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2002 Chevy Full Size Van Overheating, No Heat


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wub
New User

Jul 11, 2012, 10:31 AM

Post #1 of 5 (1947 views)
2002 Chevy Full Size Van Overheating, No Heat Sign In

Hello all,

I am trying to help a friend diagnose an overheating problem.

2002 Chevy Full Size Van (I think it's a 1-ton, but could be 3/4 ton)
5.7 Liter Engine

The van has been overheating. It takes a long time to reach the yellow on the temperature gauge, but eventually it pegs out. The heater only blows cold air. We've replaced the radiator and t-stat. We flushed the system really well.

I removed the heater hoses going to the vacuum controlled valve ahead of the heater core and confirmed that water can flow through the valve in both positions (I'm assuming one position bypasses the heater core and the other allows fluid to flow through).

I did a pressure test of the coolant system. I pumped it up to about 16psi, and it held that pressure for about 5 minutes. After 5 minutes the pressure slowly dropped to about 14psi and then maintained (maybe this is a problem??).

I also used that block test kit to check for combustion gasses or whatever in the coolant system. This tested normal as well.

Any advice will be greatly appreciated.
Thanks!


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jul 11, 2012, 11:07 AM

Post #2 of 5 (1929 views)
Re: 2002 Chevy Full Size Van Overheating, No Heat Sign In

?No heat is a clue that it is too low on coolant or boiling -perhaps some other reason but with overheating those are most common reason IMO.

Fans working for radiator? If a clutch type is it pulling air thru well?

If radiator is real weak hosing it down with water would probably cool it to normal and if so poor radiator itself, lack of airflow high on the list of things. Pretty tough engine but nothing likes overheating!

T



wub
New User

Jul 11, 2012, 12:07 PM

Post #3 of 5 (1915 views)
Re: 2002 Chevy Full Size Van Overheating, No Heat Sign In

Thank you for the reply. Yeah, I was thinking airflow too, but the clutch seems to be working fine. I don't know the proper way to check it, though, and I guess it could also be intermittently failing, as I'm not able to identify an exact patter for it to overheat. Sometimes it does, sometimes it doesn't. No heat is the only consistent symptom.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jul 11, 2012, 12:50 PM

Post #4 of 5 (1906 views)
Re: 2002 Chevy Full Size Van Overheating, No Heat Sign In

Fan clutch: Shouldn't have much of any forward and back free play. When hot air flows thru radiator it should tighten up to pull more air and you would notice if someone shut the engine off it should stop rapidly not just coast away.

With upper radiator hot to touch system is flowing and hot air (don't lose a hand over this) should be felt blowing off of radiator. If other things like a real thermostat that just won't open there wouldn't be hot air being blown off radiator and it would run too hot to extremes. I find that on the rare side but possible.

Other is water pump just can't pump well enough. Not so common and usually would begin with running warmer at lower RPMs and also would throw little at heater.

Without being there I'd guess the radiator itself is the most likely just being plugged up and wont flush out. Some (quick when engine off) you can feel cool spots on fan side.

Excessive bugs or dirt on A/C condenser or perhaps junk in between that isn't easy to see.

Just those off the top of my head for now and if all checks out and still runs warmer that normal or hot shut it down and let's find the cause as this isn't doing it any favors,

T



Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jul 11, 2012, 6:05 PM

Post #5 of 5 (1886 views)
Re: 2002 Chevy Full Size Van Overheating, No Heat Sign In

Are the heater hoses even hot at engine operating temp or just luke warm?





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