Oil Pressure: Too High?

[William Miller]

I installed my rebuilt engine last week.
I followed Waynes book and installed the oil line restrictors.
They have increased oil pressure as predicted.
The needle is arround 1 bar (This depends a little on tempature) at idle and it pegs the needle above 5 bar by the time I get somewhere in the 2000-2500 range.

I don't have the book with me at work, and I don't know if the oil pressure is ever supposed to get that high.
There are the 2 pressure relief pistons and springs.
I cleaned them well (one at a time so they wouldn't get mixed up.)
that doesn't mean they wern't mixed up before.

Before the rebuild the oil pressure was good base on the information in the various manuals I have. Bently, spec book etc.

Those of you that have followed Waynes book and installed the restrictors please let me know your experience.

Anyone know when the relief pistons are supposed to open?
Thanks!

[Jim Richards]

My experience is that the restrictors increased pressure by ~10 psi.

[HawgRyder]

There was a thread not long ago about this problem.
The answer seemed to be a mismatch of sender and guage.
If you have the wrong combo...you get twice the reading on the guage.
Bob

[Wayne 962]

Right - check the sender first before you start to scratch your head...

-Wayne

[William Miller]

The gauge and sender seemed to work fine before except the needle did not move smoothly. I still have the same sender and gauge.
I think it's reading correctly. I have more pressure when cold and it slowly tapers off as the engine warms up.

Wayne, I read that section of your book again last night. I believe you said that it will raise the pressure 10-15psi at idle. You didn't mention anything from there up.

I did find this in Bent;y's book:
Oil Relief valve opens at 6.2 +- 0.8 bar (88.2+-11psi)
Safety valve opens at 8.0 bar (113.7 psi)

Since the 6.2 is above the limit of my gauge I wouldn't know if it's working or not. I wouldn't know if it reached that point.

Wayne do you have a unit conversion section on your site?
what's 10-15 psi in bar.

If you devide 113.7 by 8 you get 14.21 psi per bar (Is it linear)
So if the restrictors increase the pressure 10-15 psi all the way up the scale then that adds about 1 bar. I'm not far off. Am I?
I may need a sensor and gauge that reads higher scale to be sure.
I'm not sure anything is wrong. What is the limit on the gauges in the cars where these restrictors were original equiptment?

If my safety valve is working is high oil pressure bad?

[kstylianos]

William,

I've experienced the same phenomenon on my rebuilt motor. Richard's (ex) Carrera has the updated restrictors and displayed the same pressures as yours and mine.

High or very high oil pressure is hard on the oil seals, etc....Just take extra care that the oil is sufficiently warm before getting the rev's high.

[Porsche_monkey]

14.50377 psi = 1 bar. Yes, it's linear.

[William Miller]

Thanks Charlie, and PHE has anyone had long term experience with this?

Anybody have a car where the restrictor fittings were stock?
If so does the scale on the gauge go higher?
Can the existing gauge and sender be retrofitted?
Thanks!

Charlie, you mentioned somewhere that you were going to build a custom gage for A/F and Volts I think. Are you planning something for your oil pressure?

[Porsche_monkey]

Why don't you replace the sender with a gauge (temporarily) and see what you really have?

[William Miller]

Good thought as a test, Can I get one cheap? Where?
Are the fittings standard sizes?

I bought a cheap water temp gauge for $14 last week just to get a black gauge holder. The only gauge holders I could find locally were chrome.

[Porsche_monkey]

I said it would be a good idea. I did not say it would be easy. I think you will need to get some metric to NPT adapters, or solder up some old fittings for try-out.

[1fastredsc]

As a side note, not directly related. My old 944, before i rebuilt the engine created 5 bar of oil pressure at about 3.5k roughly when at operating temp. When rebuilding, i read that an update was to make sure you had a late model oil pressure spring and use a turbo oil pump. It was already a late model and i so happen to have a spare turbo oil pump laying around. After the rebuild and since, at operating temp, it creates 5 bar of oil pressure at 2.2k rpm now, and hasn't had a problem in the 10k miles that i drove it.

[davidl]

Hello, Guys.

Please could some kind soul post the size of the hole in the restrictors?

I can then make a pair..

kind regards
David

[Tim Walsh]

David,
It's just a banjo bolt with a 2.5mm orifice in it. Put in an order from pelican.I'm not sure how difficult they would be to make but they're only like $20 total from pelicanparts. Even at my college level income it's like an hour and a half of my time.

[davidl]

Thank you so much for that.

I'll make some and tell you.. being in UK does not help!

Kind regards
David

[William Miller]

I know it's not related, but on Saturday my new rebuild began pouring oil out of one of the left side oil return tubes. (The joint at the cam shaft case. I pulled it out and found that the new (Green colored) O-ring split.

This is the second major leak.The first turned out to be the rear main.
When I pulled it the outer lip had a gap between it and the crankshaft.
The new one is sealing fine. I'm not sure the method used installing it as you install the crankshaft into the case is the best Idea. All I can think of is that the seal was defective or somehow it got pinched or deformed when I torques the case bolts.

This car's got it in for me!

At least this time I don't have to pull the engine. I removed the heat excanger. It's like butter when those nut's arn't rusted!

I don't know if the seal was defective or I somehow nicked it during installation.

(Be Careful!)