Replacing Valve Stem Seals (in situ) Pitfalls?

SteveA said:

I could interpret your reasons for doing an in situ seal change as:

'You don't want to take the head off to do the job, because you don't want to find, piston ring and bore wear that would demand a full strip and rebuild! Thus losing you a riding season.'

All ways round this is a little head in the sand. I usually work on the bench when engine building will have the head on and off several times in the afternoon, but in the frame it will take much longer, but I reckon I can remove and replace a head within a day, working at a leisurely pace as long as I am not fitting new valves or springs, take the weekend.

You can still ignore the piston and bore wear if you want!

But at least you will know where you stand on this.

300 miles a quart is way worse than my 4 cylinder air cooled 1200 Yamaha with 168K miles on it. And half of the oil use on that was that they typically boil the stuff and it evaporates......

BTW, I hope that slide hammer has 5/16" x 26 tpi cycle thread the other end, not the coarse thread we can see......and don't be too surprised if it doesn't work right away!

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I would interpret your post as ignoring the 1st rule of maintenance and repair. Always try the simple inexpensive fix 1st.

I have been working as a mechanic/skilled tradesman for over 50 years and as a novice I often made the choices you advocate only to find that I went to a lot of expense and work doing the worst case scenario repair only to find that it was something simple.

How would I be ignoring piston and bore wear? If the simple repair works to reduce oil consumption to a reasonable level I have accomplished my goal. If it does not do the trick then I know that further work is needed.

You remind me of my son, always wanting to tear thing apart before investigating the simple things that might be the root of the problem.

Remind me to never take a vehicle to you for repairs. I don't have money to throw away on work that might be unnecessary.

Re oil level...We used to see excessive oil use in "performance" auto engines that were filled to the "full" mark on the dipstick. It was VERY common to "run a quart low." I have to admit, however, that although I can understand the physics involved with a wet sump engine/high oil level/oil usage, I really can't with a dry sump - changing the oil level in a dry sump tank doesn't change the oil level in the engine sump.

OTOH, I am not arguing with the fact that Commando oil consumption does drop if the oil level is reduced. IOW, I agree that it happens but I can't understand why!

MexicoMike said:

Re oil level...We used to see excessive oil use in "performance" auto engines that were filled to the "full" mark on the dipstick. It was VERY common to "run a quart low." I have to admit, however, that although I can understand the physics involved with a wet sump engine/high oil level/oil usage, I really can't with a dry sump - changing the oil level in a dry sump tank doesn't change the oil level in the engine sump.

OTOH, I am not arguing with the fact that Commando oil consumption does drop if the oil level is reduced. IOW, I agree that it happens but I can't understand why!

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Wet sump (performance) engines have windage trays to prevent the crank from picking up oil from the sump. In essence the sump is separate from the crank albeit still in close proximity. If the oil is above the windage tray, the sump is overfilled.

I have some 1/4" X .064" brass strip. I'm going to solder a section onto the dipstick so that I can monitor just exactly how much oil is in the tank. As Is, after the level drops by about 16oz there is no longer any oil on the dipstick. I will drain the tank, then fill 1 quart at a time and make marks on the longer dipstick.

That way I will be able to accurately monitor oil consumption as it relates to oil level in the tank.

I have a LOT of experience with performance v8 engine building/windage trays and their benefit...or lack of it. Some windage trays were not well designed and, effectively, did little to reduce the crankcase windage effect on the oil.

Mopar, in their performance engine clinics demonstrated how a big block V8 at 7k RPM without a tray or with a poorly designed one can actually suck 5 quarts of oil out of the pan and wrap it around the spinning crankshaft in a mini-tornado-like cloud.

So, as I said, I can understand excessive oil use based on 'high' static engine oil level with a wetsump engine, but not with a dry sump since the sump oil level does not change with oil tank level.

Fast Eddie said:

That rings a bell. And makes sense.

Unless oil is introduced to the cam lobe at the point it meets the follower, I would suggest it’s just going to get flung off.

Imagine spinning a cam up in a lathe and squiring oil on it… it’s just gonna fling off everywhere !

Hence cutting fluids are directed at the point of cutting.

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I don't remember commoz doing the oil feed directly to the cam lobes
But I think I read he tried reinstating the cam trough that Norton dommies had to see if it prolonged camshaft life and it made no difference?

MexicoMike said:

I have a LOT of experience with performance v8 engine building/windage trays and their benefit...or lack of it. Some windage trays were not well designed and, effectively, did little to reduce the crankcase windage effect on the oil.

Mopar, in their performance engine clinics demonstrated how a big block V8 at 7k RPM without a tray or with a poorly designed one can actually suck 5 quarts of oil out of the pan and wrap it around the spinning crankshaft in a mini-tornado-like cloud.

So, as I said, I can understand excessive oil use based on 'high' static engine oil level with a wetsump engine, but not with a dry sump since the sump oil level does not change with oil tank level.

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I too have never understood how it can make a difference in a remote oil tank
Not saying it doesn't happen but I don't remember ever experiencing excessive oil consumption from filling my tank to the H mark
In fact I always fill it to the high mark thinking about it

baz said:

I too have never understood how it can make a difference in a remote oil tank
Not saying it doesn't happen but I don't remember ever experiencing excessive oil consumption from filling my tank to the H mark
In fact I always fill it to the high mark thinking about it

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But, which Norton dipstick do you have and is it original to the bike? "H" is not the same on all dipsticks that fit a Norton oil tank and who knows how an aftermarket dipstick might be marked.

IMHO, until it causes a problem, the more oil in the tank the better but oil returning takes more space than oil leaving due to frothing. Not sure what Norton calls it but Triumph tanks have a "froth tower" to deal with that and best I can tell the hump where the tank breather hose connects serves the same purpose in a Norton tank.

The 750 Rider's manual says: "It is most important not to exceed the "H"." The MKIII Rider's manual says: "If the level falls below the "L" mark, serious engine damage will occur; if the oil is above the "H" mark, oil may pass into the airbox and foul the air filter."

Dan1950 said:

Why is everyone thinking that this is a brand new build when I have repeatedly cited otherwise?

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If you read Greg's post again you'll see that the " Brand new build" is one of his customer's bike , not your bike.
Also, he's actually agreeing with you that it's worth giving the rope trick seal replacement a shot.

Regarding some of the comments questioning the value of valve seals etc.-
The only bike I've ridden that came from the factory without valve seals then later had them fitted was the Vincent.
Without seals it used a lot of oil. The Riders Handbook states that normal oil consumption is " 1 Imperial gallon per 1500 miles".
That would be for an engine in good condition. You could likely double that figure with a worn engine.
I rode it for a couple of months the rebuilt the top end and added seals to the inlet only. The bike also got low expansion pistons at this time.
The first long ride post rebuild was from Vancouver BC to central California, 2800 miles round trip.
Total oil consumption was 8 ounces.

I wouldn't worry about the seals causing undue valve stem wear.
After 60,000 miles the worn portion of the stem measured 2 tenths smaller than the unworn portion. Somewhere around half a thou is enough to warrant change, so the valves went back in and will likely see me out with that bike.

Now if you think about the mileage that the average Commando does, ( 2-3000 annually?)valve stem wear shouldnt be an issue.

Glen

You'd be done by now if you had started when you posed the question regardless of the method.

Schwany said:

You'd be done by now if you had started when you posed the question regardless of the method.

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I have plenty of other "things" to do with Trixie.

I'm waiting on the seals and extractor tool and I have to make some undersized spindles.

Dan1950 said:

I have plenty of other "things" to do with Trixie.

I'm waiting on the seals and extractor tool and I have to make some undersized spindles.

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One thing that is hard to run out of with a Norton is things to do. I'm just ribbing you.

Schwany said:

One thing that is hard to run out of with a Norton is things to do.

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It never ends!

marshg246 said:

I wonder the same thing, especially with iron guides. Purely guessing but I figure that they last about as long as the exhaust - the exhaust environment is way worse, but the intake gets less lube.

Someday I'm going to experiment with reducing the overall oil flow, turning at least the intake rocker spindles the "wrong" way, and getting rid of the seals. AFAIK, the reason we need the seals is because we flood the intake side with oil often reaching higher than the top of the guides.

Triumph and others need no seals - they have minimal oil going to the rockers and the drains are huge compared to the single small drain in the Norton head on the intake side.

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The pushrod tunnel is a pretty significant drain.

Danno said:

The pushrod tunnel is a pretty significant drain.

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Yes, on the exhaust side - until the intake side is well flooded it's not a drain at all for the intake side.

baz said:

Couldn't agree more
How long does it take to remove the head check everything over and change the seals
And replace it ?

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a full day?
Longer if you pull a stud.
And don't forget to retorque the head and rose nuts twice.
The first time can be a challenge, but with the right tools, changing a seal in situ shouldn't take more than one hour.
The rope trick is time consuming. Use a valve stop tool:
1. Letting the valve sink against the piston makes removing/replacing the spring much easier.
2. Wiggling the loose valve will give you some idea of guide wear.
(both not possible with the rope)
Leave a leak free cyl.head and oil lines undisturbed, and save yourself a gasket set.

baz: why 'decoke'?
a thin layer of carbon on pistons and combustion chamber works as an insulator.
The engine will run cooler and better ( hotter combustion, cooler head..)

Dan1950 : get the right tools:



If you lived any closer, I would give you a set for free.
They are easy enough to make.

Dan1950 said:

And neither did early '60s Harley Davidson Big Twins and "acceptable" oil consumption was a quart of oil in 250 miles.

Early SB Chevy V8s did not have valve seals and when the guides got worn it was not unusual to add a quart of oil at every fill-up.

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I lived that while owning my first car - 68 Chevelle with a 307.

ludwig said:

a full day?
Longer if you pull a stud.
And don't forget to retorque the head and rose nuts twice.
The first time can be a challenge, but with the right tools, changing a seal in situ shouldn't take more than one hour.
The rope trick is time consuming. Use a valve stop tool:
1. Letting the valve sink against the piston makes removing/replacing the spring much easier.
2. Wiggling the loose valve will give you some idea of guide wear.
(both not possible with the rope)
Leave a leak free cyl.head and oil lines undisturbed, and save yourself a gasket set.

baz: why 'decoke'?
a thin layer of carbon on pistons and combustion chamber works as an insulator.
The engine will run cooler and better ( hotter combustion, cooler head..)

Dan1950 : get the right tools:

If you lived any closer, I would give you a set for free.
They are easy enough to make.

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Maybe not the decoke
But personally I would remove the head to check everything out

Dan1950 said:

I would interpret your post as ignoring the 1st rule of maintenance and repair. Always try the simple inexpensive fix 1st.

I have been working as a mechanic/skilled tradesman for over 50 years and as a novice I often made the choices you advocate only to find that I went to a lot of expense and work doing the worst case scenario repair only to find that it was something simple.

How would I be ignoring piston and bore wear? If the simple repair works to reduce oil consumption to a reasonable level I have accomplished my goal. If it does not do the trick then I know that further work is needed.

You remind me of my son, always wanting to tear thing apart before investigating the simple things that might be the root of the problem.

Remind me to never take a vehicle to you for repairs. I don't have money to throw away on work that might be unnecessary.

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I won't need to remind you not to bring stuff to me.....Transatlantic shipping would be the least of your problems!

The other thing you should remember is that as a racer it has been my experience to put in 40 hours work for 1 hour of track time, assuming nothing actually went wrong!

What I am saying to you has been said by others.

If you had just had at it and pulled the head, it would be done by now, and you would 100% know the condition of parts you have not seen before, because you are reluctant to open it.

In terms of 'make work', you are planning to make 'undersized spindles' which I have never made, or needed. At least they will be from soft materials, so that should not consume any more time than it would take me to lift a head. I am assuming you already have materials and your labour is free!

In terms of costs, I am talking mainly labour, today, my labour is definitely free! I have not been paid by anyone to do anything for several years of retirement, and the last time I was paid, as a specialist engineer in aerospace, it was as a consultant. I didn't get my hands physically dirty for money for longer than I can remember. Which means, generally I got paid more than most individuals (including me!) could afford!

Happy days but long gone. Living on a pension time is something I have a fair amount of (hence the odd long post!)

As far as my current consultation offerings to you, you get them for free. I will be waiting until later in the year when you start a thread discussing cylinder head removal!

Several smileys because I don't want you to think I am hostile, you are definitely thinking about what you do and are up for learning.

But for all of your years of mechanic/skilled tradesman work, you did tell us before this is your first Norton. I built my first Norton engine in 1975 and last stripped one last year to change and time a cam. I lost count of how many times the cam drive was on and off in that build, but the head probably only 2 or 3.

What I do find often on this and other forums is that people do as you say, and try other things to avoid doing a task. History says, by percentage, they will end up doing it anyway.

I personally think it is often more efficient just to go straight to it. I am not often wrong. Even if it is just a popped seal, with an engine I didn't have 100% records for, I would want to pop the valves and remove the carbon build up you say is there on one side, grind the seats anyway and check the valve springs.

Last year I had a friend come round with his 850 Norton head, he wanted to change the seals, I had the tools he needed. I 'forced' him to go a step further and grind the seats, he was grumpy and said they were OK as they had only been done a few thousand miles before, by the previous owner. They weren't shot, but they weren't OK either with noticeable pitting, the extra work took less than an hour, and when he put it back together he commented how it was running better!

Enjoy the rope trick, and the riding season.

Actually, I tried the rope trick once, on a recently built motor with a suspect seal, it wasn't a Norton, but I admit I never made it work!

If and when the time comes to remove the head, it can be a pain in the ass or relatively straightforward depending on your technique. I've not tried the method you're attempting because, personally, I can have the head off and on again within a couple hours to replace, say, a blown head gasket (all my studs are time serted, so I don't worry about pulling them). As for sealing the head, IMHO, issues here usually result from ham fistedness, not ensuring surfaces are clean and parallel, not preparing gaskets and sealing washers, using "goop" where one shouldn't, over tightening, etc... The trickiest part, as most will attest to, is managing the pushrods. I find that by removing the front ISO bolt, and with a lever jack under the motor, I can tilt the power unit/cradle assembly down a few degrees... just enough to give the clearance needed to make the job much easier.

I wouldn't count on the Time Sert for much, they pull like they are in soft cheese.

Steve Maney is at the top of the Norton tree as a machinist and mechanic. There's only one other fellow I would put at that level and we all know him.
This Maney race engine regularly goes back to Steve for rebuild after a few hours of use, I can't remember how many but it wasn't very long.
Note the head joint leakage.
Steve noted that this wasn't bad.
Its strange that many forum users here can pop a Norton head off an on like nothing and have it turn out perfect while Steve Maney can't figure it out!
He has a fantastic shop, tremendous experience and skill, has manufactured scads of complete engines that are far superior to original Norton engines, but the head joint still leaks when used.

If you have a working Commando with a perfectly sealed head joint, you have a rare model.