Oil pressure drops to 0 when cornering hard

[andrew_mx83]

did oil and water mix when it did the gasket? if so the bearings will have copped it leading to less pressure.

it still sounds like surge tho, not sure about the 1g but 7m's surge something fierce during hard righthanders

[LeeRoy]

The weird thing is it used to have excellent oil pressure like 50Psi + while cruising, until i blew the head gasket, and got the head port n polished, it has been low ever since. It Only nearlly drops to zero when really throwing the car in hard. The sump is modified to fit in a hilux, an because of this the pick up has been spun around to suck oil from the deeper part of the sump.

Is it possible that some head gasket gunk has got stuck on the oil gallerys? When i was getting off the old head gasket i was heaps careful and even used a vaccum to suck up any muck that fell into the galleries. The only other thing i can think of is that when the car was running before it was winter, and now its much warmer and using 10W-40 might be to thin weight oil?

did oil and water mix when it did the gasket? if so the bearings will have copped it leading to less pressure.

Remember that pressure is related to resistance, so if your oil galleries were all clogged before then that would have cause you to have higher oil pressure. Then, after the head gets overhauled and cleaned these restrictions are removed and the oil pressure will drop. The drop however is not necessarily bad, provide it's still within a suitable range.

[banana_socks]

Remember that pressure is related to resistance, so if your oil galleries were all clogged before then that would have cause you to have higher oil pressure.

Wouldn't this depend on where the clog is? A restriction at the exit of the system would increase the pressure throughout, but after a restriction the pressure would be lower than normal.

[abently]

Oh yeah abently, if any of my engines were to run as low as 8psi at idle, it would be out stripped down and rebuild before something expensive went bang - road car included. Your rule of thumb sux, I run engines to 9,000 applying your rule would be 90psi, you better rithink that before offering this advice to anyone else.

30psi idle to 65psi when the relief valve opens (approx 4,000 rpm) is the rule, no exceptions. Anything below this means worn bearings, failed pump or leaking relief valve.

I'm not getting into semantics here... Toyota engines and their factory clearances may not like 8psi at idle, okay I accept that, but other manufacturers have no issue showing it can be done.

Btw it's not my rule of thumb, it is the rule of thumb regarding oil pressure and rpm.

Thanks though, I will rephrase such advice in future better.

[love ke70]

im with abently, pressure is a restriction to flow, high pressure isnt always a good thing.
and also leads to higher bearing surface temperature.
while 8 psi is low, my ute will see that on a hot day at idle after a couple of hours running, and at 2500 can fall from 40 to as low as 26

[oldcorollas]

mayeb you need a higher viscosity oil? or a higher weight at temp.

[love ke70]

maybe, but it used to drop similarly, just at higher pressures with a heavier oil, and alot of people i spoke to claimed that the heavier oil (penrite) was a leading contributor to sludging of motors, and to use the shell rimula i am now. which is still a 15w40

once it reaches that 8psi it wont go lower, no matter how much further you drive, i did a kakadu trip, continual 400+ EGT's and the oil pressure would start at 40 at cruise, drop to 28 and creep to the 25 by the end of a 10 hour drive, 900+ kms

is 10 PSI per 1000 enough pressure?

and with the 1g, while your pick up might be shite and your getting oil surge, check your oil pump, i deaded a 1g motor by assuming i had a crap gauge after a rebuild, and then found out when i replaced the oil pump that 1 psi at idle i had been getting was accurate and it was much happier with the 15 after pump replacement, so could be a worn pump not pushing enough once the oil thins out...

[oldcorollas]

check your oil temps.. maybe it's getting cooked

[love ke70]

haha, ive wondered that, if its been getting cooked, its been getting cooked for about 100K now, what are acceptable oil temps on a 4.2 patrol diesel, with aftermarket turbo?
im assuming oil temps are oil temps, but info never hurts...

cheers, andy

[akmehd]

I changed my oil to 15-50W and added some oil stabilzer and the cruise pressure is alot better 55-75psi, obviously because it is thicker oil. It still only seems to drop to zero if i really throw it in hard, but the funny thing is it only seems to do it to the left.

surely the oil temp is not geting to hot. one would think that if it needed an oil cooler the 1g would come with one standard?

and Ke70 that's what oil pressure I get now at idle, once Ireally flog the car and its nice and hot. What weight oil were you running in yours to achieve that pressure ?

cheers guys

[Shifty]

Based on what facts? Lol...

10psi per every 1000 RPM is an O.K rule of thumb to live by.

8psi at idle is fine and 20psi at cruise (say 1600rpm) is fine also.

I'm no expert but I call shenanigans on these figures. As a general rule I'd expect a healthy, running engine to be around 30-40psi (low rpm) to 70-80psi (high rpm). This qwould obviously vary depending on the exact model etc but based on my limited experience this is a good guide.

[oldcorollas]

It still only seems to drop to zero if i really throw it in hard, but the funny thing is it only seems to do it to the left.

surely the oil temp is not geting to hot. one would think that if it needed an oil cooler the 1g would come with one standard?

first, japan doesn't get as hot as oz... regardless, oil coolers are good if oil temp is too high.

turn to left = starve = oil pickup on left hand side being uncovered and sucking air = bang .
run a bit more oil and see if it helps, alter sump, see if ti helps tc etc, as all said before...



or drive a bit slower around left hand corners

[Shifty]

unless you're using it for motorsport, there's a problem. it shouldn't surge in near-standard form.

[love ke70]

its also probably got less space around it to keep cool in its new engine bay.

think i was running 15 50 aswell, a penrite substance anyway.

i personally wouldnt wanna run 70 or 80 psi all the time, just excess heat on the bearing surface in my opinion...

[oldcorollas]

it also means your oil pumps pressure relief valve might be rooted.