'74 2.0

When I got the car I was told to change EVERY gasket that had to do with oil and gas. I took a more targeted approach.

Though I changed all of the gas lines (stainless), I addressed the oil leaks as follows:

I first changed the push rod tubes
- thsi helped but there were still leaks

I then changed the oil cooler gaskets WITHOUT TAKING THE ENGINE OUT
- this is a level 5 of 5 manoeuver. It is not a procedure, kinda like a triple Lindy
- still leaked

I thought I saw a dribble from the cam covers
- changed the gaskets (twice, long story) and there were still leaks

I then pulled the engine

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Seems this seam was keeping the washer from seating right

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Part of the washer worked and the rest just leaked. Yes, I could have wrenched it tighter that may have helped.

Instead I did this:

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Though I read about an engine build where the guy mounted the block on his bridgeport and took care of this. I went at it with a little file, collecting EVERY tiny filing as they came off the block

Will report back as to the effectiveness of this, I also am considering modifying the engine tin so I can mount the pressure combo switch right on the block - get rid of the extension hose.

However, I can report that there was oil all over the engine from this point down the front and then trailed to the back of the car.....sigh.....


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Nice find for the leak path. @ctc911ctc

Take a close look at the washer. That oil pressure port is a 1/8" NPT tapered pipe form. The threads between the male and female are a tapered, interference fit that should not require any sort of washer for sealing purposes. The stock oil pressure sensor would never touch the top surface of the aluminum where you filed down the casting line. That flat surface is not meant to be a sealing surface.

I don't know why there would need to be a washer in there and the introduction of the washer could infact be preventing the NPT thread forms from developing an interference fit as they should by preventing the NPT section from threading in deep enough.

May have something to do with that brass adapter that's associated with the non OEM flex hose but I can't tell from end view of the threaded portion if it is tapered or not. Is the washer rubber or somthing deformable that is trying to act as a seal? Take a look at that brass adaper and make sure it is 1/8" NPT. Using straight threads in a NPT bore will always be prone to leaks regarless of what the washer or O-ring seal is. See link below for a graphic if there is any question of difference between tapered and straight threads.

http://blog.parker.com/what-are-the-differ...traight-threads

Also on side note. You don't need to mody tin to run a dual pressure sensor.

A lot of folks will take issue with what I'm about to say but I used it on my orignal teener for 100K miles no issue. Use the shortest stub of brass tube 1/8" NPT as a short stand off to get the dual pressure sensor up above the tin. The imperative thing is to keep it as short as possible. A long tube will create a cantilevered load that will be prone to vibration and stress fatigue. Yes, it is very tight to the distributor as installed. Honestly, I did it before I even knew better. But it worked for ever with no issue in my case. The flex hose is a far better alternative but you need to make sure the end of the flex hose is 1/8" NPT. Ditch the adapter. Local hydraulic hose suppliers (like Parker) should be able to make you what ever sort of hose you want without any trouble.

I do not run a flex hose on a 914. I had one break at the block on my 2.0 years ago and spray hot. high pressure oil everywhere. I have always run a very short npt pipe, and a T fitting on Betty's 914. I mount the oil pressure sender on the side, and I put a clamp around the sender and anchor it to the engine case. That prevents movement that can fracture the pipe. I then put the idiot light sender on the top. I also change it out the pipe and T once a year, when I adjust the valves. After 430,000 miles, I can say that the only oil leak I had from that area was a bad idiot light sender.

Clay

Picture please (of the clamp setup)
Thanks

I like it, but would love to see how you've done it.

.

In the interest of full disclosure and admitting that I'm wrong -- the pressure sensor hole is tapped for M10x1.0 Taper not 1/8" NPT.

Per earlier post I've used 1/8 NPT fittings in that hole for years without any issue.

Go visit this thread for full details regarding my mistake in saying that it was tapped 1/8 NPT.

http://www.914world.com/bbs2/index.php?showtopic=347614

Everyone learns something new. I was always under the impression that it was 1/8" NPT too.

Clay

I just got the engine back from the body shop on Saturday. I have to tear it down for replacement tin, so I will take pictures when I do.

Clay

Thank you!

Why in the world would a German car have them weird imperial inch something or the other threads?

M10x1 taper and 1/8 NPt are dimensionally close enough to not cause a problem

Because of weirdness like this.....

Tires are sized in half metric, half SAE. 205/50-15 is 205mm tread width, 50% of tread width is sidewall height, and the rim it goes on it 15 inch. So Porsche (and every other German car manufacturer) used 15 inch rims instead of 127mm rims.

Wheels make sense because wheels have been around much longer than cars and Germany used to use "Zoll" for measurement before the metric system.
Wheels were measured in Zoll and Zoll happens to be a close match for your imperial Inch.

But threads and thread pitch are a completely different animal.
There is no reason for Porsche to use a one-off non-metric thread on their engine when everything else is metric.

When using 1/8"npt fittings in the oil pressure tap on the crankcase it is best to chase the threads with a 1/8npt tap. The metric 10x1 tapered thread is a smidge smaller and fittings only go in a couple turns before tightening up.