Rover V8 4.0 Serpentine Oil Cooler

[Arnold Cunningham]

Hi All,
I'm redoing the oil cooler setup on my defender V8 - it has a 3.9/4.0 Serpentine motor in from a 1997 Discovery.

For packaging reasons, I'm thinking about switching to a thermostat filter head, but wanted to confirm a few things first - and I am getting slightly conflicting info from different LR & Rover V8 forums though:

1. Does the extended OE oil take off fitting (part no. PBP101150) go on the side or bottom? None of the diagrams make it clear, but I think this fitting, if used, goes in the side? It will fit either position.

2. If I don't use this fitting and put a remote stat filter head on instead, can I just blank off both holes on the engine?
When the "blanking" section on PBP101150 is then not there, this allows oil to flow internally? I have seen some cases where people are putting a loop fitting between these 2 bits - but then also responses where people say "don't do that" and that I can just plug the holes.

Thank you
Matt

[GreenV8S]

Are you trying to add a remote filter head or a sandwich plate? They look similar but do completely different jobs.

[Arnold Cunningham]

Sandwich plate for oil cooler.

[Arnold Cunningham]

So. Lying under the car, it’s definitely a better package to use a thermostatic sandwich plate.

Just need to confirm I can just block off the existing ports on the front cover, which I think I can since there’s an internal bypass?

[GreenV8S]

You can do that, but if so it would be polite to remove the pressure relief valve spring and plunger so the whole engine flow isn't fighting against that back pressure and restriction. You should be able remove them via the plug above the oil cooler return.

[Arnold Cunningham]

Thanks. There’s more going on than I expected then.

Is this just an oil cooler pressure relief valve and there’s another one somewhere in the system to regulate the pressure overall? Plus a 1 bar bypass valve in the filter itself?

How different is this serpentine + dizzy motor compared to the earlier non serp motors that ran the oil pump off the cam?

Finally, if there’s a cooler bypass pressure relief, what’s the purpose of the extra long takeoff fitting? I thought it was to block off the recirculation of the oil internally and make it go external, but if there’s also an internal pressure relief, I don’t understand the point of the extra fitting to block the internal flow off?

Edited by Arnold Cunningham on Sunday 6th November 07:42

[Arnold Cunningham]

Just had a poke around on it. If I poke a "stick" in from the side port, it runs through with no restriction at all to the bottom port.

This suggests it's a bypass as expected, but there is no vlve in it - it is only blocked off with the fitting above in place, but otherwise allow unrestricted flow internally (no pressure relief valve, otherwise I would not have been able to get from one side to the other in a straight run.

[Arnold Cunningham]

Just thought I'd close this post off.

In conclusion, on a 3.9/4.0 Serpentive Rover V8 with distributor, the special side oil cooler hose closes off the oil path and direct into the filter and forces oil to go round the cooler route. So to either not run an oil cooler, or to run a seperate oil cooler takeoff, all you need to do is plug the lower & side oil cooler outlets with an M20x1.5 blanking plug. There is no pressure release valve in this area of of things, once you remove the special oil takeoff fitting on the side, the oil pump goes directly to the filter housing inlet.

If you google this, it's a bit different to what is mostly written up for the Rover V8 - but if you look closely, you can see the filter mount on the front housing is different compared to most rover V8s.

Also means that, since I didn't know this when I put the original install together 14 years ago, I've not been running an oil cooler since the hotter oil will just have been redirecting internally. Oh well, it has frequent oil changes anyway, so I doubt it's a problem.

Edited by Arnold Cunningham on Thursday 10th November 12:05

[GreenV8S]

What you're describing is not a serpentine engine. If you have a poly-V belt with a distributor, it's an Intermediate front cover. That is quite different to the Serpentine cover I was describing.

[Arnold Cunningham]

That seems to be the case. I thought the one you are referring to is the "Gems" cover and mine was the serpentine.

Edited by Arnold Cunningham on Friday 11th November 10:01