why does the oil pressure take so long every start?
Discussion
sorry if this has been asked a zillion times before BUT....although I know they all do that sir, why does it take so long for the pressure to build (i.e light go out) when you start up, even though it ran only yesterday!!
the motor is new (with new big & mains only a month ago again after it had apparently been run 'dry')and it also has a recon front cover/oil pump/rotor etc.
the filter IS the right one, with anti-drain valve, and my other 350i doesn't seem to have this problem (with the same filter) to the same degree at all (yes it does take a while to prime after standing for ages, but day to day use and the red light goes out quite quickly...)
are they all a bit variable in this respect? or do I perhaps have another fault?
how quickly should the red light go out? is there a 'typical' duration?
the motor is new (with new big & mains only a month ago again after it had apparently been run 'dry')and it also has a recon front cover/oil pump/rotor etc.
the filter IS the right one, with anti-drain valve, and my other 350i doesn't seem to have this problem (with the same filter) to the same degree at all (yes it does take a while to prime after standing for ages, but day to day use and the red light goes out quite quickly...)
are they all a bit variable in this respect? or do I perhaps have another fault?
how quickly should the red light go out? is there a 'typical' duration?
Even cheaper - take the oil pressure switch off the 'good' car and swap it with the 'slow' one.
It might be that the switch threshold pressure is higher on the slow one. Usually the light will go out during cranking or very soon after but you don't get much pressure until after she starts. Do you also see the light flicker on tickover when hot on the 'slow' car?
This shouldn't be a massive problem because when the revs are that low, you still have residual oil in the bearings and on the cam - you only need to worry if you've driven for 5 miles on no oil pressure.
It might be that the switch threshold pressure is higher on the slow one. Usually the light will go out during cranking or very soon after but you don't get much pressure until after she starts. Do you also see the light flicker on tickover when hot on the 'slow' car?
This shouldn't be a massive problem because when the revs are that low, you still have residual oil in the bearings and on the cam - you only need to worry if you've driven for 5 miles on no oil pressure.
Possible leak where the pickup pipe fits into the block allowing oil to drain down?
I'm getting rid of the oil cooler circuit too in mine - it doesnt need it and it adds complication to the already complex oil system.
I've been round silverstone in a 5 litre car for 20+ minute sessions without oil cooler, and it wasnt an issue - I figure my little 3.9 road car would get away without it...
I'm getting rid of the oil cooler circuit too in mine - it doesnt need it and it adds complication to the already complex oil system.
I've been round silverstone in a 5 litre car for 20+ minute sessions without oil cooler, and it wasnt an issue - I figure my little 3.9 road car would get away without it...
My previous car, and only car I've fitted an oil temperature gauge to, before the 350I was an E30 3-Series BMW with a turbocharged E34 535I engine running at around 300bhp.
It didn't have an oil cooler and even thrashing it on track the temperature never went above around 110 degrees, in fact it got just as hot sitting in traffic for a long time, so I wouldn't be too worried about losing the oil cooler myself.
But it is surprising how much longer the oil temperature takes to rise than the coolant temperature, so don't thrash engines too hard as soon as the tmperature gauge is up to normal!
It didn't have an oil cooler and even thrashing it on track the temperature never went above around 110 degrees, in fact it got just as hot sitting in traffic for a long time, so I wouldn't be too worried about losing the oil cooler myself.
But it is surprising how much longer the oil temperature takes to rise than the coolant temperature, so don't thrash engines too hard as soon as the tmperature gauge is up to normal!
Edited by ROOODBOY on Monday 29th March 02:53
to answer your queries, no the light doesn't flicker when hot, and I think the problem is that it is just draining down overnight somehow - I could try another filter but I think this is the 3rd!!
the other problem is that the electrical pressure guage is crap and I just don't trust it - it doesn't seem to respond in the way that it should to changes in temp/revs. It also reads back to front so I suspect someone has swapped the polarity at some stage. Tried to get at the guage from under the dash but that seems impossible - do I have to remove the dash? how do you do that?
I am tempted to fit a proper wet guage anyway, to get a true pressure reading - otherwise I'm always wondering what's going on with the electrics.
thanks for all the help & advice so far.
the other problem is that the electrical pressure guage is crap and I just don't trust it - it doesn't seem to respond in the way that it should to changes in temp/revs. It also reads back to front so I suspect someone has swapped the polarity at some stage. Tried to get at the guage from under the dash but that seems impossible - do I have to remove the dash? how do you do that?
I am tempted to fit a proper wet guage anyway, to get a true pressure reading - otherwise I'm always wondering what's going on with the electrics.
thanks for all the help & advice so far.
Not sure that taking an oil cooler off of a car that has one fitted is necessarilly a good idea without knowing exactly what the oil temp is doing. For example, I have fitted a capilliary type gauge, and on trackdays in summer I will see up to 130 deg. C as an oil temp., and that's with a cooler fitted. Some engine oils will start to deteriorate at that level, which is part of the reason I use Motul.
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don't forget all cars are designed for various markets - cooler probably is a good idea in hot climates/track days etc but since we live in the cold & wet (like today) you'd probably get away with it!!! I agree with the comments about oil temp vs. coolant temp, oil takes ages to warm through and most engines shouldn't be pushed hard until oil is at 70deg C, and it takes about 20 miles on a motorway to get to that, even though coolant reaches that temp in about 2 minutes/.....
VR1 20/50
I have found an oil leak which may be around the sandwich plates so will check what that's all about as I have been told this could be the issue, also to check whether the oil pick-up was fitted with a gasket (to the block) when the engine was put back together after bottom end rebuild, as this can also cause priming issues apparently....
I have found an oil leak which may be around the sandwich plates so will check what that's all about as I have been told this could be the issue, also to check whether the oil pick-up was fitted with a gasket (to the block) when the engine was put back together after bottom end rebuild, as this can also cause priming issues apparently....
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