Acceptable oil pressure?

After having my newly stroked (3.4l) engine mapped last week, I discovered an issue with the oil pressure that has made my car all but undriveable.

On boost, my oil pressure peaked at up to 9-odd bar but when pulling up at lights (for instance) it would sink so low (0.4bar-ish) that my Syvecs cut the engine.

Before stroking the engine, I would see around 2 bar at idle and an absolute maximum of around 6bar when driving.

Romain from 2BarTuning plugged his laptop back in to the ECU and diagnosed the problem as a faulty oil pressure sensor.

I have now replaced the oil pressure sensor and I'm still experiencing very similar symptoms at the peak on boost (although I actually hit as high as 10bar today during my test drive), but seemingly without it dropping off entirely when coming to a complete stop.

So... My question here is: what is an acceptable oil pressure range?

My old oil pump was just that, old, so I'm prepared to believe that my oil pressure on a freshly stroked engine with a brand new pump could well be higher, but is 10bar really ok? Or does this point to an underlying mechanical fault?

I now i dont have a build 3.4 or anything but mine is

80 psi cold start up at idle

17 - 20 psi hot at idle

69 - 75 psi at wot

Seems odd that you can see 10bar at high RPM and only .4 at idle, the 10bar would make me think the pressure relief valve is sticking or is running too much spring, what RPMs is your idle, and what oil grade are you using?

I am inclined to think the pump has too much clearance, so is unable to maintain pressure at low RPM.

Pumps seem to be the luck of the draw, I replaced mine because of front main seal problems, IE the pump was over pressuring the seal due to leakage through wear, yet it could still maintain perfectly adequate oil pressure even at idle, and the replacement from one of the US tuners was actually immovable when received so I rebuilt it, and the idle pressure was less than my worn out pump...go figure.

Seems odd that you can see 10bar at high RPM and only .4 at idle, the 10bar would make me think the pressure relief valve is sticking or is running too much spring, what RPMs is your idle, and what oil grade are you using?

I am inclined to think the pump has too much clearance, so is unable to maintain pressure at low RPM.

 

Pumps seem to be the luck of the draw, I replaced mine because of front main seal problems, IE the pump was over pressuring the seal due to leakage through wear, yet it could still maintain perfectly adequate oil pressure even at idle, and the replacement from one of the US tuners was actually immovable when received so I rebuilt it, and the idle pressure was less than my worn out pump...go figure.

I had this horrible feeling it might be the pressure release valve... I REALLY can't be doing with that to be honest.

My idle is set to around 900rpm and currently there's 5w40 oil in there, although I intend to change that back to 10w50 (or at least I had intended to - my understanding is that the higher the grade of oil, the higher the pressure, which wouldn't really help matters right now...).

Needs an accurate gauge on their to measure it so your not seeing the wrong thing

Is the calibration of the sensor correct?

Would be worth putting a mechanical gauge on to confirm what the other gauge is reason.

If the oil pressure at idle is lower than before then that indicates something is going on

Should be 1.5-2 bar at idle when warm depending on viscosity

We would be using 10w50 or 10w60 in that engine

Have the oil squirters been removed?

Mine runs when warm at 6 bar in throttle, 2.5bar on idle, what has Paul said, that would be my first port of call, you are always going to get a bit of snagging on such a big build and the Syvecs is doing its job annoying as it must be

Needs an accurate gauge on their to measure it so your not seeing the wrong thing

 

Is the calibration of the sensor correct?

 

Would be worth putting a mechanical gauge on to confirm what the other gauge is reason.

 

If the oil pressure at idle is lower than before then that indicates something is going on

 

Should be 1.5-2 bar at idle when warm depending on viscosity

 

We would be using 10w50 or 10w60 in that engine

 

Have the oil squirters been removed?

I did wonder about the calibration, i. e. the ECU or the DASH2 is simply interpreting and / or displaying the information incorrectly. How would I go about fitting and getting a reading from a mechanical sensor?

It seems now that at idle the pressure is much what it used to be, around 2bar. When I first turn on the engine from cold it's reading as around 7bar and then drops to ~2bar when everything's up to temperature. That said, that's only today after my first test since fitting a new sensor, so I reserve full judgement until I've done a more thorough assessment.

Could using the correct viscosity oil (10w50) have any positive effect on this...?

I'm not sure on the oil squirter situation. What are the effects of having them fitted compared to not?

If its already been checked presumably when the new sensor was fitted, I doubt its a calibration problem, but it could be worth a double check with a mechanical gauge, which can either be T into the current sensor position (which is currently where?) or substituted temporarily, changing the oil hot viscosity will have a small effect on oil pressure, but shouldn't be used as a band aid.

Seems fine how it is now then, that's what I would expect to see

Keep an eye on it, if it changes again would be worth checking it with another gauge to make sure before worrying too much.

If your thinking of changing the oil may be worth dropping it and having a close look at it.

Should give you an indication if anything is going on inside the engine.

I did wonder about the calibration, i. e. the ECU or the DASH2 is simply interpreting and / or displaying the information incorrectly. How would I go about fitting and getting a reading from a mechanical sensor?

 

It seems now that at idle the pressure is much what it used to be, around 2bar. When I first turn on the engine from cold it's reading as around 7bar and then drops to ~2bar when everything's up to temperature. That said, that's only today after my first test since fitting a new sensor, so I reserve full judgement until I've done a more thorough assessment.

 

Could using the correct viscosity oil (10w50) have any positive effect on this...?

 

I'm not sure on the oil squirter situation. What are the effects of having them fitted compared to not?

Seems fine how it is now then, that's what I would expect to see

 

Keep an eye on it, if it changes again would be worth checking it with another gauge to make sure before worrying too much.

 

If your thinking of changing the oil may be worth dropping it and having a close look at it.

 

Should give you an indication if anything is going on inside the engine.

Ok, that sounds like good news!

So 9-10bar is an acceptable high-RPM pressure? What would you say is TOO high, i.e. "if I see x bar, I should start to worry again..."

I'll change the oil tomorrow morning and see if there's anything untoward in there. Fingers crossed...

It's higher than I would normally see when the car is up to temp but cold they will be that high

Ok, that sounds like good news!

 

So 9-10bar is an acceptable high-RPM pressure? What would you say is TOO high, i.e. "if I see x bar, I should start to worry again..."

 

I'll change the oil tomorrow morning and see if there's anything untoward in there. Fingers crossed...

It's higher than I would normally see when the car is up to temp but cold they will be that high

Gotcha. So is it high enough (on boost / at high RPM) to be cause for concern, or is it within acceptable parameters? I've been reading horror stories of 'popped off oil filters' and all sorts...

Gotcha. So is it high enough (on boost / at high RPM) to be cause for concern, or is it within acceptable parameters? I've been reading horror stories of 'popped off oil filters' and all sorts...

I would still want confirmation that this gauge is reading accurately first but if you can check what it's doing when over 80degrees

Maybe pull a log off after a run

I would also say the hot pressure needs looking into, 130+ psi is OK for cold pressure but I would want to be seeing under 100psi at high RMP when hot, if the PRV is not doing its job and limiting pressure its can cause other problems, and the one that I would be most worried about would be the over pressure getting past the pump rotors and popping the front main seal, which can quickly empty all the oil from the sump, its also not good for the bearings.

Has it got steel main caps on it? Very few places in the UK can line bore them properly, and if they are not done right you will have bearing problems and oil pressure issues. As Lee says, trust a good mechanical gauge over an electronic sensor. Always mount electronic oil pressure sensors on -3 Aeroquip type flexi hoses, away from engine heat and vibration. Even the good ones can be temperamental. Cheap ones are a nightmare. Most garages will have (should have....) a universal oil pressure test kit with various adaptors and T pieces)

I would also say the hot pressure needs looking into, 130+ psi is OK for cold pressure but I would want to be seeing under 100psi at high RMP when hot, if the PRV is not doing its job and limiting pressure its can cause other problems, and the one that I would be most worried about would be the over pressure getting past the pump rotors and popping the front main seal, which can quickly empty all the oil from the sump, its also not good for the bearings.

Yeah, it's safe to say I'm more than fairly concerned about all of that... I've never seen oil pressure as high as this before the engine was stroked.

Has it got steel main caps on it? Very few places in the UK can line bore them properly, and if they are not done right you will have bearing problems and oil pressure issues. As Lee says, trust a good mechanical gauge over an electronic sensor. Always mount electronic oil pressure sensors on -3 Aeroquip type flexi hoses, away from engine heat and vibration. Even the good ones can be temperamental. Cheap ones are a nightmare. Most garages will have (should have....) a universal oil pressure test kit with various adaptors and T pieces)

Interesting. I'm basing this purely on the invoice, but I'm fairly certain that the engine hasn't been fitted with steel main caps. Titan don't list them as coming as part of the stroker kit and although main studs are listed on my invoice, main caps aren't. That raises another question, of course, in that should an engine that's supposed to be capable of silly-high power figures (turbo choice etc dependant) have steel main caps fitted really...?

One problem at a time... Back to the issue at hand, my electronic sensor is - as it always has been thus far - fitted to a sandwich plate for the oil filter. To be honest, given that sandwich plates are provided specifically for the purpose of adding sensors to an oil system I'd never considered that to be a problem... If they're meant to be fitted to a flexi hose, where does that physically get plumbed in? Or is it that one end of the hose gets fitted into the sandwich plate and then the sensor into the other end of that, placed somewhere else?

If an oil pressure test is a fairly common requirement I'll endeavour to get one done locally - understandably I'm not keen to drive my car very far or very much right now to try to limit the chance for any drastic problems occurring... Any recommendations on WHERE is best to get that done (in London) gladly accepted, though.

Surely it's best to put it on a lorry and hand it back for any issues to be rectified?

I know this doesn't answer any of your questions, but if I'd just spent the kind of money I imagine you to have, I'd be p!ssed at having to put my hand in my pocket again to rectify issues that should be covered by some kind of warranty.

Hope you get it sorted buddy!

Some will say that you can get a different pressure reading depending on the take off point, IE sandwich plate or Lexus bolt, but this should only happen if the sandwich plate is sub std and drilled in the wrong gallery,

The sensor is fitted directly to the housing/bolt if electric type, if mechanical, a capillary tube is fitted via a union and the tube taken to the cabin for the gauge, for a garage to fit a temporary gauge to check it will be fitted to the points i mentioned above, most garages will have a Snap on gauge which are pretty accurate.

Yes, adaptor in sandwich plate, hose in adaptor, sensor in other end of hose, remotely mounted away from the engine.

Steel main caps can open a totally different can of worms, lots of places in the USA to do the line bore and line hone, very few who can do a long straight six block here in the UK. I would be grateful badly bored mains can't be your issue here

You are obviously not afraid to spend money, just buy your own cheapish kit, Sykes Pickavant do a fairly good. Now, getting in there and connecting it up could be a PITA. If you had a remote sensor you'd just unscrew it easily and fit the adaptor and hose to the mechanical gauge in its place

Some will say that you can get a different pressure reading depending on the take off point, IE sandwich plate or Lexus bolt, but this should only happen if the sandwich plate is sub std and drilled in the wrong gallery,

The sensor is fitted directly to the housing/bolt if electric type, if mechanical, a capillary tube is fitted via a union and the tube taken to the cabin for the gauge, for a garage to fit a temporary gauge to check it will be fitted to the points i mentioned above, most garages will have a Snap on gauge which are pretty accurate.

Gotcha, makes sense. The sensor has always (for very nearly 3 yrs, since I went single) been in the same place on the sandwich plate, so I think I've got to assume it's correct seeing as the readings I have had for the previous incarnations of my engine were what would be expected.

Yes, adaptor in sandwich plate, hose in adaptor, sensor in other end of hose, remotely mounted away from the engine.

 

Steel main caps can open a totally different can of worms, lots of places in the USA to do the line bore and line hone, very few who can do a long straight six block here in the UK. I would be grateful badly bored mains can't be your issue here

 

You are obviously not afraid to spend money, just buy your own cheapish kit, Sykes Pickavant do a fairly good. Now, getting in there and connecting it up could be a PITA. If you had a remote sensor you'd just unscrew it easily and fit the adaptor and hose to the mechanical gauge in its place

Good news about the main caps then!

I replaced the electronic sensor myself fairly easily last week (access is improved slightly with my front-facing plenum believe it or not), so assuming fitting a mechanical sensor - temporary or otherwise - is a case of 'unscrew one, screw in the other' it shouldn't be too much of a problem. Uh, hopefully...

Time to Google 'Sykes Pickavant'.

Thanks for all the info, all, it's really appreciated.