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P38 Cooling system presurising


mmd
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Hi,

New to this but hope you can help.

Bought a 97 4.6 p38 hse on which the head gasket promptly failed due to the o rings on heater leaking.

Heads tested/skimmed gaskets fitted new thermostat and new o rings. Since then the cooling system is building pressure and overheating. radiator removed and flow checked by Kendal Radiators, no bubbles etc in cooling system sniff test proves clear, no cleaned pistons/ plugs, runs absolutely fine.

Only thing i have found, is the rad bottom hose to stat remains cold and does not presurise, as does the bottom part of the stat housing, where as the top does get hot. The other thing is that the expansion bottle also appears to stay cold. Have tried changing new stat with old that did work, but same problem. Compression test fine. This engine has only covered 36k.

Did think of losing the stat until i realised the amount of pipes attached to the housing and that it cannot be split.

Willing to try anything, has me beaten.

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Thought I replied but it has disappeared into the ether:-)

A neighbour of one of my mates had same model and similar problem some years ago...from memory it was to do with the water pump, either the impeller came loose or fins came off or deteriorated, basically water wasn't circulating as it should.

He had a lot of "Experts" check it out, had both the block and radiator flushed, replaced radiator with a thicker core but it was the water pump that was the problem.

I can't ask him for specifics because he returned to the UK a couple of years ago.

Good luck I hope this helps.

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Thought I replied but it has disappeared into the ether:-)

A neighbour of one of my mates had same model and similar problem some years ago...from memory it was to do with the water pump, either the impeller came loose or fins came off or deteriorated, basically water wasn't circulating as it should.

He had a lot of "Experts" check it out, had both the block and radiator flushed, replaced radiator with a thicker core but it was the water pump that was the problem.

I can't ask him for specifics because he returned to the UK a couple of years ago.

Good luck I hope this helps.

Hi,

Was wondering that myself, just did not really want to throw more money at it when it could need a new engine fitting. Let you know what happens will give it a go.

cheers

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I'm guessing the truck is off the road anyway? In which case, you don't need to risk anything financially, just some work - remove the water pump and inspect it - if it's faulty order a new one (you've probably found the issue), if not you've eliminated another potential cause without spending money on it.

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  • 2 weeks later...

Hi,

So called experts, waste of time. Stripped the pump and replaced it, no great difference, decided nothing to lose so pressurised the whole engine thinking something has to give at some point and if the worst happens its a new engine anyway. Air started to circulate with the water eventually and i drained the system refilled and presto it works. Done 300 miles no problems so far, fingers crossed.

thanks

Thought I replied but it has disappeared into the ether:-)

A neighbour of one of my mates had same model and similar problem some years ago...from memory it was to do with the water pump, either the impeller came loose or fins came off or deteriorated, basically water wasn't circulating as it should.

He had a lot of "Experts" check it out, had both the block and radiator flushed, replaced radiator with a thicker core but it was the water pump that was the problem.

I can't ask him for specifics because he returned to the UK a couple of years ago.

Good luck I hope this helps.

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