What's the definition of overheating?

[BarryS]

022Dave Thanks for the warning. I sort of guessed it might be

marshman That's a subtle check that I understand. Thanks for that.

flying farmer Thanks for that.

DJT Thanks for those pictures.

Thanks everyone else also for your very helpful suggestions. Much appreciated.

[BarryS]

Hi Folks,

Just an update on this:

Did a full backflush and the rust and discolouration was intense. 3 flushes to get it completely clear. Took off the drain plugs; totally blocked. Took ages to clear out all the rubbish.

Loaded up with Prestone flush and ran again until warm. Also cleared out the expansion tank which had large amounts of rust and sludge on the bottom.

Then did another backflush out through the drain plugs. This time LOTS of sand, lumps of rust etc. etc. Implies it may not have been done from new! Also, a lot of this had collected along the bottom of the radiator (which was new) and so had to flush through again via the bottom hose.

Also noticed a previous owner has stripped the threads on the thermostat housing (on the pump manifold). Had to re-tap these. Also noticed that the upper bolt had a blind hole and the lower bolt had gone through into the water jacket. I'm not sure if this was meant to be a blind hole originally (?), but it was clear there was air getting in and/or water getting out along the thread of this lower bolt. Once I'd retapped it larger and was using a bigger bolt this stopped happening.

Sealed everything up and used the main water pressure to test for leaks. Not sure if anyone has tried this but it works a treat. The expansion tank fires at around 20psi and so overflows, but the water pressure is greater than that (well here anyway) and this meant I found even more leaks on loose hoses and some bolts that needed retightening.

Filled with glycol mix and ran it until warm. Let it cool. Topped it up. Did this 3 times including a short drive to ensure ALL the air locks came out (they were there!).

Previously the top rad hose had been empty when I'd checked by inspection at the rad plug after cooling down. After, each time I checked the top hose it was completely full. I think this was the main propblem; water was leaving as steam/vapour and so the water level was going down without an obvious culprit.

The average position on the temperature guage now sits at about a third increasing to halfway on a hot day or when idling for long periods in traffic for a long time.

So far looks good.

Thanks again for all your suggestions. Next job is the Triump "Click" (new starter motor).

Rgds.

[Lingen]

Barry. Final line above. Are you sure? There are various other causes that are far simpler/cheaper to check out before lashing out on a new starter motor.
Mike.

[wilf]

A good clear out of the cooling system works wonders as you have found. Well done.

[richardthestag]

Next job is the Triump "Click" (new starter motor).

Find the boat shaped connector just above and rear of the starter motor. It is for the gearbox loom.

It will be full of crud

clean it, ideally with a contact cleaner and then reassemble.

If your car is fitted with a manual gearbox. cut the two white/red wires on the engine side of the connector - i.e. not the gearbox. and splice them together.

If automatic then the white/red wire needs to go via the gearbox inhibit switch which prevents your starting the car in gear or reverse

[DJT]

Good work Barry. I am sure this is the reason for most Stag 'overheating'.

[BarryS]

Find the boat shaped connector just above and rear of the starter motor. It is for the gearbox loom.

It will be full of crud

clean it, ideally with a contact cleaner and then reassemble.

If your car is fitted with a manual gearbox. cut the two white/red wires on the engine side of the connector - i.e. not the gearbox. and splice them together.

If automatic then the white/red wire needs to go via the gearbox inhibit switch which prevents your starting the car in gear or reverse

Thanks richardthestag/Lingen I had a look at this while I was underneath. The starter looks like its probably one of the only original parts on the car; almost everything else has been replaced, so I'd already bought one with a view to returning the original for refurb so just thought I'd go right in and replace.

Rgds.