924Board.org

[Peter]

This weekend I took apart the leaking oil hose that runs from the oil pain to the turbo with a T connection that runs up to the head –Porsche part No 931 107 108 08 which retails for $ 400!!! ( See http://www.924.org/parts/parts.htm for a picture of this hose installed).
This $400 hose is a basic hose with a T connection, which once you cut off the surrounding metal box around the T connection reveals a perforated metal pipe. Yes boys and girls, Porsche charges $400 to put holes in a metal pipe. The best visual I can give everyone is that the exposed metal pipe looks like a riffle silencer that you see in the movies, but not as long. I took pictures of the cutaway and would be happy to send them to Senior Webmaster to be posted in the parts section.
I am in the process of trying to come up with a cheap, more durable substitute for this $400 part. I will keep everyone informed.
-Peter A. Holiat

[bacook]

I ended up ordering a salvaged one from Chicago Parts Werks. It is in great condition and cost $100.
bc

[924RACR]

Salvage certainly sounds good; I suspect it could also be replaced with Aeroquip fittings, but that'd be almost a break-even with all the adapters required. One promising alternative should be to take it to a place that makes hydraulic hoses for industrial equipment, and have them replace the hose but re-use the fittings.

To find such a place, probably the thing to do is ask a place that sells and services agricultural equipment or the like...

_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Peter]

Parts Werks has a good reputation and I am sure they would pressure test the hose before a sale.
I looked into steel-braided hose with AN/Metric fittings and T fittings with steel-braided hose up to the head. It would be around $100. However steel-braided hose would last much longer than OEM rubber and it looks so much better.
-Peter

[Zuffen]

Unless the metal canister is leaking the hoses can be replaced at any hydraulic hose or AC shop. They will cut off the crimp and install a new crimp and section of hose. Farm implement or industrail repair shops can do this. The cost should be about 20 bucks a crimp and 10 for the hose. If you want braided expect to pay more.

The canister is an air seperator and a surge supressor, I also feel it induces back pressure.

[Peter]

The metal hose to the metal canister broke.
I took apart the metal canister and the air/oil separator is only a preforated metal tube. I called the dealer & the OEM assembly is $300 new. Too much for a perforated metal tube. Kokelen makes a real air/oil separator for the 944 series, unfortunately it is a complete kit with oil cooler, metal hoses, etc --which spells $$$$. ( http://www.kokeln.com/944/Engine/airoilcooler.htm )

The 931 air/oil separator is a simple perforated metal tube encased in a metal box. I am thinking of fabricating a replacement. I will speak to the machine shop and ask them to weld a small diameter preformatted metal tube into a larger metal tube, put 12 AN bulkhead fittings on each side and a 6 AN bulkhead fitting on the top. I am thinking $50 maximum.

The head I found to replace my cracked 1982 head is a 1980 head without the hole on the head to vent the air into the camshaft. Using steel-braided hose, AN fittings and Metric adapters a non-air/oil separator hose can be fabricated for less than $70. When I get the air/oil separator made, I will just screw it right onto the line. (Ofcourse the vent hole on the 1980 head will be drilled already)

-Peter

[numbers]

Since I have an unmoded '80, I am not familiar with the tee connector. However, when my oil return hose started leaking, I just cut off the crimp part of the connector with a hack saw, by working around the hose and being careful not to cut the barb part of the connector. Then I just replaced the hose with 3/4 inch heater hose and two hose clamps. This is not a pressure hose. Just a drain for the oil that is pumped to the turbo. The first replacement hose was in my car about seven years, with no problems, when I noticed it was getting a little spongy. So, I replaced it again, and the current hose has been in there about three years. Total cost for the hose was about a buck fifty. Can you do something similar with the tee type hose?

[Zuffen]

Peter what failed on the 82 head and is it up for sale? I'm looking for failed heads for future flow testing and porting experiments.





_________________
Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

[wdb]

just a thought about cracked heads;I posted several links in the engine transplants section about cast aluminum,I've read on one of those sites that one of the ways of casting aluminum parts is with plaster of paris.I'm wondering if it is possible repair cracked heads by recasting them. place a head in a steel bucket,fill said bucket with plaster of paris.the head will be completely incased.heat it till aluminum becomes molten,cracks go away ,then let it cool.then just chip off plaster and clean up head.there are some details of course.cracks need to be heated to burn off any oil that might be there,vibrate plaster to avoid air bubble,plaster has to be dry,few days of air drying few hours of 300 degree oven.head may need to be lapped to provide smooth mating surfaces,but I think it could be done,and who knows,there might be a 400+hp turbo charged 4L 924 some day. people were casting copper 10'000 years ago,I think we can figure it out.whadeya think!

[wdb]

Turning to the technical issues. It is possible that you could re-melt the cylinder head in the way you suggest. Distortion might be a problem since the head will already be machined to size, so that a re-machining would get all dimensions under size. I am not sure whether this will be soluble.

Anyway, the real problem with the remelting of an aluminium alloy is that any crack will be faced on both its sides with aluminium oxide. This does not re-melt until 2050 C. Also, the oxide is chemically very stable. Thus this is permanent damage, and after re-melting will be likely to remain in place, and re-solidify as a crack. (Other alloy systems such as cast iron for instance would not have a problem in this way). There is no known way to remove this oxide.

Thus I am concerned that the re-melting would not remove the original cause of the failure. It is just possible that the sides of the crack may be closer together than originally, and so might leak less, but this would be purely fortuitous. It is possible that the crack may open more as a result of all your efforts. It will certainly not be sealed nor repaired.

Even welding of a crack in aluminium alloys often fails, and only works if the welder rabbles the liquid melt pool so as to disturb and so mechanically break up the oxide film. The welder will be lucky if all this effort does not introduce additional oxide films that re-create the problem.

Thus I think your idea is inventive, but I regret that there are fundamental reasons why aluminium alloys are resistant to being repaired.

Best of luck with your work.

Yours sincerely

John Campbell

Professor of Casting Technology
IRC in Materials, University of Birmingham, B15 2TT UK




[ This Message was edited by: wdb on 2001-08-14 16:02 ]

[Rick MacLaren]

That #### pipe is going to cost me a fortune. Any reasonable cheap solutions in the USA or Canada?