Oil pressure

[inovermyhead]

Finally got my supplementary gauges sorted and working and noticed this reading on the oil pressure gauge.
First photo at tick over, warm engine
Second photo at 2500 rpm
No red idiot light ever

 

[jmackro]

Are you asking whether you should be concerned about the low oil pressure at idle when warm? My answer would be "no, that's pretty typical". Your bearings are happy as long as there is some oil pressure at low rpms. And your 2,500 rpm pressure looks great!

 

[Mike Goble]

What weight oil are you running? With 20-50 oil my pressure is about 25 psi at idle and 75-80 psi on the highway.

 

[Honolulu]

When I put an oil pressure gage in my '70 VW van I was surprised to learn a few things... Cold idle pressure was 8 bar, due to "thick" oil. Hot oil pressure about 8 bar, I assume it was opening the pressure relief valve. Hot idle pressure would flash the "low oil pressure" light.

A neighbor who built a Bug up quite a bit said he frequently blew off the aftermarket oil filter if he incautiously revved his motor when still cold.

The photos look like your pressure is right where it wants to be.

 

[Stevehose]

Ditto

What weight oil are you running? With 20-50 oil my pressure is about 25 psi at idle and 75-80 psi on the highway.

 

[inovermyhead]

Thanks guys for your feedback, I was just a little concerned with the low numbers when idling and on start up.
It also sounds a bit ‘tappity’ for the first minute or two but this soon disappears so I assume this would be related to the oil getting up into the valve train, tappers were set probably 2K ago.

 

[m5bb]

I was not happy with low oil pressure on my M30 after a rebuild in 2014. My motor is a 3.5 from late 80's. Probably less than a 150k on it.
After rebuild with new bearings all around and a rebuilt B35 head it still ran around 20-25 at idle when fully warmed up.
While I had the engine out for the recent complete body restoration I wanted to do a couple more things to the motor like powder coat the oil pan.
The old while you are in there comes up. Oh yeah, low oil pressure.
I did some investigating and asking some other engine guys and since new oil pumps are NLA I determined that I could replace some parts that were still available.
I took my existing pump to my friendly machinist and we went over all the tolerances in the pump and all seemed to be reasonable. One thing I did notice was a fair amount of wear on a plate that is next to the rotor pieces that are the actual pump. There is a flat plate called an intermediate plate. For $3.00 I replaced that with a new one.
Now I have 40 PSI at idle on a warm motor and 70-80 at speed.

Number 9, number 9, number 9.......... Oh sorry that was the Beatles song.

 

[bluecoupe30!]

I was not happy with low oil pressure on my M30 after a rebuild in 2014. My motor is a 3.5 from late 80's. Probably less than a 150k on it.
After rebuild with new bearings all around and a rebuilt B35 head it still ran around 20-25 at idle when fully warmed up.
While I had the engine out for the recent complete body restoration I wanted to do a couple more things to the motor like powder coat the oil pan.
The old while you are in there comes up. Oh yeah, low oil pressure.
I did some investigating and asking some other engine guys and since new oil pumps are NLA I determined that I could replace some parts that were still available.
I took my existing pump to my friendly machinist and we went over all the tolerances in the pump and all seemed to be reasonable. One thing I did notice was a fair amount of wear on a plate that is next to the rotor pieces that are the actual pump. There is a flat plate called an intermediate plate. For $3.00 I replaced that with a new one.
Now I have 40 PSI at idle on a warm motor and 70-80 at speed.

Number 9, number 9, number 9.......... Oh sorry that was the Beatles song.

View attachment 87340

Well done, way to hang in there and find a solution. Great result, thanks for reporting this.

 

[stphers]

I wonder if it is the same one that the 2002's use? Different part numbers but it still may fit. Been putting those into oil pumps for quite a few years now, even if the pick up section plate surface is ok It is aluminum and the plate is steel so much longer for wear

Thanks, Rick