Porsche Enthusiasts Club Forum

just replaced the oil filter after only @1000 miles. If I left the car for 24 hours all the oil in the filter appears to run back into the sump. When I restarted it takes a few seconds for pressure to come back up. If I left the car for 5 - 6 hours no problem full pressure almost instantly.
All seems OK now with a new filter (MANN) but I am a bit concerned. Is there a non return valve built into the filter or is there a separate non return valve in the engine somewhere?

Hi
Yes the filter does have a type of non return valve...cheap filters either don't have this or don't have a good enough valve to stop the oil draining as you have found. This will lead to excessive wear if not rectified, as you probably had noticed the engine is noisy before the oil has pressurized again....best practice is to only use genuine filters for these cars..

Regards

Pete

I would say that goes for all cars TBH.

On Mk3 Mondeo TDCIs I would say to only use genuine fuel filters despite them costing over three times the price of an ECP item unless you wish to scrap the car.

Hi Folks -

All oil filters leak out, even Porsche spec too. Best to start your motors at least once a week. Decent oils these days also protect your engine. I run a 10W 40 Shell Helix 7 in my S2 - still like honey when I change it. Always use a Porsche filter...

Dave

bit of an update - oil running down within @ 6 hours now. So I guess I have either a cracked pickup pipe or the oil pump seal to the crank case has failed. Will take the sump off etc and try and find out.

how long does it take for the pressure to come back, hope your not going by just the gauge

do you get a top end rattle on start?

is it 8 or 16V

Also an oil non return valve in the head.

Oil filters and thermostats are two items for any car that I have found to be really poor in the aftermarket no matter what brand name is on the box or the make of car.

For a Porsche it needs to be genuine or Knecht/Mahle. There was a time when the Porsche stock of genuine 964 or 993 filters (cant remember which) were faulty on the non return valve yet the Knecht/Mahle ones were ok, which was odd. But usually, genuine is the way to go, or a proper OEM (not what some vendors call OEM, do your homework and know for yourself)

Out of interest, has the belts been changed recently? Your symptoms sound a lot like a poorly torqued up crank pulley, they rely on the tight torque to drive the oil pump and in colder weather (thicker oil and harder to pump) can slip initially.

thanks for the replies,
oil pressure comes up in @ 3 seconds with top end rattle so its not the sender/gauge. Crank bolt was seriously tight too.
where is the oil non return in the cylinder head?
my car is a 2.5 non turbo. I think the engine is 1990, but the cam belt tensioner is still a manual adjustment not spring loaded so I'm not 100% sure. (it was replaced by porsche as original went bang at 60K - did someone do the cam belt wrong????). Where is the engine serial number I can't find one on mine?

so far I have stripped off the oil cooler, pressure sender and oil pressure relief valve, oil sump and pick up pipe (no sign of any cracks), about to take off the oil pump (want to clean everything before I take it off, lots of muck all around it). So far not found anything I can point at directly but having read previous threads it could be any of the above with only a slight leak for the air to get in and let the oil run down. So I have decided to pull off anything oil pressure related and redo it anyway. Easy to do it now whilst I have got the steering rack, support beam etc off anyway. Oil filter is a brand new Porsche original I put on a few weeks back just in case it was that.

Also found that the engine mount under the exhaust manifold was loose - the mount was previously replaced by a "Porsche Specialist" who has cross threaded the bolts! and then couldn't tighten them up, what a tw@t, also found the the balance shafts are nowhere near aligned correctly which is possibly why the internal leak has started. Looks like previous muppet who change the cam belt etc made no attempt to align them. Lesson learned, I should have checked them when I bought the car.

bit of an update. Put everything back together today. All new seals. O rings etc throughout. I have stripped and cleaned out the oil cooler too. When I started to take the oil pump off, oil immediately started leaking out as soon as I slackened the first bolt. When all the bolts were out the oil pump just fell off. The loctite bond had clearly failed either through age or incorrectly set up balancer shafts.
Engine runs beautifully now, no vibration at all from the engine. I've got everything crossed for tomorrow that the oil pressure comes up immediately when I start it in the morning.

Hi Kashurst -

Yup - I hope your motor is ok after all your hard work!

As regards oil filters - from my local official Porsche Centre - they are stamped as 'Made in the USA' ! Which is great - God Bless America!

Dave

Well good news - 2 days in and the oil pressure comes up immediately every time - result!
not only that but the engine runs really well with the balancer shafts correctly lined up. I can't believe the difference. It's incredibly quiet as well.
As a side effect my rough idle has gone, now it just sits there at @ 850 rpm purring. As a result of fitting the engine mounts correctly the judder when I reverse has gone too. I also had to remove the power steering, pump etc and I discovered it had a minor leak. Thats now fixed as well and the steering with new fluid in it is transformed - not sure why its made much difference but I'm really pleased. It was a lot of work pulling it all to bits, but the results have been well worth it. Recommend to anyone who has just got a 944 or similar to get the balance shaft alignment checked out.