Tacho drive oil leak solutions (2013)

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Old Bloke

Old Bloke

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Feb 14, 2013
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Tackling leaky Tach drive. I've read through most of the forum and web stuff on the Tacho oil leaks, and would appreciate your recent views. I see Norvil(I'm in UK) still advertise the mod + proper seal for £20. Have any members had this done and was it succesful? Failing that any success with "DIY" options? I do see occasional mention of using an oil pump feed washer, but tbh I can't work out how you would fit that, any ideas?
I'd like to go the Electronic tacho route, but cost, and would hate to loose the lovely instruments I have now. :p
Peter
 
Old Bloke said:
Failing that any success with "DIY" options?
Click to expand...

I bored the base of the tach drive housing just enough to take a proper 7 x 14* x 4mm oil seal that I happened to have in the spares box. It has never leaked since.

*(It doesn't need to be quite as large as 14mm O/D, that size just happened to be what I had)
 
There will be many who say simply relieving crankcase pressure (using a PCV valve) will stop the leak. I fixed my leak before getting around to using a valve, so I can't say from experience.

My fix has been semi-permanent and costs 59 cents at my local Ace Hardware store - it consists on an appropriately sized O-ring.

Disconnect the cable and take it with you to the hardware store (unless you have an O-ring assortment on hand).

At the end that connects to the engine you can see that the seal is basically the aluminum "nut" against an aluminum flange on the cable. Get an O-ring that will just barely fit over the flange, snug to the cable. The O-ring fits "above" the cable flange and under the nut. Then when the cable is reinstalled and the nut tightens down to the engine, the O-ring seals against oil flowing out at the nut-to-flange/metal-to-metal seal.

A basic advantage to this over the also tried and proven "Honda oil seal method" is the cable lower end lubrication is unaffected.

Well, now that I typed all that, the above assumes the leak on your setup is at the metal to metal seal where the cable itself goes into the nut that attaches it to the engine.
 
Thanks greatly for the feedback.

LAB: I haven't the means to accurately bore a recess to fit a seal myself, so that would have to go to Norvil or similar, but heartening to know it works good.

Having read the weighty tomes regarding Crankcase breathing, I'll be fitting a reed type valve in the breather hose, machining stuff for fitting to the cases is beyond me. If it improves things thats a bonus, if it doesn't, well no great expense on the valve! But moving on from that can of worms......

Lbridges: You've explained that idea well, I saw it before in another thread, but there were a few bits I wasn't clear on, which you have just elaborated on! As you say, the leak on mine is where the cable itself goes into the nut that attaches it to the engine, so the O'ring might be worth having a try at.
 
Old Bloke said:
Thanks greatly for the feedback.

LAB: I haven't the means to accurately bore a recess to fit a seal myself, so that would have to go to Norvil or similar, but heartening to know it works good.

Having read the weighty tomes regarding Crankcase breathing, I'll be fitting a reed type valve in the breather hose, machining stuff for fitting to the cases is beyond me. If it improves things thats a bonus, if it doesn't, well no great expense on the valve! But moving on from that can of worms......

Lbridges: You've explained that idea well, I saw it before in another thread, but there were a few bits I wasn't clear on, which you have just elaborated on! As you say, the leak on mine is where the cable itself goes into the nut that attaches it to the engine, so the O'ring might be worth having a try at.
Click to expand...

+1 for Reed Valve! I installed a Reed Valve two years ago and since then, not a single oil leak or oil weep anywhere! A good Reed Valve (re: XS 650) really does the job.
 
SGOUD2 said:
Old Bloke said:
Thanks greatly for the feedback.

LAB: I haven't the means to accurately bore a recess to fit a seal myself, so that would have to go to Norvil or similar, but heartening to know it works good.

Having read the weighty tomes regarding Crankcase breathing, I'll be fitting a reed type valve in the breather hose, machining stuff for fitting to the cases is beyond me. If it improves things thats a bonus, if it doesn't, well no great expense on the valve! But moving on from that can of worms......

Lbridges: You've explained that idea well, I saw it before in another thread, but there were a few bits I wasn't clear on, which you have just elaborated on! As you say, the leak on mine is where the cable itself goes into the nut that attaches it to the engine, so the O'ring might be worth having a try at.
Click to expand...

+1 for Reed Valve! I installed a Reed Valve two years ago and since then, not a single oil leak or oil weep anywhere! A good Reed Valve (re: XS 650) really does the job.
Click to expand...

+1 for the XS650 reed valve. No leaks. Anywhere.
 
concours said:
SGOUD2 said:
Old Bloke said:
Thanks greatly for the feedback.

LAB: I haven't the means to accurately bore a recess to fit a seal myself, so that would have to go to Norvil or similar, but heartening to know it works good.

Having read the weighty tomes regarding Crankcase breathing, I'll be fitting a reed type valve in the breather hose, machining stuff for fitting to the cases is beyond me. If it improves things thats a bonus, if it doesn't, well no great expense on the valve! But moving on from that can of worms......

Lbridges: You've explained that idea well, I saw it before in another thread, but there were a few bits I wasn't clear on, which you have just elaborated on! As you say, the leak on mine is where the cable itself goes into the nut that attaches it to the engine, so the O'ring might be worth having a try at.
Click to expand...

+1 for Reed Valve! I installed a Reed Valve two years ago and since then, not a single oil leak or oil weep anywhere! A good Reed Valve (re: XS 650) really does the job.
Click to expand...

+1 for the XS650 reed valve. No leaks. Anywhere.
Click to expand...

Thats the type I have for fitment during the rebuild, so fingers crossed :mrgreen:
 
Old Bloke said:
LAB: I haven't the means to accurately bore a recess to fit a seal myself, so that would have to go to Norvil or similar, but heartening to know it works good.
Click to expand...

I did it using a hand drill (as that's all I had at the time). It only needed drilling to a depth of 4mm.

Don't you know anyone local who has a bench drill?
 
L.A.B. said:
Old Bloke said:
LAB: I haven't the means to accurately bore a recess to fit a seal myself, so that would have to go to Norvil or similar, but heartening to know it works good.
Click to expand...

I did it using a hand drill (as that's all I had at the time). It only needed drilling to a depth of 4mm.

Don't you know anyone local who has a bench drill?
Click to expand...

Actually I have a pillar drill, but had assumed since it was a seal fitment, it would have to be bored to really tight tolerances. Maybe confusing it with bearing fitment? I'll have a look on website later and see what seals available.

So from your 1st post, id=7mm, od=14mm(or smaller), depth=4mm ?
 
Old Bloke said:
Actually I have a pillar drill, but had assumed since it was a seal fitment, it would have to be bored to really tight tolerances. Maybe confusing it with bearing fitment?
Click to expand...

As it's a 'rubber' seal I see no need for any great level of accuracy, as long there is some degree of interference fit. I did Loctite it in position 'just in case' but it's never loosened, and with the tach gear spindle in position it can't drop out.


Old Bloke said:
So from your 1st post, id=7mm, od=14mm(or smaller), depth=4mm ?
Click to expand...

Yes.
 
I just wrapped mine several times under the nut with teflon pipe tape. When the nut tightens down it conforms and makes a good seal. I did it in 1975, still in there, no leaks. (Storage for 25 years, though).

Jaydee
 
jaydee75 said:
I just wrapped mine several times under the nut with teflon pipe tape. When the nut tightens down it conforms and makes a good seal. I did it in 1975, still in there, no leaks. (Storage for 25 years, though).
Click to expand...


That doesn't stop the oil getting to the tach. cable, as it has been known for the oil to be forced up the cable far enough to reach the tacho.

oil-tachometer-t1525.html
 
L.A.B. said:
jaydee75 said:
I just wrapped mine several times under the nut with teflon pipe tape. When the nut tightens down it conforms and makes a good seal. I did it in 1975, still in there, no leaks. (Storage for 25 years, though).
Click to expand...


That doesn't stop the oil getting to the tach. cable, as it has been known for the oil to be forced up the cable far enough to reach the tacho.

oil-tachometer-t1525.html
Click to expand...

Wow that sounds unpleasant, what happens then, the Tacho fills up with oil? :shock:
 
:mrgreen:
Old Bloke said:
L.A.B. said:
jaydee75 said:
I just wrapped mine several times under the nut with teflon pipe tape. When the nut tightens down it conforms and makes a good seal. I did it in 1975, still in there, no leaks. (Storage for 25 years, though).
Click to expand...


That doesn't stop the oil getting to the tach. cable, as it has been known for the oil to be forced up the cable far enough to reach the tacho.

oil-tachometer-t1525.html
Click to expand...

Wow that sounds unpleasant, what happens then, the Tacho fills up with oil? :shock:
Click to expand...

Yup, that's how oil filled gages were discovered... :shock:
 
L.A.B. said:
That doesn't stop the oil getting to the tach. cable, as it has been known for the oil to be forced up the cable far enough to reach the tacho.
Click to expand...
Sorry to jump in on a really old thread but after fitting the RGM modified tacho housing I'm seeing oil forced up the tacho cable as far, as you said, to the clock itself. Any know fixes?
 
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AN scrolled drive gear..... Might need to start greasing your cable, though!! (I've done the garter seal one and although a marked improvement, a couple of motorway hours had it weeping)
 
EstuaryBoy said:
AN scrolled drive gear..... Might need to start greasing your cable, though!! (I've done the garter seal one and although a marked improvement, a couple of motorway hours had it weeping)
Click to expand...
Thanks yes that might at least make it more difficult for engine oil to get pushed up the cable. I've also installed the reed valve from Holland Norton Works that cured much of the crankcase leaking so a bit surprised there's still enough pressure to push oil that far up the cable!
 
My recent experience with this issue was on my 71, which was leaking quite a bit at the tach housing / cable junction. I first tried to solve it by replacing the standard timed breather with the beautiful (and not cheap) sump reed valve unit supplied by NYC Norton. That change had no noticeable effect on the leak. I then pulled the housing in order to add the oil seal per the INOA tech digest and several threads on this forum. Surprisingly, I found that the shaft on my tach drive gear has no groove for an 'O' ring and, of course, no 'O' ring either. That probably explains why it was leaking. To do the oil seal mod, I used the Honda seal, 91207-222-000, which is listed as 7mm x 14mm. The OD of this seal is actually 14.5mm (which is also what is printed on the side of the seal) so the 0.51" drilling of the housing specified in the INOA tech digest is nowhere near large enough to allow the seal to be fitted. I increased it to 9/16" and even that was very tight and not easy to get in. For good measure, I also stuck an 'O' ring at the top of the housing where the cable sheath screws down, as I believe others have described doing on this forum. Final result - no more leak. Clean & dry after 50 miles of use.
 
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