P38 2.5 diesel engine overheating

feyniriel · Jun 7, 2024

Hi, the engine in question is 2.5dse (m51 BMW engine)
I have been driving my Rangy in Finland without problems. This summer we came to Romania, a mountainous area with temperatures frequently around 30C and the engine is overheating even while just driving on a straight road, especially in the cities. We do use a lot of A/C, but turn it off and turn the heat up when it overheats and it cools down quickly. Driving up a mountain, we have to take breaks to cool down the engine every 300 meters. We recently changed the oil to 10W40. The car has green coolant, that's what people use in Finland, but I heard in Romania everyone uses red coolant, is there a specific coolant that this engine should use? It does not lose coolant. Thermostat opens and closes.
Thanks!

brianp38dse · Jun 7, 2024

Does the viscous fan make a roaring noise if not the fan has gone ,just because it's turning dose not mean it is locking up and turning at the correct speed, ther is a test with engine up to temp try stopping the fan with a rolled up news paper if it shreds the paper it's good if it stops it fan is no good

Datatek · Jun 7, 2024

As above, viscous fan has failed, common problem which is why I use electric cooling.

feyniriel · Jun 8, 2024

brianp38dse said:
Does the viscous fan make a roaring noise if not the fan has gone ,just because it's turning dose not mean it is locking up and turning at the correct speed, ther is a test with engine up to temp try stopping the fan with a rolled up news paper if it shreds the paper it's good if it stops it fan is no good

We did try stopping the fan with some rolled up paper while the engine was hot, couldn't quite make it stop but it slowed down considerably. Upon removing the paper it remained slow, seemed as if it was trying to catch up speed.

Datatek · Jun 8, 2024

feyniriel said:
We did try stopping the fan with some rolled up paper while the engine was hot, couldn't quite make it stop but it slowed down considerably. Upon removing the paper it remained slow, seemed as if it was trying to catch up speed.

It's knackered. Either replace it or do my aircon fans mod to use electric cooling.

Grrrrrr · Jun 8, 2024

feyniriel said:
Hi, the engine in question is 2.5dse (m51 BMW engine)
I have been driving my Rangy in Finland without problems. This summer we came to Romania, a mountainous area with temperatures frequently around 30C and the engine is overheating even while just driving on a straight road, especially in the cities. We do use a lot of A/C, but turn it off and turn the heat up when it overheats and it cools down quickly. Driving up a mountain, we have to take breaks to cool down the engine every 300 meters. We recently changed the oil to 10W40. The car has green coolant, that's what people use in Finland, but I heard in Romania everyone uses red coolant, is there a specific coolant that this engine should use? It does not lose coolant. Thermostat opens and closes.
Thanks!

Colour of coolant doesn't matter so much as what is in it. The two different types don't mix so you don't want to mix them up.

It has an aluminium head so that has to be protected.

feyniriel · Jun 28, 2024

So whilst ordering a new fan they sent us a V8 fan instead... The blades are different but it seems to fit otherwise, will the V8 fan fit on a diesel or should I send it back?

Datatek · Jun 28, 2024

feyniriel said:
So whilst ordering a new fan they sent us a V8 fan instead... The blades are different but it seems to fit otherwise, will the V8 fan fit on a diesel or should I send it back?

Send it back, the V8 fan rotates in th opposite direction to the diesel if I remember correctly.

feyniriel · Jun 28, 2024

The guy said it was a fan from a BMW with the same engine, not a V8 after all.. they look pretty different to me though (P38 above, BMW below). Went on a drive to test it out and while idling for 5+ minutes with A/C high in the sun, the temperature gauge started climbing up. Upon revving a bit it quickly went down. I suppose the fan isn't good? Haven't had the chance to test it on mountainous roads yet.

Mark Piercy · Jun 28, 2024

If the temps are climbing don't test on the mountains, you'll boil it. Which fan is the new one

If in doubt of the fan change it for a new one. It's far cheaper than a cracked cylinder head!!!
The fan should roar on start up and then free off after a minute or two. If it doesn't roar on start up it's buggered.

pwood999 · Jun 28, 2024

Pitch looks similar, so surely the extra blades on the P38 fan will pull more air through the rad ?

Datatek · Jun 28, 2024

feyniriel said:
The guy said it was a fan from a BMW with the same engine, not a V8 after all.. they look pretty different to me though (P38 above, BMW below). Went on a drive to test it out and while idling for 5+ minutes with A/C high in the sun, the temperature gauge started climbing up. Upon revving a bit it quickly went down. I suppose the fan isn't good? Haven't had the chance to test it on mountainous roads yet.
View attachment 320323

The lower fan is no good, half the number of blades

pwood999 · Jun 28, 2024

Datatek said:
Send it back, the V8 fan rotates in th opposite direction to the diesel if I remember correctly.

Exactly plus the P38 fans have RH thread compared to EDC LH. Blades have different orientation, so fan needs to go the other way to pull air in.

Keith, why not PM him the AC Fan mod just in case.

feyniriel · Jun 30, 2024

The blades do have the same orientation. Today whilst driving up a mountain for half an hour with the A/C blasting, it didn't overheat. So it seems to work for now.

P38 2.5 diesel engine overheating

feyniriel

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brianp38dse

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Datatek

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feyniriel

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Datatek

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Grrrrrr

Technician, Bodgit & Scarper Ltd

feyniriel

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Datatek

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feyniriel

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Mark Piercy

Well fumbled member....

pwood999

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Datatek

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pwood999

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feyniriel

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