Druck seems low...

[lateapex911]

I just took my 73 911 out for the first ride this spring. I've driven it and warmed it up thru the winter but this was my first 29 mile drive.

I noticed half way through, that my oil pressure, (it's a euro car, so it's "Druck" and is in bars, 0,1,2,3,4,5.) seemed low. It's a new motor, well, it's 5 years old, but MAYbe 10K miles on it. Weekend driving, summer only, pretty much. Rick Deman built it, for those who are familiar with Porsche shops in the NE.

I'm prepping the car for a 400 mile to Watkins Glen to instruct at a two day Drivers ed event.

Normally, the oil pressure tracks the RPMs, if a tad low. Often its nearly zero at idle. Today, it was definately zero at idle, and once I noticed it, it never got above 3 bar, no matter the revs.

I will change the oil and filter, as I know the Webers have been running rich (another story) so the fuel might have thinned the oil a bit.

It could be the sender, or the guage, and i will test them, but, as a matter of "feel good", I was thinking about just getting an oil pressure guage and checking it with that to confirm or deny a core engine issue.

So, can anyone tell me the easiest method of hooking up such a guage? I think I prefer electric, as I could easily run the wires to the cabin temporarily, so what I need is the location of where to plug the sensor in and the thread size etc. Absolute accuracy won't be important, I don't think...I can live with the electric inaccuracies, right?

And any suggestions about how this is common, uncommon, or whatever would be much appreciated too!

I'm a little worried, so thanks for your help!

[304065]

If the late Harry Pellow were here he would hook up a direct reading gauge with about an 8" dial and read the oil pressure to the nearest half pound. Since he has long since Flown West (R.I.P. Maestro!) you are stuck with me.

Now, a few questions. What kind of oil pressure sender setup do you have? On my '66 I have a sender on the top of the engine next to the thermostat, and that engine does not use an "idiot light." However, later cars are equipped with an "idiot light" which utilizes a second terminal on the sender. On my '71 race car with Carrera Tensioners, I have a pressure gage on top of the engine and an idiot light sender plumbed into the oil line for the starboard chain tensioner with one of those machined junction blocks that are common on the later cars.

So the answer to that convoluted question determines the easiest way to tap into your engine's circulatory system. Were it I, I would tap in next to the thermostat on top.

Now, we know that the oil pressure sender has an M10 x 1.0 thread. It threads into an adapter that goes into the block that is M18 x 1.5 thread. Rather than monkeying around with trying to unthread ANYTHING from magnesium and live to tell about it, I recommend you use an M10 x 1.0 barb fitting in lieu of the sender. But where to find such an esoteric accessory? The problem is that M10 x 1.0 adapters and fittings are pretty hard to find, and you do NOT want to accidentally use an 1/8 NPT (national pipe thread, a tapered thread common to muscle cars, old airplanes and the plumbing in Barbie's Dream House) lest the threads be Buggered Beyond Repair. So an adapter like the one sold by McMaster as their 4822T41 (and NOT, mercifully, offered by Pelican) will get you started.

Now, you COULD use a pressure isolator like an intelligent person would use on a direct-reading fuel system, but I assume that you intend to use this for Diagnostic Purposes Only, and furthermore will exercise Due Caution and ensure that you do not inadvertently have a loose connection inside the car that would result in hot engine oil being pumped into the cabin while the car is in motion. So with that warning expressed, one could then use a simple 1/8 NPT barb fitting to 1/8 ID hose, like McMaster's 5346K61, and then as long a hose as you find convenient. At the other end of the hose, another barb to 1/4 NPT female, (quarter inch, because it's going to the gauge) such as a 5346K82, and then finally, the piece de resistance, a SWISS oil pressure gauge, mechanical, such as the Wika 9767452, 0-100 PSI with a 4" face and accurate to 1% of the span! http://www.wika.ws/pdf/23X53.pdf

That's what I would do, and I would NOT move the car while testing. Make sure all the connections are tight and use some teflon tape on the joints. Bonus: if your car has a pressure gage AND and idiot light, tap into the hole for the light so you can calibrate the electric gage with your mechanical one!

Good luck!

[lateapex911]

Thanks John! Did I mention the DE is Monday?

I appreciate the info, and will get rolling right away...although the Wika item seems a bit non consumerish...they have a guy here in CT, I'll call him tomorrow.

You're still chuckling over the concept of an electric guage, aren't you?

When is the Lime Rock PCA race? Are you participating?

[304065]

Jake, the Wika gauge is very easily obtained online, probably even overnight. Mechanical is the way to go because it's more reliable than electric and won't be affected by the same things that would mess up the in-car gauge.

My MFI pump is still with Gus, so I can't make it. I might not even make the Glen. I am not happy about this, but I WILL be driving the car up to the ALMS race in her full race regalia.

[lateapex911]

Really? I missed that part on the website, I'll recheck.

RE: Gus. Sigh..........the major downside of MFI... Sorry to hear that. Tough pill to swallow when the PCA season is so short.

[304065]

Well, McMaster also sells a pressure gauge for $15, 4089K81, that would be one-stop shopping and probably overnight from their warehouse in NJ.

Alas, it's my own fault: I didn't mail the pump to Gus until January. And the car needs a front spoiler and I've got this great Setrab cooler, RS-style, ready to go in, and an accusump for the oil system. Which, by the way, I am going to plumb into the oil pressure port (but using an M18 to AN-10 adapter). So I may end up sitting out this season and working on the car, not so bad, particularly when you consider that I'm also rebuilding the engine for my '66 and collecting parts for the body restoration.

But like Karl Wallenda says: "Life is on the wire. . . "