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Discussion Starter · #1 ·
Hey fellows,

I thought that I had dealt with this problem a few months ago (it was before I was actively participating on this forum), when I replaced the 'O' ring, but the problem seems to be back.

The problem is this: There's oil leakage from the left-side of the exhaust rocker spindle.

This is on my '78 T140E, which you all have been assisting me with (electrical & throttle cable).

Last time, I took out the 'O' ring, which was clearly shriveled and cracked. I had ordered a new one, though it looked a lot thinner than I thought it would. Still, I put my faith in my supplier's capacity to get me the right part. Also, after I installed it, it did the trick. No more weeping.

However, the weeping is back. I did get a spare O-ring (pictured) in the set I ordered.

So, my questions are these:
  • Does this look to be about the right size?
  • Are these things known to 'cook' and stop doing their job properly?
 

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Grandpaul is right. At the same time thne tool has to be machined correctly, many are not.

When using tool it must be held very very tightly to rocker box. Ring will try to force it out as it transitions to box.

I pre assemble tool onto spindle, then put in spindle, finally tapping spindle in very gently with a wood dowel. Again after tool contacts box, hold it tight to box.

Also make sure there are not sharp edges on box for ring to catch on. Also bore in box must be smooth for ring to seal against.

Lunmad videos he chamfers box bore & doesn't use tool. I don't like to do it his way. Still hard to not damage ring his way.
Don
 

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I used the tool and still shaved a little bit off the o-ring. It is not easy to get that ring in without damage. After a 1000 miles I could see mine were starting to leak ever so slightly. Quick wipe with a rag and probably good for another 200 miles.
 

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i don't use the "tool" but i do use a little sealant / liquid gasket in addition to the O ring- invariably a little rubber gets shaved off - all surfaces must be cleaned and degreased - can be replaced with the rocker boxes still on the engine - removed oil pipes and gently drive the shaft out just enough to expose the O ring
 

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The trick is to get a smear of sealant on the o-ring in place on the shaft with the tool further on, then slide the tool back just to the o-ring.

Then, insert the shaft and wrangle it all the way up to till the tool is about to tough the rockerbox, and set it up squarely, just touching.

Next, one sharp push with a rubber/plastic hammer against a soft drift or even a deep socket to seat it fully home. Any fiddle-faddling, and you risk slicing the o-ring. It has to be one swift "injection".

Having several spare o-rings is a good idea, "just in case". If I see the slightest rubber trimming bit, I start over.
 

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The way I do it with no problem is

1. chamfer the opening

2. put dielectric grease on oring

3. put the nut on and tighten and it draws the o-ring into place

TD
 

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I did some years ago, and I, like Dale, lubed up the rings, but didn't chamfer the holes; when the rings began to go into the holes, I used a Popsicle stick, or some other small flat wooden bit to "ease" them in gently. Never leaked again.
Just the $.02 worth of the "village idiot": Jim
 

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Discussion Starter · #10 ·
The previous time I did indeed use the tool though that tool does not seem to be tapered. It's parallel and fits flush around the rocker spindle.

Also, that O-ring just does not strike me as really all that fat enough to get much sliced off. When I was doing it, I was thinking I just had the wrong O-ring, but when it stopped the oil flow, I figured it just didn't need to be as fat as I thought. With the oil flow having returned, I'm returning to my original theory that the O-ring was not the right one.

Right or wrong, since I do have a spare one, I'm thinking of just replacing the one I put in, and seeing if it works. I'll take pictures of it all as I go and post them here.

But, your collective advice is:

* Hold tool very tightly (TR7RVMan), and tap in with dowel - So, I should tap it in with a dowel, rather than tightening the nut on the other side?

* Use sealant (wol)

* Chamfer the opening and use grease (Tiger Dale) - I did get and use that advice the last time (at least about the chamfering). However, I wonder if that might be a mistake with regard to the tool. Wouldn't the chamfer create some space for the O-ring to expand into past the tool, and thus make it more likely to be shaved as it is forced to compact back in?

*Popsicle stick (jimballard) - This does not seem possible in conjunction with the tool. I wonder what the tradeoffs are in this regard.
 

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Drawing it in requires 2 people, but should work just fine.
Paul you have forgotten more than I will ever now but I had no problem doing it all by meself. Don't recall whether I chucked the box in soft jaws or just pinned it to the bench...whatever it was that long ago and still no leaks.

To others...not any grease, dielectric grease....

Respectfully,

td
 

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Discussion Starter · #13 ·
To others...not any grease, dielectric grease....
Okay, that begs the question: Why dielectric grease? The O-ring is not insulating anything, aside from the outside world from the greater spew of oil. Does dielectric grease have some other benefit?

Is it because dielectric grease is a type of silicone grease, which helps preserve O-rings? (I can use Wikipedia!)
 

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From Permetex Instructions:
"It is important to note that dielectric grease will melt silicone rubber over time, and thus should not be used on connectors, such as o-rings, that are made of this rubber."

Because you have no idea what that "o" ring in that gasket, or seal, kit it is made from it is not the best idea to use dielectric grease to install these "O" rings.

While very few of the 650-750 twin rocker boxes have a bevel to compress the "O" ring during installation it is on the drawing. If you have any experience with 500 twins you will typically find that the bevel was cut on their rocker boxes during production. You will find putting a shallow chamfer on the 650-750 rocker box very helpful with you being successful.

There are 2 sizes of "O" rings (70-3253 and 60-3548) listed in the parts books. The groove cut in the rocker shaft are exactly the same for both of these. The 70-3253 is a thicker and a small diameter and needs to be stretched a lot to get it over the shaft. The 60-3548 is thinner and larger in diameter. It is much easier to deal with. Given the choice I use the 60-3548, but those small 70-3253 "O" rings do work.

I have been convinced that keeping the sealing area free of any oil, or grease, gives better chance of long term success. Some 10-15 years ago I was introduced to a water based rubber lubricant called P-80. I found installing rocker shaft "O" rings a perfect solution to installing these shafts.

I have a pocket sized screw driver that has had the tip bent 90°, edges broken and narrowed. I use it to press the "O" ring into the hole as the shaft is drawn in. I also use it to remove circlips from pistons.


I, and a lot of people I respect, have found the factory "O" ring tool a total waste of money.

• I prefer the 60-3548 "O" ring, but either will work.
• Cut a shallow (15°-20°) chamfer on the leading edge of the rocker shaft hole in rocker box.
• Lubricate the "O" ring with P-80 rubber lubricant (the company will send you a sample).
• Bring the "O" ring up to the chamfered edge of the hole, and as the shaft is drawn into place, go around the "O" ring and "worry" it inside the chamfer. You go around the shaft gently pushing the "O" ring into the rocker box. Draw the shaft in slowly. Pushing the "O" ring into the rocker box should be done with small sections of the "O" ring and with a gentle hand.
 

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In addition, whenever you cut metal, a burr is created, ie chamfering. After creating the chamfer use a finishing pad like Scotch brite or a fine grit emery to smooth the edge. Check ring groove for burring. When I first worked on my boxes I was appalled at the poor condition of everything. I eventually added a second groove and have 2 o-rings per shaft. No leaks.

BTW o-rings can be ordered in quantity from McMaster Carr or similar for not a lot of $$. And you can select from different materiials, viton, buna, etc.
 

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I don't have the factory tool, but I made one from a 50 calibre [I think it was] army machine gun brass shell for my T150V. It has a taper shape to it and is very thin so gets right to the box face. When I do it the tool actually gets drawn in to the rocker box face by the O ring and friction. Seems to work fine for me.

Not sure on the actual calibre because I cut off the head and threw it in the recycle bin, just using the neck and shoulder. Plus I did the same with another shell for my T140W which has a slightly larger spindle diameter.

Can't remember how I came by the shells, might have been a swap meet or garage sale?
 

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Just re-read this thread as i needed to fit some O rings to my rocker shafts ( i had the larger rings)

Generally followed Johntioc description -- but used red rubber grease and didn't chamfer the edge of the hole

using the dome nut with a stack of washers under it i drew the shaft in until the O ring touched the edge of the rocker box - then with a narrow flat screwdriver (slightly worn without any sharp edges) started to tease the O ring into place - rotated the nut 1/2 a flat at a time and repeated the teasing - kept repeating 1/2 a flat at a time until the O ring was fully into the rocker box - 100% success ; no rubber shaved off

(had to add washers to the stack as the shaft was drawn in as the dome nut bottomed out on the thread)

thanks again to Johntioc for sharing his experience
 
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