Technical 2007 Tranny engined XU250 MoHo.

[KeithWalden]

I've had to replace the pipe from expansion bottle to cyl head, no prob, little coolant loss, easy top up. Ran engine up, checked for leaks & air lock's, no prob's.
Went for a drive and temp guage went off the clock (both fans came on), no excessive pressure in coolant hose's then radiator sprung a leak.
New rad fitted (not used). refilled with new coolant, engine ran up and temp guage wen't off the clock again!!!!
No high pressure, no leak's.
Heater working OK but get this, radiator top hose cold bottom one warm.
WTF is going on?

 

[Crossingkeeper]

The standard reply to no water circulation is faulty thermostat or air lock; but this seems too easy after all the work you've done! (the heater take-off's are before thermostat)

You can check the operation of the thermostat by heating it in a saucepan or just trying the engine without it fitted.

 

[KeithWalden]

Thanks for the early morning contribution Crossingkeeper.
I've just been out and stared under the bonnet of this thing. Water level has settled a little overnight so I'm tempted to just give it another go before I dismantle anymore of this bugger.
Can you explain to me where exactly the thermostat is hiding on this thing? It is a plumbers nightmare in there!

 

[KeithWalden]

Well, I must say I'm very dissapointed in the response from you lot, thought it would have been an easy fix!
I won't bore you with all the details but it appears we have a duff temp sensor (which is going to be a PITA to get at). Hopefully that wil be the fix.

I'll let you know in due course.

 

[corcai]

I won't bore you with all the details but it appears we have a duff temp sensor (which is going to be a PITA to get at). Hopefully that wil be the fix.

Hopefully, but why did you have to replace the pipe to the expansion bottle in the first place if it was burst could be a sign of genuine oveheating.

 

[KeithWalden]

It hadn't burst, there was a lot of corrosion on the exterior. The change was made as a precaution (it is sited across the top of the engine and suffers from the well known water dripping from the bottom of the windscreen).

 

[KeithWalden]

Just in case anyone wants to know, the culprit was a cylinder head temperature sensor:devil:
PITA to get at and a 15mm deep socket had to be sacrificed. Happy days!

 

[jackwhoo]

How silly to make it so hard to replace