Diesel P38 UNDER-heating

dean68uk said:

I had this problem. The stat opens ok but is slow to close.

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Please accept my apologies for dismissing your suggestion so quickly. I'll now admit that I was prejudiced when I found that there was a BMW stat in the engine and it consists of roughly twice as much metal in the operating bits as the after market one that I had bought. Both passed the boiling water test.

HOWEVER - with SWMBO still in bed I've been playing. I've got one of her cooking pots full of water on the stove with two stats strung from the extractor fan and her jam making thermometer. What I've found is that both stats open at almost the same temperature but the old BMW one is a lot slower to close.

So whilst I'm still convinced that my fan has seen better days I will also be replacing the stat. Thank you

Sean said:

ave read some crappy advice on here over the years but holding onto the fan and having the engine turned over wins the stupid advise of the decade award by a long long way

someone of your apparent experience should be ashamed of yourself for making that suggestion wammers

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It's the experience that enables me to do it that way. As i said it's not the way to go IF you don't know what your doing. Fortunatly for me i do.

dogsbody said:

Sorry WAMMERS but I've been out this morning to see if I've made a balls-up of this but I stand by my saying that you cannot get the fan out without taking the cowl off and on my Rangie it's a one piece cowl that's clipped under the bottom of the rad so there is no way to lift it.

So, the only choice I had was to move the rad forward to clear the fan so the oil cooler had to be moved.

Before I rebuild I think that I'll be taking 'P38on22s' advice and modifying the bottom of the cowl.

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You cannot get the fan out without removing the cowl. You cannot get the cowl out without removing the fan. But you can if you remove them both at the same time.

Houston, we have heat.

With a replacement stat (what a nice, simple job that is on this engine) and the viscous fan on the floor in the garage the temperature gauge is rising nicely.

Took my time re-filling her, 5 litres of Halford's finest then filtered water, and had no problems with air locks etc. Ran it on the driveway for 30 minutes and the gauge rose slightly. Been for a blast now and it's sitting steady at about 11 o'clock. AND THE HEATER WORKS!! Oh, and for the first time this winter the bonnet de-iced itself.

So it looks like a viscous fan running permanently can keep a 2.5 litre diesel lump so cold that it hardly registers on the gauge.

dogsbody said:

2000 P38 2.5 Diesel

I've owned this for just under a year and the temperature gauge has only ever got out of the cold section when pulling up a long hill. It's not the gauge or the sender because the heater doesn't put out much heat either.

I'd always assumed that it was either a faulty or missing stat and, with all the posts on here about overheating and cracked heads I was in no hurry to sort it out.

Today I've gone for it and got the stat out. It's stamped 'Made in Germany' and, using the boiling water test, it's working pefectly!!

However on my way through I found that the viscous fan wasn't turning easily. I've never played with a viscous fan before. So, three questions.
When it's cold how easily should it spin?
Could a permanently turning fan hold the engine temperature right down?
Whilst I'm that far in is there anything else worth checking?

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We have heat. The ice has gone from the bonnet! The heater works!

A new stat - what a nice, easy job on this engine - and the viscous fan left in the garage seems to have done the job.

Another big thank you to those who helped out, including the guys who have posted in the past about avoiding air locks when re-filling.

dogsbody said:

Houston, we have heat.

With a replacement stat (what a nice, simple job that is on this engine) and the viscous fan on the floor in the garage the temperature gauge is rising nicely.

Took my time re-filling her, 5 litres of Halford's finest then filtered water, and had no problems with air locks etc. Ran it on the driveway for 30 minutes and the gauge rose slightly. Been for a blast now and it's sitting steady at about 11 o'clock. AND THE HEATER WORKS!! Oh, and for the first time this winter the bonnet de-iced itself.

So it looks like a viscous fan running permanently can keep a 2.5 litre diesel lump so cold that it hardly registers on the gauge.

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Well done that man. Best to stick a Kenlowe on it worth the extra above the new viscous.

wammers said:

Well done that man. Best to stick a Kenlowe on it worth the extra above the new viscous.

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No need for a Kenlowe if you have aircon,you can get a stat for about £14 plus a box to mount it and I can tell you how to wire it in to operate the aircon fans. Works a treat. No cutting hoses or obstructing water flow either

What size fan? I am assuming it would fit on the back of the rad in place of the original.

Datatek said:

No need for a Kenlowe if you have aircon,you can get a stat for about £14 plus a box to mount it and I can tell you how to wire it in to operate the aircon fans. Works a treat. No cutting hoses or obstructing water flow either

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Yes please. This is an ideal time for me to investigate this. I reckon with this weather I won't need any sort of fan for a while and once it starts to change I'll be re-fitting my air-con condensor and it's fans.

wammers said:

It's the experience that enables me to do it that way. As i said it's not the way to go IF you don't know what your doing. Fortunatly for me i do.

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Due to my temp gauge currently sitting rather close to the blue than I like all the time - I may also be investigating a replacement stat.

I do however think that I will probably not be sticking my fingers in the fan to check the viscous unit...lol I know you say experience, but I'm just wondering how many fingers one must loose to gain that experience. After all you do only have 10 goes at getting it wrong before you have to start calling on your friends Christmas spirit to take over.

dogsbody said:

Yes please. This is an ideal time for me to investigate this. I reckon with this weather I won't need any sort of fan for a while and once it starts to change I'll be re-fitting my air-con condensor and it's fans.

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PM me with an email address and I'll send you the details
I'd re-fit the condensor and fans now, if you get stuck in traffic it will overheat and maybe cook the head

jwaldron said:

Due to my temp gauge currently sitting rather close to the blue than I like all the time - I may also be investigating a replacement stat.

I do however think that I will probably not be sticking my fingers in the fan to check the viscous unit...lol I know you say experience, but I'm just wondering how many fingers one must loose to gain that experience. After all you do only have 10 goes at getting it wrong before you have to start calling on your friends Christmas spirit to take over.

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You plonker, don't believe everything you read - I didn't end up in Bristol Royal Infirmary, it was Southmead hospital.

If you're driving a diesel then getting to and replacing the stat is NOT a simple job and then there's the issue of getting the thing re-filled with coolant. I would strongly suggest that you check your viscous fan first. I've learnt a lot about these in the last few days and this is how I now believe they work. At start up FROM COLD the fan will spin for a short while until the fluid inside gets spun up from the bottom where it has gathered. Then the fan is not driven (it may still spin lazily) until the internal fuid is warmed up, thickens and drives the fan. I keep reading on here that many owners can hear a reduction in noise from the fan as this happens. Then you should be able to stop the fan with a rolled up newspaper. Confetti = fooked fan.

If you do it this way you should be able to have whatever part or parts you require before you start stripping and be able to do the whole job in one hit.

dogsbody said:

You plonker, don't believe everything you read - I didn't end up in Bristol Royal Infirmary, it was Southmead hospital.

If you're driving a diesel then getting to and replacing the stat is NOT a simple job and then there's the issue of getting the thing re-filled with coolant. I would strongly suggest that you check your viscous fan first. I've learnt a lot about these in the last few days and this is how I now believe they work. At start up FROM COLD the fan will spin for a short while until the fluid inside gets spun up from the bottom where it has gathered. Then the fan is not driven (it may still spin lazily) until the internal fuid is warmed up, thickens and drives the fan. I keep reading on here that many owners can hear a reduction in noise from the fan as this happens. Then you should be able to stop the fan with a rolled up newspaper. Confetti = fooked fan.

If you do it this way you should be able to have whatever part or parts you require before you start stripping and be able to do the whole job in one hit.

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I might just leave it then...