Typical oil pressure 4.2

[malcolm]

On the series 3 thread, I saw a post suggesting that oil pressure on the V12 is about 10PSI for every 1000 rpm, give or take. I'd be interested to know what people get on there 4.2s?

[tim wood]

On a mechanical gauge mine is approx 60+ psi at about 2000 rpm when cold.
At normal operating temp around 40-45 psi .
When I purchased it it was reading around 20+ psi most of the time on the electrical gauge. I took a gamble and was pleased to see the current readings on changing the gauge.

Having said all that over the winter break I’m going to drop the sump to change the crank oil seal and will possibly/ probably renew the oil pump and maybe the rod bearings. I will at least check them.
My car has 56k miles from new.
Will be interested to see other responses

Tim

[Mark Gordon]

Tim, my 4.2 registers pretty much the same as yours on a mechanical gauge, running 20W50 oil. Just short of 60psi cold, around 40psi fully heated up at 2500 rpm and dropping down to about 25psi at idle when hot.

[SimonBrown]

Hi Tim
My Series 2 shows 60+ psi when cold only dropping to 55 psi when hot and ticking over.
The engine was rebuilt about 1000 miles ago and runs 20w50 oil
Regards
Simon

[Moeregaard]

I saw 45--50 psi on both of my 4.2-liter cars at 2,000 rpm hot, with pressures dropping to 20--25 psi at idle. Both were checked with a mechanical gauge, and the sumps were filled with Castrol 20/50.

[JerryL770]

My rebuilt car/engine has now done some 4k miles. Electric gauge was pretty useless so I installed a mechanical (Bourdon tube) gauge.

I get ~60psi cold and well over 50psi hot. I'm using Castrol XL.

Also getting about 23.8mpg on the normal gasoline.

[chrisfell]

My standard gauge and sender indicate as follows:-
Cold start 40 at fast idle, 60 at 2,600rpm
Warm 40-50 at 2,000rpm
Very hot 40 at 2,000rpm

This is on a shagged engine more than 60,000 miles since new pistons rings and crank bearings.

I found early on that the pressure release spring in the oil filter head was a little soft, and the replacement was little better, so I ‘helped’ it a bit by putting a washer under it. This means that cold pressure maxes at just over 60 on the gauge.

As long as the components of the oil pressure ‘system’ are working well, the actual numbers are not important, what is important is to note any changes. Changes indicate something has gone wrong. No changes indicate all remains fine and dandy under the bonnet.

[malcolm]

Interesting. I used to get 50-55 when hot at anything over 2000rpm, and 35-40 at hot tickover. Then I had my recent incident with a sudden loss of oil and the engine running dry for a few seconds. I now get figures similar to most of the above; 20-25 when hot at slow tickover, 40-45 at 2000 rpm or more. Strangely, after constant running at over 3000rpm for 10 mins, it creeps up to 50-50and a bit.
So figures ok, but not what they were. Think I may have run the big ends out a bit.

[christopher storey]

This is on a shagged engine more than 60,000 miles since new pistons rings and crank bearings

Your engine is very unusual if it is shagged out at 60,000 miles, and indeed the pressure figures you cite are very much against the engine being unsatisfactory. I know I have recounted this before, but in c.1960 my Father sent his Mark VIII back to the Brown's Lane Service Department with a big end knock at 100,000 miles. Back came the car with a bill for new shells and a report that the crank had been examined and would have been passed for installation in a new car !

[chrisfell]

The engine was shagged before the new pistons rings and crank bearings. None of the internal components has been balanced; the valve guides are worn; the timing chain is at the limit. In short it is, and has been for all the last 60,000 miles a bag of nails. But, Christopher, you are right, the engine is a bullet proof unit, very under-stressed in its standard state of tune, and as you correctly stated, the oil pressure indicates that there is much more life in it yet. It is amazing what regular oil and filter changes can achieve.

[malcolm]

Which has more effect on oil pressure - big end shells or main bearings?

[johnetype]

Mains.

[malcolm]

Ok, thanks. Of course, it would be the tricky ones.

[mgcjag]

Hi Malcolm....what guage are you useing.....electric or mechanical. ...Steve

[malcolm]

Electrical Steve. I know they aren't accurate or reliable, but I'm looking at "before and after" (the oil loss incident) figures, so it would be a stretch to think that the guage changed co-incidentally from immediately before to immediately after. Which means I have suffered an oil pressure drop from something to something else.

[mgcjag]

Hi Malcom...before making any assumptions you need to check with a proper guage....Steve

[Mladen]

Hi all, oil pressure problems....4.2 2+2 69, cold 2000 rpm 50 psi, the warmer it gets pressure falls. on normal temperature 0-10 psi on 2000 rpm. Oil castrol 20/50. Fans working ok. Tried another used oil pump, even worse results. Mechanical gauge. Have testing videos but it does not let me attach them? Help

[mgcjag]

How to post video. .http://forum.etypeuk.com/viewtopic.php?f=2&t=1315

[Mladen]