P38A Loud engine/fan when cold

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P38Seb

P38Seb

Well-Known Member
Posts
121
Evening all,

In the ever continuing journey with the P38 I’ve got another problem/issue/querk I’m stumped with.

Engine is the 2.5D to help work out.

When the engine is cold, it is unbelievably loud - almost like a beating has gone, but once the engine is warm, almost exactly as the needle hits the middle, the noise stops and it’s just the calm purr of the 6 cylinder.

The noise I can only describe as a woosh/roar and is directly affected by engine RPM, so I doubt it’s gearbox/drivetrain issues.

Anyone able to offer any insight?
 
The viscous is normally like that but for only a short time. The bi-metallic control on the front of the unit may be corroded and seized. I binned the viscous years ago and have a mod to use the aircon fans for cooling. More reliable, quicker warm up in winter and quieter.
 
On the drive to work is screams going through the village but once I’m up the hill after a couple of minutes it’s back it’s quiet ways.

I’ll take at the controller and see the state of it. Thanks!
 
So next question..

Any link to the mod.. and can it be used without fully working air con? I have a book symbol I’ve not gotten around to sorting yet and a leak somewhere
 
P38Seb said:
Evening all,

In the ever continuing journey with the P38 I’ve got another problem/issue/querk I’m stumped with.

Engine is the 2.5D to help work out.

When the engine is cold, it is unbelievably loud - almost like a beating has gone, but once the engine is warm, almost exactly as the needle hits the middle, the noise stops and it’s just the calm purr of the 6 cylinder.

The noise I can only describe as a woosh/roar and is directly affected by engine RPM, so I doubt it’s gearbox/drivetrain issues.

Anyone able to offer any insight?
Click to expand...

Sounds like the viscous fan. Take it off and see if it stops. It should roar on startup but usually stops after a minute ir two although it can take until I get to the bottom of the hill in cold weather.

I wouldn't bin it. It is very reliable usually and very good at keeping the engine temperature stable. Worth doing the mod to bring the aircon fans in if the engine temp starts to climb too high like the later models if you have an early car.
 
Grrrrrr said:
Sounds like the viscous fan. Take it off and see if it stops. It should roar on startup but usually stops after a minute ir two although it can take until I get to the bottom of the hill in cold weather.

I wouldn't bin it. It is very reliable usually and very good at keeping the engine temperature stable. Worth doing the mod to bring the aircon fans in if the engine temp starts to climb too high like the later models if you have an early car.
Click to expand...
The viscous fan reliable? You are joking, there are countless tales of woe related to the viscous fan failing. Electric, as used on many modern cars, is more reliable, quicker warm up, gives maximum cooling at low revs in high temperatures when the viscous produces least cooling etc etc.
 
Datatek said:
The viscous fan reliable? You are joking, there are countless tales of woe related to the viscous fan failing. Electric, as used on many modern cars, is more reliable, quicker warm up, gives maximum cooling at low revs in high temperatures when the viscous produces least cooling etc etc.
Click to expand...
Don't want to be contentious but I've always found viscous fans reliable in various cars inc. my '79 2.6 safari & four RRC's.
I had to replace such a unit in my old 5 series BM last year as it wasn't locking up properly during the exceptionally hot summer, but the 'leckey aux. fan kept the car from boiling until the local garage had a time to replace the viscous.
 
norseman said:
Don't want to be contentious but I've always found viscous fans reliable in various cars inc. my '79 2.6 safari & four RRC's.
I had to replace such a unit in my old 5 series BM last year as it wasn't locking up properly during the exceptionally hot summer, but the 'leckey aux. fan kept the car from boiling until the local garage had a time to replace the viscous.
Click to expand...
True on most cars, not true on the P38.
 
Thanks for all the replies. Datatek has given me his guide to the mod which I’ll be using, seems like a very easy and simple mod to do!
 
Datatek said:
You may find unscrewing the viscous fan a challenge, I had to cut one off :eek: Don't forget to also remove the fan cowl.
Click to expand...
Hopefully it won’t come to that. I’m known at work for fixing a bike puncture with a hammer, so brute force I’m pretty good at.

I was going to ask why the cowling needed to be removed? Does it affect the air flow, or..?
 
P38Seb said:
Hopefully it won’t come to that. I’m known at work for fixing a bike puncture with a hammer, so brute force I’m pretty good at.

I was going to ask why the cowling needed to be removed? Does it affect the air flow, or..?
Click to expand...
With the viscous fan removed, the cowl serves only to reduce airflow so has to be removed if the electric fans are to give maximum cooling.
 
Okay, thought it might be something along those lines. Once the car is through the MOT later this week, I’ll get it sorted!
 
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