1971 2.2 T Oil pressure / temperature

[timothy.miles]

only having driven my new* 2.2T for about 500 miles I'm unsure what I should expect / hope for!

The temp gauge does not have numbers graded on it - a white bar at the bottom of the gauge indicates 'cold' ,a section in the middle is without marking - 'normal' temp and the top of the gauge is yellow / red 'hot' I think this gauge is from a sportomatic ?

so - when driving in ambient temperatures of about 10degrees on A roads or motorway at no more than 70mph, temperature sits just above the 'white' section of the gauge and oil pressure at 3000 RPM is just a shade under 30 (psi I presume?)

However, if motorway speed increases to 80 or 90 mph temperature rises a chunk - needle moves by say 3 mm. and oil pressure can then be read as something like 20 psi at 3000 rpm.
when speed is reduced to 70 mph the temp does not drop very quickly back to 'just above the white', but over a long period of time it does drop.

At idle once at temperature oil pressure reads zero. oil light does not come on or even flicker.

Q's:
Does this sound like good bad or indifferent oil pressure? (i'm not anticipating that it is 'good' !)

What temperature scale could be applied to the sportomatic gauge? - ie. how hot is my engine getting?

Should temperature be so slow to fall, do I need an oil cooler (don't think it has one fitted )

Where can I get a good 2.7 engine to swap mine out while i rebuild !

[Barry]

Hi Tim, I'm sure there will be many more experienced people here than me, but just to have a stab at this:

1) Oil Temp: sounds fine to me, I think usually the gauge hovers around this level (which is around 170-180 I think?): as I'm sure you're aware some gauges are graduated, some are not. Either way, it would be normal for it to creep up under harder conditions, and then drop back down again. I'd relax about it . Don't forget there's just about two gallons of oil there, so once hot, there's a lot of heat energy to dissipate, so it would normal for the temperature to take a little while to drop back down again. Don't know whether it is possible to get an airline blow-gun to the underside of the engine mounted cooler, just to make sure that it's not a bit clogged with muck though? Might be worth it to be on the safe side, if not don't worry.

2) Oil pressure: really you are looking for about 1 bar (14 psi?) per 1000 revs, with 15-20 psi at idle being ideal. Anything below 10 psi is getting a tad low, although even when there's nothing on the gauge there's probably still plenty of 'flow'. A few things you can do if you're worried:

a) Borrow an accurate 'mechanical' oil pressure gauge, and temporarily plumb it into the oil supply: you could probably do this near the oil pressure sender in the middle of the engine. This would confirm the accuracy of your guage, although your readings sound about right for a 'well run in ( ) engine'.

b) Change the oil to a very good quality 20/50. If you are really, really worried, re-mortgage and put Redline fully synthetic 20/50 in: beware, it's very expensive (£40 + per 3.8 litres ). Amazing stuff though, added 5-10 psi and took off 20DC temp from my 2.4T.

c) Consider oil line restictors: these go between the head-feed oil lines and the head, and drop the oil feed hole form 6mm to 2.5mm. It sounds dramatic but in actual fact the effective flow of oil to the heads isn't as much as the 6mm hole would suggest. I made my own at 2.9mm and they added about 10 psi to the idle oil pressure. These restrictors were introduced by Porsche on later air-cooled engines, as they considered the heads were being-over supplied with oil, which in turn meant that the scavenge side of the oil pump was working hard to keep up with the oil flowing into the sump.

d) Before you do any of the above, to reassure yourself, you could remove one of the upper rocker covers and get someone to flick the engine over (don't start it!). You'll be amazed at the quantity of oil flooding around there.

In all I suppose this was a long way round of saying, it'd be nicer to see some more presssure but don't worry too much: keep an eye on the temperature, use good oil, keep it topped right up and if you notice any changes investigate promtly .

P.S. As you've probably heard, these engines use a very high flow / medium pressure pump, rather than the low flow, high pressure pumps we have in our British cars. As it's the oil film and not the pressure that does the lubricating, the ultimate oil pressure in a 911 is less of an issue.

HTH

[timothy.miles]

Barry,

Thanks for the reply - you've improved my peace of mind no end!

Where can i find out more about these oil line restrictors?

[Barry]

I read about them in Wayne Dempsey's 'How to Rebuild and Modify Porsche 911 Engines' ISBN 0-7603-1087-4: page 83, from memory ( ).

Anyway their real name is 'camshaft housing oil pressure restrictors', Porsche part no: 901.105.361.01. According to the book they have a 'circumferential groove around the adaptor to differentiate it from the original adaptor'.

Best bit: 'Engines that normally read low or near-zero oil pressure at warm idle will show increases of 10-20 psi after installing the flow adaptors'.

I would underline, however, that your engine is probably fine anyway. If you did try these, it might be worth puting them in, get the car hot, and see what the pressure is. If it's much above 15 psi at really hot idle, I personally would be tempted to open the holes out .1mm (point one) at a time until the idle pressure is about right. The reason for this is that the oil to the heads is also operating as a coolant, so I'd think there was a value in trying to strike a balance between oil pressure and flow to the heads, if that makes sense.

Again, as above, if you put them in, worth getting your assistant to flick the car over with a rocker cover off, just to make sure all's well with the installation, and there's still plenty of lube flying around .

[davidppp]

Barry is as ever on the money.

Its very easy to make these restrictors by soldering or brazing the hole, and drilling to 1/8 inch..then replate them, ideally.

Kind regards
David

[Barry]

I just turned a couple of inserts up that sat in the fitting: by their shape they couldn't go anywhere: took about an hour to make both and fit them .