Oil Pressure Advice On A 944
Discussion
I'm loking to buy a 944 and have seen one I like, but I'm concerned that the oil pressure seems high.
When starting the engine, the pressure guage goes over 5 bar (max on guage), and on the short drive I took it for, it didn't move. When I spoke to the seller, he said that it drops after it's been driven for a while.
Does anyone know what this may be? Does this sound like a problem that I should walk away from?
When starting the engine, the pressure guage goes over 5 bar (max on guage), and on the short drive I took it for, it didn't move. When I spoke to the seller, he said that it drops after it's been driven for a while.
Does anyone know what this may be? Does this sound like a problem that I should walk away from?
Could it be a clogged oil filter or very thick oil?
I get him to have an oil and filter change and see if that improves things.
If not, I'd walk away, as my next guess would be to investigate if there's a pressure regulator valve somewhere that might need replacing. Which I would see as enough reason to walk away from the car.
I get him to have an oil and filter change and see if that improves things.
If not, I'd walk away, as my next guess would be to investigate if there's a pressure regulator valve somewhere that might need replacing. Which I would see as enough reason to walk away from the car.
Edited by willdew on Thursday 15th February 12:53
Colesy21 said:
I'm loking to buy a 944 and have seen one I like, but I'm concerned that the oil pressure seems high.
When starting the engine, the pressure guage goes over 5 bar (max on guage), and on the short drive I took it for, it didn't move. When I spoke to the seller, he said that it drops after it's been driven for a while.
Does anyone know what this may be? Does this sound like a problem that I should walk away from?
When starting the engine, the pressure guage goes over 5 bar (max on guage), and on the short drive I took it for, it didn't move. When I spoke to the seller, he said that it drops after it's been driven for a while.
Does anyone know what this may be? Does this sound like a problem that I should walk away from?
Sounds normal enough. After a long drive with the engine warmed up plenty you should see it drop down the gauge a little, but only at idle.
NJH said:
Sounds normal enough. After a long drive with the engine warmed up plenty you should see it drop down the gauge a little, but only at idle.
Not sure I agree. I don't think it's normal to be off the scale at any point. Especially as I presume the cars done a fair few miles in it's life, so pressure will have dropped over the years. If it was reading 4 to 4.5 when cold, I'd think it was "normal", and I would then guess it would drop to 2 or so on idle when properly warmed up.
refill said:
My S2 consistently reads round about 5 warm or cold.
I don't know anything about engines so I don't know if that's good or bad, but I've done 12,000 miles in the car so far and it all seems fine to me.
I don't know anything about engines so I don't know if that's good or bad, but I've done 12,000 miles in the car so far and it all seems fine to me.
Agreed. I have done just under 70K miles in my S2 and I don't ever remember seeing less then about 3 on the gauge. Most of the time I will see about 4 to 4.5 and when cold it will be rock steady on 5. The car is on almost 170K now and doesn't loose oil or smoke on over-run so even the valve guides are still good.
You do have to be careful here.
Just switch on the ignition but don't start the car - and look to see if the oil pressure is reading zero (as it should be) or 5 bar.
A simple cut on a particular wire (or a damaged oil pressure sender or wiring fault) will make it read 5 bar whenever the car is switched on and can fool buyers - then if it seems right it should be under 3 bar hot on tickover of about 850rpm.
If it ticks over @ too high revs - drive it in 5th slower and slower until the revs drop to 850 and see what the oil pressure is then.
Anything at or over 1.5 bar hot on correct tickover (on a square dash car) and 2 bar on a curves dash car is fine.
Any more of these tips and you won't need to buy from the likes of me to find a good car!!!!!!
Baz Hartech
Just switch on the ignition but don't start the car - and look to see if the oil pressure is reading zero (as it should be) or 5 bar.
A simple cut on a particular wire (or a damaged oil pressure sender or wiring fault) will make it read 5 bar whenever the car is switched on and can fool buyers - then if it seems right it should be under 3 bar hot on tickover of about 850rpm.
If it ticks over @ too high revs - drive it in 5th slower and slower until the revs drop to 850 and see what the oil pressure is then.
Anything at or over 1.5 bar hot on correct tickover (on a square dash car) and 2 bar on a curves dash car is fine.
Any more of these tips and you won't need to buy from the likes of me to find a good car!!!!!!
Baz Hartech
I really doubt Porsche would design a gauge that when the reading is "normal" is would be off the graduated scale and so be a figure that could not be measured/indicated. Surely if the oil pressure was supposed to be above 5 bar they would have a gauge capable of reading higher?
My 968 is just over 4.5 bar when cold and when at higher revs, and just under 3 bar when hot and at idle, and my interpretation is for that to be very healthy (it's just had an engine rebuild 1000 miles ago). Prior to the rebuild, it was at about 4 bar when cold and revving, and 2 bar when hot at idle, so the "new" engine shows the sorts of tangible oil pressure improvements I expected.
My 968 is just over 4.5 bar when cold and when at higher revs, and just under 3 bar when hot and at idle, and my interpretation is for that to be very healthy (it's just had an engine rebuild 1000 miles ago). Prior to the rebuild, it was at about 4 bar when cold and revving, and 2 bar when hot at idle, so the "new" engine shows the sorts of tangible oil pressure improvements I expected.
Check the oil on the dipstick (wipe on a tissue to see how dirty) and use a mirror and torch to carefully checkout how much crud is under the rocker cover. Check your own car to calibrate!
Get an idea of how well maintained the car is by checking out how clean the service items are (oil filter, air filter, engine bay etc.
Get an idea of how well maintained the car is by checking out how clean the service items are (oil filter, air filter, engine bay etc.
Globulator said:
Check the oil on the dipstick (wipe on a tissue to see how dirty) and use a mirror and torch to carefully checkout how much crud is under the rocker cover. Check your own car to calibrate!
Get an idea of how well maintained the car is by checking out how clean the service items are (oil filter, air filter, engine bay etc.
Get an idea of how well maintained the car is by checking out how clean the service items are (oil filter, air filter, engine bay etc.
Yeah and check that they are not all Fram filters.
Just so as you understand that the maximum oil pressure is governed by a pressure relief valve. It can stick (although rare - more likely to cause low oil pressure by sticking open because it only has the return spring force to return it - than too high because it is stuck shut because the oil pressure then is high enough to probably move it) but once the car is started and warm the oil pressure at tickover is lower because the pump speed is not high enough to reach a maximum pressure yet. However you do not need maximum oil pressure unless you are driving a higher revs under power.
When the engine revs up the oil pressure increases until the oil pressure relief valve opens - after which it remains at that pressure however high you rev the car.
So hot tickover oil pressure gives a clue as to the condition of the engine and the revs at which the maximum oil pressure is reached also contributes.
Many guages read incorrectly and it is always worth checking with ignition on and the engine not running - that it reads a true zero - or adjust readings accordingly.
Thicker oil does offer a slight increase in the pressure reading as it seals better around the relief valve.
There are three basic versions of the 944 oil pressure relief valve - a simple piston and spring (no rubber seals) and a more complicated dual action pressure controlled valve that offers better low speed pressure through better sealing pressures and a rubber "O" ring seal. The latter has 2 types of fittings on the end seal, depending upon the engine type. A seal on the end against a flange is used for the older type piston valve engine as an improvement and the later engines with different machining have a seal im a groove a few milimetres along from the end of the valve.
Baz Hartech
When the engine revs up the oil pressure increases until the oil pressure relief valve opens - after which it remains at that pressure however high you rev the car.
So hot tickover oil pressure gives a clue as to the condition of the engine and the revs at which the maximum oil pressure is reached also contributes.
Many guages read incorrectly and it is always worth checking with ignition on and the engine not running - that it reads a true zero - or adjust readings accordingly.
Thicker oil does offer a slight increase in the pressure reading as it seals better around the relief valve.
There are three basic versions of the 944 oil pressure relief valve - a simple piston and spring (no rubber seals) and a more complicated dual action pressure controlled valve that offers better low speed pressure through better sealing pressures and a rubber "O" ring seal. The latter has 2 types of fittings on the end seal, depending upon the engine type. A seal on the end against a flange is used for the older type piston valve engine as an improvement and the later engines with different machining have a seal im a groove a few milimetres along from the end of the valve.
Baz Hartech
Gassing Station | Porsche General | Top of Page | What's New | My Stuff