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4.6 rover v8 gems oil flow

Posted: Sat Oct 06, 2018 8:29 am
by nismoit
Good morning to everybody

I fitted a 4.6 gems in a tomcat offroad and i used the stock inlet and outlet to fit a mocal oil cooler.
Oil cooler is placed in front of car and coolant radiator is rear mounted, so oil cooler isn't warmed by radiator like stock p38.

I live in north italy nearby mountains, quite cold place in winter, and i was concerned about oil heating with low temps.

I watched official P38 workshop manual, it seems that there is not a proper oil thermostat, but from the drawing (chapter 12, page 8) seems that in some way oil can bypass the cooler circuit.

But in description, land rover says that "pressurised oil from the pump passes through the oil cooler and returns to the full-flow oil filter element", so it seems that oil (also when cold and thik) always passes through cooler.

Can u help me?

Re: 4.6 rover v8 gems oil flow

Posted: Sun Oct 07, 2018 7:50 am
by ChrisJC
The P38 oil cooler is separate to the Radiator. It is in front of the radiator, so it gets the cold air before it gets to the Radiator.

I think that there is a pressure valve in the Timing Cover such that if the oil cooler circuit is blocked (by an external thermostat), then the oil will bypass and go straight to the filter. But you would have to prove this by looking at the timing cover.

Chris.

Re: 4.6 rover v8 gems oil flow

Posted: Mon Oct 08, 2018 7:37 am
by nismoit
Is true, oil cooler il before radiator so it takes cold air.

I can't imagine that a car born to be used in cool environment has not a system to bypass oil cooler since oil temp reaches at least 80 ℃.

Surely the trick is in timing cover, as u said...

Re: 4.6 rover v8 gems oil flow

Posted: Mon Oct 08, 2018 12:17 pm
by nismoit
I just discovered that somewhere (don't know where, neither the item code or at which temp it opens) there is an "oil cooler relief valve" (p38 manual call it like this).

Someone else, speaking about serp engine from 93 to 2002, says that there is a "bypass valve" that at certain pressure force the oil directly to the filter bypassing the cooler (i.e. In case of cooler failure)...

Quite mysterious

Re: 4.6 rover v8 gems oil flow

Posted: Mon Oct 08, 2018 5:11 pm
by ChrisJC
I thought the design looked like it would work with an external thermostat, but I've never seen one fitted!

Chris.

Re: 4.6 rover v8 gems oil flow

Posted: Tue Oct 09, 2018 1:00 pm
by SuperV8
The remote oil cooler take off pipe for the P38 has a special fitting to divert flow through the cooler.
The front cover also has two sprung valves, but no oil thermostat I don't believe.
One relief to manage maximum oil pressure, and the other i'm 'guessing - thinking out loud' may bypass flow around the oil cooler if the oil is cold (and thicker)?

Tom.

Re: 4.6 rover v8 gems oil flow

Posted: Tue Oct 09, 2018 4:36 pm
by nismoit
I was guessing about this too, but i think a sprung valve must be too sensible to detect pressure difference caused by oil temp/thickness...