oil pump pressure relief valve.

(semi) Goodday guys

I had the tread abbout what oil to use for high rpm redblocks.

Well... Removed my oil pump, it was done. Took a new pomp ported the passages a bit, Cleaned it up and installed with some fresh rod bearings.

All seemed fine. 4bar pressure on the starter and never above 5.5 when revving. Till yesterday when i lost oil pressure AGAIN. I suspect the pressure relief valve. when idling pressure is scary low roughly 1 bar and when revved it climbs up again. The pump i took out had the valve stuck open and made sure the new one was funcioning smooth as it should.

Never heard of this being an issue and am quite suprised why a supposed to be good engine keeps failing on me (had countless issues with this POS)

are there people that know abbout this issue and know a solution? Getting frustrated to pull the oilpan again.

are you using the Volvo OEM orange seal on the tube?

Having a hot oil idle (what rpm?) pressure of 1-bar doesn?t seem too scary to me.
You?re not going to have, or need, 4-bar idle pressure.

fwiw my hot idle is like half a bar according to the Volvo gauge, but that's with a 30+ year old stock pump, not a new one.

Oil pressure can get quite low at idle when it's hot. Nothing to worry about since there isn't much load on the engine, just needs to keep the bearings lubed.

I pulled the specs from a Haynes manual I have sitting here.

Min pressure at idle is 10psi (.67 BAR)

Min pressure at 2000rpm is 36psi (2.48).

The manual shows a break down of all the different B21, B23, B230, except in this case. So I ASSuME that it is a general pressure across the red blocks. I tried to find my green manuals, but the ones I need are buried under some windows.

Jordan

1 bar oil pressure was cold start. When oil temps got to 120*c i had only 0.9bar left at 3000 rpm.

It defenitly has the pressure relief valve stuck on this pump also. Since it's the second time the oil pump ****s me over i was wondering if i'm just the unluckyest person in the world or that other people may have found a fix.

I have 5lbs at idle but it rises quickly off idle. Seems to go to 40lbs pretty quick, I used to stress about it but I just dont worry about it any more. This was with a new mellings pump on a new rebuild. Id just run it if it was me.

First things first, have you checked with a mechanical gauge? I've found some HUGE variances as the pressure sender warms up. Had one that freaked me out, did all the usual checks, finally mechanical and found it was fine, sender **** the bed. Another was a gauge that when sitting in the sun all day (pillar mount), it read different than overnight, but the sender was the same resistance either way.

KISS man, start there.

apachechef said:

are you using the Volvo OEM orange seal on the tube?

Click to expand...

This.

i did mount a known good mechanical gauge to verify and replaced the seals with oem volvo seals.. i guess i'll be pulling the pump again somewhere in the next weeks.

Depending on oil weight it?s doubtful it?s going to run against the 5-bar bypass/pressure relief at idle warm even in perfect health?1-1.5 bar is fairly typical with real hot thin oil from what I?ve observed?

Book spec is 30-50psi at 2000RPM?pressure spec is much narrower for B234 belt driven pump, but gives a range for the earlier SOHC engines?

Is the engine worn out junk or oil pump seal lousy, pinched/pushing out or oil pump worn?
Early short gear oil pump or ~91+ ?tall gear? oil pump?

Casting quality of the pump you get from ?Volvo? isn?t what it used to be and I don?t trust the melling pump for the Volvo application (pressure problems, casting quality, horrific whine & quality control on those).

I?ve given up and just try to use later tall gear pumps from mild climate highway driven PNW N/A donor cars without working a/c + clutch fan or NOS dusty shelf older OE pumps, steam clean the pressure relief & spring & inspect.

Of used pumps I?ve had ok luck having the gears coated with a 0 clearance coating after getting one with minimal wear, but that was some time ago & there?s probably been significant advancement in that since?
Don?t know what else to do?

If you install a late tall gear oil pump in an earlier engine, make sure you get the good fitting transfer pipe with it, they?re a matched set in my experience but seem to fit the early block ?fine? (no issues so far or any fit that looked ?different? from the early pump & pipe, anyway?). But early pipe and late pump didn?t fit quite ?right? (such as there is a ?right? with that design ?)

The OE squirters seem to pop off ~10psi-1bar?
Even If the engine is tight, in extreme heat with thin oil and good transfer pipe seals ~10-14psi @ LH3.1 540RPM idling speed is totally normal/not surprising.
Don?t live somewhere real hot, but tight B21FT with tight NOS pump & hot oil idling is 1-1.5 bar (900-950RPM) with mech gauge or OE sender was fairly typical, but picked up fast to 2.5-4 bar just off idle?