rockin95

i had a new water pump put on about a month ago, today my engine overheated. im wondering why.

- my hoze from the engine block to the top of the radiator is hot, so the thermostat is opening.
- fan is functional and is running
- coolant was a bit low, no external leaks, no puddles on the ground or moisture on the block.
- engine has been pinging/ knocking, but not really running rough, ive been trying to correct that

is there any way the coolant could be leaking inside the block, possibly from one of the heads?

maybe this would explain the low coolant and the engine pinging?

i havent had any noticible loss of power and there is no smoke coming out of the tailpipes.

any help is greatly appreciated,
thanks,
matt

HATCHEDIN87

If you suspect a head gasket go to a parts store and rent a compression tester and check the compression at each cylinder. Compare the numbers to the manufactures specs. Also while you are there rent a pressure tester. Pump some pressure into the radiator and see if you have any leak down. This could tell you if you have a leak some where in the cooling system. I went through the entire cooling system on my 89 and the last thing I replaced(radiator) was the culprit.

Chopper

Make sure the pressure cap hasn't failed.If i'ts just starting to go it will only leak when the engine is under load and the leak won't show up as a puddle.If you haven't driven the car very much since the waterpump change you could still have air in the system and this will cause overheating.

rockin95

driven the car quite a bit since the water pump was replaced

the overheating only happens after the car has been sitting for more than 10-12 hours. this is what happens

after starting up, the water temp needle will remain on C for about 5 minutes (dosent warm up gradually). all of a sudden it will spike, sometimes going all the way to hot, and sometimes just topping out the normal range. it will then go back down and stay at normal and run properly. the temperature spike will occurr at a random time, not having anything to do with accellerating or idiling or anything.

02StanGT

I wouldn't rule out something really being wrong. Have you tried changing the coolant temperature sensor? Also is your coolant constantly low?

rockin95

i am going to try to replace the sending unit tomorrow.

i have noticed that the fluid was a bit low, and im praying there is no internal leak.

is this a tough job? im guessing its not too bad

ShadowDrake

If replacing the sending unit doesn't help, your thermostat may be sticking and the coolant may not be flowing, which would explain the sudden, large jump in temperature at your dash... if it all of a sudden pops to wide open, a rush of very hot coolant will flow over the sensor making it read extremely high, and as the coolant circulates, it gradually gets back down to normal temperature.

This could also explain why it happens if your car has been sitting... The thermostat has had enough time to resettle and stick closed again. If this keeps up, I can put money on it that it isn't good for your engine block.

Had a similiar problem like this in our 87 Bronco, except it wouldn't unstick... engine overheated and coolant started blowing out of everywhere... Happened right after leaving a Ford stealership because the alternator went bad. Had to get towed back and have them fix that too.

rockin95

thanks for the tip, i thought about that too, and i might pick up a thermostat right away.