So I have a very intermittant upper hose collapse on my 93 k2500, and subsequent temperature spike. I know this is thirdgen, but this forum has the talent.

This has occured since I put on vortec heads 906 from boat, gmpp dual plane high rise square bore, and other necessary mods. I have not done any modifications to the cooling system with the exception of the heads. I have bled the system since the install, and in the past the same parts work fine. I have tried a new t-stat just in case it got messed up during the install but the problem is still there. I don't have any reason to believe that it is the headgaskets; plugs look good, no coolant in the oil etc. The radiator is only a few months old, so I don't suspect that being an issue. I have confirmed that my heater hoses are routed correct.

Finally today I pulled the t-stat to drive it home and it ran cool 100f. So it looks like I have plenty of cooling capacity.

The only things I have left, that I know of from a diag standpoint are a pressure test on the cap and the system.

Anyone have any ideas? Is it the head and intake combo?

 

Solved. After some research and a trip to home depot for a 1/2 npt 3/8 barb and a 3/8 npt 3/8 barb and a 3/8 hose I installed a bypass hose to the top of my tbi water pump.

I found somewhere that you are supposed to run a bypass with an aftermarket intake on a vortec block. This can be achieved by drilling holes in the t stat or running a hose from the front of the inbtake to the pump. Well holes in the t stat didn't let me get to temp so I tried a bypass hosem worked great up to temp fast and stable as can be. Lesson learned try to find the instructions for any used afternarket part you buy even if you think you know all about it.

 

Yeah you have to run a bypass.
I am a little surprized a 3/8'' hose bypass works so well, because I have never seen a bypass hose that size on any thing larger than a 50hp diesel engine.