My current engine has only ~12k miles on it and it's from a '01 car. Now I've noticed that oil pressure isn't as high as it should be at high rpms. It's an I-4 engine that spins up to 8500rpm and oil pressure only goes up to ~65psi (measured by an autometer electrical gauge).
Ideally I should expect to see about 75-80psi near redline. I have added a small mocal oil cooler that has added an extra qt. of oil to capacity. I'm using 5W-30 Mobil 1 SuperSyn oil. My question is should I try using a heavier weight oil like 10W-40 in order to see the necessary oil pressure? I know this is a relatively tight clearance engine (as are most imports) but I highly doubt the loss of oil pressure would be from worn bearings at such a small amount of mileage. I did pull this engine from a salvage car, so I don't know what kind of care went into it for the 12k miles it wasn't mine.
Thoughts?
Low oil pressure at high rpms, my dilema...
- Thread starter MidEngine4Life
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What should your oil pressure be according to the manufacturer?
Also. Any sharp bends in the line to the cooler will drop the pressure. I have a book by Smokey Yunick thay says that every 90degree bend will drop the pressure 5psi.
You need to find out where the engine's bypass valve kicks in. A quick run up may kick it in as its usually just a spring behind a metal cover. Some folks put washers behind the spring to raise the resistence. The bypass should only be relevant typically when the oil is not at operating temp (and thick).
Aside from that, I have found a lot of engines reach a kind of equilibrium when hot and don't show a linear rise in pressure per rpm. As the other poster said, an oil cooler will show some pressure drop, maybe 4-5 psi.
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If the crank bearings are worn, oil pressure will be low at high RPM. Just a thought, not a diagnosis. ![[Wink]](images/icons/wink.gif)
quote:That's what my initial thought was, but as I mentioned above the engine only has 12k miles on it. I haven't gotten around to checking the clearances but I'd like to think they're ok considering this is a relatively low mileage Toyota engine. Going by the old rule of thumb of 10psi per every 1k rpm, I should be seeing around 80psi. Other people who have this same engine can verify and normally see 75-80psi. My oil cooler setup involves, a mocal thermostat sandwich plate, two 90 degree fittings there, the lines run up to the oil cooler with two more 90 degree fittings at the inlet/outlet. Would that be enough to cause a 10-15psi drop in oil pressure?
Originally posted by moribundman: If the crank bearings are worn, oil pressure will be low at high RPM. Just a thought, not a diagnosis.
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I do track my car also, so running at a max of 65psi with a redline of 8500rpm for 15mins at a time just doesn't sit right with me. I was hoping to hear what all the oil experts here think I should try? I've read on these forums that synthetic M1 normally shows a slightly lower oil pressure also, is there any truth to that?If it never goes above 65 I would think that is what the max pressure setting is. I am not sure the rule of thumb is all that accurate at high RPM's. Like Chris said check what Toyota says the max should be.
Usually the manufacture will give a minimum pressure at a given rpm. They do this because of different oils and stacking tolerances of parts. Are you above the minimum pressure at RPM?
Toyota lists a relatively broad range of pressure as acceptable:
Idle - 5psi+
3k - 43-80psi
The majority of the people are all getting readings in the 75-80psi max w/o an oil cooler. They all have pressure drop down to 60-65psi after they've been driving it hard for a while. They're also using the same type of gauge taking readings from the same place as I am.
I'm thinking about trying M1 0W-40 or Castrol Syntec 10W-40. I also live in a pretty hot climate since I'm in Hawaii. We never see anything below 60 and right now we normally see temps in the 80s. Does that sound like a good idea?
I'm going to swap out my oil for an analysis this weekend. What level percentages should I most be concerned about if I want to see whether or not it's my bearings? Thanks.
FIrst by pass the cooler completly. You can leave it in the car but on hook all the plumbing! REcheck your reading's. Elimanate the unknown factors first to establish a good base line. Check against factory bypass setting. The specification for warranty repair are not the key concern.
10psi/1K rpm is a decent rule of thumb for a SBC that had rather small main passages. I would be VERY surprised if any OEM engine had a relief spring that allowed >65psi hot regardless of RPM.
besides, the oil filter cannister might be burst tested to 100psi, the filtering media aint. You really dont want filter guts circulating to the bearings.
another thing to be wary of, as the oil superheats from a pull, dont confuse increased flow with low pressure.
Which engine is this? 2zz-ge or 4a-ge? I know the 2zz has it's relief valve open at areound 75-80psi (which is what I'm getting).
Sounds like enough pressure to me - any evident problems? I don't think that ancient '10 lbs/1000RPMs' is applicable to modern high revving enogines.
quote:This is on a 2ZZ-GE. I think I recognize your name from NewCelica.org. I also doubt my oil cooler is at fault. I was using this setup on my old engine and it showed 75+ psi. Who knows? I'll try unhook it and see what happens. There's definitely no way I'll be running at the track without it though. I see oil temps up to 270F with it!
Originally posted by 00 scrub: Which engine is this? 2zz-ge or 4a-ge? I know the 2zz has it's relief valve open at areound 75-80psi (which is what I'm getting).
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quote:I believe the 10 psi per 1000 RPM needs a baseline of more than 1000 at idle. See JohnBrowning's August 28 post about this (about the 12 or 13th post) in this thread.
Originally posted by mechtech: I don't think that ancient '10 lbs/1000RPMs' is applicable to modern high revving enogines.
one 1FZ-FE user had more of a problem but along the same lines, new pressure relief plunger and spring was the fix, they are externally accessable on that motor, just pull a large plug on the timing cover near the oil pump and they both come out,
replaced mine as PM after hearing about that is was arround 10$ for the spring plunger and metal gasket for the plug from the dealer
not sure if any of that applies to that motor
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