101 replies to this topic

[booton]

ok.

i've built a 998 with a 940 head. ruins well etc.

but i primed the oil pump for the first run, got oil pressure and it ran fine. left it for a hour fiddling etc, restarted the engine and it started fine with oil pressure.

But if i leave the car for a day, when i got to turn it over there is no oil pressure as the light has not gone out. i then reprime it and its fine.


unsure where to start with this really as, if i prime the oil pump there is no problems.

any one got any ideas,

could it be a bad oil filter. not sealing.

[jaydee]

A not sealing oil filter will leak A LOT of oil.
Check the oil pressure relief valve, its probably dirty.

[booton]

checked that seems, could try one from a different engine

forgot to mention there are no oil leaks at all on the engine.

[racingbob]

we use dto fit ball bearing on the race car and it sat in a little cup and then the spring

my road car got ordinary set up but will change if have any problems

[adam thirty]

Ive heard of sticky oil pressure relief valve giving probs. Also how do u prime the oil pump?

[booton]

i primed it by undoing the bolt above the pressure relief valve attached to oil feed from the oil filter and putting a small amount of oil straight into the pump.

[booton]

did you add the ball bearing to give extra tension on the relief valve.

unsure why you would put a ball bearing in?

[jaydee]

Dont bother with the ball bearing, and just use the standard plunger.

[Cooperman]

Ball bearings as relief valves can cause more problems than they solve.

[booton]

ok so my plan of attack should be change the plunger from my other engine see what happens.

anything else.

[MRA]

Make sure it is nice and smooth and free to move in and out, I use a valve lapping stick with a little bit of tape wrapped around the end to wedge it in, this allows you to "feel" the plunger on its seat.

Also balls to balls. they are not a good idea .

[booton]

finial had chance to have a look at the mini today.

i changed the relief valve and spring from a good ruining engine and it makes no difference.

it feels smooth but when i took the second one out it has a few small scratches on it. But it did move about freely.

would this relief valve stop the oil pressure light from going out., Not sure how they are linked. I think i'm barking up the wrong tree.

[cooperrodeo]

A worn oil pump can have difficulty picking up the oil in the way you describe. This is exactly the problem I had on a Morris 1100 a very long time ago.

[dklawson]

The relief valve is as you have seen a plunger held against a seat by spring pressure. When the oil pressure is high enough, it lifts the plunger off the seat and that allows excess oil to be diverted back to the sump/gearbox. If the plunger gets stuck in the open position you will develop little or no oil pressure as the bulk of the oil goes from the pump right back into the sump. If the plunger sticks closed you can have tremendously high oil pressure as excess oil is not allowed to be diverted back to the sump.

The oil pressure warning light comes on when pressure is low (the switch opens in response to applied pressure). If your light is not going out, you are not developing sufficient oil pressure and if the plunger is stuck open, that could be the problem. However, slight scratches on the plunger are not likely to cause that unless they are somehow deep enough to keep the spring from pushing the plunger against its seat.

by the way, I have the ball bearing conversion in my car's engine. It has never caused me a problem. I've heard the argument made that it affects the oil by causing "flutter" in the pressure level. However, I have yet to hear of anyone actually putting a fast response time pressure gauge on the lube system to monitor or record the high-speed changes in oil pressure. So far all I have ever heard is pure conjecture. I have also not heard an explanation for why flutter in the pressure would be particularly bad.

[booton]

thanks for the reply s. oil pump is brand new.

might try the ball bearing kit.
i take it the ball bearing replaces the aluminium shapes piece.

could it be anything else, other than this valve.

all seals everything is brand new. nothing old in the engine really.
it just strange that is i prime the oil pump by putting oil directly in to the oil pump through the large bolt attached to the top of the feed pipe.

Could it be anything else.