Board index Flathead Power-Technical Questions, Answers, and Suggestions Knuckles case joint is leaking

case joint is leaking

Post Mon Aug 24, 2009 4:09 am

Posts: 109
Location: holland
Running in my freshly revised engine I noticed more oil on the ground than normally before.It didn't come from the frontchainoiler,instead it appears to be the lower joint between the cases is leaking.
Took off the protective bottom cover an found the leak
In cold condition every hour a drop comes down (sae60).
Though I don't like the idea ....I don't want to dissamble everything again, and plan to put a good sealer on , what would you suggest?
It's a small leak zone ,1/2 inch long, one inch behind the front bottom bolt..

Post Mon Aug 24, 2009 7:11 am

Posts: 3158
Location: Central Illinois, USA
Rein!

I share your anquish, as I remember when Yamabond4 gave it up on my Pan after six years.

If you think a band-aid patch is in order, I would suggest first scraping the seam with a dental pick to remove any exposed sealer. Then after thorough de-greasing, paint the seam repeatedly with an isocyanate urethane.

I have resorted to this only a few times, but the urethane managed to set up inspite of continual oil contamination.
One fellow's '49 had developed a leak at the top behind the rear cylinder (where hydraulic forces are high), and he confirmed recently that the patch has held for a decade.

...Cotten

Post Mon Aug 24, 2009 8:26 am

Posts: 109
Location: holland
Hi Cotten,

Cotten wrote:

isocyanate urethane.



would you consider a PU glue (polyutherane )the same ..
I can buy a 2 component set ,which hardens fast, over here .

Post Mon Aug 24, 2009 9:19 am

Posts: 641
Location: Wisconsin, USA
Pull the drain plug, lay the bike over to the left to keep the patch area dry. Spray it well with carb cleaner and air until its clean and dry. I've had good luck with a high quality clear silicone. It will last for years, but if there is a failure, it is very easy clean up to repeat the procedure.

Post Mon Aug 24, 2009 11:19 am

Posts: 251
Location: Hudson, Florida
When using clear silicone, what cleans it off of the surface and out of the pores if you need to reseal? I have had problems getting paint or sealer to stick to these surfaces in the past.

Post Mon Aug 24, 2009 2:28 pm

Posts: 24
Location: My-am-mah, Flor-a-duh
amklyde wrote:
Pull the drain plug, lay the bike over to the left to keep the patch area dry. Spray it well with carb cleaner and air until its clean and dry. I've had good luck with a high quality clear silicone. It will last for years, but if there is a failure, it is very easy clean up to repeat the procedure.



This probably doesn't need to be said: if you go the "lay the bike over" route, drain the gas out of the tanks first.
Steven

1946 knucklehead
1976 shovelhead
2006 road king

Youth and enthusiasm is no match for age and treachery.

Post Mon Aug 24, 2009 5:18 pm

Posts: 109
Location: holland
s eagle wrote:


This probably doesn't need to be said: if you go the "lay the bike over" route, drain the gas out of the tanks first.

Yeah ,also drained oiltank,took battery out.. sealed off the transmission vent..otherwise would be messy for sure .
Will get me 2 component alu epoxy tomorrow ,clean cases and put a little bit on. Hope it sticks.
Thanks for all your advice!
Rein

Post Thu Aug 27, 2009 6:25 am

Posts: 3158
Location: Central Illinois, USA
Rein!

Whichever goober you choose must be able to set up and stick inspite of oil contamination.
I avoid RTV and other acetic acid silicones for that reason, among others.

Let us also consider the possible causes for the leak.
I blamed my Pan's petcock, as any leakage with parked OHV is liable to travel all the way into the motor, and contaminate the oil with digestive injector cleaners and other detergents.

Your patch must be able to withstand fuel additives as well as oil, in the event of a failed or forgotten petcock.

....Cotten

Post Tue Sep 01, 2009 12:54 pm

Posts: 79
Location: No. Andover, Mass. USA
Hello,

What form or name does this isocyanate urethane come under? I ask because isn't crazy glue a isocyanate product? I thouht I'd seen when buying some craxy glue gel one time that it was good for use where it may become in contact with contaminants such as oil etc. I can visualize cleaning the joint well with an exacto knife blade and acetone and then squeezing crazy glue gel in there with your fingers. Just don't stop moving the fingers.

Dick

Post Tue Sep 01, 2009 8:09 pm

Posts: 767
Location: CA USA
Rein,
I have successfully sealed an oil leak caused by a crash, then rode it about 800 miles back home without problems. The product that I used is named Seal All. I cleaned the crack with carb gum cutter at a service station, dried it with a paper towel and applied the Seal All as directed by the station jockey who told me about the stuff. Once it dried it held just fine even though it was bathed in hot oil the whole time. I was riding an airhead R90 BMW [1975] and crashed the valve cover into a rock and cracked it. I'd say that the valve cover gets at least as warm as a HD case does and has a pretty good amount of oil in it. If you follow Cottons procedure and use this product I think you might have a good outcome. If it doesn't, you've only lost a little time. Good luck.

Post Wed Sep 02, 2009 7:32 am

Posts: 3158
Location: Central Illinois, USA
Dick!

I think 'crazy glues' are acrylonitriles, but I forget.

Beachdog!

Seal-All is great stuff, but ultimately it would suffer if fuel accidentally got into the oil.
(USA fuel, anyway....)

The isocyanate urethane that I use is an industrial coating from TNEMEC, now called Series 530 Omnithane.
A more common isocyanate is 'Imron', but since I am not a painter, I have never tried it.

....Cotten

Post Wed Sep 02, 2009 9:22 am

Posts: 767
Location: CA USA
Can't speak to the ability of Seal All to withstand modern fuel additives.
I've used imron clear to cover custom paint jobs with good success. Not as nice looking as some other stuff but really stands up to abuse from careless riders like me.
If I remember my ancient history, when I first heard about it in early 70's the DuPont literature showed imron painted on a cement truck drum where the cement had been allowed to set up. Small explosive charges were used to loosen the hard cement for removal. The after shots of the paint showed no visible damage. That sold me. The colors were industrial truck shades which weren't what I wanted, but the clear was great for covering acrylics. I still have several paint jobs that were cleared with imron 30 plus years ago and look as good as the day they were finished.

Post Fri Dec 04, 2009 9:26 am

Posts: 79
Location: No. Andover, Mass. USA
That's cool about the Imron clear. I have like 20 year old paint with clear on it and noticed that it did yellow a bit but only on the surface and just needed polishing to bring it back to clear again. It's plenty thick ad polishes well. I think later formulations of Imron are improved in this area.

Dick


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