Slight Overheating Causes and Tests

[Blanco]

Just back from a run down to Lot et Garonne to collect some of my workshop machinery that has been gathering dust for nearly 3 years. So loaded up the faithful Ifor Williams (weighed it at 3.5t) and loaded the car with wine (as you do), must have been pretty well up to the max permitted, and set off for Cherbourg and the ferry. No real problems on the run except that when presented with an incline the cruise control did its best to maintain progress and the box kicked down and the temperature went up sometimes into the red. I started to manage it by dropping out the cruise and slowing more, staying in the middle gears if possible, rather than rev the nuts out of it, but the red light came on briefly at one point even though I was down to about 20kmh. As soon as the hill was crested and the revs dropped the temperature went down very readily (happily). Weather and ambient temperatures were quite 'English' and not the cause.

Coolant is fresh and level stayed good. Just wondering about the best way to test the viscous fan and I'll set about flushing the rad I guess.... just wondered whether folks had any other good tips about what to look for please?

I know it was working hard but I have done much the same in warmer weather with a Td5, probably nearer 7t all up and the needle never moved, I think it should have handled it really. I will say that with the air suspension we were much more comfortable on the trip though!

[FridgeFreezer]

Think your idea of looking at the viscous fan is probably the best 1st step.

[Ally V8]

Two things, P38 diesel rads are not the best and many aftermarket ones are very poor in cooling effectiveness. Secondly, TD5 temp gauges do not move from the normal position unless the engine ecu sees it overheating.If you monitor the actual temp as seen by the engine ecu it will vary quite a bit,going up in stop start traffic and steep hills/heavy loads - but dropping off as speed /airflow increases.

[Blanco]

I thought that the Td5 gauge was curiously steady, that makes sense now, thanks.

 Well, just tested the fan by sticking a rolled up piece of card in the side (in my case the Stena ferry mirror card) and the b thing works perfectly, damn. Rad looks good too but may well be aftermarket.

As an aside I found the source of a funny noise I was getting when backing off the revs ........ so that's what a turbo waste gate sounds like!