Greg_L

I had a leaky oil (return?) pipe, which was replaced very recently - this is it - the solid metal one:


Not much oil was removed for the job - as its not necessary. It was topped up with the same stuff - Castrol Magnatec 10w40 (the same stuff i've used for 2.5 years). The oil is only a few months old, and the filter was done at the same time.

Here's the issue.
The oil pressure gauge reads about 1+ bar at idle until the car heats up, then it drops to just above zero (0.2) at idle, and the oil warning light comes on. When revs increase, the light goes off and pressure is back to normal (at high revs 4.5bar - as always), then at idle it drops again and the light comes on. The oil level gauge seems to be working fine - oil is just over 3/4 full on the gauge, same on the dipstick. The car drives exactly the same. The rpm hasnt changed from its solid 900rpm, the engine temp isnt any hotter and rarely sees 9 o'clock, the only difference is that the pressure gauge is dropping low at idle.

I've spoken to 2 specialists and one thinks grit might have got into the oil pressure relief valve during the pipe fitting. The other specialist thinks that any grit would have gone into the filter and that the pipe fitting is a coincidence and the oil pressure sender is kaput.

I'd like to hear YOUR ideas!

Andy Roe

Hi Greg!! I see what you were talking about yesterday now. Does that pipe flow into the Oil Filter or into the Oil Pump? It looks as though it would flow into the filter so this should have stopped any grit.

I'd still be looking at the pressure sensor.

Good Luck!

Andy

Greg_L

Hi Andy, i'm pretty sure the pipe goes into the oil filter. Looks like the sender might be the first thing to change.
Thanks for the ride yesterday, your car is in mint condition!

darth

I'd put a good quality guage on one of the oil pressure ports just to be sure that the oil pressure is in fact not low. Also, avoid running the engine until the oil pressure is confirmed. Starving this engine for oil can be unforgiving and lead to some expensive repairs.

Bill
90C2

warmfuzzies

Bill,

that was my suggestion too, I think that a quick check of the oil pressure sender wouldn't go amiss either, quick clean if poss and replace the O ring.

kevin.

Greg_L

Will do, thanks.
I thought that as the pressure at high rpm is good, it would be ok ?

Kevin, i think i'll order the part (£27.50 from euro) and send it back if cleaning does the trick. I need to do some miles at the end of the week. I've looked at Adrians book's guide and it looks like a PITA job. I have to BUY a 24mm crowfoot spanner before i can modify it !

darth

All of the things I suggested are what "I" would do if it were my car. It maybe a coincidence that the oil pressure sender decided to die at the same time the tube was replaced and "I" think it's a pretty big coincidence. I would think if the oil sender is kaput it would not be selective in the pressures it is misreading. Typically the pressure sensors have no "smarts" built into them they're just variable resistors. I think the pressure is low across the whole range and the guage isn't precise enough for you to notice it at the hi end. The direction of oil flow in the tube you replaced is into the filter but who knows where dirt could have fallen. I might go as far as to put the old tube back on and see what the pressures look like. The lower pressure may be explained by the oil flow having less restriction or similar and opposite to a person having clogged arteries and hence hi blood pressure. Did you happen to notice if there was any difference in the inside diameter of the tube you replaced? I really wouldn't drive the car in this condition and even starting it and reving it up while sitting could be damaging but less so than if the engine is under load.

Sorry if I sound over cautious
Bill
90C2

Greg_L

Thanks for the comments Bill. I plan to check the pressure this week. The old pipe had a huge split in it and i think its been binned now.

cheers,
Greg

LeRoux Strydom

I would at least replace the oil filter. Some crud may have dislodged during replacement of the pipe and could now be partially blocking the filter, resulting in starvation and low pressure at idle.

Just IMHO.

Le Roux

Greg_L

Right the next update . .

Had my mechanic come over on saturday to check over my car and see why i was getting the oil light come on at idle and a tapping noise under acceleration.
Turns out my oil gauge is reading higher than it should. The car was low on oil by about a litre and a bit - i did check the dip-stick a couple of times, but i must have miss-read it. We put 2 litres in and the pressure came up to about 0.7/0.8 on the gauge. We then took the top off the secondary dizzy and the rotor arm would move freely so the belt has gone causing the pinking i heard. I'd never heard pinking before so i couldn't identify it. So i ordered 2 caps, 2 rotors and a belt (£107.51 from EuroCPs).

i went for a gentle drive on the primary dizzy after the coil lead for the 2nd diz tucked up in the top left of the engine bay had been disconnected. No oil problems, a solid 0.8bar when hot at idle.

Mechanic fitted the dizzy belt, caps and rotors and fired it up, he listened and listened for any untoward noises. But it sounded good he thought. and smoother which i guess is because the old caps and rotors were pretty tired looking. Drove the 20mins home, easy at first, later at some speed, the car performing perfectly. Stopped for fuel, and after leaving the petrolstation, the next light i stopped at the oil light came on as the pressure dropped to nothing.
I drove home and parked up. Next day i took the car to work and the problem is still there. . . I'm thinking i should change the oil pressure sender next and do a pressure check while the unit is out - hopefully the problem lies with that unit and it will go away like it did for Jeremy Pinsly recently.
If i have to drop the oil to change the sender i might put in some 15w50 rather than 10w40...

Shaun Leahy

Greg
after a track day at Goodwood I has same problem, now solved. At idle the oil pressure dropped well below the 1 bar setting, where it used to sit at idle before. The oil pressure was manually tested and the oil press gauge proved OK.
Turns out oil press relief valve was blocked, probably related to track day pressure sending grit thru the system and blocking the way too much at low pressure.
Not sure where ti is but after claning and £300 punds of cheking it works fine for the last year since.

oscarmpn

The pipe looks like a Porsche part and will be the correct size and specification. It may be a coincidence that another component was disturbed during the pipe change. Firstly, I would not drive the car until it is resolved. As the upper scale of your oil pressure seems unaffected, my money would be on the "Oil Pressure Relief Valve" being partially stuck open and so bleeding off the precious low rpm oil pressure. Remove it, clean it and fit new seals. Whilst you are there, remove the new pipe and check it for obstructions/packaging infact anything that could affect the oil flow. Infact it is a good time to change the oil. Good luck.

Greg_L

Thanks for the replies guys, i will check out the oil pressure relief valve again. We briefly took it out last weekend, just to see if there was any krud in there but it seemed ok. I'll check that again and change the seals and the oil and see how i get on from there.

Greg_L

One more thought, when i recently took a little oil from the engine via the oil filler i pushed an inch thick clean plastic tube down into the oil tank. Could this have dislodged/bent/broken anything important with regard to oil pressure? I guess that about a meter of the pipe went in there.....

oscarmpn

"I guess that about a meter of the pipe went in there....."

Well I think you should spend a couple of days striping everything out to retrieve this pipe. It could be restricting the flow????