overharting lb7 2004 duramax
 

i have an overheating problem with my truck it had a leaking water pump so i changed it and ran it about twothousand miles before any trouble, i had to take my daughters to a rodeo,i was pulling a very steep grade and smeld antifreze but no smoke the temp dint go high or the trans temp high ,i made another fifty miles and the low coolant light came on so i pulled over and checked it looks like the new pump has started to leak around the bottom of the pump and it is makeing noise like a crank bearing ,i hauled it home to the shop and started diagnosis the coolingsystem is building pressure in it slowly there is no water in the oil it seeems to have more blowby with the oil cap off and it builds more pressue in the cooling system when i pump up the cooling system to 15 psi with the cooling system hand pump when it has no pressure pumped in it will make a negative vacume when you throttle up then on decel of the motor it sucks a vacume on the gauge any help i need this truck for work and transportation and hoped that someone has had to deal with this please help thanks

Re: overharting lb7 2004 duramax
 

Exhaust gases present in cooling system?

i cant smell any but i would guess that there are with the pressure tester gaining and sucking vacume at start up i havent seen one ever suck vacume then build presure there arent any leaks when i pump it up to 15 psi, but it builds really fast past the top end of the gauge when running it at 3000 rpm and 15 pounds pumped up in the colling system thanks for your help

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i think i can smell exhaust gasses in the oil fill tube my luck its probly a slipped sleeve hope not

Re: overharting lb7 2004 duramax
 

I would invest 60 bucks in a combustion leak detector. If so I would start with compression/leak down testing to verify location of leak. I really prefer compression then leak down on low cylinders. Considering it appears to be cooling system related I would bother with a wet compression

i have a compesson tester ill start there thankyou so much then ill post the results as to what that says thanks again