Leakproofing my MKIII

nberg · Jun 14, 2015

Hi all.

In the attempt to create a leak & mist proof Norton...I am curious as to what everyone uses as sealants, if any:

MKIII primary gasket
Timing cover gasket
Gearbox cover gasket
etc.
drain plugs (oil tank, engine, gearbox, etc.)
MKIII gearbox neutral switch.
Any other points.

Thank you all for any suggestions.

Hobot · Jun 14, 2015

That like asking what color of oil is best but can not go wrong with the one stuff does everything Blue Hi Temp Racer Hylomar from RollsRoyce aircraft days with an organic fiber thread laid in seams like old aircooled alu case aircraft, but 50 bux a tube and a number of other common cheaper goops works for most - if they tame case pressure venting by factory or after market gizmos. Synthetic treads melt at runing temps leaving breaks and hollows in the sealant. Once really oil tight then the steel fasteners will rust exposed threads and washers more so than the nuts, so highlights your dry success to cover or clean up not to be thought a lazy fella leaving cycle out side all the time or not hardy riding enough to get oily. I dislike the tar like goops as tends to glue parts together and gave up on the thick grey stuff under cyclinders as if running well into red line hi fuel hi heating extremes the elastic engine distortions of seams and bolt stretch can crack its hardeness to leave paths of oil weeps or simply blow out the crumbles. I only use red sillycon rocker cover re-useable rocker gaskets last 15 ys but after dozen+ reuses on two Combat finally broke up to need more. I Hylomar TS cover gasket to the cover and just grease the engine side and so far do not know how many times that can go on off good and easy. Other areas of tranny and tach etc need special attention and parts.

tpeever · Jun 14, 2015

nberg said:
Hi all.

In the attempt to create a leak & mist proof Norton...I am curious as to what everyone uses as sealants, if any:

MKIII primary gasket
Timing cover gasket
Gearbox cover gasket
etc.
drain plugs (oil tank, engine, gearbox, etc.)
MKIII gearbox neutral switch.
Any other points.

Thank you all for any suggestions.

I like Wellseal. Stays liquid and doesn't block oilways if you happen to be a little too generous with it. Hylomar is also good. Avoid silicone. Blocks oilways.

I have found that a lot of the aftermarket gaskets are fairly thick. So if your mating surfaces are clean and flat, a sealant should not be needed. I don't use any sealant on the timing cover gasket for example and have never had any leaks there. A good tip I learned a while back is to put a thin smear of grease on gaskets which allows them to be removed more easily and reused.

My Commando and Dominator (same AMC gearbox) both leak a bit of gear oil from the kickstart shaft where it passes through the gearbox outer cover. Common leak with Nortons. I plan to fit a true oil seal in place of the stock O-ring but haven't gotten around to it yet.

I use the silicone gaskets under my Commando rocker inspection covers. Cured a small leak I had there with the paper gaskets.

L.A.B. · Jun 14, 2015

nberg said:
In the attempt to create a leak & mist proof Norton...I am curious as to what everyone uses as sealants, if any:

MKIII primary gasket
Timing cover gasket
Gearbox cover gasket
etc.

Greased standard gaskets, no sealant.

nberg said:
drain plugs (oil tank, engine, gearbox, etc.)

Just the standard sealing washers, etc..

nberg said:
MKIII gearbox neutral switch.

Never been any problem.

nberg said:
Any other points.

I did the oil seal mod. to the tach drive-as that was the only place I can recall where oil would occasionally leak from.

Danno · Jun 14, 2015

I use Permatex Copper Gasket Spray on all the paper gaskets and used Hylomar the last time the cases were split. Have also used Yamabond, Kawasakibond, and now use Permatex Moto Seal where Hylomar would have worked in the past. You can use it on the paper gaskets, but it's a bitch to remove them. The problem I've found with paper gaskets is the acids in oil turn them to mush and melt them out from between the cover halves etc. The Copper Spray should preserve them a bit better than just greasing them or soaking them in oil until they swell, which is kinda old school.

tpeever · Jun 14, 2015

In addition to Wellseal and Hylomar, I have also used Three Bond Liquid Gasket 1194 (maybe same as Yamabond??) and it was also very good.

Hobot · Jun 14, 2015

Between seasoned advisers and me just running out of gaskets I Peel ran w/o any gaskets but head and rockers, trany included and need time out Trixie will skip stupid head gasket too so only rocker silly con gaskets as simpler that applying goop. The benefits of expensive Hylomar w/o gaskets and long terms faults in all other goops does not or should not ever show up until operating or events happening beyond sane expected. Old school tach seal was stracking one or 2 oil pump nipple into the drive and thin foil back up in KS oil ring groove with RTV mold on greased surfaces. Again sad downside to really oil tight like me and ashley spoiled on is crappy rust rings and bleeds on the steel studs and washers even if the rest shiny SS. I found clean wheel coat only lasts a couple 3 seasons then cooked off enough rust appears. I will try Strongram penetrate protestant oil next time will till cooked off is water and air repellant but if still wetish will collect a cake of dust

Btw its fun to use just an air jet to reach nooks but hard to beat me and Wes pwer washes before stopping in towns. Peel will have air station to lick her self clean like a cat ears to rear, spokes to sump plug. There are nano particle sprays now that repell everything so good for at least seats and jackets boots & maybe take heat to keep fastens nice. Commandos look so obsolete ungainly antique to me when dirty or rusted patina so most the time avoid glancing at mine even though their canted engine cuteness-rareness is their best feature in this era.

pete.v · Jun 14, 2015

You can use any goop you are comfortable with but nothing will give more success than being criticle and maticulus with the mating surfaces. Be thorough with with the fasteners applying them equally, evenly and torquing tham by the book.

The gearbox doesn't need sealer persae but I use a copper spray to keep the gaskets in place. If they get a little off and offer a gap, there will be nothoing yuou can do but do a reset.

Again being anal (which also means Access Norton Analytical Lunacy) with this stuff is needed. Sometime all you can do is throw your best shot at it and except what you get.

Make sure the little hole in the gearbox inspection cover is open. This will also help from gearlube migrating to the clutch.

Make sure your inner primary is adjusted properly. If the outer does not touch flush all around than the gasket cannot do its job and you sure do not want to over tighten any of those fasteners just to stop a leak.

john robert bould · Jun 18, 2015

my MK 3 with 6000 on the clock as one weep from the rev counter drive..."O"ring should do the trick. It's never been apart since Norton assembled it .

Guido · Jun 18, 2015

Anyone mention a proper breather system?

Danno · Jun 18, 2015

Guido said:
Anyone mention a proper breather system?

ad infinitum in other threads.

Biscuit · Jun 18, 2015

hobot said:
Between seasoned advisers and me just running out of gaskets I Peel ran w/o any gaskets but head and rockers, trany included and need time out Trixie will skip stupid head gasket too so only rocker silly con gaskets as simpler that applying goop. The benefits of expensive Hylomar w/o gaskets and long terms faults in all other goops does not or should not ever show up until operating or events happening beyond sane expected. Old school tach seal was stracking one or 2 oil pump nipple into the drive and thin foil back up in KS oil ring groove with RTV mold on greased surfaces. Again sad downside to really oil tight like me and ashley spoiled on is crappy rust rings and bleeds on the steel studs and washers even if the rest shiny SS. I found clean wheel coat only lasts a couple 3 seasons then cooked off enough rust appears. I will try Strongram penetrate protestant oil next time will till cooked off is water and air repellant but if still wetish will collect a cake of dust

Btw its fun to use just an air jet to reach nooks but hard to beat me and Wes pwer washes before stopping in towns. Peel will have air station to lick her self clean like a cat ears to rear, spokes to sump plug. There are nano particle sprays now that repell everything so good for at least seats and jackets boots & maybe take heat to keep fastens nice. Commandos look so obsolete ungainly antique to me when dirty or rusted patina so most the time avoid glancing at mine even though their canted engine cuteness-rareness is their best feature in this era.

hobot said:
That like asking what color of oil is best but can not go wrong with the one stuff does everything Blue Hi Temp Racer Hylomar from RollsRoyce aircraft days with an organic fiber thread laid in seams like old aircooled alu case aircraft, but 50 bux a tube and a number of other common cheaper goops works for most - if they tame case pressure venting by factory or after market gizmos. Synthetic treads melt at runing temps leaving breaks and hollows in the sealant. Once really oil tight then the steel fasteners will rust exposed threads and washers more so than the nuts, so highlights your dry success to cover or clean up not to be thought a lazy fella leaving cycle out side all the time or not hardy riding enough to get oily. I dislike the tar like goops as tends to glue parts together and gave up on the thick grey stuff under cyclinders as if running well into red line hi fuel hi heating extremes the elastic engine distortions of seams and bolt stretch can crack its hardeness to leave paths of oil weeps or simply blow out the crumbles. I only use red sillycon rocker cover re-useable rocker gaskets last 15 ys but after dozen+ reuses on two Combat finally broke up to need more. I Hylomar TS cover gasket to the cover and just grease the engine side and so far do not know how many times that can go on off good and easy. Other areas of tranny and tach etc need special attention and parts.

hobot. not for nothin' man, but in all good humor, you posts are like some sort of weird 50's poetry. 8) 8)

Torontonian · Jun 19, 2015

Permatex. :!:

Commando Cam · Jun 29, 2015

I have a MKIII. I put the valve covers on dry and clean (never been deeper into the top end). Primary side - Yamabond. When I first bought the bike back in the early 90's she leaked at the tach drive. The fix was to install a Honda oil seal. Been so long I can't remember the details. Anyway, it worked.
Cheers,
Cameron

o0norton0o · Jun 29, 2015

nberg said:
Hi all.

In the attempt to create a leak & mist proof Norton...I am curious as to what everyone uses as sealants, if any:

MKIII primary gasket
Timing cover gasket
Gearbox cover gasket
etc.
drain plugs (oil tank, engine, gearbox, etc.)
MKIII gearbox neutral switch.
Any other points.

Thank you all for any suggestions.

A norton (or any parallel twin) may leak out of it's seals (or gaskets) because of crankcase pressure like on the primary side crankcase seal just because it's factory crankcase breather system is poorly designed. Modifying the crankcase breather system, by adding a reed valve to the system, lessens the pressure on all the seals and gaskets. If you have your bike apart for a rebuild and you don't modify it's crankcase breather system, you are missing a chance to correct one of the biggest flaws of the commando, and one that is partially responsible for all parallel twin designs to be reputed as " leaky bikes". You should use the search function here and check it out before you rebuild your engine. Sometimes it involves drilling or milling parts while they are off the bike....

Good sealants in the right spots help too.... good luck

Leakproofing my MKIII

nberg

Hobot

tpeever

L.A.B.

Moderator

Danno

tpeever

Hobot

pete.v

john robert bould

Guido

Danno

Biscuit

Torontonian

Commando Cam

o0norton0o

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