Know there are lots of threads on this subject but I found nothing specific to my problem. New build with 2500 miles on crate and new waterpump - running large electric fan with stock 36 radiator that has been cleaned - all worked fine for 2500 miles including running ac. Now she warms up to 180 and then blows out coolant thru overflow when themostat opens. Erupts like a geyser with cap off and blows out overflow reservor with cap on (tried 2 different pressures and just loosley covered). Thought I would pull and drill air hole thru thermostat next to see if I have a blocked air problem in block. If Not - Question - can a bad water pump cause this? I have to take off the whole frontend (I know - great design) to get to it and just want to make sure!! Thank You. Ed
A bad water pump could cause the overheating; is there any leakage around the pump shaft? Pretty rare, but I have had the impeller come loose on the shaft, so it doesn't move the water. Have you pressure tested the cooling system? Done a cylinder compression test(blown headgasket)? After the first overheating episode, did you install a new thermostat? Once they have been overheated they are suspect. Sometimes the wax will have been cooked out of them. Any air trapped in the system? Do you see any bubble is in the radiator?
My guess is the thermostat is not opening all the way But we need to know what kind of motor you have Please
Hopefully its the thermostat, but check out this cheap piece of crap water pump I had go out after a couple thousand miles. Replaced it with a pump with a cast impeller
No weeping on pump -Engine has never been over 220 on gauge - I am sure it gets a little warmer when I first shut it off. From above comments - I think I will drill thermostat and try again with no pressure cap tonight - if it bubbles immediatly and still overheats then I will check compression/plugs etc. - What do I look for to make sure I have a cast impeller on water pump? Meantime - I will check invoice for water pump. Thanks for all the advise - That is why this site is so KOOL. Ed
If your going to tear it apart just leave the thermostat out. Check water flow by looking in the radiator to see the fluid moving. This will tell you 2 things 1. if you have water flow and 2 if the thermostat was bad. Good Luck
This may not be your problem but on late model cars you have to bleed the water system - I do not know if your radiator is lower than the thermostat housing however on later model shitters we "burp" the baby so as to speak. Sometimes you get an air bubble caught in the system somewhere and when the engine heats up the air gets soo hot it boils the water and kapow you are in trouble - never had an issue with an old car where the radiator hose is higher than the thermostat housing however....................
X2 on this. The car should run and cool just fine without the thermostat for test purposes. If the problem goes away, install a new thermostat and re-test. Always look for the simplest solution first, especially if the car cooled properly before, and just started overheating "all-of-a-sudden". Good luck!
Thanks everyone -thermostat change cured so far on about a 15 min trip running AC (hot day) with a couple of thrashes -did not get over 180 til I shut it down and the thermostat controlled fan kicked on for a couple of min. Will take a longer drive later tonight. Lesson? So what was happening was at some temp the thermostat was trying to open with nothing but steam behind it - thus the blown coolant - right?
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