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ET: Engine (Twin) Push rod tubes

paulgoodson

New Website User
VOC Member
I am in the process of removing the cylinder heads from my Black Shadow, which I’ve never done before. I’ve unscrewed the nuts holding the pushrod tubes in place but they are all completely stuck. I can’t shift them at all. Any suggestions gratefully received.
 

vibrac

Well Known and Active Website User
VOC Member
I have now inserted the two X two O rings I did find that 'a smear' of silicone sealant is a difficult thing to achieve, and I wonder if my rare excursion into metric (ie useing 19mm ID instead of an imperial size) was a mistake as one of the packer o rings seemed loose on the tube, however they are all set in place now I used a torch and a screwdriver to check that quarter of the seal against the barrel is OK and all seems fine I shall now wait and check nothing has popped up before continuing the assembly.
Trouble is its a long way up and a long way back if it doesn't work, but I have found a wooden box and a large clamp to hold the UFM & Forks alongside on the primary side without disturbing the wiring or cables so just the oil lines need reconnecting but I guess it will be next week before testing can take place
 

vibrac

Well Known and Active Website User
VOC Member
Re the reassembly: the one job on a Vincent I hate is the insertion of the push rods especially with a closed timing chest I prepared myself as always with narrow nosed pliers and a prayer mat and after meditation 'dropped' them in and I think for the first time since a member of HMs government was hit by a front numberplate they actually dropped into the followers without a lot of fiddling and swearing. Dont get excited but I may be on a roll...:cool:
 

Glenliman

Well Known and Active Website User
VOC Member
The Videan seals for the pushrod tube uppers work really well. I did not have good luck with the rest of the seals in those kits, all of the other areas are back to stock stuff now.

Glen
 

peter holmes

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VOC Member
The Videan seals for the pushrod tube uppers work really well. I did not have good luck with the rest of the seals in those kits, all of the other areas are back to stock stuff now.

Glen
I find that hard to understand, I find all the banjo seals, oil drain and level plug seals, and also the inspection cap seals excellent, none of those areas weep oil once fitted, and you can use them time and time again, what do you dislike about them, the appearance?
 

vibrac

Well Known and Active Website User
VOC Member
Peter: I never reuse standard seals the cost of new ones are nothing compared to a mistake in tears and time But I agree assembled carefully all the standard seals are OK except the one seal I have problems with are the lower pushrod seals we are discussing
 

greg brillus

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VOC Member
Nothing personal but I don't use Neal's seal either.........The inspection cap ones tend to either split or melt........Obviously they split from being over-tightened which is a problem from folk getting carried away. The ones over the valve caps melt from the engine heat........they are difficult to get to, so i don't use them.....Or If I do only on the shallow ones on the kick start cover and primary cover caps. The alloy washers that sit bellow the oil return lines are too hard and may or may not seal.......I use the original ones, but use small 1/4" ID dowty seals under the 1/4" BFS bolts, this seals really well without over tightening the bolts, this will start to crush the top of the banjo fitting..........The ones Glen is talking about do work ok, but again they melt and weld themselves into the head, making removal difficult........ I find the original seals available from the VOC the best. Again I only use "O" rings on all the lower pushrod tubes now, easy to do and nil leaks. If the extra smaller one is used immediately above the main sealing one, then they look fine without leaving a large gap.
 

Glenliman

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VOC Member
I find that hard to understand, I find all the banjo seals, oil drain and level plug seals, and also the inspection cap seals excellent, none of those areas weep oil once fitted, and you can use them time and time again, what do you dislike about them, the appearance?

I've had two of the inspection cap seals break at the Aluminium ring, both at very inopportune times, hundreds of miles from home. One at the top of the engine let go. This requires dropping engine to replace. That one let go about 1500 miles from home, lots of oil everywhere. I opted to run for home spewing oil all the way. In hindsight, I probably should have bitten the bullet and done the work roadside.
I found the banjo arrangement with its Al. ring took quite a bit more bolt pressure to seal than the stock arrangement does. At least it did on my two Rapides.

This is a concern as the banjo hold down bolt only hangs on by a few fine threads. So I've gone back to stock on those too. All nice and dry at present!
However, as mentioned, I still have the Pushrod tube seals from the kits in place and they are dry.
I do put quite a few miles on and the problems with the split rings did not show up until several thousand miles down the road.


On edit
Greg posted similar info just as I posted this





Glen
 
Last edited:

peter holmes

Well Known and Active Website User
VOC Member
It would seem I have had a lucky escape, I have not had my UFM off the bike since I started using the Neal Videan seals, so all the inaccessible caps are still on standard sealing washers, and still using copper washers on the rocker oil feeds, I did have one tappet cap seal split, but I do like to check my tappets frequently and have had the standard tappet cover seals fail also. I suppose if you are really clever (as some are) you could recess the caps and O ring them, but I have always assumed that lowering the cap in the cylinder head could cause problems with the operation the rocker arm and maybe the valve spring clearance also. All the other V3 seals I have found to be excellent, especially the banjo seals.
 

vibrac

Well Known and Active Website User
VOC Member
Well I have now given the 19mm X 3mm and 2.5mm o ring bottom push rod tube solution a good blast and there is some weeping on the inlet tube but no worse than the standard seal. Never mind I certainly am not going to take the head off again . What is it they say on the girls advert?
"A little weeping is not going to stop me"
 

MartynG

Well Known and Active Website User
VOC Member
Well I have now given the 19mm X 3mm and 2.5mm o ring bottom push rod tube solution a good blast and there is some weeping on the inlet tube but no worse than the standard seal. Never mind I certainly am not going to take the head off again . What is it they say on the girls advert?
"A little weeping is not going to stop me"
For any seal to work THREE things are essential
1. The OUTER surface must be smooth and free of any burs or distortion
2. The INNER surface must also be free of any burs or distortion
3. The 'seal' must be uniformly deformed and in full contact with BOTH the inner and outer surfaces.

  • It is reasonable to assume that the machining in the crankcase for he pushrod tubes is smooth and undistorted.
  • It is unreasonable to assume that the pushrod tubes are undistorted, especially if anyone has ever applied any form of clamp trying to remove them.
So, irrespective of the type of seal the pushrod tubes must be perfectly round, free of burs or distortion. Mine leaked for years but they looked OK to the eye.

I replaced them with new tubes (ET46) and the leak was cured. I do acknowledge that at GBP20 each it would have been cheaper to purchase oil.

As to pulling the head, why not? With COVID restrictions here in Oz were not allowed to go pleasure riding anyway.
 

vibrac

Well Known and Active Website User
VOC Member
All the points mentioned were attended to but I did notice that the 2.5mm ring did not seem to be tight enough on the tube when fitting to hold the ET127 nut up as mentioned in passing, so my only question is the 19mm the correct internal dimension for the O rings? ( that was my assumption since only thickness has been mentioned)
(If it isn't that's my punishment for using the dreaded metric system)
 

greg brillus

Well Known and Active Website User
VOC Member
The ones I use are a snug fit in the case mouths and then the push rod tube is a snug fit into these lower "O" rings..... the upper thinner ones are only a packer really and don't do much except fill the extra space above the lower one. That's the reason I use a slight smear of sealant to act as a lubricant to aid the pushrod tube passing through it without it slicing any of the rubber as they are prone to do.
 

vibrac

Well Known and Active Website User
VOC Member
If you have bothered, the above is a sad tale of a pushrod tube oil leak in my Comet, the sad saga was ended when the engine still oozing oil from the tubes base, stopped working effectively (that turned out to be a big bore piston issue). But on the bright side it forced me to look at the push rod tube problem afresh
One thing for sure I will never ever again engage silicone (especially clear silicone) in an attempt to stem the flow. Today I have just spent an hour with tweezers picking minute strands of silicone out of the push rod tube recess in the crankcase (with the hole to the followers blocked with a couple of bungs). In my defense I can only say I dont normally get near the stuff but I was just desperate to cure the leak.
Taking advice of the elders I have invested in two new push-rod tubes and the standard seals and since I am also reverting to standard barrels and head (for the moment) I am hoping the tube angles will be appropriately in line with the head and a smear of gasket glue may be added but thats all, we shall see if I have been successful in the spring.
 

peter holmes

Well Known and Active Website User
VOC Member
I think I have this correct, but I am going back a good few years and the old memory can play tricks, when Tony Maughan rebuilt my engine he told me that the factory pushrod tubes were crap, crudely made that guaranteed distortion, Tony's solution was to turn them from solid bar, maybe with slightly thicker side walls and a beautiful flat surface where the tube enters the head, bog standard new seals where the tube enters the crankcase, result - never had a oil leak or seep in more years and miles that I care to remember, but my engine does wet-sump! what went wrong Tony?
 

MartynG

Well Known and Active Website User
VOC Member
If you have bothered, the above is a sad tale of a pushrod tube oil leak in my Comet, the sad saga was ended when the engine still oozing oil from the tubes base, stopped working effectively (that turned out to be a big bore piston issue). But on the bright side it forced me to look at the push rod tube problem afresh
One thing for sure I will never ever again engage silicone (especially clear silicone) in an attempt to stem the flow. Today I have just spent an hour with tweezers picking minute strands of silicone out of the push rod tube recess in the crankcase (with the hole to the followers blocked with a couple of bungs). In my defense I can only say I dont normally get near the stuff but I was just desperate to cure the leak.
Taking advice of the elders I have invested in two new push-rod tubes and the standard seals and since I am also reverting to standard barrels and head (for the moment) I am hoping the tube angles will be appropriately in line with the head and a smear of gasket glue may be added but thats all, we shall see if I have been successful in the spring.
I have had the 'new design' Videan pushrod tube seals in place for over 10,000 miles and at least TWO cylinder head removals and those original seals have been reused and are totally leak free!

Neal advertises under the name V3 in the back of MPH - look it up then send him an email for more info.

Was fully described in OVR #45 - extract attached.

Martyn
 

Attachments

  • Proper Pushrod Tube Seals.pdf
    208 KB · Views: 18

oexing

Well Known and Active Website User
VOC Member
To be open, I am a bit puzzled why there is all this trouble with sealing pushrod shrouds, not really rocket science I´d think. Provided there are no deep scratches on shrouds or case counter bores some standard o-rings should do . Some ovality should not be critical with o-rings but scratches are. No way can an o-ring reach down in deeper scratches for sealing there, so a bit of polishing out scratches may help. Misalignments don´t seem to be a problem with single o-rings down in the case but you have to check the upper part in the gland nut place so it will not do side loads on the lower o-ring 20x3 mm when tightening the nut.
I came up with sort of spherical washer on top of the shroud and a suitable Viton o-ring that gets squeezed by the gland nut for sealing there, no seal between top of shroud and head bore face, the spherical washer there is meant to prevent any side load reaching down to the bottom o-ring when faces of components are not parallel.

Vic
P1080898.JPG

P1080901.JPG

P1080909.JPG
 

greg brillus

Well Known and Active Website User
VOC Member
Having just spent three days this week at a state championship classic race event, I found the rear inlet pushrod tube lower "O" rings leaked quite a bit after each race........ I had added a PCV valve to the breather which came from the hole where the generator normally goes (this on a Comet engine)........The leak occurred for 2 reasons, one is the PCV valve is too restrictive causing too much crankcase pressure, and the second is with the extra added oil pump feeding the cam and followers, there is much more oil being flung around in the timing chest.......Added to that issue, I have not done enough to baffle the outlet from the breather to the vertical line back to the catch tank........The catch tank is quite small with a capacity of about 300 ml and after 2 race events, the tank was near full of oil..........Having said that, the cam and followers are showing no signs of wear, with no visible signs of any metal at the bottom of the timing chest. This proves that if the crankcase pressure is too much, then leaks will occur, no matter what you do. For those interested I came 2nd in my class in a field of about 22 bikes of various kinds and sizes. Cheers for now....... Greg.
 

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