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-   -   why do mag cases loose oil pressure? (http://forums.pelicanparts.com/porsche-911-technical-forum/146614-why-do-mag-cases-loose-oil-pressure.html)

birel23 02-01-2004 02:30 AM

why do mag cases loose oil pressure?
 
if the main bore housings are strait,& the oil update has been done and all clearences are correct why would a mag case drop alot of pressure when it warms up?

Early_S_Man 02-01-2004 05:27 AM

birel23,

What are the numbers you have to base this question upon? Pressure at idle [900 rpm] ... 1500, rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm, 5000 rpm, 5500 rpm, 6000 rpm ... all at 190F???

If you are still using the early pre-76 oil pump ... it has the smallest of all of the pressure pumps, and it has been well-discussed regarding low pressure at idle! As long as full spec pressure is met with hot oil at 6000 rpm, there is nothing to worry about!

HawgRyder 02-01-2004 09:14 AM

I think Birel23 is refering to losing pressure when reved up?
If the pressure relief springs were old and tired...perhaps they would allow the relief pistons to move too early.
Fortunately they can be changed from the outside of the case.
I would try these first...cheap and easy to get to.
Bob

birel23 02-01-2004 05:00 PM

no when i reved it up it went up but not as much as i exp[ected but when i started engine at idle it was fine but after a few minutes it looked like the key was off unless you reved it up? i was using the older style pump but im installing 964 now.

Grady Clay 02-01-2004 05:11 PM

What are you using to measure the oil pressure?

Best,
Grady

birel23 02-01-2004 06:45 PM

factory gauge & before and after motor rebuild. i did not build this motor i took it to a local who is suppossed to be the best before motor was built it had good pressure after at idle hardly any so i changed sender,no change.so i changed gauge still no difference. i pulled motor took it back to them they disasembled it and said all was fine they thought somthing was wrong with turbo i sent turbo out they said it was perfect. i then pulled motor out of shop and decided to reasemble my self and check everthing i had paid for, well i was charged for a new pump. the original date (74) was on the quote new pump that is when i bought 946 one.there were a few other things i paid for that were not there but everthing did look ok. even with old pump it made great pressure. i just want to make sure i do it all right this time.


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