Replacing stem oil seal (2012)

Hi Lads,

Looks like I need to replace an inlet valve stem oil seal. (1975 MK3)

I've had a look at ludwigs clever way of doing this without removing the head: post76177.html?hilit=ludwig

I have two questions:

1. Has anybody used ludwigs method BUT used rope in the cylinder bore to hold the valve in place? Can anybody think of a reason why this would not work?

(I used this method of locking up the engine quite successfully for removing & replacing the stator nut)

2. I've come across info. on the interweb about using compressed air in the cylinder bore to keep the valve in place while you remove the spring. My brain can't figure out how this could work? Has anybody attempted this with a Norton?


Kevin

click said:

2. I've come across info. on the interweb about using compressed air in the cylinder bore to keep the valve in place while you remove the spring. My brain can't figure out how this could work?

Click to expand...

I've never tried it but you would need an airline with a fitting suitable for connection to the spark plug thread.

If the piston of the particular cylinder in question is placed at TDC on compression so both valves are fully closed, the crank is then locked in that position and air pressure applied to the cylinder through the plug hole fitting which will keep both valves shut. Obviously some air will escape past the rings but any decent compressor should be able to keep up with the rate of loss.

click said:

I've come across info. on the interweb about using compressed air in the cylinder bore to keep the valve in place while you remove the spring. My brain can't figure out how this could work? Has anybody attempted this with a Norton?

Click to expand...

I've never done this with my Norton but we've often done it over the years at my shop. It works great on some vehicles and not at all on others because of space considerations.

You need an adapter which screws into your spark plug hole and is designed to connect to a steady source of compressed air. The easiest to use are those which have a quick disconnect attached to the part which screws into the spark plug holes - you install it in the head and, when ready, attach an air hose connector to the quick disconnect. If you don't have one, you can make one using an old spark plug and quick disconnect fitting. Often compression gauge kits will include something like this but sometimes they come with a hose as part of it and that makes it harder to work with although it shouldn't be a problem with the Norton.

Anyway, you screw it in, add the air pressure and that holds the valves closed while you work. There are considerations however:

1) You must have a significant and continuous/reliable supply of compressed air. If it peters out mid job, your valves will be inside the cylinder you're working on.

2) Make sure the cylinder you're going to add air to is already at or near BDC because the air pressure will drive the piston to the bottom of the cylinder in a hurry if it isn't. Also, of course, the rockers must be removed before adding air; If the rockers are still in place one of the valves won't be closed at BDC.

3) The pressure will cause a blow by effect past the rings and will try to pressurize the crankcase if steps aren't taken to avoid this.

Hi lads,

Thanks for the replies. I think no.2 is off my list I don't have a good enough compressor.

I'm leaning more towards the rope trick. Anybody see any major issues with this method?


Kevin

Anybody know the thread type/size of the tappet adjuster screw?

I'm starting to make up the tools I need as per ludwigs instructions and thought I'd have something in my 'bits' fastener box but nothing comes close.

On another forum a chap mentioned he used an M7 set screw which he says fitted fine?


Kevin

click said:

Anybody know the thread type/size of the tappet adjuster screw?

Click to expand...

[Edit] 9/32" - 26 TPI (Cycle thread Whit Form)

Thanks L.A.B.


Kevin

click said:

..On another forum a chap mentioned he used an M7 set screw which he says fitted fine?..

Click to expand...

I mentioned that in the thread . M7x1 is a really close fit and won't damage anything .

If you think you 'll do this more than once in your life , it really pays to make the correct tool to hold the valve up.
The rope trick may work ,but I found the rope to be too spongy .

Hi ludwig,

Many thanks for the reply.

I started working on the tools tonight, I've bent some flat bar in a 'U' shape. I'm going to use the body from a TDC tool instead of gutting a spark plug.

I just need to get some fasteners tomorrow to finish off the tools & I should be ready to go!!


More anon

Kevin

ludwig said:

click said:

..On another forum a chap mentioned he used an M7 set screw which he says fitted fine?..

Click to expand...

I mentioned that in the thread . M7x1 is a really close fit and won't damage anything .

If you think you 'll do this more than once in your life , it really pays to make the correct tool to hold the valve up.
The rope trick may work ,but I found the rope to be too spongy .

Click to expand...

I've used the rope method on Chevy V8s anf Toyota 4 cylinders without issue. You need to use the soft nylon white rope and make sure you get lots of it into the cylinder with piston at least half way down then rotate to raise the psiton. You will need to find a way to hold the crank so it won't rotate and let the piston drop releasing the pressure on the valve.

Bob

bobunome said:

ludwig said:

click said:

..On another forum a chap mentioned he used an M7 set screw which he says fitted fine?..

Click to expand...

I mentioned that in the thread . M7x1 is a really close fit and won't damage anything .

If you think you 'll do this more than once in your life , it really pays to make the correct tool to hold the valve up.
The rope trick may work ,but I found the rope to be too spongy .

Click to expand...

I've used the rope method on Chevy V8s anf Toyota 4 cylinders without issue. You need to use the soft nylon white rope and make sure you get lots of it into the cylinder with piston at least half way down then rotate to raise the psiton. You will need to find a way to hold the crank so it won't rotate and let the piston drop releasing the pressure on the valve.

Bob

Click to expand...

Hi Bob,

Many thanks for the reply.

I'm going to give ludwigs method a try & if that does not work I'll try the rope trick & if that does not work the head is coming off!

I got all my 'bits' today, not easy getting a 7mm machine bolt in Ireland!! Hopefully I'll get some time this evening to finish off the tools I need.

More anon

Kevin

I have used the rope trick on my Norton with out any problems. I had an intake valve seal that went up & down with the valve stem.
:wink: The tricky part is getting the valve spring compressed and not losing the valve keeper. Pack the head & intake with paper towels so that the keeper halves can not go far. Use heavy wheel bearing grease to make it easier to re install them.

Bruce MacGregor said:

I have used the rope trick on my Norton with out any problems. I had an intake valve seal that went up & down with the valve stem.
:wink: The tricky part is getting the valve spring compressed and not losing the valve keeper. Pack the head & intake with paper towels so that the keeper halves can not go far. Use heavy wheel bearing grease to make it easier to re install them.

Click to expand...

Thanks for the advice on the collets, I'll have the whole area covered in paper towels, it will look like a surgical operation :mrgreen:

Kevin

Hi Lads,

Looking for more advice.

I see on Old Brits they have two types of oil seals:

11-062726 Oilseal, Inlet Valve 12 - 3.97
11-062726/A Oilseal, Inlet Valve, Special with Spring 22 - 3.93

Anybody use the one with the spring? What's the idea behind this?

Can anybody recommend any other type of seal worth considering?


Thanks

Kevin

My two heads use the spring backed up seals. Considered an upgrade to minimize needing do em again as soon or ever again till something else wears out. Can't say if the sales pitch works out as advertised as ain't lost or worn out any yet.

hobot said:

My two heads use the spring backed up seals. Considered an upgrade to minimize needing do em again as soon or ever again till something else wears out. Can't say if the sales pitch works out as advertised as ain't lost or worn out any yet.

Click to expand...

Hi hotbot,

Thanks for the info. I'm trying to figure out if anybody on this side of the pond (Ireland / UK) stock the seals with the spring?

Going to attempt removal of the seal tonight, fingers crossed!


Kevin

Give the upper spring retainer a good tap to break the collets loose before compressing the spring. Good luck.

batrider said:

Give the upper spring retainer a good tap to break the collets loose before compressing the spring. Good luck.

Click to expand...

Hi,

Thanks for the tip & good wishes.

Well I'm just in from the shed and . . . . . . . . it worked a treat :mrgreen:

Bit fiddley getting the collets out but that was expected.

The 7mm bolt I used was a little long, I did cut it but not quite enough. It was about 65mm, I'd say 55mm-60mm would be better. No problem getting it on but when you remove the collets and release the spring tension it obviously pushes the whole compressor tool up a bit higher and in turn the top of the 7mm bolt was hitting the head steady before I had completely unscrewed it from the rocker!

With a bit of technical 'giggling' I got it out.

I felt like I was performing open heart surgery on my Norton!

Part two will have to wait until I got some seals and a few gaskets etc.

More Anon

Kevin

Small update. I talked to a Norton spares supplier in the UK and they explained that the valve guide seal with the spring is a Rover part and they would not recommend it as they felt it would restrict oil lubrication?

I'm going to use the standard seals for the moment. At least if I change my mind I know how to change them!

Have to wait till next week before I get the parts.

More Anon

Kevin

Update:

Got my parts today, great service from RGM in the UK.

Getting all my 'bits' together to put back on the bike & I noticed there was no heat insulator under the lower valve seat?

I got some spare heat insulators with my order, so, do I put it back together as it was with no heat insulator or do I use the heat insulator?? My gut feeling is to use the heat insulator as it was specc'ed for a reason!

Anybody see a problem if I put the heat insulator on the RH inlet only for the moment? I'm not doing the LH inlet as the seal seems OK, I'm presuming the LH heat insulator is also missing! and probably the front also!!.

Advice appreciated.


Thanks

Kevin