Hey my names Jon , I'm from New Jersey and I bought a 2002 gmc Sierra 2500hd duramax lb7 that was in Arizona it's whole life until now, it's been pretty cold out lately(5 - 40 degrees Fahrenheit) and my heat only works if my engine temp is 175-200(the highest I've ever seen the temp and I was going pretty fast down the highway) when I first bought the truck the engine temp wouldn't go above 140 and then I replaced both thermostats and made the engine reach 180-190 when cruising around. If my truck is on full blast heat when idling it will blow cold air and it will also blow cold air if the heat isn't turned all the way up ( even at operating temp going down the road). As soon as my truck starts idling after running 180-190 the engine temp will dip fast sometimes even all the way Down to 115 degrees. I also noticed that the switch for the lower/upper heat vents and defroster don't switch to how you want the heat to come out. Low coolant light comes on and goes away , need help figuring out the problem
Hey guys help needed lb 7 heat not working
- Thread starter Dirtytothemax
- Start date
No coolant is where it should be , the when I opened the cap to the tank it had a lot of pressure and it squirted some anti freeze out the overflow hose but it was just shut off after going for a. 30 minute drive
Doesn't matter. Unless its overheated you should be able to slowly remove your cap and just get a little bit of pressure out. Bubbles or puking coolant out are a sign your headgaskets are leaking compression into the cooling system. So is losing heat while idling.....
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Well how would I confirm that head gaskets are bad? And would the truck show any signs performance wise?
I used a tester comparable to this from my local napa store.
http://www.summitracing.com/parts/lil-75500?seid=srese1&gclid=CJu1hdHGp7wCFZTm7AodCk4A8w
http://www.summitracing.com/parts/lil-75500?seid=srese1&gclid=CJu1hdHGp7wCFZTm7AodCk4A8w
Hey checked the truck this morning I could squeeze the hose a little bit but not too much and when I opened the tank cap it had pressure in it and it shot a little antifreeze out the overflow
Check the temp going into you heater core see if the line is hot. with heater off the line coming out should be almost as hot. I had to Back flush my heater core cuz it was pluged. Took water hose and reversed flow threw it and all kinds of stuff came out. My buddy had a head gasket issue and put in some Blue Devil and has held for 100K on his work truck.
no you have a cup or headgasket issue sorry man... when you get it fixed I'd put head studs in it save the headache latter could do some screw in cups as well if you wanna make it bullet proof from this stuff but that's a lot more $$$ for screw in cups
So what do you mean by cups? This is my first diesel that I have owned so I'm a little familiar with diesels but not too much and how much do you think headgasket and studs would run me thank you for your help guys
The ARP head studs are around 600 and head gasket kits range from 200 to 600
"Cups" are injector cups. The injectors sit in these cups which seal off coolant, combustion pressure and oil. They can sometimes lift and allow pressure into the coolant.
Can a lifted cup allow oil into tue cylinder or combustion into the crankcase? Or just coolant only?
And would that injector be acting weird in a balance rate test or no?
And would that injector be acting weird in a balance rate test or no?
Only way it'd let oil in or combustion into the crankcase is if an injector was loose. And you'd most likely hear that. A lifted cup will cause a pressurized cooling system, coolant hydrolocking, or burning coolant way before it'll let oil into the combustion chamber or pressure into crankcase.
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