Right side crank oil seal blown

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JimNH

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I pulled my timing cover and discovered the right side crank oil seal had rolled over. I have no idea how long it had been that way but I think it's a good reason to install an oil pressure gauge. It's been years since I've run this bike and it's getting a good clean-up, re-seal everything, new tires, etc.

I've read that an oil pressure gauge on a Commando will just scare you but a sudden change like this seal going could be spotted.
 
That seal see's no oil pressure only crankcase gaseous pressure, though some claim with 'sufficient' wet sump oil + good swift kick has popped this seal out. Could imply and oil pump path issue going by the presently generally accepted above wet sump assumption.
 
i do not know why your crank seal blew.
but i do know that installing an oil pressure gauge is a very worthwhile upgrade.
got mine from Old Britts - and it is an easy install that works.
you cannot put a price on peace of mind.
 
JimNH said:
I pulled my timing cover and discovered the right side crank oil seal had rolled over. I have no idea how long it had been that way but I think it's a good reason to install an oil pressure gauge. It's been years since I've run this bike and it's getting a good clean-up, re-seal everything, new tires, etc.

I've read that an oil pressure gauge on a Commando will just scare you but a sudden change like this seal going could be spotted.
Click to expand...

An oil pressure gauge might also alert you that an over pressure relief valve has seized up. I have seen a few and had to dismantle and clean and free them up. Also many years ago there were some timing side seals that were not up to the task and were doing what you are experiencing but at lower pressures. Happened to us down the back straight at Mosport in Canada.

A good seal will hold over 125PSI... But a cold norton engine without a functioning OPRV will hit 150psi easily.
My gauge is 160 PSI full scale.
 
hobot said:
That seal see's no oil pressure only crankcase gaseous pressure, though some claim with 'sufficient' wet sump oil + good swift kick has popped this seal out. Could imply and oil pump path issue going by the presently generally accepted above wet sump assumption.
Click to expand...

Are you thinking of the drive side oil seal?
 
Ugh good catch LAB sorry I glossed over which crank seal. The oil feed sealing has two gasket/seal combo's to match up to model &or on cover gasket thickness. Vendors like Old Brit sell in pairs to avoid mismatching. Oil pressure gauge is still good idea even if had nothing to do with the basic failure if just ordinary range of pressure developed on wrong combo.
 
It's the crank seal, not the conical seal and it does see full pressure. I thought that perhaps the relief valve may have jammed but when disassembled I found it in good condition with no evidence of binding.

The Old Brits kit is nice if a little pricy. I'm thinking of using a double banjo bolt and another banjo fitting and plumbing off the rocker feed. I can cut a piece of sheet aluminum and drill it for a gauge and the fork bolt and mount it outboard of the tachometer.
 
I have heard that some outfits have sold the wrong seals to unsuspecting customers. maybe that blown seal was one of them. Use only the genuine seal???????????
 
It happened to me a long time ago. 50W oil, revved from cold before oil had warmed + the seal was a thinwall type, straight out of a Norvil bottom end rebuild kit!! Their individual replacement was a totally different heavy duty NAK seal I recall. It got changed recently after 30k miles, just as a precaution.
 
Oil pressure gage is the VERY FIRST thing I did to the bike. The naysayers claim it has no value, can't stare at it. It's about verification, trending. Get one. You now have a question mark hanging over your rod bearings from the seal failure.
 
concours said:
Oil pressure gage is the VERY FIRST thing I did to the bike. The naysayers claim it has no value, can't stare at it. It's about verification, trending. Get one. You now have a question mark hanging over your rod bearings from the seal failure.
Click to expand...

'Zactly! My hope is that it blew the last time I ran the bike; the cold night, miles from home when the sprag locked up and I revved the $hit out of it trying to unlock it. Before that I always warmed the bike before any revving.

The new seal I put in had exactly the same markings as the old one. It was a thumb press with the snap ring retaining it. I also got a seal from a different supplier that had metric markings and was not a thumb press. I checked all my seal catalogs and none had a 9/16X1-1/8 seal so went with the usual suppliers hoping to use whichever arrived first.

The bike now has a Dyno Dave starter, a 3 phase alternator, a Pazon Altair, and a lot of new wiring to avoid the voltage drop that caused the early Boyer to fire advanced, locking the sprag in the first place.

Thanks Dyno Dave for the research on the Boyer.

I also found the anti-kickback wouldn't release at all within the range of a 250 lb/ft torque wrench! A complete dis-assembly and cleaning/polishing of the parts made it reliably adjustable.
 
JimNH said:
concours said:
Oil pressure gage is the VERY FIRST thing I did to the bike. The naysayers claim it has no value, can't stare at it. It's about verification, trending. Get one. You now have a question mark hanging over your rod bearings from the seal failure.
Click to expand...

'Zactly! My hope is that it blew the last time I ran the bike; the cold night, miles from home when the sprag locked up and I revved the $hit out of it trying to unlock it. Before that I always warmed the bike before any revving.

The new seal I put in had exactly the same markings as the old one. It was a thumb press with the snap ring retaining it. I also got a seal from a different supplier that had metric markings and was not a thumb press. I checked all my seal catalogs and none had a 9/16X1-1/8 seal so went with the usual suppliers hoping to use whichever arrived first.

The bike now has a Dyno Dave starter, a 3 phase alternator, a Pazon Altair, and a lot of new wiring to avoid the voltage drop that caused the early Boyer to fire advanced, locking the sprag in the first place.

Thanks Dyno Dave for the research on the Boyer.

I also found the anti-kickback wouldn't release at all within the range of a 250 lb/ft torque wrench! A complete dis-assembly and cleaning/polishing of the parts made it reliably adjustable.
Click to expand...

I too, was avoiding the OldBritts gage setup, $$$, and I'm not a braided hose fan unless required for the task, but, my time to fab a bracket, etc., I just pulled the trigger, only down side is it hits the fender when forks are at full travel... but then there's that frost heave BS indigenous to the snow belt... :oops:
 
If I recall correctly, this seal can and has been installed incorrectly before. Because it is installed in the cover with a circlip, its direction of function can be misconstrued.

This serves the crank journals and is fed by the pump through the conical seal. When removing the cover always look for witness of contact to the timing cover on the conical seal and replace this seal while in there. This is critical.
 
As noted, neither of the crankcase/crankshaft seals "sees" engine oil pressure so a seal letting go has no affect on engine oil pressure per se. Whether a gauge is needed or not is a personal decision. I have never had one on a Commando - either back in the day or now and have not seen any reason to install one. But that's ME, and others totally disagree so do whatever makes you feel comfortable.

FWIW, do any motorcycles have OP gauges? I don't think I've ever seen one on a stock motorcycle...at least that I can recall.
 
mike996 said:
As noted, neither of the crankcase/crankshaft seals "sees" engine oil pressure so a seal letting go has no affect on engine oil pressure per se. Whether a gauge is needed or not is a personal decision. I have never had one on a Commando - either back in the day or now and have not seen any reason to install one. But that's ME, and others totally disagree so do whatever makes you feel comfortable.

FWIW, do any motorcycles have OP gauges? I don't think I've ever seen one on a stock motorcycle...at least that I can recall.
Click to expand...


The seal on the right does, it transfers oil pressure/volume to the crank to supply the rod bearings. Triumph, same way. (my buddies T140 recently lost oil pressure, the snap ring groove was damaged 30 years ago, never properly repaired, and finally let go, allowing the seal to spit out. The warning lamp tipped him off. He decided to ride ten miles after that. Oh, well. :idea: )

As to the gage being on any bike from new, I haven't seen one either (that I remember). BUT.... MOST bikes DO have a low oil pressure warning lamp in lieu of a gage.
I added a gage to my '86 GTR1000 a week after I bought it. Just to know what's happening.
 
mike996 said:
As noted, neither of the crankcase/crankshaft seals "sees" engine oil pressure so a seal letting go has no affect on engine oil pressure per se. Whether a gauge is needed or not is a personal decision. I have never had one on a Commando - either back in the day or now and have not seen any reason to install one. But that's ME, and others totally disagree so do whatever makes you feel comfortable.

FWIW, do any motorcycles have OP gauges? I don't think I've ever seen one on a stock motorcycle...at least that I can recall.
Click to expand...

Generally speaking, you are correct. It's just that these damn 72 scavenge setups sucks so bad (pun) that they sort of beg the question on to their [op guages] validity.

I have one and although I am not alway glancing down on it all the time, if there is ever a question, the information is only a glance away.

An idiot light, and maybe a buzzer, may make more scense, and actually could be incorporated into the line to the guage. Hmm. Nothing wrong with a little redundancy here.

This could also work in conjunction with an inline ball valve instead of a micro switch on the handle or a wire tie around the kickstart.
 
I'd agree with mike996 that putting a gauge is a personal choice. But stating the crank does not receive pressurized oil puts his opinion as totally not credible.
All norton heavy twins since the beginning in 1949 have cranks pressurized and in about 1966 the rockers also got pressurized. Otherwise, what is the purpose of even building in a oil pump. Did the crank get oiled like a Briggs and Stratton lawn mower engine....by splash? :roll:

Since I refuse to put stainless braided lines on commandos, my oil pressure gauge just uses 1/8" black nylon from my custom LH rocker banjo. It is a 1/8 compression fitting that detaches if needed for maintenance. It's been like that, on my 72 combat, since about 1988.
 
SS braid lines are like files on a vibrating Commando and collect grime and grit and don't appeal to my eye like nice factory hoses though not a bad Idea for brakes. Its very common to see OP guage on Harleys which are kissing cousins to Commandos so quite appropriate on them.
 
1up3down said:
Since I refuse to put stainless braided lines on commandos
Click to expand...

curious, why is that?

thanks
Click to expand...

I don't mean to answer for Dave here. Just commenting.


My guess would be appearance. There are those who are pro-bling and those who are anti-bling. Most of the ant-bling crowd are reluctant to make any modification unless it is performance or reliability related.
 
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