When it is overheating, stop the engine and feel the radiator all over for cold spots, if it is not the same temp all over it is probably blocked and will need either unblocking or replacing. Look at the fins on the radiator, are they clogged or are they corroded and powdery? if so then they will not be able to take the heat away from the cooling tubes. A blocked air con rad will also reduce the airflow to the radiator, possibly causing overheat. In my experience the aircon fans always come on instantly the aircon is switched on. If they are not, then the aircon may not be working for any number of reasons, most commonly low gas. Get somebody to switch the aircon on when you are looking under the bonnet, you should be able to hear a click when the motor (aircon motor) engages and the engine speed should slow momentarily
 
spadgr - the ac work well no real probs, prob could do with a regas at sometime in the future AC Fans do not however come on when AC is switched on - the compressor does kick in and the cabin has fine cold air circulating so i take it that the Ac is working just not the Condensor Fans!!!!
 
Thef ans only work when they need to - i.e. Air con on and coolant temp too damn hot - unlikley in the UK :)
 
ok now really ****ed off tried everything - drove around town for over an hour car fully warmed up AC on no probs! Max 30mph but lots of traffic
Took her along the dual carriageway at 60mph with AC on, within a couple of mins car over heats!!!!!!!!!!!!!!! Turn AC off and heater on, car runs at normal temp no matter what speed and for how long????
IS IT ME?????
I have now run out of ideas
I have also spoken to my local RR Dealership, who have done a lot of heavey breathing and tutting and have told me that the heating system in a P38 is not that simple and would need a full diagnostic test - oh yeh!!!! They also couldn't or rather wouldn't tell me how to test the temp sensors but with my limited school boy electronics and a Multimeter I am sure its not Rocket Science! After all some div put my car together in Coventry didn't they???????
 
rrmonty said:
ok now really ****ed off tried everything - drove around town for over an hour car fully warmed up AC on no probs! Max 30mph but lots of traffic
Took her along the dual carriageway at 60mph with AC on, within a couple of mins car over heats!!!!!!!!!!!!!!! Turn AC off and heater on, car runs at normal temp no matter what speed and for how long????
IS IT ME?????
I have now run out of ideas
I have also spoken to my local RR Dealership, who have done a lot of heavey breathing and tutting and have told me that the heating system in a P38 is not that simple and would need a full diagnostic test - oh yeh!!!! They also couldn't or rather wouldn't tell me how to test the temp sensors but with my limited school boy electronics and a Multimeter I am sure its not Rocket Science! After all some div put my car together in Coventry didn't they???????
Click to expand...
no mate some div put your car together in solihull ,and that div just may of been ME:D
 
Thought that might happen!!!!! if i give you the VIN number could you get me the name of the Div and I can personnally thank him or her for the years of hell not to mention the £'s I've spent on a car, that if it had been built by the Nips then I would still be driving, not pulling my hair out on a car which I am told is full of so many COMMON FAULTS (standard response at the dealerships) - designed over 40 years ago!!!!!
 
you either have insufficient cooling, or an electrical problem. The fact that it runs ok at low speeds and only overheats at higher speeds indicates a coolant flow or airflow problem. If it was electrical, it probably wouldn't matter what speed you were travelling at. Airflow is simple to check, just look to see if there are any restrictions to airflow through the radiator or corroded fins in the radiator. Coolant flow could be any number of things ie thermostat not opening fully, water pump fins corroded or damaged, slipping fan belt, or blocked radiator. I am unsure of the type of cooling fan that is fitted to a petrol model, but if it is the viscous type then when the vehicle is hot, pop the bonnet and with the engine switched off spin the fan. If it spins freely like a bike wheel then it is w##*ed and needs replacing. I have a p38 diesel and it has an electrical problem intermittently where the temp gauge fluctuates between warm and red hot when the vehicle is idling. The first time i noticed it i shat myself, made a right mess of the seats, but i noticed that if i turn the heater up or pressed the brake pedal that the temp gauge also went up likewise turn the heater down and the temp went down, indicating an earth problem. Have a play around and make sure that your problem is not similar.
 
I have checked the Viscous Fan when car is at working (norm) temp. the fan turns without too much friction but stops when I stop turning it - is the fan ok or does it need replacing????
 
rrmonty said:
I have checked the Viscous Fan when car is at working (norm) temp. the fan turns without too much friction but stops when I stop turning it - is the fan ok or does it need replacing????
Click to expand...

The viscous fan should not be neccesary ar 60mph, the airflow should be sufficient.
 
spadgr said:
When it is overheating, stop the engine and feel the radiator all over for cold spots, if it is not the same temp all over it is probably blocked and will need either unblocking or replacing. Look at the fins on the radiator, are they clogged or are they corroded and powdery? if so then they will not be able to take the heat away from the cooling tubes. A blocked air con rad will also reduce the airflow to the radiator, possibly causing overheat. In my experience the aircon fans always come on instantly the aircon is switched on. If they are not, then the aircon may not be working for any number of reasons, most commonly low gas. Get somebody to switch the aircon on when you are looking under the bonnet, you should be able to hear a click when the motor (aircon motor) engages and the engine speed should slow momentarily
Click to expand...

The aircon fans almost never operate on the diesel on European spec cars. Yours is either a different spec or has been modified.
 
Look at the design..the aircon condenser is in front of the engine radiator, so the cool air hits the aircon condenser first and that has first bite of the cherry. After the air has passed through the condenser, it's warmed up and then hits the engine radiator. Common sense tells you that you need ambient air temperature to efficiently maximise the cooling process...what is mor important, having a cold cabin or preventing engine overheating??
The condenser fans are unlikely to cut in given the UK climate as the condenser is cooled sufficiently by the air, assisted by the viscous fan passing over it. The Engine radiator however is not so fortunate, it relies on the viscous fan to do everything. On petrol models the condenser fans are linked to the engine temperature sensors but they will not cut in until the the temperature gauge has almost reached the upper dead stop.
 
Ok Guys, here is the update - I have decided to change the H20 Rad but at the same time I am going to change the AC Condensor Rad too - what do you guys think re the degassing of the system - should I do it myself (what is the procedure) or is it best to get someone in the know do to the job, and lastly what should a degass and regass cost me?
 
rrmonty said:
Ok Guys, here is the update - I have decided to change the H20 Rad but at the same time I am going to change the AC Condensor Rad too - what do you guys think re the degassing of the system - should I do it myself (what is the procedure) or is it best to get someone in the know do to the job, and lastly what should a degass and regass cost me?
Click to expand...

Unless you own a vacuum pump to evacuate the system before refill you can't do it yourself. Well you can but don't expect it to last long. About £50.00
 
The latest update!!!
I have decided to buy a new Radiator & Condensor - £86 & £62 - not too bad!!!
The AC man is coming next week to Degass (FOC) and then at the end of the week to Regass (£49)- again not too bad me thinks!!
Does anyone have any tips on removing both Rads, I am sure there is an easyway and a hardway, I seem to only find the latter first!!! Any tips would be much appreciated
Thanks again for all you help
 
replace all the pipes to the rad whilst its out. They may have sprung a small leak or letting in air. Main stealers not too bad on these.
Have you taken the bottom hose off the rad and flushed from the top to clear any crapola out, and to see what the flow rates like
 
Hi Guys
Its about time you had an update.
I have now replaced the H2O rad - a bit of a pain in the arse but got it out and a new one fitted in less than a couple of hours (not bad as I've never done it before!!!)
The old one was completely knackered I am going to get my 11 year old to take a pic and upload it for you to see, 'cos as you can imagine if I do it then we'll be still waiting at christmas.
Anyway the car is back to it's old best (for the rest of the weekend!!!!) no doubts I'll be filling some sort of problem again soon!!!
Anyway I really want to thank you all for your help, comments and of course your patience it has really been appreciated - all the best
 
The fans behind the grill are the air con fans, they will come on to aid engine cooling. they cannot be relied on to cool the engine, the main fan is a big plastic one attached to the water pump. Have you tried, as suggested by j the range, the viscous coupling on this engine driven fan? It sounds like the fan is cooling around town, but is not speeding up when at high speed.
 
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