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Discussion Starter #1
Hi does anyone know of a hotter rated stat for our cars.
the standard is 88c. I’m looking for around 95c.
 

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Discussion Starter #5
Basically the car never got hot. It ran warm but never up to temp.
the gauge would just about get off the blue mark -the heater was non existent and driving with ya coat on just was not fun.
yes I confirmed engine temp at stat housing -the best I got was 50c after a 40 mile drive at motorway speeds 70+mph but all hoses were Luke warm at best
I tried various stats and yes bought an ORIGINAL from flying spares which was worse then some others I tried.
found the BMW 92c stat. It’s 2mm smaller in dia but comes with a rubber ring that takes the gap up and bingo.
the engine now sits in the middle of the gauge I have a heater and now the engine gets up to temp she runs better.
 

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Thanks for the explanation Blue, underheating is an unusual problem when the correct thermostat is fitted and working properly but your solution seems to have cured it. Happy motoring.
 

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Don't know what is an "original" from F/S.
I strongly suggest to get a real original with original spec, for all cars and above all Turbo.

Upgarading calorstat temperature just means it will open later, so some parts of the engine might be too hot. Sensor is just measuring the temperature where it is located, so not necessarly at the hotest point.

I never had this isssue on several RR & Bentley, and here it can be very cold or very warm.

You probably have another issue, either the visocus fan does not disengage enough, either the heating valve does not open enough, either the calorstat you have are not original ones or have defects, either heating radiator is stuck inside, either something else... Do not forget to replace coolant with a premium coolant every 3 years.

Original recommandation was UE36600, then after many years, recently they replaced by PG58252PA .
The last one has no lead fuse which is much better, it is in a different material so no more galvanic corrosion, it is also not known for failure such as stuck open or close.
PG58252PA is suppposed to be the best compromise for those engines.
 

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Given that the engine gets up to temperature and that the heater works well with the hotter opening thermostat I suspect that the root of the problem might be the radiator fan, either the viscous fan sticking on or electric fan cutting in before the engine reaches optimum temperature.
 

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We don't know which car / year is concerned, but sensors could be involved too if they give a wrong temperature information.
In any case, putting a hootter thermostat does not solve the original issue but increase the risk to damage the engine.
Much better studying and searching why the engine seems cold and why there is not enough heating.
 

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Discussion Starter #12
Hi car is a 92 Eight.
so to answer a few questions..

An original from F/s. Is the stat you talk about. It’s original spec PG58252PA
Fitted New heater tap.
fitted new viscous
fitted new radiator
fitted new fan sensor-although original was working at spec.
back flushed engine AND heater inc removing block plugs
coolant changed with original spec from F/S.
Never took reading of temp from just one point. Took several temp readings including at various locations on the block itself
 

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OK, you did a good and complete job
Have you check temp with an infrared device in several point ?
Keep the thermosat from F/S and indeed check it in hot water to make sure it opens and close.

Have you replace the main radiator or the heating radiator ?
You need to make sure when you put temp max on the dashboard, the infomation is going from the ECU to all components, including heater tap

You may have also some air in the system.

You may have to test the complete A/C system with this kind of tool to make sure the electronic side/ ECU.... is perfectly working:

Giving high level anti pain seems to solve the problem, in fact it does not, it just hide it and make it bigger.
This is why you should digg and consider your issue is not solved, but just hidden behing a hotter thermostat which put the engine in danger.
Even if your car has no turbo, you do not need hot point which can damage headgasket....
 

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Discussion Starter #14
Hi Jean.
I changed BOTH heater and main radiators
yes the correct information it’s being relayed to the hot tap ( I did try temp bypass just in case while investigating)
im an A/c tech so yes confirmed that it was working properly
I fill my cars using vacuum system to insure no air
also yes I use a gun to check the temp I also have special temp sensors that you attach at various points …both sides of block -at front middle and rear of heads if need be - hoses …both rads etc to confirm heat points.
no no turbo on mine …and its Only running at 89c and that’s even across the block so quite happy /relaxed regards engine temp.
 

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You did a a large and great job.

So the guilty might be the new calorstat from F/S ?
Maybe an aftermarket from medium quality ?
Or a guenine one with a factory defect ?
I suppose you put it the right way up and down ?

As you are an A/C expert, we might not be able to help you !
 

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Discussion Starter #16
Ha ha. Yes I put it the right way around.
see o did think about the F/S stat but when I acquired the car it had this heating fault and the stat was the first thing I could think of but the original stat fitted was working perfectly that’s when I started trying different stats. Ending up with the BMW one now fitted.
been working with A/C for the best part of 15yrs now. Started on aircraft now do cars.
 

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Could it be the temperature sensor inside the car which give a wrong temperature information to the A/C ECU ?
 

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Discussion Starter #18
Hi. No. As I said ALL hoses on the car were warm at the touch. Not one of them was hot even after 30+motorway miles.
the car just was not getting up to temp.
I did disable the A/C in an attempt to see if the A/C was pulling all the heat from the engine via the heater circuit
 

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Shows your radiator is doing a very good job of pulling heat. Was it replaced in recent memory? BTW the cooling system is known to trend toward the cool end of the range.
 
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