low oil pressure

[chazmac]

Hi

my oil pressure gauge is reading low

Have just put in another v8.

I have checked the mains big ends fine
put new shells in anyway

changed the front cover and oil pump fine SD1

old cover had uprated oil pump checked fine new high pressure gears 12k miles ago

changed rockers old rockers fine no difference

Oil warning light goes out and stays out even in D1 when warm

The engine sounds great and Ive checked everything.

Engine was recond reground crank 010 and new real steel hurricane cam shaft

followers etc 12K miles ago

Engine is very clean inside and in great condition no noises smoke etc

engine filled with duckhams classic 20 -50 with winns additive and new proper

oil filter

So the sender or gauge is telling porkies

Cold it wont go past N

then when hot at idle drops to start of green

then when revved goes to N but never beyond

Old P5b engine was exactly the same gauge readings

took this apart perfect shaft and shells rockers fine

The temp gauge is reading low as well never really leaving the Blue even when

hot. I am not sure about the fuel gauge whether this is accurate or not.

If this can be fixed then great. If not then will have to live with it.

My P6 engine oil pressure is great really high cold and 30 when hot idling

This is also an sd1 but does not sound as healthy as the vittesse unit in the P5

The car sound great and drives really well

Past its MOT 2 Sundays ago

checked the emissions for a laugh it eventually passed the rev test in the green

Any ideas guys

I have tried a couple of senders no difference if anything worse. I have not tried a new one

Cheers Chaz

[johnwp5bcoupe]

Chaz have you checked the 10 volt supply to the guages?

[Phil Nottingham]

The old gauge is not via the stabilised supply but should never be relied on to give any more than indication that some pressure exists. Subsitute an accurate bourden gauge before pulling the engine apart and use Search re thsi regularly occuring topics.

A Cold engine should give a much higher reading - it's the hot reading that is the important one and even 25 on on one these engines is good enough if no undue rumblings

Use you senses not the instruments!

[harvey]

I agree, check the pressure with a known master gauge. The SD1 covers and oil pumps are not high pressure, they're high volume, if you want higher pressure you need to fit a spacer to the oil pressure relief valve spring.

[johnwp5bcoupe]

In regards to oil pressure I realise that it is not from the 10v If the water temp and the fuel level are incorrect these are both fed from the 10v so it would be worth checking! in regards to oil pressure best eliminated with a bourden gauge as Phil suggests the fact that you have all the same readings as you had before must I would have thought be a bit suspicious

[chazmac]

Hi

thanks guys

Phill I think you're right forget the gauge and use common sense. If this was a salon with no oil gauge and just the warning light I would not be writing this now

I have now used 3 different oil pumps with 3 different front covers 3 different filters and two different engines all with virtually the same readings

These changes were carried out for a variety of reasons not because of the oil pressure gauge.

However it would be good to get to the bottom of this.

both engines healthy with no rumbles ,bangs, rattles or taps

The oil pump I'm using now has a perfect piston and pressure spring. The gears and body are fine and it primed very quickly with no problems.

I will try the sender from my P6 which is working well and check the voltage at the gauge end. I will try another gauge as well possibly try the smiths gauge from my mk2 jag with the P6 sender and a different positive feed.

Cheers Chaz

[chazmac]

Hi guys

I changed the pressure relief spring and piston.

I also put the oil pressure sender from the P6 onto the coupe

Oil pressure was much better well clear of the N when started 3/4 of the way


up

As i said previously my temp gauge did not move from the blue.

I bought a new water temp sender on ebay and the temp guage came to life

quickly registering N on the guage

The oil presure guage was reading just above the N at this stage with the car

idling beautfully ticking over like a clock

Smug satisfaction ensued

rising healthily when the loud pedal was pressed


Howevre when I took the car for a drive the Temp guage climbed to near the

red even when on the move not cooling down at all and the oil presure dropped still in the green but near the red when in D but no oil warning light

when idling rising to N on the move

I checked the engine which was full of water and had been bled properly

The pipes and engine were far to hot The top of the rad was very hot the rest of it pretty cold really at the bottom.

I am using the same inlet manifold and rad as the old engine which used

to pink badly Temp gauge ( lying ) never leaving the blue. But obviously

overheating

So I will need to change the thermostate and look at the radiator

possibly recoring or replacing the Rad

The car has a new waterpump

The car also gets very fummy when run for a while I have checked all the

breathers and cleaned or replaced them

I am getting there I am no longer concerned about the engine or oil.

The car drives great and sounds lovley

Its all about the cooling sytem right now.

At least I'm seeing how hot the car is really getting

I have hardly used the car so dont think any damage has been done

The lockup is about 2 miles from the house and the car is geting very hot and

bothered in this time while driving no traffis or lights and not a particularly warm day either. Although it was idling for a while in the drive when it was registering N


Any ideas guys

chaz

[dorsetflyer]

Top of radiator hot, bottom cold, sounds like a classic of an air lock in the system. It will need bleeding, which might clear the problem.

[Phil Nottingham]

I wouls suggest that you have the rad flow tested to see if the core blocked if you think you have a problem. Its not a big job if you take teh rad off and along to a rad reconditioner

[dorsetflyer]

A source of fumes entering the car from the engine will be down to entry points in the bulkhead. If there are any holes there fit new blind grommets. If there are any grommets where wires or other parts transfer through to the inside and they are perished they will need to be replaced. I found one of the worst ones was the grommet that the steering column goes through, and once replaced made a hell of difference.

[chazmac]

Cheers guys

glad to see your back phil

I will try these things, possibly tomorrow and get back to you

cheers chaz