No heat, help
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Freshman User
Joined: Sep 2011
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From: Williamsburg
No heat, help
My friend has an 08 4.6. He has replaced the thermostat with 3 different ones all with different temps, still nothing. Temp gauge reads normal but after driving it for a bit he can take off the radiator cap while it's running and not get sprayed in the face with coolant, almost like there is no pressure in the system. Any thoughts or idea would help. Plus it would shut up a Chevy guy that says just junk it lol. Thanks in advance for the help.
Fleet Mechanic
Joined: Jan 2007
Posts: 1,293
Likes: 18
An '08 has a radiator cap? Do you mean the surge tank cap? Yes, if you take that (or a radiator cap) loose on a hot engine, you will be severely burned by the forceful expulsion of hot coolant. If that doesn't happen, its running cold. If it gets to normal temp but the cap is not holding pressure, coolant will overflow because there's no pressure to resist it. I'm a little stumped at the moment as to what's going on. Let me think about it.
Thread Starter
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Freshman User
Joined: Sep 2011
Posts: 36
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From: Williamsburg
yes i mean the surge tank. wasn't sure what it had cuz on my 95 i have an actual radiator cap. anyway he says that there is no pressure there, that he can take it off right after he gets done driving it but he says he's not losing any coolant
Fleet Mechanic
Joined: Jan 2007
Posts: 1,293
Likes: 18
So, the engine is not running hot, the thermostat has been replaced, gauge shows normal, there is no heat in the heater, it is not losing coolant and there is no pressure in the system. Tell me - how does he know its not losing coolant? By looking at the surge tank level? That is not definitive. If there is a leak in the system, no pressure will develop, so the fluid does not expand into the surge tank. When it cools off, there is no vacuum to draw it back into the system, so the surge tank level stays the same. What he has to do is loosen the upper radiator hose on a cold engine and see if coolant is still up that high in the radiator. All you have to do is look at the surge tank level cold every so often and then when its hot, to verify that the fluid is expanding and contracting. This verifies a tight system.
My best guess; There is a pressure/vacuum leak and enough coolant has been lost that the heater core is high and dry, hence no heat in the cab. Sooner or later the truck is going to run hot.
My best guess; There is a pressure/vacuum leak and enough coolant has been lost that the heater core is high and dry, hence no heat in the cab. Sooner or later the truck is going to run hot.
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