Temperature gauge and radiator fan not working

[cbeeson]

Confused! On my R reg diesel Bongo the temperature gauge has stopped reading. Also the tickover speed remains high and the radiator fan isn't coming on. Does the gauge run off the same sensor as the radiator fan? I've seen reference hereabouts to two different sensors. If they're both on the same sensor then I know what's probably gone wrong and will check the sensor; but if there are two separate sensors then what's likely to have happened.

I doubt this is relevant, but I've just fitted a Haydn coollant level alarm.

[Simon Jones]

Yes you do have one sensor for the gauge and one for the ECU that controls the fans. You can test the rad fans are working by switching the air con on while the engine is running. Typically, rad fans generally wont come on unless the engine has been idling for a long time or you've just come to a halt after long hill climb.

[cbeeson]

Simon, thanks for that. I've now checked the rad fans with the aircon, and they work ok. I can go on from there to check the temp gauge circuit and change the sensor if necessary. And then practice the mysteries of coolling system bleeding.

[Northern Bongolow]

the wire that is to the temp sensor goes from the alternator wiring loom area over the front edge of the rocker cover to the sensor which is on the front end of the head at the drivers side, this wire is a single and is very short in length so can get pulled or remove it to clean the connection and test again.

im nearby if you want a crash course in bleeding a bongo.

[cbeeson]

Thanks NB. I've installed a new sensor, having checked that the circuit was ok by earthing the connector. It's working fine now.
I bled the system, following the procedure in the workshop manual. However, since then I've watched the three-parter on YouTube and developed advanced paranoia! The coolant hasn't been changed since I bought the Bongo five years ago, so that's the next job, but for various reasons I'd rather entrust it to a garage - time, facilities, other priorities. There's a Fury-recommended garage near Garstang, or the garage that does the annual servicing, but I haven't asked if he knows about Bongo bleeding. But either way, how can I tell afterwards if the job's been done properly? If there's no sign of overheating, does that mean everything's ok? I've fitted a coolant level alarm, BTW.