1988 K1500 Cooling Problems HELP

boxcarcop · 08-07-2005, 01:06 PM

I have a 1988 Chevy K1500 that has a problem cooling that I can't figure out. I had the water pump replaced by a mech. a few weeks ago and all was find for a couple of days. I noticed that the temp guage was going to about 215 before the thermostat would open so I replaced it myself. Again all was find for 2 days. The truck runs fine and cools fine when going down the road but when I stop at a red light the temp climbs to about 220-225. As soon as I start moving it goes back to normal (185 deg thermostat). I checked the fluid level and found it was low in the radiator and high in the overflow tank. It seems that the coolant is being pushed out of the radiator when the engine heats up but not sucked back in when the engine cools like it should. I just tried a new radiator cap but that didn't help. I really have no idea what to do next so any help would be good.

84ranger · 08-07-2005, 05:21 PM

When was the last time your coolant system was flushed out?

linuxmann · 08-07-2005, 07:51 PM

If it only overheats at a stop, it could be a fan issue. As far as the radiator being low and overflow not, sometimes they don't like to suck coolant back in from the resevoir. Cooling system problems are hard to diagnose because it could be so many things. If the water pump and thermostat are both new, the next step would be to check for head gasket failure. Is oil getting in the coolant/ coolant getting in the oil? Does it blow white smoke? Before all of that though, I would do a coolant flush. It might be a clog in the radiator, or even just an air bubble in the system somewhere.

Mulie1 · 08-09-2005, 12:43 PM

Take a look at your fan clutch and have your radiator boiled out and tested. If GM antifreeze got mixed with conventional antifreeze you will get a sludge buildup that won't come out with a regular garden hose type flush. Hope this helps... Mulie1

08-07-2005, 01:06 PM	#1
boxcarcop Junior Member Join Date: Aug 2005 Location: Atlanta, GA Posts: 1	1988 K1500 Cooling Problems HELP I have a 1988 Chevy K1500 that has a problem cooling that I can't figure out. I had the water pump replaced by a mech. a few weeks ago and all was find for a couple of days. I noticed that the temp guage was going to about 215 before the thermostat would open so I replaced it myself. Again all was find for 2 days. The truck runs fine and cools fine when going down the road but when I stop at a red light the temp climbs to about 220-225. As soon as I start moving it goes back to normal (185 deg thermostat). I checked the fluid level and found it was low in the radiator and high in the overflow tank. It seems that the coolant is being pushed out of the radiator when the engine heats up but not sucked back in when the engine cools like it should. I just tried a new radiator cap but that didn't help. I really have no idea what to do next so any help would be good.

08-09-2005, 12:43 PM	#4
Mulie1 Junior Member Join Date: Aug 2005 Posts: 2	K1500 Cooling Problems Take a look at your fan clutch and have your radiator boiled out and tested. If GM antifreeze got mixed with conventional antifreeze you will get a sludge buildup that won't come out with a regular garden hose type flush. Hope this helps... Mulie1

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08-07-2005, 05:21 PM	#2
84ranger Full Member Join Date: May 2005 Location: Florida Posts: 28	When was the last time your coolant system was flushed out?

08-07-2005, 07:51 PM	#3
linuxmann Full Member Join Date: Jul 2005 Posts: 17	If it only overheats at a stop, it could be a fan issue. As far as the radiator being low and overflow not, sometimes they don't like to suck coolant back in from the resevoir. Cooling system problems are hard to diagnose because it could be so many things. If the water pump and thermostat are both new, the next step would be to check for head gasket failure. Is oil getting in the coolant/ coolant getting in the oil? Does it blow white smoke? Before all of that though, I would do a coolant flush. It might be a clog in the radiator, or even just an air bubble in the system somewhere.