Jun Oil Pump Problem

[drgnball34]

Hi guys. I need a second opinion on my GTR. When i start her and let idle to warm up, after about 5mins high pressure steam shoots from the engine bay. Its fkn lound like air from a compressor and i nearly shat my pants. So not to take chances i towed it to the workshop and let them suss what happen. The first few times they stared her up it happened again and then this recent start up nothing happened. They said the radiator did not need that much toping up maybe 1/2 liter and there was no obvious signs of coolant on the radiator etc. Apparently temp gauge was reading fine although the twin thermo fans went on. They need time to find out whats going on. But they stated that my oil pressure was way to high. The defi gauge was running almost to max. And when she reved the pressure increased and apparently its not meant to? Coz i run a JUN pump it has a adjustable vavle to prevent this. the oil pump needs to be taken off to inspect and adjust valve if needed. But aprrently this is trial and error as there is no info on jun pumps as to what adjustments equal pressure. Said it will be labour intensive as the sump needs to be taken off to acces the pump and the cradle, radiator, balancer needs to come off. It has thin run in oil for the bottom end which may effect oil pressure? I remember last time that the oil pressure was high at start up but came back down after she warmed up. Can i grab people opinions and advice as to whats happening?

[N I B]

I hear its well over 8Bar even with a master gauge, Thats sure a lot of pressure.

[vidospace]

Damn! Not much advice from here but I do feel for you, sounds like a major headache.

[Beer Baron]

well when cold the oil pressure is quite likely to be around 8bar. that's not really a problem and it will change a fair bit depending on what type (and weight) of oil is in there and also what the ambient temp is (colder it is higher it will go).

now, the real concern should be what the oil pressure is once the car is at operating temp (80 degrees C give or take 5 degrees). at those temps pressure should be around 2 bar at idle and will increase with revs. ideally it should go much higher than 8bar at max rpm when at operating temp as things can go bad with too much pressure.

these two problems may not be related at all. and if it's just a matter of seeing 8 bar pressure at cold start then that's not really a problem at all.

[R33 Eddy]

i would check the thermostat first to see if that's opening at all.. water shouldn't be boiling just from oil pressure being so high at start up.

make sure the water pump is still working as well.

also where is the steam coming from?

these two problems may not be related at all. and if it's just a matter of seeing 8 bar pressure at cold start then that's not really a problem at all.

+1

[rob82]

well when cold the oil pressure is quite likely to be around 8bar. that's not really a problem and it will change a fair bit depending on what type (and weight) of oil is in there and also what the ambient temp is (colder it is higher it will go).

now, the real concern should be what the oil pressure is once the car is at operating temp (80 degrees C give or take 5 degrees). at those temps pressure should be around 2 bar at idle and will increase with revs. ideally it should go much higher than 8bar at max rpm when at operating temp as things can go bad with too much pressure.

these two problems may not be related at all. and if it's just a matter of seeing 8 bar pressure at cold start then that's not really a problem at all.

I take it you meant to say it "shouldn't go much higher than 8bar at max rpm when at operating temp as things can go bad with too much pressure". I have seen similar issues when relief valves get stuff shut. I have seen up to 9.5Bar pressure dead cold with a slight rev to 2000rpm with this issue. consult your engine builder for what he expects the oil pressure should be - they all have different opinions.

[R31Nismoid]

^ Agreed RE: builders idea.

Im fairly certain mine is well above 8bar when starting cold (given it's a factory sensor i don't trust it 100% but it's certainly goes up nice and high)

[N I B]

John said its 8+ bar and rising sharply hot when rev'd, Was not that high when he built it.

Relief must be stuck. Dont know about any engine overheating, I was just asked for an opinion on the oil pressure.

[Deano 1]

it depends alot with oil weight. when i was runing 30W oil my pressure would only goto 4bar on start up cold, now with 50w oil it gose to 6-7bar cold startup

[ali-turko]

iv got a tomei oil pump and it sits on about 2.6-2.8 bar at idle

at bout 3000rpm usally aroung 5-6bar

arnt jun pumps the highest flowing oil pumps for rb26s?

[Marlin]

It's common with these pumps, they have replaceable shims to alter the preload on the relief valve.

8 bar is too much, consult the folks who sold it to you.

[N I B]

I had a good look at it today, Oil pressure gauge moves like a Tacho, Don't know how high it would go if you keep reving it.

John was taking the Sump off this arvo.

[Swiper the Fox]

bypass valve jammed shut.

[Duncan]

is he really going to pull the sump off? that's a shitload of work, just pull the motor out.