a c3500 pickup. These blocks don't have the bypass hole drilled like older small blocks do, they use a hose to the intake like big blocks. I do have holes drilled in my t-stat and a heater core so I thought that would be enough of a bypass.
Could it be the heads lifting under boost? Would the w/p gaskets be the first things to blow anyway?
Any thoughts would be appreciated.
Thanks, Steve

[blown69nova]

Anyone have a thought?
Steve

[Carver67]

How hot did it get when you were having cooling issues?
Just thinking out loud here, but is it possible the mounting flanges on the pump are no longer true due to heat warpage(real word?).
Do you have access to a pressure tester to see what kind of pressure is in the cooling system? I suppose that would only work correctly when the t-stat is open but at least you'd know whether it's really a "pressure" problem or could move on and check other things.
Good Luck.
Mike

[dhardison]

Steve, Is it possible that you're somehow pressurizing the coolant system under high boost? Maybe pressure is blowing past the intake gaskets directly in to the coolant passsages (between intake and head).

When the car is idling do you see any air bubbles coming up through the radiator? How about when you rev the engine and the boost increases?

[HILROD]

Also look at the mounting bolts for the water pump. I once changed short block on a running combo. The later style block I used second had shallower mounting holes. The bolts bottomed out before applying enough force on the gaskets. I did get good at changing them though, before I found the cause. A couple of thick washers fixed it. FRANK

[blown69nova]

Thanks for the replies guys.
I ended up locating and drilling the standard bypass hole in my block into the water jacket and now I'm using a stock Delco iron pump. It runs a little warmer, but so far, no blown gaskets/leaks. I may try the Edelbrock pump again in the future, but for now, I'm happy to have a drivable car.
By the way, 15 psi boost at 5800 feels pretty cool!
Thanks again, Steve