Oil Line woes

[mygatts57]

I just finished tearing down my 71 engine. Time to reflect and ask a lot of questions. For starters....

Picture #1: Way back when I disconnected the hard oil line that originates in the engine from the soft line I had to use a pipe wrench to remove the round metal collar on the rubber portion. The only wrench fitting is on the hard line and it is welded on. As I turned the collar it just went thump, thump, thump as it turned.
Is this normal or have I screwed up?

Picture #2: On th end where the hard oil line connects to the case, I thought I'd be diligent and take the fitting off, reseal it and put on a fresh washer - BIG MISTAKE. It will not budge!! I stopped trying until I get some counsel lest I destroy the case. Anyone else have this problem? Any tips on getting it off.

Thanks for your help

[Grady Clay]

Picture #1 service is a 2-step process when disassembling.
First is to unscrew the fine-thread fitting from inside the hose and collar.
This unscrews in a normal CCW manner.
You will need to turn the entire hose / pipe assembly pieces against each other.

Once the fine-thread fitting is removed, the collar unscrews ‘backwards’ in a ‘left-hand’ CW manner.
The collar has very ‘course’ inside gripping ridges.

Theoretically, you can replace just the hose and re-use the pipes and fittings.
In practice, the fine threads in the aluminum fitting(s) is very fragile and subject to galling.
Most service these assemblies replacing these fittings with crimp-type fittings.

Assuming the pieces are serviceable and you can secure original-type replacement hose, you can reassemble the assembly in reverse order.

Critical is to install the collar partially on the outside of the hose.
This installs by turning the collar CCW, ‘to the left’ on the new hose.
The ‘gripping threads’ inside the collar are tapered.
As the collar goes on the hose, it compresses the hose.

Once the collar is partially on the hose (just enough to have some ‘grip’), you can start the taper of the fine-thread fitting into the collar / hose assembly.
This is very difficult as several things must happen simultaneously.
Critical is the taper must start inside the end of the hose and not push the hose out of the collar.
A little X-Acto de-burring of the inside corner of the new hose helps.
There are lubricants specific for this operation.

Once the fitting taper is started inside the new hose, it is difficult to start the fine threads of the fitting in the aluminum collar without starting to ‘cross-thread’ the threads.

Once you successfully have the fitting threaded inside the collar, you can proceed.

The entire reason for all this left-hand right-hand complexity is to grip-seal the hose between the two parts while being able to rotationally align the fittings.
When the assembly gets tight on the hose, the angle fittings must be positioned in the correct direction / orientation.

There are some ‘grip tools’ that are far better than a pipe wrench.
The old aluminum fitting may crack longitudinally when gripped (crushed) with a pipe wrench.


You appear to have an aluminum collar with a steel fitting.
This operation is more difficult when you have both parts aluminum.
The fine threads are very inclined to be corroded or gall and cross-thread when attempting assembly.


There are several vendors around who can supply these hose assemblies with original-type fittings.
Most common is to replace with crimp-type fittings.
Porsche did, starting about 1973.



Picture #2.
This needs a 36 mm socket and an impact wrench.
Many sockets this size have a large ‘lead-in taper’ and need to be lathe trimmed flat on the end.
If you start with a reinforced ‘impact socket’, it may need trimming of the OD to clear the pressure relief boss.

A new fitting (999.136.008.00) and a sealing ring (900.123.011.30) A 22x27 DIN 7603-al are in order.

I hope this helps.

Best,
Grady

[mygatts57]

Thanks Grady - this helps a lot. I had no idea. I had actually removed the two pieces completely - I just pushed them together a bit for the picture. If I understand your comments correctly, you are saying that the side of the invisible fitting that fits into the soft hose is threaded CCW into the soft hose and after installed in the soft hose it connects to the hard line in a CW manner. Is this correct?

As far as the fitting on the case goes, I do believe I'll need a new one as I managed to bugger up the threads. I'll have it removed by the machine shop so I don't do even more damage.

Thanks again for you response.

Dave