Thorneycroft T80 Overheating

[chrishscorp]

I have a chum who has a Thorneycroft T80 which is overheating, marine engineer has checked the intake, tube stack and pipes, the water pump was new last year as was the impellor. Tube stack has been taken out and cleaned, no impellor blades anywhere. Oil does not appear to have water in it.

Engine seems to run ok untill you rev her over 1900 revs then temperature starts to rise quickly.

Intention is to look at the new pump and the exhaust elbow tomorrow.....

Anyone with any experience of this engine had similar issues ? fingers crossed the hive mind can come up with some bright ideas

 

[PaulRainbow]

Check for a leaky head gasket.

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[penfold]

Was it running OK last year? Does the volume of water from the exhaust look the same as last year? Are the strainer and seacock clear? Is the water injection side of the exhaust elbow clear? Is the thermostat working?

 

[chrishscorp]

Thermostat is ok. volume of water looks ok but the boat was new to him last year, strainer and seacock clear.
Water injection side is being checked tomorrow

 

[QBhoy]

Hi. I’d check that the coolant tank pressure relief cap isn’t compromised. Allowing atmospheric conditions instead of being pressurised, of course.

 

[penfold]

Then we're into more complicated things; PR's possible head gasket failure or perhaps a coolant pump failure.

Thermostat is ok. volume of water looks ok but the boat was new to him last year, strainer and seacock clear.
Water injection side is being checked tomorrow

 

[chrishscorp]

Having heard from my chum late this morning it would appear they have found the problem, the brand new impellor that was fitted last year has all of two vanes still attached, either the wrong one was fitted or the old one put back in in error instead of the new one. Hopefully that is him sorted and its not the Head gasket.

 

[oldharry]

Having heard from my chum late this morning it would appear they have found the problem, the brand new impellor that was fitted last year has all of two vanes still attached, either the wrong one was fitted or the old one put back in in error instead of the new one. Hopefully that is him sorted and its not the Head gasket.

Where have the old vanes gone? OK if they are accounted for, but if not they are somewhere in the cooling system, and overheating will continue to be a problem. I lost just one vane, and found it fairly jamming up the thermostat.

 

[penfold]

Good chance they will be in the inlet plenum of the intercooler, unlikely to make it through the tube stack.

 

[chrishscorp]

Good chance they will be in the inlet plenum of the intercooler, unlikely to make it through the tube stack.

They had all of that out yesterday and no vanes or bits found so not sure where they have gone, but boat is back on her mooring under her own power so all good, thanks for all the suggestions.

 

[oldharry]

Good that they are up and running, but those bits must be somewhere. As Chrischorp says, they are unlikely to have got through the heat exchanger.