Topic: Fork Leak After Oil Change-- Over Filled, Maybe?

[Popwood]

Working through the routine stuff after buying an old bike, finding lots of smaller problems. I had maybe 100 miles on the bike and didn't notice any fork oil leak. But after a fork oil change, I'm getting some leaking.

Tonight I removed the forks anticipating a seal replacement (might as well do both, right). So with the forks off, but the fork caps still on and all the oil still in, I see no oil coming from the seal area when I pump them by hand. Now, let me add that on the fork that was leaking, I find a shallow scrape in the fork tube. I can compress the fork so that this imperfection goes below the seal, but still no leak, but that could still be a problem, yes?

But after the fork oil change, I read something about oil amount to add when "dry", which is the manual spec, vs. when "wet," which I presume means after an oil change? The "wet" amount to add was like 4.5 oz. vs. the 7.1 "dry" amount for a 750.

When doing the oil change I found it difficult to pump the forks to force out the oil. Much harder than on my 550. And boy, what came out was crap. Still, wondering if I got enough out, I tried to collect as much as I could it is was something like 4.5 oz., far short of 7+.

So, after all this background, if I didn't get all the old oil out and added back 7+ oz., could it be overfilled and could that result in a leak? Can overfilling cause a leak in a seal that is otherwise good? Could the scrape in the tube push the problem just enough to cause the leak? Will the scrape ruin new seal?

[1timduke]

Will the scrape catch your fingernail?   If so, it may be the source of the leak, also possibly overfilling.   Did you notice handling changes after the change?   I've got a scratch on my 550 forks and I fixed them with JB Weld and a bit of patient sanding, haven't had a leak yet.   I found the trick was to apply the JB and let it really sit up, like a couple days at least, then a new razor at just the right angle to shave most of it off.   That kept me from using too rough a grade of sandpaper and risk really ruining the chrome.

How much leaking are you getting, just a little seepage or is it greasing the whole bike?

-Tim

If I recall, I believe the fluid amount should be around 4.5 or 5.5 oz's I think that's what my Haynes sez.

[Popwood]

Last Sunday I took the bike out for the first real ride after the oil change and a new front rim and tire replacement. Did about 60 miles. When I parked found less than an oz. of oil on the floor below the fork. Later noticed my pant leg was sprayed. So it wasn't spewing everywhere.

Like the JB Weld solution on the fork tube. Thanks.

Any other thoughts?

[scondon]

If your first draining of the forks produced awful sludge, then it's probably a good idea to just drain them again and add the proper "wet" amount of fluid. Flush out remaining gunk this way. What weight fork oil did you refill with?

[Popwood]

I used 10w 40 motorcycle engine oil after reading numerous opinions about ATF vs. motor oil.

So with the forks currently off, I can remove the caps and really give them a good flush. Pour out what's there from the top and squirt out by compressing from the drain screw? Should I flush with ATF?  But then, should I go ahead and replace the seals? Should I fill that scrape on the tube that passes the seal when the fork compresses?

And what is the recommended amount of oil (and what kind) to add when final filling? This "wet" amount seems very inexact.

Thanks for the reco's.

 

[MCRider]

Working through the routine stuff after buying an old bike, finding lots of smaller problems. I had maybe 100 miles on the bike and didn't notice any fork oil leak. But after a fork oil change, I'm getting some leaking.

Tonight I removed the forks anticipating a seal replacement (might as well do both, right). So with the forks off, but the fork caps still on and all the oil still in, I see no oil coming from the seal area when I pump them by hand. Now, let me add that on the fork that was leaking, I find a shallow scrape in the fork tube. I can compress the fork so that this imperfection goes below the seal, but still no leak, but that could still be a problem, yes?

But after the fork oil change, I read something about oil amount to add when "dry", which is the manual spec, vs. when "wet," which I presume means after an oil change? The "wet" amount to add was like 4.5 oz. vs. the 7.1 "dry" amount for a 750.

When doing the oil change I found it difficult to pump the forks to force out the oil. Much harder than on my 550. And boy, what came out was crap. Still, wondering if I got enough out, I tried to collect as much as I could it is was something like 4.5 oz., far short of 7+.

So, after all this background, if I didn't get all the old oil out and added back 7+ oz., could it be overfilled and could that result in a leak? Can overfilling cause a leak in a seal that is otherwise good? Could the scrape in the tube push the problem just enough to cause the leak? Will the scrape ruin new seal?

My Clymer copy -1977, says 7.3+ for early forks. 6 for later forks (yours).

You could probably stand a good rinsing out of the lower legs. Use something like kerosene or parts cleaner, someone said ATF, might work. ATF would be good as if any is left behind it is a recommended fork oil, so no harm.

If I were you I might try the measureent method. Clamp the leg assy in a vice. Without the top nut and spring. Let the tube drop to fully compressed position. Fill the leg with 5 oz, pumping a little as you do. Measure down from the rim of tube to oil level. Should be about 5.5 in. Absolute level not so important as that they are equal.

Reassemble and try them out. Add equal amounts as necessary to get the ride you want.

Questions: Probably is overfilled BUT if the seal is good it won't leak in the garage, but it might on a bumpy road.

The scrape is problematic. I'd use 4oz of fork oil/ATF and 1+oz of seal conditioner stop leak. See if you can seal it up. This worked for me, put off a fork seal replacement for a few years. Straight ATF is a recoommended hydraulic oil and often has stop leak properties in it. Use that instead of the motor oil.

A real shade tree mech approach would be to fill the scrape with some ceramic/epoxy type appliance touch up paint, clear or silver, if you can find it. Buff down with VERY fine emory.

I did this once to the drive shaft of a washing machine that had deep rust pits in it and was leaking. Fixed it, never leaked again for 10 years.

PS: Link to fixing scratches:  http://www.salocal.com/sohc/tech/frkng/debur.htm

[Popwood]

Thanks, MC. My book spec is 7.3 oz. I think I'll follow your procedures and forgo the seal replacement for now but still fill in the damaged tube area. To clarify one point, the leak in the garage was from oil that had leaked and run down the fork leg during the ride then dripped off. The freeway part of the ride I was on was bumpy-- you know, those poorly repaired seams in the original concrete that occur every 75 feet or so. It was getting a pretty good pounding. No leaking while just sitting there. 

[scondon]

      With the forks off the bike, you can drain from the top by working the tube up and down. Since they are already off it wouldn't hurt to attempt repair on the scratched tube. Fork seals are not expensive, so if you have time you can do them now.

 You say that the forks didn't leak at all before this last fluid change, which would make me suspect that something occurred during the process. Manual calls for 10-30 oil, but I'm not sure they mean motor oil. There is fork specific oil and I would suggest you use that. I use a straight 15w fork oil.

I own a later model 750 with different oil capacity, but the difference between "wet" and "dry" amounts is only 0.1 oz. Honda Shop Manual states 5.3 - 5.5 oz ATF for K1 - K4 models. I'm guessing that your bike falls in this range. The 7.1 - 7.2 oz is for K0 bikes. Possible that your forks were overfilled?

   If it were me, I would flush ALL the motor oil out and start with fresh fork oil. Since I'm a cheap bastard, I would check the seals for gouges, cracking, and if they passed visual inspection I would try them again with proper oil and amount. Not suggesting that you skip replacing the seals, just stating what worked for me in the past. My seals are a bit hard to remove when they are old, and I took a gamble that worked.

MC, ya beat me to it while I was tapping this out. Posting anyway

[Popwood]

Thanks, Scondon. Given the only varible here is the oil change, I think I may skip swapping out the seals, flush out what's in there, go with actual fork oil and repair the scrape on the tube. Once I clean up the tops of the forks, which are a bit rusty and took some doing to remove, pulling them again if I need to should be easy. But debating myself, replacing the seals, which are probably ancient, would take that chore off the table for some years to come. My Honda dealer has OEM seals for $10 each.

[Duke McDukiedook]

Might as well change your fork seals while you are in there- you don't know how old they are and you don't want to go back in to just change them if you don't have to.
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