Expert cooling mystery.....

[anewshape]

hey there folks - any help on this one would be gratefully received - it's frickin' stumped me after hours of testing etc....

basically,

it seems the radiator part of the circuit isn't being involved

fitted new thermostat

coolant is forced out of the reservoir until dry

plenty of pressure in the system

heating works fine in the cab until running low in reservoir

temp guage fluctuates between 70 - 90 degrees

rad fan NEVER get's to kick in

pipes to radiator are pretty solid but only ever get warm (not HOT)


tried a coolant leak sealer but to no success - just foamed up and ejected from top of reservoir!

[risky1]

Have you checked Waterpump.....Maybe look for circulation in the header tank...
What do you mean by "it seems the radiator part of the circuit isn't being involved" do you mean the rad is'nt getting hot or doing its job..?
Ron.

[Scotcruz]

Originally Posted by anewshape

hey there folks - any help on this one would be gratefully received - it's frickin' stumped me after hours of testing etc....

basically,

it seems the radiator part of the circuit isn't being involved

fitted new thermostat

coolant is forced out of the reservoir until dry

plenty of pressure in the system

heating works fine in the cab until running low in reservoir

temp guage fluctuates between 70 - 90 degrees

rad fan NEVER get's to kick in

pipes to radiator are pretty solid but only ever get warm (not HOT)


tried a coolant leak sealer but to no success - just foamed up and ejected from top of reservoir!

Temperature Gauge Fluctuates - REPLACE temperature sensor (just under the thermostat)

Fans dont work - CHECK Resistor Coils, Check Continuity from ECU to Fan connector

good luck

[anewshape]

thanks for the replies -

when i say the radiator part doesn't seem to be involved i mean that although the thermostat is brand new and working there doesn't seem to be enough heat getting to it for it to open and thus allow cooling via the flow to the rad -

this would suggest that there is no/not enough flow for the hot water to heat it - meantime, the water is getting so hot it's boiling/forcing back up through the reservoir cap!

we removed a pipe below the large one that feeds the rad and turned the engine over and witnessed a good flow (presumably from the pump?)

i read somewhere earlier that a faulty reservoir cap can cause this to happen - i know i'm heading towards a head gasket failure but am quite perplexed by the different symptoms and obviously want to rule other things out first....

is there an easy way to test the pump?

[risky1]

It's very difficult to say weather the water pump has failed or not...You say it has a good flow...??.if the header tank cap is blowing out pressure/steam then it does look like there is compression from the cylinders leaking past either the head gasket or tru a crack within the head...A head gasket would be cheaper than a cracked head.....has it ever over heated...??
Ron.

[anewshape]

never over heated.

replaced cap today and it's still escaping from the top - it must be head gasket - there's no other explanation i can think of.

am tempted to try "Steel Seal" first - anyone got anything to say about this product?

thanks everyone for your help,

mark.