Question - not for the feint-hearted

Datatek · Oct 28, 2012

n18rks said:
correct - how do you do a flow test ?

With difficulty, old washing machine pump plumbed into stat and some very hot water

BenKenobi · Oct 28, 2012

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.

n18rks · Oct 28, 2012

BenKenobi said:
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.

"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

BenKenobi · Oct 28, 2012

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 · Oct 28, 2012

Datatek said:
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.

stemac33 · Oct 28, 2012

is the pump working correctly. only ask as i have fitted a new pump before and it turn out that when it got hot and the engine revved the shaft was spinning faster than the pump impellor

n18rks · Oct 28, 2012

BenKenobi said:
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.

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.

n18rks · Oct 28, 2012

stemac33 said:
is the pump working correctly. only ask as i have fitted a new pump before and it turn out that when it got hot and the engine revved the shaft was spinning faster than the pump impellor

replaced pump a few weeks ago, thought that pump that i replaced may be faulty so bought an OEM pump.Def not pump.

clarkie · Oct 28, 2012

sounds like the rads fooked to me have you done the marble test to see if the baffle is still there?? if no baffle the water just passes across the top and not through all of the rad.

n18rks · Oct 28, 2012

clarkie said:
sounds like the rads fooked to me have you done the marble test to see if the baffle is still there?? if no baffle the water just passes across the top and not through all of the rad.

new rad - when no thermostat it gets hot all over

dogsbody · Oct 28, 2012

Wiganerdan said:
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.

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 · Oct 28, 2012

dogsbody said:
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.

I'll agree to disagree with you.

dogsbody · Oct 28, 2012

clarkie said:
sounds like the rads fooked to me have you done the marble test to see if the baffle is still there?? if no baffle the water just passes across the top and not through all of the rad.

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 · Oct 28, 2012

Wiganerdan said:
I'll agree to disagree with you.

You can't 'disagree' with a statement of fact.

n18rks · Oct 28, 2012

dogsbody said:
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.

- 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 · Oct 28, 2012

dogsbody said:
You can't 'disagree' with a statement of fact.

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 · Oct 28, 2012

clarkie said:
sounds like the rads fooked to me have you done the marble test to see if the baffle is still there?? if no baffle the water just passes across the top and not through all of the rad.

dogsbody said:
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.

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.

dogsbody · Oct 28, 2012

n18rks said:
tested stat - all working ok - zzr1200 from this forum can round and we tested it together

So your stat works in the kitchen but not on the car ?!?!?!

n18rks · Oct 28, 2012

correct

Datatek · Oct 29, 2012

Wiganerdan said:
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.

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.

Question - not for the feint-hearted

Well-Known Member

New Member

New Member

New Member

New Member

Well-Known Member

New Member

New Member

Active Member

New Member

Very senior member

New Member

Very senior member

Very senior member

New Member

New Member

Well-Known Member

Very senior member

New Member

Well-Known Member

Similar threads