P38 viscous fan

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Datatek said:
You jest.
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Just so. The so called viscous fan spanners are light weight and of no substance. And for what they are expensive. Just use the correct spanner out of your toolbox and a sharp blow with a persuader.
 
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Grrrrrr said:
Nah, both 36mm, only the thread is different. Think the 32mm is for Volkswagen or somesuch.
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Diesel is 32 mm left hand thread. As said many many times viscous fans ALWAYS undo in their direction of rotation.
stemac33 said:
32mm for the fan on the bmw m51.
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Correct diesel is 32 mm. I don't really care what the petrol one is. But i will have something to fit it. Have not got a clue where reference to 36 mm came from must be ready for a brew. :D:D
 
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They are so big and heavy for what they are, and ridiculously expensive (in my tight opinion). I’ve always been pro viscous, but my mind is swerving towards Datateks ideology lately.

The E36 one won’t stop - it broke my stick and is undamaged so think cheap ones are exactly that. @Grrrrrr i will still keep it as emergency spare even though it spins all time it’s so much lighter than original should be okay. I will send it to you if you ever need one
 
RangeRoller dt said:
They are so big and heavy for what they are, and ridiculously expensive (in my tight opinion). I’ve always been pro viscous, but my mind is swerving towards Datateks ideology lately.

The E36 one won’t stop - it broke my stick and is undamaged so think cheap ones are exactly that. @Grrrrrr i will still keep it as emergency spare even though it spins all time it’s so much lighter than original should be okay. I will send it to you if you ever need one
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Thanks for the thought but I have enough broken stuff in my shed waiting to be fixed already ... 2/1/4 tons of red metal for a start!
 
Personally i would not ditch the viscous and shroud. The viscous draws air from the entire radiator surface because of the shroud. The aircon fans service only part of it. Use the aircon fans as backup by all means but also retain the viscous.
 
I took the vicious fan off three years ago, with the thought that I would eventually replace it.
Mine is 2001 DT and, as Datatek pointed out to me, has a temp sensor (I believe at the rear of the cylinder head) which brings the aircon fans on when it gets hot.
So I was happily running around, with no viscous fan on, and I found myself towing a trailer with a mini digger up a hill, in the summer.
The temperature gauge showed no movement above normal but I heard the aircon fans start up. Not on for long and they went off again. On again a little while later and then off again. Seemed that they were cooling sufficiently.
Ever since then I've relied on that alone for assisted cooling. The only time they come on is during fairly testing driving (eg.see above!) or sitting in traffic on a v hot day.
I have taken the shroud off to allow maximum airflow around rad and engine.
Works for me...
 
wammers said:
Personally i would not ditch the viscous and shroud. The viscous draws air from the entire radiator surface because of the shroud. The aircon fans service only part of it. Use the aircon fans as backup by all means but also retain the viscous.
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But you say there is no drive to the viscous some of the time and there is certainly no drive when it starts to fail, in that situation the cowl actually obstructs ram air flow. Many more powerful cars than the P38 diesel are just fitted with electric fans including all front wheel drive vehicles, they cope very well especially with latent heat at the end of a hot run. I do't care what others do, I have run almost all my cars with electric fans for over 50 years, the P38 diesel runs well with no viscous and is noticeably quieter with a quicker warm up in winter..
 
Datatek said:
But you say there is no drive to the viscous some of the time and there is certainly no drive when it starts to fail, in that situation the cowl actually obstructs ram air flow. Many more powerful cars than the P38 diesel are just fitted with electric fans including all front wheel drive vehicles, they cope very well especially with latent heat at the end of a hot run. I do't care what others do, I have run almost all my cars with electric fans for over 50 years, the P38 diesel runs well with no viscous and is noticeably quieter with a quicker warm up in winter..
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Keith you do as you want no problem. Most of the time whilst driving the engine is cooled by ram air. But the viscous fan is variable drive it's not just on and off.
 
No apparently it just comes on when the head temp goes up a bit. It obviously is pretty effective in that it cools the rad, then goes off again. As I said, barely a flicker on the temp gauge. I'm not that carefree tho'! I must admit I do take care not to overdo it!
I've been running like this for about three years and the fans have come on maybe a dozen times and no harm done.
 
RangeRoller dt said:
The thing is when either work they are fine, it’s when they play up - not broke just iffy. I’m just glad we have options :)

@plumbfisher i thought the backup usually only comes on impending overheat when it’s too late?
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105 degrees, if he is happy with that so be it, personally i would not be. The engine should run in the 85 to 95 degree range for long life.
 
I don’t have the 3rd sensor anyway. Could make a system but my P38 doesn’t seem to like it slightly too hot.
Probably few degrees above normal on long hard pull it doesn’t like going near tickover. If I cruise at 30mph in 5th for few minutes the gauge slightly goes down then she’s happy again. I believe this to be partly cheap thermostat I fitted as couldn’t be sure at time if stat was problem.
 
Datatek said:
Variable drive true, a little drive even when cold after the initial burst
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No no drive after medium is returned to storage other than friction from seals. Whilst valve is open medium is constantly circulated back to storage. But amount valve is open varies with temperature. So amount of medium circulating also varies giving a controlled air flow. When engine is stopped and fan stops medium settles at lowest point. Engine cools and valve closes but there is still a pool of medium at lowest point. When engine is started that medium causes the fan to be driven until medium is dispersed and returned to storage by centrifugal force. That causes the temporary roar. The shroud is designed to draw cooling air from the entire radiator area when the viscous is active and to direct a flow of air back across the engine to cool the block externally. when ram air cooling is being used. So removing the shroud is not a very good idea.
 
wammers said:
No no drive after medium is returned to storage other than friction from seals. Whilst valve is open medium is constantly circulated back to storage. But amount valve is open varies with temperature. So amount of medium circulating also varies giving a controlled air flow. When engine is stopped and fan stops medium settles at lowest point. Engine cools and valve closes but there is still a pool of medium at lowest point. When engine is started that medium causes the fan to be driven until medium is dispersed and returned to storage by centrifugal force. That causes the temporary roar. The shroud is designed to draw cooling air from the entire radiator area when the viscous is active and to direct a flow of air back across the engine to cool the block externally. when ram air cooling is being used. So removing the shroud is not a very good idea.
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It's not just centrifugal force the removes the fluid, centrifugal force moves the fluid to the periphery, there is a crude little metal block with a V in the leading edge to evacuate the fluid, the metal block is on the drive plate runs in a groove in the driven plate. There is a lot more air going over the block in a RAM air situation with the viscous and cowl removed.
 
Datatek said:
there is a crude little metal block with a V in the leading edge to evacuate the fluid, the metal block is on the drive plate runs in a groove in the driven plate
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So how do I get this open to flush and fill with fresh oil? :D

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I’ve had good look at the rads and grille. The way the air goes in biggest thing blocking flow appears to be the air con fans and shrouding for them. They are just there in the way few holes may help flow

I’m not even sure why I’m doing this :confused: I don’t have a cooling problem just a ducky viscous. It’s a sure sign :rolleyes::D
 
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