Oil pressure at idle

[maf260]

My M52 conversion is almost complete. Fitted my new Danthe loom in place of the old home brew version and all is good. One point though - at idle (around 500-600 rpm) the oil pressure warning light comes on. A small blip or increase in revs makes the light go out, but this is obviously worrying. Oil & filter are brand new, oil is to the top of the dipstick. Any ideas/pointers to what I can do or check to stop this happening?

[DanThe]

Does it do it when cold? Or does temp not matter? Could be a weak or damaged pressure relief valve spring on the pump

[maf260]

Yes, does it from cold as well as when warmed up. Can I access the spring easily, or is it a pump removal job?

[DanThe]

I would be checking the pressure switch first. Getting to the pump is a sump off job

[Andyboy]

Why is it idling at 500 rpm? The idle speed is 700 rpm on an M52 and there's only 7psi at that speed. Any less and the lights going to come on.

[DanThe]

They can be anything between 500 and 800 depending on throttle body/ICV bits etc that usually get swapped with M50 stuff

[e30-EVN]

i had this on mine when i first put it in, i found that the slightest blip of the throttle ans the light went out.... idle was slightly low so i raised it a touch - light out

never did it on my m50 at all but like i say, the idle on my m52 was lower than that of the m50

hope this helps

[maf260]

Thanks everyone. Update on this - I've been driving the car around, runs beautifully. Oil light doesn't come on when cold, only when the engine has warmed up a little. Idle sits about 600rpm, temp gauge sits bang in the middle of the gauge, electric fan governed by a Danthe (thanks again!) loom keeping everything in order. Inlet manifold is M50, throttle body is M52. Shall I just wind the idle up a bit?

[e30-EVN]

just turn the idle up a notch.! i did this and have not seen the light since

[Demlotcrew]

Not sure thats a good idea, low oil pressure is a sure sign of bottom end problems, worn shells and worn pump. Oil pressure is always measured between the oil filter and the block oil ways

[Andyboy]

It's only 7 psi at idle. Doesn't need much at 700 rpm without load.

[Demlotcrew]

Andy I will check TIS and come back to you, but I would have guessed oil pressure at idle should be anywhere between 30-40 psi cold.

[DanThe]

Im sure my track car shows 1.5bar at idle

[Demlotcrew]

Mines is 75psi cold and 50psi hot at idle, max pressure recall shows 180psi.

[youngman]

hi, i had the same problem as you in my 328 compact i check pressure mine was .7 bar , so i change the oil, check the oil pick up point, fitted a new oil pump and the engine started knocking after 3 days, i ended up fitting a new engine in the end up costing me £1100 wayne

[DanThe]

Dug the pics out, this is at idle with cold oil



And a minute or two later with some revs on -

[e30-EVN]

since turning my idle up (and i dont mean by 1000rpms lol, more like 50), my engine has given me near 2 years of service, no knocking ect and i dont give her an easy time

i dont see a problem at all

[StefanAnghel]

And how do you turn the idle up?
Thanks