P38 Coolant - confused.com...!
- Thread starter P38 Monkey
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Only one thermostat for the p38 as far as i know.
The aircon fans are triggered for extra cooling, but only when the temp is already too high 108-110c
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- 31,478
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- North Shropshire
Leading the ac on helps cooling but also keeps the interior electrics dry
P38 Monkey
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Good solution - and I will feel a lot less guilty about leaving the a/c on!
Datatek
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- 43,990
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Only on the V8 and later diesels.
Datatek
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- 43,990
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The aircon should always be on in the P38 especially in winter, it stops damp causing corrosion in the connectors
P38 Monkey
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That sounds typical JLR - like the "only one solution" tyre pressures - f28 r38 all loads, all speeds, all terrain, all everything. From now to the end of the world (OK, it's not that far away, probably).
Datatek
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Thermostats that open at different temperatures that fit the P38 are available, but running an engine below it's optimum temperature is not good for the engine or the fuel consumption.
P38 Monkey
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Agreed. I think the main thing is that when it does open (starting at 88C I believe) cooling needs to be max effective. No dodgy viscous couplings. Those couplings degrade over time presumably, and no real way of checking them. And from what has previously been said, the temp gauge does not appear to be any use in telling you there's a problem until the liners drop into the sump...??
Datatek
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The P38 viscous fan is a poor design and a regular failure item, that's why I dispensed with it on both my diesels. I reckon it's responsible for more engine failures on both the diesel and V8 than any other single item.
Using the aicon fans alone is not sufficient for the V8 but I now have an additional mod for another fan to be fitted.
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i think.. *think* the 'choke'/cold running map is switched off at around 70-75 so running 80+ is fine, though emissions may still be worse than design.
They only run so hot for emissions purposes.
The stock map is less than optimal
Datatek
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Optimum running temperature affects fuel consumption and the production of corrosive elements in the exhaust. The L322 runs at 105C as you say for emissions, anything less than 95C is not good.
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Agree. No idea about emissions, but running cooler didn't seem to affect the mpg of my p38 to a noticeable degree, was always 18-21 depending on journey type. Running hot means less co2 and more no2? Something like that
P38 Monkey
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Thinking of fitting an electric fan anyway - anyone got an opinion on the Revotec kit?
You can follow on nano
Personally I have never removed the bleed hose on mine and never had any probs. As already mentioned milk the top hose and get the blled hose "weeing back into the reservoir at decent revs. Monkey, I think the prob on your procedure is "taking car that the level does not drop below Low" which you mention when running it. You also need to make sure the reservoir is levelled when cold, and before you replace the cap, else you will not have the correct air gap.
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I noticed if the level was even a bit low it would ruin hotter than normal
Datatek
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You don't need a kit, just a 16" fan and my aircon fans mod.
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- Buckinghamshire, UK. ('95 DT)
The AC fans don't come on for my age of diesel but people trigger them with a little kit for when the temperature goes over 96C.
It wouldn't surprise me if earlier cars had a stat that opened earlier. Later cars tend to run at higher temperatures for emissions targets.
P38 Monkey
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Many thanks, as ever, for all the useful advice.
The great thing is that the above suggestions are based on experience and evidence, not just opinions.
My policy with my Japanese import P38 4.0SE is that I replace (within reason) items that are critical even though they might be OK, continuing on a known firm base, so to speak.
My 90k miles car has an extensive service history, but all in hand-written Kanji on meaningless little diagrams. Very pretty, but totally impenetrable.
So on that basis I plan to replace the fan viscous coupling, and I note that Febi Bilstein make one. Although more expensive, it lacks Britpart's Russian roulette feature....
The great thing is that the above suggestions are based on experience and evidence, not just opinions.
My policy with my Japanese import P38 4.0SE is that I replace (within reason) items that are critical even though they might be OK, continuing on a known firm base, so to speak.
My 90k miles car has an extensive service history, but all in hand-written Kanji on meaningless little diagrams. Very pretty, but totally impenetrable.
So on that basis I plan to replace the fan viscous coupling, and I note that Febi Bilstein make one. Although more expensive, it lacks Britpart's Russian roulette feature....
