Low oil pressure at idle, also fuel smell in oil!

[Dub-Se7en]

after forging the engine everything has been running sweet as a nut, even the little CT9 is coping with 1.2 bar ok (so far )

but the one thing that has bothered me is the car has always suffered from low oil pressure on idle.

if the engine is cold or i am driving along the oil pressure is fine, when cold it's almost 100psi and when warm and driving about it's around 50 psi.

but when up to temp and idling the oil pressure drops to as low as 14 psi. which can't be good. it's never been low enough to bring the oil warning light on (well once it did, but the engine was ticking over about 400rpm) but i see that warning light is a 'whoops too late, your engines fucked' light.

this engine has had a lot of work internally, oil galleries have been opened out and de-burred. the oil pump area has also been slightly ported out and de-burred. i was wondering if this has something to do with it? or maybe a weak pressure relief valve but surely the pressure would be low accross the board? (except when cold, obviously)

was thinking of changing oil grade to something thicker like 20w50 but wanted peoples thoughts first

Cheers

Ian

 

[danturbo4311]

Alright mate i had the same problem with mine before, did you replace the o ring on the oil pick up pipe as they are known to leak if not replaced, and i am assumming you replaced the oil pump when you rebuilt it, sounds like the pressure relief valve is working ok

 

[Dub-Se7en]

yep new pump and o-ring. could still be leaking from there, though. good thinking.

it almost seems as though the oil is too thin when warm, i'm using decent quality 10w40 semi synthetic with power enterprise oil filter. that's what is making me think try 20w50 next time round and see how it behaves.

 

[danturbo4311]

when i rebuilt my engine i didnt check it like a doughnut i used it for a while but like yours it idled at 14 psi pressure fluctuating alot oil light never came on thou,its supposed to idle around 2 bar of pressure, normally when oil light comes on its at dangerously low pressure and damage is already done.

What i found with my pump was that it had little scratches on the rotars so obviously when i started it the oil was thicker and the pressure was good however once it was at running temp oil is thinner and leaked back down the cracks throu the rotars into the pick up pipe making me loose pressure and idling at 14psi however if you changed the pump it should be fine.
But i carried on driving it but damaged my bearings lol.

If i was you check for any small cracks in the pick up pipe, double check o rings and pump also is your gauge definetly accurate you could try changing oil and see if it makes a difference

 

[Gee]

Don't know why you think it could be the oil grade. Mine is 5w/30 fully synthetic and has no oil pressure problems.

 

[Dub-Se7en]

it could be a number of things, hence why i posted.

 

[weeJohn]

this engine has had a lot of work internally, oil galleries have been opened out and de-burred. the oil pump area has also been slightly ported out and de-burred. i was wondering if this has something to do with it?
Ian

De-burring the galleries will improve oil flow back to the sump. I am assuming by opened out you mean the return galleries as well?

When you say the oil pump area do you mean the cast block roughness taken off or the machined area that the pump sits in?

I would assume this has been done with experience of the 4e engine who would know where the restrictions are and where they need to be removed to improve oil flow.

The fact you have good pressure at cold but does not mean no harm has been done, the pressure relief valve could be restricting the oil pressure to this level when cold, but not when hot. I would not use synthteic oil in my engine to be honest, as I think it is to thin and can cause problems in an engined designed for thicker oil, but thats just my opinion.

Changing to thicker oil to see what results you get is the easiest and cheapsest test option Ian, I would give it a go. Try mineral oil also.

 

[Gee]

Google:

In order for a lubricant to be classified in any SAE grade (10W-30, 10W-40, etc.) it has to meet certain guidelines with regard to viscosity ("thickness").

For example, it makes no difference whether it's 10W-40 petroleum or 10W-40 synthetic, at -25 degrees centigrade (-13F) and 100 degrees centigrade (212 degrees F) the oil has to maintain a standardized viscosity or it can't be rated a 10W-40.

 

[sx_turbo]

what oil pressure are you seeing when idle?

idle pressure does always tend to be low at idle any way,

 

[Broomy]

but when up to temp and idling the oil pressure drops to as low as 14 psi.

 

[jimmer]

what are all the recommended oil pressures in all circumstances? Is it meant to be the same for every 4efte engine? or is there a leniency for them?

 

[Gee]

Give or take:

5-6 bar on cold start
4 bar when warm and driving
2 bar when idle

 

[Dub-Se7en]

De-burring the galleries will improve oil flow back to the sump. I am assuming by opened out you mean the return galleries as well?

When you say the oil pump area do you mean the cast block roughness taken off or the machined area that the pump sits in?

I would assume this has been done with experience of the 4e engine who would know where the restrictions are and where they need to be removed to improve oil flow.

The fact you have good pressure at cold but does not mean no harm has been done, the pressure relief valve could be restricting the oil pressure to this level when cold, but not when hot. I would not use synthteic oil in my engine to be honest, as I think it is to thin and can cause problems in an engined designed for thicker oil, but thats just my opinion.

Changing to thicker oil to see what results you get is the easiest and cheapsest test option Ian, I would give it a go. Try mineral oil also.

cheers for the advice John

yeah we opened out the returns and removed any casting defects too.

i only have an early pic of the work we did to the pump area but it gives you an idea of what we did

the pump is new, as is the o-ring seals for both pump to block and pickup pipe. we did an oil pressure test before final assembly using a drill to power the pump and all seemed well.

we decided on a semi-synthetic 10w40 based on advice both on here and from our machine shop.

last night i did a test, i drove a 20 odd mile trip on decent speed a-roads but stayed in vacuum almost the entire time. at the end of this run the oil pressure was just shy of 25 psi. i'm thinking maybe running the turbo beyond it's limits is having a significant effect on the temperature of the oil.

question, would changing grade have any effect on the bearing tolerances etc? i was thinking maybe running a thicker grade oil could be an easier solution to stripping the sump off and oil pump etc.

 

[Dub-Se7en]

right i think i've figured what the problem is.

borewash. when i was changing the oil over at my mates garage he commented on how 'petrolly' it smelt. i thought nothing of it at the time but i was about to change the oil for a thicker viscosity type and it stinks of petrol again (this oil is 400mile old)

thing is, my settings are not really above the norm and things checked out fine when i had the car rolling roaded and all was well come mot time too. fpr is set to 3.2 bar turbo running 1.2 bar. i'm hoping it's not piston ring related. i suppose a compression test will tell me that though.

in the mean time i'm going to change the oil again for 10w40, return fuelling and boost to around standard and disable the fcd.

one question, what is standard fuel pressure?

 

[Starlet_Sam]

right i think i've figured what the problem is.

borewash. when i was changing the oil over at my mates garage he commented on how 'petrolly' it smelt. i thought nothing of it at the time but i was about to change the oil for a thicker viscosity type and it stinks of petrol again (this oil is 400mile old)

thing is, my settings are not really above the norm and things checked out fine when i had the car rolling roaded and all was well come mot time too. fpr is set to 3.2 bar turbo running 1.2 bar. i'm hoping it's not piston ring related. i suppose a compression test will tell me that though.

in the mean time i'm going to change the oil again for 10w40, return fuelling and boost to around standard and disable the fcd.

one question, what is standard fuel pressure?

Around 2.3bar

 

[Dub-Se7en]

cheers mucker

 

[Chris@CCM]

i dont think this is ur prob mate tho y not just change the oil go for a hard run and then see. if it is bore wash theres no way the oil will be full of fuel after one run

 

[Dub-Se7en]

this oil was changed only a few days ago, infact i would say it'd got 200miles on it max (i know i said 400, but it was only done on friday night so that can't be right :homer and it stinks of fuel, almost to the same degree like opening the fuel tank.

it won't hurt to go back to standard and see if it happens still, i've noted all the settings the reg etc was on and haven't messed with the timing etc so i can restore the car back easily

 

[Chris@CCM]

flip me thats wild bud .tho if u just change the oil then go for a real hard run it wont bore wash cos it will only do that driving easy

 

[Dub-Se7en]

true that you may have a point and could be nothing to do with borewash because:

i can pull 300 miles from a tank
it doesn't smoke apart from the odd puff of black on gearchanges.
it was set up correctly on a rolling road using a wideband
the emissions were acceptable come mot time.

but, it is something simple i wanna rule out before more drastic measures are taken and the procedure is completely reversible

Ian