engine doesn't get hot

[mlc240z]

Nasty idea, don't even know if it's mechanically possible but.......

a crack or hole internally in the engine which is allowing coolant to bypass the thermostat?

Allowing constant flow of coolant even with a closed thermo?

[ozconnection]

How old is your water pump?

I've seen old ones where the vanes have eroded away from not using proper engine coolant and the water pump dies a slow death. Remember it's the coolant that carries the heat away from the head and block to the radiator and a faulty pump might be the problem.

[ozconnection]

Nasty idea, don't even know if it's mechanically possible but.......

a crack or hole internally in the engine which is allowing coolant to bypass the thermostat?

Allowing constant flow of coolant even with a closed thermo?

FYI, not all the coolant goes directly through the thermostat in some models of Datsuns. In later models, Nissan put in a bypass line from the thermostat housing to the inlet side of the front cover just before the water pump.

This setup was designed to lower the pressure of the coolant in the block so that excessive pressure wasn't forced through the engine before the thermostat cracked open. An example is pulling straight onto the freeway, accelerating up to speed, using revs to do so and with the engine cold and thermostat still closed.

[yetterben]

Oz makes a good point i pulled my pump during my rebuild and saw the steel veins where being eaten away. Since have switched to the ld28 cast pump.

[Frankensteinz2]

all better, it was 2 faulty thermostats, 1 from MSA, 1 from O'reily's, went to autozone today and bought a 192 degree thermo, put it in and let her idle for a bit, thermostat reads straight up and down, i got a gun and the bottom of the thermo housing reads 180 at running temp

thanks for everyones help, don't buy cheap ish

on to the next thing to fix on the old girl

Frankie

[EScanlon]

How old is your water pump?

I've seen old ones where the vanes have eroded away from not using proper engine coolant and the water pump dies a slow death. Remember it's the coolant that carries the heat away from the head and block to the radiator and a faulty pump might be the problem.

Oz makes a good point i pulled my pump during my rebuild and saw the steel veins where being eaten away. Since have switched to the ld28 cast pump.

Wouldn't the eroded vanes result in an engine OVER-heating and not UNDER heating which is what his original (now resolved) complaint was?

2¢

E

[geezer]

Wouldn't the eroded vanes result in an engine OVER-heating and not UNDER heating which is what his original (now resolved) complaint was?

2¢

E

Glad the problem is solved.

When I read Oz's post I took it to mean, it would cause the engine to run hotter with damaged vanes in the water pump but because the coolant wouldn't be circulating, the coolant could possibly be trapped, not moving and much cooler at the temp sensor, thus giving the lower temperature reading at the gauge, when in reality, the engine is running hot. I thought to myself... hmmn, that could be a possibility.

Edited June 26, 2010 by geezer