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Oil pressure relief valve
Hi Gents, Are the oil pressure relief valve adjustable. My 911SC oil press is a bit low. Regards Chris |
As far as I know its determined by the spring for bypass so none adjustable.
What do you mean by a " bit low" |
TKS Iceman, The oil press needle had been jumpie for quite some time before I cleaned the terminal of the sencor. I now get a nice steady indication, however on cold start pressure does not peg the needle at the top of the guage and at warm idle the needle drops very low. Not zero but very low. Unfortunately, I am in the UK at present and do not remember the gauge increments. Going from memory and expressing it in percentages I recall that cold start press would indicate about 80% and warm Idle about 5% with a steady needle. It is a 1983 911 SC with 270,000 km. Regards Chris |
Chris i have very similar milage. " pegging " the needle only happens in cooler temps for me if i remember but i will recheck. If its warm out in start ( ambient not engine temp) car dies not kick into high idle so keep that on mind too. Currently we are at about 28c here.
What viscosity are you running ? Also at idle fully warned up some cars even flicker the light. Mine does not . But i have heard this is not unusual |
TKS Iceman, Unfortunately I don’t know what grade oil was put in during the last service. I took her to our Porsche guy in Cape Town for service and brake pads and fluid change, etc. I only fixed the oil press contact afterwards, so never asked him. I’ll find out when home in about three weeks time. My high idle kicks in like clock work. However during warm ambient conditions, like 28 plus, it will settle down quite quickly as it should, and yes, I also get low oil press and alternator flicker at times. My E Type has the same low pressure indication and I was advised to shim the pressure relief valve, which I will attempt when back home. I was hoping that a similar simple fix would be possible with the Porsche as well. Much appreciated. Regards Chris |
I hope your shop didn't put 0w-40 or 5w-40 oil in there since thats trouble.
These engines need high ZDDP oils in either 15w-40, 15w-50 or a 20w-50 oil. You should have 10psi per thousand RPM. |
TKS Steve, I am quite sure it would be 20w-50, which is what I use to top up, but I’ll check when I get home. IIRC it idles at about 8 psi and goes up to about 30 @ 3000rpm. Regards Chris |
That actually sounds about right. Sometimes the low oil pressure light will even flicker at idle. You could consider installing the restrictors on the cam oil lines to increase oil pressure slightly, at the expense of some oil flow to the cams (part number 901.105.361.02). I've seen mixed opinions on the wisdom of using these, though.
Steve, do you use the restrictors in these engines? Mark |
Originally Posted by Mark Salvetti
(Post 15134855)
Steve, do you use the restrictors in these engines?
Mark Reducing oil flow to the hottest parts of the engine (heads, cams, valve springs) is completely and totally counter-intuitive to me. With proper bearing clearances, good oil, and the proper oil pump in good condition, they are not needed. |
^ What he said both posts.
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Thanks Gents, much appreciated. Chris |
I'm a newbie to this - having low oil pressure in 2000 Porsche C4 and would like to replace the oil pressure relief parts - have them on order from pelican but...planning ahead, I looked under car from rear and think I found the plug on the left (drivers) side almost even with Rear wheel. Brass plug - my manual says it should be a M18 but it looks much larger than that (M28?). So I'm not sure I have the correct location. Can someone send me a picture of the location for this plug?
Thanks gmorris552 |
Originally Posted by gmorris552
I'm a newbie to this - having low oil pressure in 2000 Porsche C4 and would like to replace the oil pressure relief parts - have them on order from pelican but...planning ahead, I looked under car from rear and think I found the plug on the left (drivers) side almost even with Rear wheel. Brass plug - my manual says it should be a M18 but it looks much larger than that (M28?). So I'm not sure I have the correct location. Can someone send me a picture of the location for this plug?
Thanks gmorris552 |
Thanks - sorry about that.
Gmorris552 |
Dumb Q - My 83 SC oil pressure is low when warm, fine at cold. Was attempting to check out my pressure relief valve (vertical one under the engine), as well as the safety valve (horizontal). Wondering if I need to drain oil or I can just remove them without removing oil? I just did a fresh 15w50 oil change so hate to waste them. Hoping I find some work / set spring or piston, and that is my root cause for low pressure causing higher temperature....
Thoughts? |
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