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Hi friends, i need to test my oil pressure and I am wondering which tool sources people have used that have the appropriate fittings.
The WSM says to use VW 1342 tool in conjunction with two adapters: M10 x 1 adapter (Part No. 999.105.013.02) plus and M10 x 1 / M18 x 1.5 adapter (Part No. 901.101.175.01). I am assuming the Oil Pressure sender threaded port is M18 x 1.5.
What have others used or rented? I am looking at this tool renting
from the local AutoZone, I'll need the M10/M18 adapter still, but I am open to other tools. Does anyone wanna rent one?
Also what tools have people used to remove the sender without removing the alternator. I've heard about using a crow's foot but what size?
Why am I testing my oil pressure? My max pressure on the dash gauge reads low at 4.2bar (15w50 oil). The factory specifications are 5-bar @4000-rpm measured at the pressure sender port. The gauge seems to function normally, reading max pressure (4.2) when cold, and fluctuates with RPM when hot but never reading above 4.2 Bar. Electrically things checkout (new front harness) good solders and connections at 14-PIN, grounds cleaned, and gauge pins cleaned. So I am going to test my oil pressure next to see if the sender is bad or if there is an oil pressure problem. Cold start at idle
Last edited by Michael Benno; 07-09-2020 at 01:00 PM.
Michael, let me have a look tomorrow. I've got a gauge and have done this test, so I must have the M18 adapter-- but I will have to check the toolbox. I've also got the crow's feet, will check the size.
The sender maxxes out at a certain value that is nominally 5 barg and the oil pressure as measured directly may be higher than that shown on the gauge. Cannot remember the set pressure of the oi pressur erelief valve but it is something like either 7 barg or 8 barg. What you actually displayed on the dash panel is also dependent on the calibration of the sender and any signal losses so just beucase it maxxes at an indicated 4.3 barg does not mean that is what it is. I suspect many owners have been chasing oil pressure issues when in fact there is no problem with oil pressure thus why Porsche recommend checks with a good old fashioned mechanical analogue gauge that can be calibration checked.
There is also a specific oil pressure reading at a specific rpm point for test purposes.
If you have an S4 then you need to check if the oil pens have been replaced in the cylinder heads if one or two of them fall out you’ll get low pressure when it’s hot and it will be about 4.2 max
Hi Stan, thanks, and yes, I am thinking this is a possible cause of the oil pressure loss. I read through this thread where you identify the missing pins (PN 928 105 262 00). I figured I would test the pressure first before cracking open recently refreshed my valve covers again. Are the senders prone to fail in a manner where they read low max pressure?
Also, I know the part number for the alloy pins, but are the rubber caps available as well? what is the part number.
FYI, here is a picture I took when I had my covers off for refinishing back in January. This is the right side head and it looks like the covers were still in there then. Who knows if they still are, or if the left side is intact.
The pins are the upgrade part ,rubber no longer made.
the rubber pins fall out due to softening of the rubber possibly from the chemicals used in the oils,
and heat degradation and shrinkage.
Test the oil pressure with a separate gauge,
Please let us know what you find.
In the few cases I have fixed once the oil was hot the pressure would never go above 4.5
And when cold the pressure was dropping lower sooner on the warm up cycle
I have a 90 GT here and need to compare the oil pressure at the block to the dash gauge, too.
I bought an adapter to put between the gauge and the oil pressure port. But, I would like to compare readings in real time. Somebody suggested a oil filter sandwich plate with ports to connect the oil pressure gauge.
I need to get a long term project off the lift to make room got the 90GT.
The car in question has a fresh GB stroker build, so I am confident there is nothing wrong with the engine internals.
For comparison purposes...
Start up oil pressure is 5 bars. At an idle I can watch the oil pressure drop as the engine gets to full temp. During that period I get the expected 2 bars to every 1k RPMs. It will peg 5 bars above 2k RPMs.
At some point when the engine has reached maximum temp the oil pressure will not go over 3.25 Bars even over 5k RPMs.
Having spent a lot of time pondering the issue I've come to think that the oil bypass valve might be misbehaving.
In the later years ether the oil temperature relief or oil bypass were deleted. I assume it was the oil temperature relief valve was deleted.
@jcorenman was kind enough to lend me his pressure tester and Crowfoot wrenches. They arrived today and I was able dig in and remove the oil pressure sender and test the oil pressure in the block.
Here are some pictures of the tools Jim sent me. The pressure gauge is in PSI, so I had to do the conversion. The WSM test pressure of 5-Bar at 4000-rpm equates to 72.5PSI. The max reading on the gauge is 100PSI which is about 7-bar. And you will note a peg on the gauge just above the word "pressure" that looks to be about 115PSI or 8-bar. Also note the lager crowfoot has been machined thinner to fit in the tight spaces. For all you DYI'er out there, you may want a gauge that goes to 11-bar, and you may want to do some machining to legs of the larger crowsfoot to make them thinner to fit in more positions.
Pay special not to the layup of the crowsfeet. You need to have the flat sides flush and the stepped sides facing outward for minimum stack height.
Note the M10 to M18 adapter this fits into the sender threads.
The hardest part about removing the sensor was snaking the crowfoot wrenches into position on the sensor and adapter. Once in please it was a simple as breaking them free. Removing the sender required a cheater bar on my 3/8" socket driver to break free. Once I had it loose I was able to remove it with my fingers. Make sure you have the test hose ready to swap to minimize oil loss. I was able to remove it and loose less than a 1/4 teaspoon of oil.
Testing was fairly straight forward. Start the car check for leaks and observe pressure. I took some videos for your enjoyment. In summary, using 15w50 Mobile 1, Cold Start the engine oil pressure was over 7-bar at idle (first video). As the car warmed, I saw the oil pressure drop as expected (video 2 and 3). Once the car was warm, radiator fans engaged, temp needle in the center zone, the engine oil pressure was above 8-bar at 4000-rpm (video 4). Also I noted the dash pressure gauge was reading 5 bar with the sensor wire disconnected, as it should. It would seem the oil pressure in my motor meets the specification requirements and the low pressure readings on the dash were a result of a faulty oil pressure sender.
This is the oil sender that is not functioning properly. I think it is original to the car, no record of replacement. You can see there seems to be heat damage on the casing.
Last edited by Michael Benno; 07-14-2020 at 01:54 PM.
07-08-2020 | 10:06 PM
Oil Pressure Testing tools
