Oil Circulation Explanation Please

[Grim.Badger 15]

I'm having oil pressure problems at the moment, part of which I know is down to scored bearings. However the oil pressure is quite a bit lower than when the last owner of the engine ran it. The only real difference between us is the fact that I have used my own oil pump. I should note that I didn't have brilliant pressure with my last engine despite the bearings looking good (amatuers impression, they could be fu**ed for all I know).

First of all I'd like to ask, how likely is it that the pump is causing some of the low pressure?

Secondly, what gets the oil to the head, is it the pump or does the oil pressure created by the bearings push it up into the head? As far as I know the oil from the bearings lubricates the bores but not much else, am I wrong?

Thirdly, if the pump is putting out low pressure, what do I need to fix this? Would a new spring do the job or does more need replacing?

 

Cheers

[Exile 0]

Hi

At first -how did You check the oil pressure? You sholdn't trust OP sensor.

I don't believe, that it is a faulty pump. Probably bearings of crankshaft or camshaft, but the oil itself may be the cause.

[pug_ham 244 3 Cars]

Try your old sender if you can, I was shocked how much difference a different one made on the engine that was in my 309 SRi.

 

The guage went from max half way on the guage to 3/4's straight away.

 

Graham.

[Grim.Badger 15]

The sensor is my old one, but you're right in that I don't trust it. The problem is that if I try and run a snesible oil, 15w40 mineral for example, the stop light can come on when the engine is hot and I'm in stop/start traffic. Oil pressure is very low on idle even when using a thick 20w50.

To be honest I'm surprised my oil pressure guage works as most of the time it didn't when it was on the last engine.

[Richie-Van-GTi 71 2 Cars]

the fact the stop light comes on and the pressure reading is low would point to actual low pressure as the 2 are independant of each other. Try and get a known good pump and spring from a trusted member.

[Exile 0]

If the oil pressure is not low when the engine is cold, then the spring is ok. You can try with another pump, but I believe it's a waste of time.

[Grim.Badger 15]

I'm going to try with a spring to start with because it's a cheap option but I suppose I will have to start saving for a new set of bearings and a check of my old crank, hopefully it won't need a re-grind and can still take a standard set of bearings.

[welshpug 1,657]

A set of big end bearings is cheap at £20, Mains are a similar price.

 

A regrind varies, but in most cases they are around the £100 mark.

[deadcatdave 0]

i've even the OE oil pressure gauge over read significantly