Can anyone tell me why my cooling system is pulling a vaccum. I have just had my intake manifold gasket fixed and when I got it back the the guy my truck has been overheating and when I let it cool down the upper and lower hoses colapse and wont open up until I take the cap off and release pressure. I have dex-cool with all the problems as everyone else with the clay like build up and I removed the t-stat cause I thought it was clogged up but since removing the t-stat it still is doing the same thing. Help Please

 

Ok, I would replace your radiator cap as well as the hose from your radiator to the overflow tank. You may also want to pull the overflow tank and give it a thorough cleaning (I find that some simple green, 2-3 golf *****, and some shop rags make for a nice clean overflow bottle when done shaking it around for a bit.

It sounds like your cooling system is pushing out some coolant somewhere, but it is not being allowed to come back in. The radiator cap is supposed to keep 16psi of positive pressure in the cooling system while operating. This will allow coolant to flow out of the system to maintain the pressure at the set level. As the coolant cools down, it will contract, lowering the pressure. If coolant is not allowed to pass back through the rad cap, the system will act as described.

Now, the reason why I suggest cleaning out the overflow bottle, replacing the rad cap, and replacing the hose between the rad & bottle are because you said you had problems with contaminated Dexcool. It is possible that the rad cap is clogged up and possibly the overflow bottle connector hose, due to the contamination of the dexcool.

All of these repairs can be done for under $20. Have you had the cooling system flushed ot get rid of the contamination?

Good luck and keep us posted.

 

Well my dad and I bought the truck from my aunt last nov and we replaced the radiator upper and lower hoses heater hoses water pump t-stat and some pulleys but did not replace the radiator cap. When we did all this we ran water through all the holes in the block that we could find until the water ran clear but I guess that didnt help that much. I am going to try to do a flush tomorrow and clean the bottle as you described. Should I do the flush my self or take to a mechanic shop and let them do it.

 

Try and run some radiator flush stuff through it. And then replace cap and radiator hoses. I think Chevy made dex-cool really corrosive so that they can ensure repairs down the road if that makes sense to you. My lower intake gasket corroded away and I was burning antifreeze like no other. I switched to the green stuff and have no problems as of now. **knock on wood**

 

Magnum, please do not spin this thread off coarse with your distaste of Dexcool. We have a thread which pretty much lays out the entire dexcool issue already started. I will say that Dexcool in a properly sealed cooling system will last and will NOT 'corrode' anything. It is more likely that your failed intake manifold gasket caused air to be entered into the system and caused the corrosion. GM is VERY well known for their poor choice of intake manifold gasket material and design. And neither the use of dexcool or the problematic design of the intake manifold gaskets should be blamed on the thought that they were going to get the repairs in the future. That just doesn't make any kind of sense, business or otherwise. You would lose more new car customers than you would gain in repair charges.

Joe... When you flushed it, how much junk came out? A failed radiator cap could have been the reason for the contaminated Dexcool. A radiator cap is cheap $$$ and should be replaced as routine maintenance if you are in any doubt that it is functioning correctly. It should especially be changed if you are experiencing any cooling system problems. Once you replace the rad cap, you also have to check the tube from the overflow bottle to the radiator to make sure that coolant can flow through it when necessary.

 

Thanks for the reply and I was not trying to start up another dexcol problem post. when we cleaned it out some junk did come out and my dad ran it till it got clear. I took it today to have it flused at jiffy lube and will replace the rad cap today and check that bottle and tube. Thanks