oil pressure

[bjdp]

i have a e30 325 m20 engine..... what should the oil pressure be on these engines because i fitted and connected up a vdo pressure gauge (from an audi) which goes up to 5 bar pressure but when i start the car (at idle)the gauge needle goes off past 5 and stays there..... any advice?????? thankyou

[march109]

Where did you fit the pressure guage? And are you sure its fitted correctly?

It should read approx 1bar at idle. Sounds like your just getting a 'live' feed to yours, and not a signal feed.

[koh]

is it a mech or electric gauge? what sender have you used if its electric,cold idle could be over 5 bar (my dirty nissan r33 gets 7 bar at idle when cold,and the gauge reads up to 9)

[bjdp]

its a mechanical gauge from a audi and i took the signal from the original oil pressure sensor (tapped into the single wire) on car. the gauge has a earth,positive and a "g" connection which im guessing means to gauge.... do i need to buy,connect, anything more to get this working correctly??.......cheers guys

[march109]

The original oil pressure sensor isn't fit for this purpose.You need an Audi pressure sensor designed for a mechanical gauge this sensor needs to be placed preferably in line where the pressure is, ie. not in the sump!!

[Grrrmachine]

This is usuallly why the gauges are cheap: the sender is about 65 quid new from VDO (cheaper on ebay/scrapyard) and the pipes and unions are about 25 quid from a company called LMA.

[bjdp]

so pls state in lamo instructions what i need to buy and do ....sorry... will an audi sensor fit my e30

[march109]

so pls state in lamo instructions what i need to buy and do ....sorry... will an audi sensor fit my e30

Of course it won't without some fiddling. But an Audi guage will most likely work with an Audi sensor.

Get the guage off the sensor its on now and make sure you put it back as it was, thats your low pressure warning sensor youwant it working wether the gauge does or not.

This should do it and be pretty self explanatory:

http://www.demon-tweeks.co.uk/Motorspor ... /1773/1861

Then you'll need the oil pressure sensor from an Audi with the VDO guages or a new one like this:

http://www.demon-tweeks.co.uk/Motorspor ... /1774/2084

[stonesie]

You will also ALWAYS get a maximum pressure reading on cold oil at it gets much 'runnier' as it heats up. My old nova did it, the MAN's at work do it (the only vehicles with gauges rather than a light) and when I finally get round to fitting the Audi sensor and gauge to mine I would lay money on that doing it too since im not using any fancy 0-XX oil, M20's like 10-40

[march109]

You will also ALWAYS get a maximum pressure reading on cold oil at it gets much 'runnier' as it heats up. My old nova did it, the MAN's at work do it (the only vehicles with gauges rather than a light) and when I finally get round to fitting the Audi sensor and gauge to mine I would lay money on that doing it too since im not using any fancy 0-XX oil, M20's like 10-40

That might be the case but mine has never gone off the scale on either of my gauge equipped e30's.

That and OP currently has his wired to the low pressure switch normally attatched to the idiot light. I am not sure but AFAIK its not designed to give any kind of signal output and is a simple ON/OFF output. That and the fact its not designed to work with the VDO guages then it will never work.

That said even my fancy oil is at higher pressure during warm up according to my guages. Not by alot though.

[stonesie]

Yes I read that, his gauge will be getting a simple on-off so he needs the proper VDO sensor, it's been covered earlier in the thread so I didn't repeat it

My post was just telling him not to be surprised if once he has the VDO sensor the gauge reads full when he starts it up... The reading at idle will drop as the oil heats up.

A mates old mini had a TIM capillary gauge and read between 80-85 psi on cold idle, about 20 once warmed up.

[march109]

I've just had a blonde moment and re-read my post, it now occurs to me that when the car starts from cold it idles faster than when warm which may account (in part at least) for the higher pressure even with fancy oil.

[e301988325i]

its a mechanical gauge from a audi and i took the signal from the original oil pressure sensor (tapped into the single wire) on car. the gauge has a earth,positive and a "g" connection which im guessing means to gauge.... do i need to buy,connect, anything more to get this working correctly??.......cheers guys

Just to clarify, an oil pressure gauge fed with oil via a cappillary is a mechanical gauge, a gauge fed with wires from a sensor is electrical.

On my M20 b25, at cold idle the pressure is 60psi, hot idle is circa 10-15psi using 5w40.

[bjdp]

thanks alot you guys thats been perfect......thankyou march109 for the links it helped alot....
one last thing b4 i go....does it matter if the sender is a 0-5 bar pressure or 0-10 bar pressure as my gauge only displays up to 5bar pressure and also what tread pattern am i after fot the t-piece adapter to fit onto my m20b25 engine...cheers again

[Grrrmachine]

If the guage is 5 bar, you need a 5-bar sender.

If using an Audi/VW sender, their threads are M10x1.0, whilst all the fittings on the BMW are M12x1.5.

Do a quick search on this forum about it; from what I've read, an oil extension pipe is needed as well as the T-piece because you won't be able to fit the T, the new sender and the original sender all in the place where the original sender is now.

[march109]

http://www.dtmpower.net/forum/e30-3-ser ... ender.html