Oil Pressure Help

[Muli]

I got a bit of a problem . . .

I have not long had my car back from having a service carried out on the car by a local BMW garage and noticed that my oil pressure light and my oil pressure gauge is hardly registering when Ideling, now when moving the light goes out and pressure is ok, not been driving eracticly I didnt want to cause any more problem (so I cant tell how high it goes upto). spoke to the garage and they seem to think its something to do with the set up?? and have advised me should be ok . . . a bit worrying really

I have jacked the car up, all is ok, no oil anywhere??

the previous owner has moved the oil filter to accomadate the BTB manifold. it now sits where a battery would normally be so there is a quiet a long for the oil lines to travel.

But before I took the car in for a service, when the engine was warm the oil pressure was sitting at about 11psi now its hardly registering and the oil light on the dash is flickering and sometimes staying on until revs start going up above idle.

Likely suspicions are that the oil used previously was a bit thicker, I have contacted the previous owner who advised that he used Mobil one. wasnt sure of the grade??

BTW the guage is mechanical and not electrical.

Any help on this matter is much appriciated

Thanks

[town325i]

if you have a trusted oil pressure gauge it sounds like the oil pump is on its way out but to make sure i would get a oil pressure test done at a local garage to make sure. if the light stays on after a 1000rpm i would be worried i had a bottom end die due to a dodgy oil pump

[Muli]

if you have a trusted oil pressure gauge it sounds like the oil pump is on its way out but to make sure i would get a oil pressure test done at a local garage to make sure. if the light stays on after a 1000rpm i would be worried i had a bottom end die due to a dodgy oil pump

Thanks for the reply bud, I'll have to get the oil pressure checked at my local garage.

after 1000rpm the light goes out and oil pressure rises. when it idles cold it sits at about 10psi, as soon as its warmed up thats when the oil pressure is dropping?

anyone have any idea on how much an oil pump is and how much I will be looking at??

I had a friend who advised me that it may be a dodgy oil filter so that has been changed and still no joy.

What the garage said before was that the low oil pressure due to the lengh on the pipes to where the filter has been re-located but this is a load of B*$$*CKS that is as I had a conversation with a guy who runs a rally car who advised this will not make a difference.

What I dont understand is, it goes in its fine and when it comes out its F*&*%$D!!!

[Jon_Bmw]

Well 11psi hot or cold(especially worrying) idle doesn't seem adequate to me, I would want 25+ ideally 35.

What does the pressure read when under load and above 2000rpm?

[Muli]

Well 11psi hot or cold(especially worrying) idle doesn't seem adequate to me, I would want 25+ ideally 35.
What does the pressure read when under load and above 2000rpm?

So I've got a nackered engine in other words??

now I thought 11psi when warm was ok? read in the bently manual that the pressure should be anything between 7-28psi and at max speed is 57-85psi which is why I didnt think I had a problem??

at 2000rpm it was showing around 20-30psi cannot remember exaxtly at the moment

[Brianmoooore]

Around 8 PSI at hot idle is acceptable according to BMW, but I must admit, not on any engine that I'm buying!

[Jon_Bmw]

Muli, it is a strange one, one that I have posted before about.

I have played around with an oil pressure guage on an m20 before and never got what I would call satisfactory Idle readings from it. It was located on a T piece from the standard oil pressure switch. Cold idle, it would register 55-65 from memory. When under load it would be in a similar position. Once it got to hot idle, it would read very low on the guage (<20 iirc) and I could never fathom out why. There shouldn't be that much difference between cold and hot idle in my experience with other cars.

My 205 sits at 70 cold idle, 35 hot idle, 28 idle after 15 minutes track time an anything between 50-70 with any throttle.

My old s4 sat at 5 bar cold idle, 2 bar hot idle and straight round to 4 bar plus with any load. So very similar to the 205's figures.

Its worth noting that both the above cars come with pressure guages as standard, and an m20 doesn't...

I don't think BMW 'do' oil pressure guages, certainly not in e30's. The s14 got the closest with an oil temp sensor.

Although location shouldn't play a part, I wonder if there is some underlying issue with location. Your cold idle is concerning.

I also don't know the stats on the BMW oil pump, they may, and from Brians post have thought it uneccessary to provide 2 bar at warm idle. But it doesn't explain why my m20 custom guage showed good cold idle

As I said at the start, its a strange one, that has always puzzled me and I have not seen a definitative answer for it.

[Muli]

Thanks for the words of wisdom jon.

So I'm still none the wiser on what steps I should take next??

Is it worth swapping the oil pump then?? or is the pressure in the engine too low?? what I dont want to do is keep throwing money at an engine thats past it!!

anyone know of anyone selling a 2.7 M20 ??? with good oil pressure???

[Jon_Bmw]

I'm not entirely sure, its been a while since mucking around with m20's

I personally would try and find the specifications of an m20 oil pump. What pressure is it supposed to supply at the different loading/RPM points.

I have re read both of your posts and hopefully I haven't missed it, but where is your mechanical gauge sender installed? I am presuming near the oil pressure switch(standard OE) but that would need a T piece as you said you have retained the standard OP light.

There is not a lot to go wrong with a mechanical gauge, so that can almost be ruled out.

Changing oil pumps is not fun on an m20 really, although easier than replacing a sump I guess...

The worrying thing is that your standard warning light is operating, and as long as that is not an electrical fault, the oil pump at best, or the engine could shortly be scrap

[Rav335uk]

Could something be blocking the strainer or pick up in the sump????
I have this intermitant fault and my pressure test was ok.

[town325i]

Could something be blocking the strainer or pick up in the sump????
I have this intermitant fault and my pressure test was ok.

to clear that problem up the sump needs to come off and if the sump is off it might aswell have a new oil pump fitted

[daimlerman]

The OP says that the filter is now located on the 'battery tray',just wondering if location is the issue,if the filter was at it's original level but moved,say,to the inner wing,would this help? The usual mod for the filter with a BTB is to reverse the housing,not move the thing higher and futher away.

[Muli]

The OP says that the filter is now located on the 'battery tray',just wondering if location is the issue,if the filter was at it's original level but moved,say,to the inner wing,would this help? The usual mod for the filter with a BTB is to reverse the housing,not move the thing higher and futher away.

Thanks for the advise guys, What I need to do is find out if the engine is shot or not, (are there any test which can be carried out to give me a definative answer?)

I really dont want to have to pay for a new oil pump if the engine is a gonner.

I'm working this weekend so its a job for nxt weekend, to pull the sump off and have a look.

Does anyone with a BTB have any more info on reversing the oil filter housing?? or what have you done to accomidate the oil filter? (its ok I was being lazy, now searched and all q's answered)

[stonesie]

Could something be blocking the strainer or pick up in the sump????
I have this intermitant fault and my pressure test was ok.

It's certainly possible, when i changed the sump gasket on my 320 there was a 4-5 inch section of gasket missing from the gearbox end... Most of it was found in the strainer

It's a job i would not do again, not with the engine in the car anyway

[e301988325i]

I'm running 10w-40. Cold idle 60+psi, hot idle (oil 85c) 15psi. When hot it reaches 60PSI after about 3000rpm

You havn't said what oil viscosity is in your car? if it's ?w-30 this would cause low hot idle figures.

I read 10psi per 1000rpm is required for proper lubrication, ie 2000rpm - 20psi, 3000rpm - 30psi etc etc