Cold start oil pressure. 4 litre GEMS engine

banzaibanana · Post by **banzaibanana** » Mon Apr 09, 2007 10:09 am

Hi all.
Just got a 2002 westfield with a 4 litre GEMS engine. It's my 1st V8 so I'm slowly getting used to all the characteristics (always had 4 pot westfields before) of the V8's.

I've got used to that fact I should only expect 3 bar as a maximum oil pressure (which I get without fail) but it's the cold start oil pressure that scares me; and this is where I need some help/reassurance etc...

On 1st cold start (engine has only done 2600 miles btw) it is roughly 20 seconds before my Oil Pressure gauge shows any flicker of movement. It then crawls its way up to 3 bar during the next 20 seconds. Subsequent starts see the OP rise to 3 bar reasonably quickly?

Is this normal? Is it particular to the GEMS engine? Is it the fault of a lazy gauge?

Oil currently in engine is Valvoline 20w50 mineral (about 500 miles old I'm told)

Thanks

ihatesissycars · Post by **ihatesissycars** » Mon Apr 09, 2007 10:13 am

Do you have the serpentine oil pump and do you have an oil pressure switch?

banzaibanana · Post by **banzaibanana** » Mon Apr 09, 2007 10:52 am

Yes it is serpentine set up. Not sure about oil pressure switch? please explain (I'm a bit of a mech numptie

...and totally new to V8's

)

ian.stewart · Post by **ian.stewart** » Mon Apr 09, 2007 11:58 am

Are you using a capillary oil gauge??

Nick Moore · Post by **Nick Moore** » Mon Apr 09, 2007 12:32 pm

The oil pressure switch controls the oil warning light on the dash. Basically, if that light goes out almost immediately after startup, you're OK.

There are two sorts of oil pressure gauges, electric and capillary. Electric are often slow to react - a fuel gauge is electric, for example, and the needle moves slowly. Capillary oil gauges have an oil-filled tube from the engine to the rear of the gauge. These gauges respond very quickly and are generally very accurate. Their only drawback is that if the tiny oil line breaks, you lose your oil. If you're lucky, you lose it in the cockpit, so you know about it before the engine runs out and siezes. It doesn't hapen very often, though.

banzaibanana · Post by **banzaibanana** » Mon Apr 09, 2007 2:34 pm

The gauges are electric. and I don't have an oil warning light on the dash.

I'm assuming then; at cold start because the oil is very thick it is taking some time to move from the sump and register a pressure and at warm oil temperature the oil is thin enough to be sucked out of the sump quicker and register an oil pressure??

ihatesissycars · Post by **ihatesissycars** » Mon Apr 09, 2007 5:41 pm

My step dad had the same problem with his esprit. The oil pressure light would go out straight away but the guage takes a while to respond but if you stopped and then restarted it the guage would pick up straight away. Your front cover should have provision for a switch if not already fitted, it would be easy to wire a light up to it so i'd do that, if the light goes out straight away then i'd worry no more.

ChrisJC · Post by **ChrisJC** » Tue Apr 10, 2007 6:59 am

Is 20W50 the right oil? I know it's right for the pre-GEMS engines, not sure about GEMS and later.

Chris.

ihatesissycars · Post by **ihatesissycars** » Tue Apr 10, 2007 7:18 am

Well this is something i'm about to find out! I believe a semi synthetic 10/40 is a wise choice for the serp engines due to the much improved oil pump however i'm sure other grades can be used also without problem.

badger · Post by **badger** » Tue Apr 10, 2007 7:21 am

20W50 is for the pre-serpentine engines with the distributor-driven oil pump. All engines with crank driven pump (Gems. Thor, Interim serpentine discovery) should run 10W40 or 15W40.
As per a previous suggestion, fit an oil warning light and sender for peace of mind.
Your slow cold pressure response is probably down to 2 things, oil slow to pass through mesh filter of pressure transmitter, and slow response of gauge itself.