Oil Pressure on start-up issue

[paultv]

I've been noticing that my oil pressure light is slow to go out - abou 4 seconds.

Needless to say the filter is new (BMW) as is the oil.

This is not good - so I fitted a gauge and watched it as I start the car - zero pressure for 4 seconds - then instant pop to 60psi.

Anyone with a verdict before I open the bottom up to check the relief valve isn't sticking or.... thermostat valve in the oil feed to the cooler??

or the relief valve in the pump.....

Thoughts from anyone?

Thanks!

Paul

[biffer]

If the car is a 325 with oil-cooler several people have highlighted this problem over the years.
For some reason it seems to be because of the filter being horizontal- if you park the car nose-up on a hill overnight and then start it the oil-pressure will likely appear instantly.
I took my cooler assembly off and now the filter screws directly to the block at more of a downward angle and oil-pressure is almost instant.

[boiliebasher]

Never really paid attention to it buts that interesting to know as I still have the oil cooler fitted to mine. Thanks for sharing

[biffer]

Normally the filter being horizontal shouldn't make a jot of difference- the anti-drain valve inside should keep the filter full, can only guess that heat from nearby exhaust manifold might affect the filter -valve for a short while after stopping the engine.

I removed my cooler 'cause i found that outlet pipe to the cooler was always hot which at the time i took to mean that the cooler-thermostat had failed.
But recently i read that this is normal-it turns out there is supposed to be a constant,small flow of oil being sent round the cooler.
Being a sucker for originality,i'd like to put the cooler back on, but the thought of that oil-pressure delay again puts me off.

[Cloggy Saint]

There's really no need for an oil cooler on the M20. As far as I know none of the M5x engines have one fitted.

[paultv]

I was aware that the position of the filter causes this to some extent - but BMW filters and some others are fitted with a "non return" valve - to help with this - but in practice
it makes no difference at all - even if there is such a valve in these filters.

As I drive a lot in Europe, and long distances at that - I'm tempted to keep the oil cooler - but I really don't like this pressure -up delay - I'm sure its worse than it used to be as well.

Maybe I'll remove the cooler fittings and test with a direct filter attached - just to verify the cause...

thanks for the input!

Paul

[Brianmoooore]

As I drive a lot in Europe, and long distances at that - I'm tempted to keep the oil cooler
Paul

You don't use 1980's oil, so you don't need 1980's oil coolers. A decent oil today out performs oils from 40 years ago by orders of magnitude, and will still be fully doing its job at any temp. your lubricant is likely to reach.

[tha881]

I've never had the oil pressure issue, but I ditched my oil cooler a couple of years ago anyway so I could do a more complete oil change. I will soon be installing an oil temperature gauge on mine. It will mean I can keep an eye on the temp when I'm on long distance motorway journeys, where I'm usually keeping revs between 3 and 4.5k in 5th.

Brian what is your opinion on zddp in oil and is it needed for our type of engine? Also if you ditch the cooler I would advise not to go for a cheap brand of oil unless you just poodle about, and especially if you use semi as I've heard the quality can vary a lot. I'm using Mobil super 2000 10w40.

[paultv]

Fair point Brian!

So I gues the best thing is to block the hose outlets on the adapter and then rotate it ?

Anyone know the thread size of the hose metal ends before I pull it to pieces?

Paul

[biffer]

I found deleting the cooler does have a noticable effect on the oil ( Shell Helix 5w40 in my case)- it darkens/goes brown a fair bit quicker than with the cooler fitted. By the time 5000 has passed the oil is v. dark-brown/nearly black and that's with using the car mostly at 70mph.

[biffer]

A possible compromise for you might be what i had on my car for a while- you can take the filter-head off and refit it so the filter is nigh on vertical- this gave instant oil-pressure on my car.
But the cooler lines arn't long enough to allow this unless they are swapped over where they go into the filter head- even then they are only JUST long enough and it also means the flow thru cooler is reversed.
It seemed to work ok. for the short while i tried it before junking the cooler.
Getting longer lines made-up to allow the filter to hang down could be another way to keep the cooler long-term.

[paultv]

Anyone know if the cooler has a directional valve or something? In bently is says to mark the hoses to make sure you put them back the same way round - implicating some direction??
Otherwise I can't see it matters very much.

On European motorways I'm driving at 80 or 90 mph for hours on long drives - summer temps around 35C.

Paul

[Brianmoooore]

Fair point Brian!

So I gues the best thing is to block the hose outlets on the adapter and then rotate it ?

Anyone know the thread size of the hose metal ends before I pull it to pieces?

Paul

The whole filter and adaptor block can be removed and replaced by a simple double ended male bush, leaving the filter horizontal at a right angle to the block, as on the 320i. See the engine pics in the third post of this thread: viewtopic.php?f=112&t=279883&p=2967626#p2967626
There is also another version found on the 320i, that uses an adaptor block, similar to that on the 325i, but simplified without the 'stat and hose connectors. This one can be rotated to leave the filter at any angle you like.
I don't think there's any one way valve associated with the cooler, but I think I remember something about it being connected as it is to prevent it draining out when the engine is stopped.

[paultv]

Thanks Brian...that would make some sense...I'm going to "re-wire" mine to see if turning the filter downwards fixes my start up sluggish pressure build..at least this will point me in the right direction...then maybe a 320 adaptor plate and remove the cooler...let's see.

Paul

[Brianmoooore]

Whatever you do, don't just plug the ports to the cooler. That will work fine, right up to the point when you oil does get really hot, at which point the thermostat bypass will close, cutting all oil to the engine!

[paultv]

Well thats fixed it - very gratifying - oil cooler still connected but filter now hanging down - instant oil pressure!

Oilf filter position new.jpg

also the filter is away from being toasted by the manifold, and easier to change.


Paul

[biffer]

How did you do it-new lines?
Some folk on internet suggested the oil-pressure delay was nothing to be bothered with citing some Vauhall engines where a delay of 7 sec. is normal, but just seems wrong,wrong,wrong to me.

[paultv]

I just reversed the lines and they fit - a bit tighter than original - and I can't see how there can be any drain back from the cooler as the pipes are higher than everything else.

The Mrs is going out for a 40Km round trip now - I'll check it when she gets back - can't really see any problem.

and I agree - 5 seconds of zero oil pressure is bloody hopeless, especially when everything has drained out over a few days standing.

by the way the flange from a 320i which allows you to delete the cooler and have the filter downwards facing is 266 euros new!!

bugger that then !!

I wonder if anyone has one?

Paul

[biffer]

Yeah i found that one of the lines was only just long enough when i reversed mine, but i cant imagine there's much relative movement between engine-block and cooler.
Think i'm gonna revert back to this set-up.
Could you confirm at some point that one of your oil-lines is warm/hot at all times, as mine used to be. If yours is one hot/one cool then my cooler was likely working as it should all along.
A possible snag with reversing the lines could be if there was any sludge in the cooler it might get dislodged- tho my cooler seemid spotless inside when i took the lines off.

[paultv]

Everthing in mine was clean - fresh oil - and yes after an hours drive today the lines are warm - one more than the other - so I think there maybe a small flow through the cooler at all times so it stays full and filtered.

Anyhow - all appears normal - instant pressure up which is the whole point -

Happy with this set up - thanks for all the pointers!

Paul

[Brianmoooore]

after an hours drive today the lines are warm - one more than the other - so I think there maybe a small flow through the cooler at all times so it stays full and filtered.

AFAIK, the thermostat in the adaptor block just controls a bypass port, and doesn't atually block flow to the cooler, so even with the 'stat fully open, the differential pressure across it will still send a small amount of the flow through the cooler.

[tha881]

Paul, as I know you do a lot of motorway miles, this may be of some help. I removed my oil cooler and my temp gauge got up to 110°c when holding revs around 4000 for a few miles. Air temp was about 20°c. Not sure what affect it would have if outside temps are 35°c? If cruising at 80ish closer to 3000rpm it was between 100-105°c. So from what I've read, there is no need for the cooler with those temps.