Just above the blue means over cooling least ways as far as the temperature sensor is concerned but the temperature in the block is likely not even.
As much as I hate to say it do a pressure test of the system with the car running both cold and and hot, need a special gauge to do it though. Test the system pressure does not increase with engine rpm and stay there, you also need to check the coolant for contamination from exhaust components.
Don't disregard anything no matter how basic, you have done everything else and done it right it would seem. To quote Sherlock Holmes "Eliminate all other factors, and the one which remains must be the truth"
A fairly simple test is to fill to the neck and look for bubbles although this isn't always going to work.
As much as I hate to say it do a pressure test of the system with the car running both cold and and hot, need a special gauge to do it though. Test the system pressure does not increase with engine rpm and stay there, you also need to check the coolant for contamination from exhaust components.
Don't disregard anything no matter how basic, you have done everything else and done it right it would seem. To quote Sherlock Holmes "Eliminate all other factors, and the one which remains must be the truth"
A fairly simple test is to fill to the neck and look for bubbles although this isn't always going to work.
"Just above the blue" was only when i had a wedged open thermostat - i would have expected this reading - what this confirmed was that i had circulation throughout with no blockages.
If the pressure was rising surely this would mean that pump was circulating coolant, if this was the case why does would it not open the thermostat as it passes through the thermostat top half.
Will do the top of the expansion tank test to see if there are bubbles - well at least until the pressure build up and coolant level rises
Pressure in the header tank should only rise with temperature no other reason, if you leave the cap off there should never be any pressure in the system and it will overheat eventually - verify that the 2 smaller pipes are in the correct locations on the thermostat housing.
Wiganerdan
New Member
Leaving the cowl off should not cause it to overheat, it does increase fan efficiency but it is as much a safety feature as anything. The diesel will run happily without fan or cowl unless in slow traffic.
That I will dispute based on years of experience. It was the biggest cause of overheating on Shadows as they tended to end up in the bin when the mounting studs rotted off the rad.
If i fill up the expansion vessel to the neck and turn engine on, after approx 7 minutes the water level rises and over flows -
I thought the same about the 2 smaller hoses on the top of the thermostat but they are different sizes and you struggle to get them the wrong way around - checked any way.
replaced pump a few weeks ago, thought that pump that i replaced may be faulty so bought an OEM pump.Def not pump.
new rad - when no thermostat it gets hot all over
dogsbody
Very senior member
I can state that it is true based on two years of driving a Rangie diesel without a fan cowl. In fact mine doesn't even overheat in slow / stationery traffic.
Wiganerdan
New Member
dogsbody
Very senior member
I'm with Clarkie on this. As a diesel driver I'm not even certain that the petrol radiator has a baffle but based on everything else I've read here the only difference seems to be that when you've got a stat in, reducing or stopping the flow, then the rad heats all over. Take the stat out and therefore have a permanent flow and your rad doesn't heat up. Definitely worth a good rad clean.
dogsbody
Very senior member
I'll agree to disagree with you.
You can't 'disagree' with a statement of fact.
- other way around:
stat in - no flow
stat out - good flow - rad heats up all over
tried 3 thermostats - last one OEM - all do the same
Wiganerdan
New Member
I'm not going to argue. I've mentioned something I know to be a fact on the vast majority of cars I've dealt with over the years working in the job I worked in hoping it may help someone with a problem. Admittedly it was a clutching at straws suggestion but a suggestion none the less.
I'm not here to create waves or arguments. I'm here because I own (Amongst other cars) an old P38 and there is a lot of useful info on here. In return I thought helping here and there with the knowledge I had gained over the years might be of some use.
zzr1200
Well-Known Member
The petrol rad doesn't have a baffle in the top tank, also the top half of the thermostat above the moving plate gets hot the bottom half of the housing housing stays stone cold. It would appear the thermostat plate isn't opening, even though it appears to be hot enough to open. I will have to test the temps.
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dogsbody
Very senior member
So your stat works in the kitchen but not on the car ?!?!?!
Datatek
Well-Known Member
I have taken the engine driven fan of every diesel car I've owned, the cooling is always better with the cowl removed as there is no restriction of airflow across the whole rad surface which means the electric fan rarely operates and when it does has to work less hard to control the temperature.
As I said, the cowl does improve the engine driven fan efficiency as it reduces fan blade tip losses. If Shadows overheat without the cowl in UK temperatures, then the cooling must be even more marginal than the P38.
