Engine/Transmission (1994 - 1998) 96 12valve Cooling system problem in GMC Conversion

[RyanB]

I have had the truck up and going for sometime now and up untill last week I have been running with a modified thermostat that Haisleys put in when they built my engine. It started getting really cold here freezing to 40-50 degree's and I wanted to drive the truck for a few more weeks before I put it away to break in the engine a bit more so I put in a thermostate. It was great and warmed up nice and things were going good!



This morning I popped the hood right when I started it and noticed right away that the upper-rad hose had colapsed on its self and once the thermostate opened it was like normal.



Does anyone have any idea's whats going on? the temperature never gets above 90 and sits around 75-85(celcius) and fluctuates just like my brothers 97 does.



one thing that I should say and not sure if this is the problem but... my engine is missing the little hose/valve going from the head and bypassing the stat and goes into the housing... not sure if thats needed but have heard its only an air bleed and doesn't operate when the engine isn't running.



Hopefully someone can help me out on this.



RyanB

 

[KAlder]

probably the radiator cap. i doubt it is hurting anything. some caps have a little brass valve below the rubber sealing ring that stick. sometimes they stick open and you lose coolant. just a thought.

 

[DonFitzwater]

I'm with kalder, probably the radiator cap.

 

[KingS]

the little hose you are missing get it put on. I'm possitive that this is why the hose is collapsing not enough flow and the system when the thermastat cycles it isn't getting enough flow so it sucks every thing out of the hose and can't pull no more so walla you problem.