What is your oil pressure? ('91 E30 M42)

[BBDirtbiking]

I just finished installing an oil pressure gauge, digital. After machining some parts to hook up both my dummy light and my gauge, I finally have a working gauge, although... I think its off with my pressures...

So at a warm idle, it reads 8-9 PSI (~700 rpm idle)... It was actually reading below 5 once, which then it just reads LO... When I have my car at 6000+ rpm it reads just over 40... My engine runs amazingly, and these pressures just seem way to low to be true... Was just wondering what a healthy M42 should have for oil pressure, warm, at different RPMs...

Thanks,
BBDirtbiking

[BBDirtbiking]

Doing this right now... http://www.m42club.com/forums/showthread.php?t=594

Figured its not a difficult job, might as well check it out. Car is coming up on an oil change soon, 500 miles...

[BBDirtbiking]

Well, no help here...

I got it figured out though, needed a better ground to the sender. Hooked up a very accurate oil pressure gauge and saw I was not close to what it was really at, so I jumped the sender to the body and found that it was reading wrong the whole time, which I figured. Disappointed in the lack of help on this forum, I find it hard to believe people do not know their pressures...

[carlos318is]

I was watching this mate as I have just got a pressure gauge and was wondering what it would run at.

So what is it running at

[bmwman91]

I think most people don't know because it takes seemingly invasive modifications to measure the pressure. Did you put some sort of Tee fitting in where the pressure switch is?

There's a spacial BMW tool out there for this that is basically a hollowed out filter lid bolt that has a gauge on it. That's the only "factory-looking" method I've seen to measure oil pressure.

I seem to recall reading 60psi as the oil pressure at red line RPM with 20W-50 oil.

[BBDirtbiking]

carlos318is, my car was running around a 18 PSI idle, although it could have probably been warmer. When I tested it with a very precise gauge it was reading 14 with a really good warm motor. When I drove the car hard, didn't hit red line on my test, I reached 59 PSI, which is on par.

According to the Bentley manual the M42 should have a minimum idle of 9 PSI, and 60-66 PSI under very spirited driving.

I am running Fully Synthetic (Mobile 1) 10W-30 oil also.

bmwman91, with some help I machined an aluminum block that had an input using the stock oil fittings to one output using the stock threading, and then another one using a Standard thread to accompany my after market sending unit. This was a costly task as I had to buy several fittings for my oil pressure cable, which they are not cheap at all...

Here are a few pictures I snapped with my camera just as a reference in case anyone else is wondering what I am talking about.

[BBDirtbiking]

I just spent a good amount of time creating a response to yours' questions and I get a stupid message saying it needs to be approved by a moderator... Why is this?

Could it because of the photos, using external links to this post? This happened earlier when I was trying to link to another thread on this site.

I will try again.

[BBDirtbiking]

I was watching this mate as I have just got a pressure gauge and was wondering what it would run at.

So what is it running at

Oil pressure at a warm idle was around 18 PSI, according to the precision gauge I had a pressure of about 15 PSI but I think this is due to my car being slightly warmer on that test...

When I took the car out to test my new set-up I reached a maximum of 59 PSI which probably took place around 5,000 RPM...

According to the Bentley manual the minimum pressure at an Idle should be 9 PSI, and driving hard around 60-66 PSI, so I am in the ballpark, which is good piece of mind.

[BBDirtbiking]

I think most people don't know because it takes seemingly invasive modifications to measure the pressure. Did you put some sort of Tee fitting in where the pressure switch is?

There's a spacial BMW tool out there for this that is basically a hollowed out filter lid bolt that has a gauge on it. That's the only "factory-looking" method I've seen to measure oil pressure.

I seem to recall reading 60psi as the oil pressure at red line RPM with 20W-50 oil.

When it comes to a 318iS I am not keen on keeping it factory, its my go-cart so oil pressure is an important modification in my books... I would keep an E30 M3 factory.

I, with help from my father, machined an aluminum block to accept the stock metric fittings to convert it to a stock fitting for the dummy light then another for the standard fitting found on the after-market sending unit.

Here are some pictures of the finished product.

[bmwman91]

Neat installation. I'll have to look into something like that in the future.

I'm not sure why you got a message about needing mod permission. Usually only your first two or three posts need approval. Your forum permissions are normal. Let me know if it happens again.

[DesktopDave]

Nice install.  Good info too.

Sorry about the 'mod' thread.  It's been happening frequently to members with low post counts.  I'm not really sure what the threshold is but your 25 posts should get you some cred here.  I approved the post, you may delete or edit as you wish.

[bwawuz02]

Here's what I'm going to run for oil temp, pressure, and switch.

1x E30 M3 Gauge Cluster
1x TRM Oil Distribution Block with stock E30 M3 temp sender in place of pressure switch
1x Adapter Bushing in the new 1/8npt port
1x Proper Pressure/Dummy light VDO Sender to my VDO Vision pressure gauge

But thanks for the info, i needed it to decide on the proper sender

[deansweet]

edited for content...