Fluid Leak

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Eric McKinley
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Fluid Leak

#1 Post by Eric McKinley »

I noticed some fluid gathering around the rim of my rear left wheel.

I believe it may be transmission fluid.

I removed the wheel and noticed that the fluid is coming from a small hole on the rear left disc.

Has anyone an idea what this could be caused by.

Many Thanks.
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Steve Raucher
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Re: Fluid Leak

#2 Post by Steve Raucher »

Hi Eric,
Have you had any bumps or bangs off road excursions?
If the rear hub is bent or out of tolerance, oil will leak as this happened to me.
Otherwise look closely and rule out one thing at a time until you find the leak source.
Good luck,
Steve
 

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Doug McDonnell
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Re: Fluid Leak

#3 Post by Doug McDonnell »

Steve Eric's car hasn't yet been on the road. Still finishing restoration.
1965 356C 2000 BMW 740i Sport 1967 Honda CL77 There is never enough time to do it right, but always enough time to do it over.

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Eric McKinley
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Re: Fluid Leak

#4 Post by Eric McKinley »

Steve,

Doug is correct I'm still in the restoration process.

I do not have any brake fluid in the system so I can rule that out.

It appears to be coming out of that small hole.

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Doug McDonnell
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Re: Fluid Leak

#5 Post by Doug McDonnell »

Time to take the caliper and disc off to see what is there.
1965 356C 2000 BMW 740i Sport 1967 Honda CL77 There is never enough time to do it right, but always enough time to do it over.

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David Jones
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Re: Fluid Leak

#6 Post by David Jones »

Looks like trans fluid and in reality what else could it be. Lucky you have not bled the brakes so the caliper removal is easier.
If I had known I would live this long I would have pushed the envelope a little harder.
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Wes Bender
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Re: Fluid Leak

#7 Post by Wes Bender »

The tube in that hole is connected to a catch ring that is supposed to collect trans fluid leaking past the seals. That keeps the fluid from getting on the brake disk. Might be a seal replacement exercise in your not to distant future, Eric.
Some days it's just not worth chewing through the restraints.....

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Eric McKinley
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Re: Fluid Leak

#8 Post by Eric McKinley »

David,

I believe it is transmission fluid.

Doug,

I read the thread you sent, it mentions a large and small O ring, and it possibly is the large O ring which is the culprit.

I shall tear it down and have a good look.

Am I correct in saying that part 12 is the large O ring, part 23, is the part the fluid is leaking out off, the small tube on this part.
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Eric McKinley
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Re: Fluid Leak

#9 Post by Eric McKinley »

Wes,

Have you completed this exercise yourself.

I just need to pin down which seals/parts need replaced, could someone advise which parts they are by using the picture I supplied above.

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Wes Bender
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Re: Fluid Leak

#10 Post by Wes Bender »

Yes, I have. You need the large O ring (#12) and you might as well get the smaller O ring (#15).
The large O ring can be a bit tricky as it will want to shrink a bit before you can bolt #18 in place.

Vic has written about a procedure that he uses. You might be able to find that (or maybe he will chime in). I found that it takes a bit of time for the rubber O ring to return to its original size, so I just stretch mine over a small cylinder and let it set a bit before installing it. I can usually get everything back together before it shrinks too much. You might consider ordering two of the larger O-rings just in case you cut the first when bolting everything back together. You'll be able to feel it being cut if that happens.
Some days it's just not worth chewing through the restraints.....

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Doug McDonnell
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Re: Fluid Leak

#11 Post by Doug McDonnell »

Vic did mine during Trans rebuild. David or Wes, Jon or Vic can probably answer your question.
1965 356C 2000 BMW 740i Sport 1967 Honda CL77 There is never enough time to do it right, but always enough time to do it over.

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Wes Bender
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Re: Fluid Leak

#12 Post by Wes Bender »

... and remember to elevate the end of the axle and block it before you take things apart. Avoids a large puddle of transmission oil on the floor...
Some days it's just not worth chewing through the restraints.....

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Eric McKinley
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Re: Fluid Leak

#13 Post by Eric McKinley »

Wes,

That's great, all makes sense.

Vic,

If you could supply the link to your procedure I would be interested in reading that before starting the work.

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David Jones
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Re: Fluid Leak

#14 Post by David Jones »

Been a while since I did mine but as I remember I just stretched the "O" ring over the bearing with the bearing sitting proud of the housing then placed the other half of the bearing housing on the bearing then drew it up with the 4 bolts that hold it in place. Also I seem to remember that there is a difference in size between the large "O" rings for disc and drum brake cars.
Here is a link to the procedure by Mike Robbins. This should be as good as it gets.https://porsche356registry.org/article/145
Last edited by David Jones on Wed Sep 27, 2017 5:13 pm, edited 2 times in total.
If I had known I would live this long I would have pushed the envelope a little harder.
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Doug McDonnell
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Re: Fluid Leak

#15 Post by Doug McDonnell »

1965 356C 2000 BMW 740i Sport 1967 Honda CL77 There is never enough time to do it right, but always enough time to do it over.

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