I have a friend with a 03 gmc, he serviced it this morning and said the top radiator hose was sucked shut, i thought i had seen this before but coulden't find it. does anyone know the cause of this. it is a duramax

He needs a new cap on the overflow tank. I hear the Autozone ones are best.

Jim

thanks for the reply jholly, i did finally find what i was searching for, it was hose collapsed not sucked in, the fix is what you suggest, new cap.

There was a thread about this a while ago, I can't find it. My top hose is collapsed most times I shut down and take a look. Is this normal? Do I need a new cap?

yeah mine does the same thing..a new cap on the overflow will fix that?

Yes, it will. That be fact.

mudbug