tom5170

93 silverado with 250,000 miles


replaced the thermostat and water pump when I first bought truck a few months ago. The engine would overheat and the upper radiator would be cold. Replaced thermostat and it stayed cool. The coolant temp gauge would go to about a quarter hot.

A few days ago I noticed the gauge was at half way and then another day it was a little past full... and then it cooled down right back to about a quarter again. Today, I drove about 3 blocks to get a pizza and then drove to mcdonalds right up the street. The temp gauge was 3/4's almost to red when I was sitting at the drive through and then when I pulled out to go get my pizza, the gauge went down a little more but then it went down to half. Then after I got the pizza and drove home, the gauge needle went to red and I immediately shut off the truck. Both upper and lower radiator hoses were hot and I could hear bubbling in the upper hose. There is more than enough coolant in the resevoir. What could it be? I almost thought that maybe it isnt sucking up the coolant into the radiator from the resevoir and maybe there isnt enough coolant in the radiator. I havent looked yet because its too hot to open the radiator cap. I thought it was because it was hotter weather now. But I dont think thats the case. Its only 67 degrees out right now.

maxxman04

bad thermostat, clogged system, faulty water pump (even new parts fail quick sometimes) internal water leak. check the oil condition for a milky like coloring, check radiator coolant for brownish/black tint.

s34n

when you replaced the water pump, did you burp the cooling
system?

tom5170

My oil looks normal. I burped the system after I changed the thermostat.

I opened up the radiator cap today and the coolant in the radiator was low so I added coolant to the top. It took almost half a gallon. The truck now cools down. I notice that the coolant resevoir always stays the same level like the coolant in the resevoir never moves. The resevoir cap is loose and sometimes it pops up. Could that be it? Or could my radiator cap be bad?

LARIDERS

have you checked all the lines going into the resevoir to make sure there was not and junk in there or a block from build up?

Flying Low

Sounds like it might be trying to tell you your eating too much fast food or it could be low on coolant due to a small leak that is keeping it from sucking the coolant from the tank.