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Hi,

Wondering if someone might be able to give me some advice before I refit my head and end up with oil leaks from the pushrod tubes.

When I removed the head and the pushrod tubes I found that the cups at the bottom had been sealed to the block with silicone (or similar red stuff). Also, the seal between the pushrod tube and the cup was a combination of a black rubber 'o' ring and more silicone. The 'o' ring is like a normal 'o' ring, that is it is round in section.

I have looked at the parts guide and the bits I have in a gasket kit and I have 4 white rubber seals. They are square section rather than round. This looks correct.

I am concerned about the seal between the cup and the block. This is metal on metal and I can image it leaking even if the pushrod tube is sealed properly to the cup with the supplied rubber seals.

I have cleaned up the tubes, cups and block to remove any silicone.

Can someone confirm if only having the white seal between the rushrod tube and the cup is correct and that I don't need any other seal at the bottom of the pushrod tubes (i.e. between the cup and the block?

Many thanks
Peter


1963 3TA (TwentyOne) Half Bathtub
1968 T120 Bonneville
(Long gone - 1975 Puch VX50, 1976 Suzuki BZ120, 1983 Honda CBR125 TDC, 1991 Honda CBR600)
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1968 T120R
1972 T120RV
Any advice given is without a warranty expressed or implied.
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Thanks Desco

That’s a useful and comprehensive article.

Not knowing the full history of my bike I don’t know what parts have been swapped or modified (e.g. head skim) over the years. Will check what I can based on the article.

The 1968 parts manual shows 2 square section seals and the “cup”. The article talks about “wedding bands”, which I guess are different to “cups”.

I will work on getting the crush right and see how it goes.

Thanks again
Peter


1963 3TA (TwentyOne) Half Bathtub
1968 T120 Bonneville
(Long gone - 1975 Puch VX50, 1976 Suzuki BZ120, 1983 Honda CBR125 TDC, 1991 Honda CBR600)
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Look up a 72 parts book to see the wedding bands. I have a 68 and a 72. Neither has leaking pushrod tubes, but they both have all the correct parts. Not a mishmash.


1968 T120R
1972 T120RV
Any advice given is without a warranty expressed or implied.
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Hi Peter, Wedding bands started in '69 & later. I haven't had earlier version apart since the early 80s.

Rabers did a video, but doesn't speak of lowers. It may or may not help you.




Here's a Youtube that shows assembly. This is a good one! The cup washer, bottom seal etc. as well as compression or "squish". Fast forward to about 45min.



Don


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Thank you for the replies.

I can see me spending hours watching the Lowbrow videos. Great to see such thorough coverage and great filming.

I have assembled with the seals I got in the gasket kit from Feked. They are E3547 at the top and E4752 at the bottom, which the part book shows as correct. However, the resultant gap between head gasket and head, before attempting to torque it down, seems massive, around 0.06" (1.5mm) I would guess. I have put the head bolts in and screwed them in light finger tight and my biggest feeler gauge (0.8 mm) is flapping around like a "d*ck in a shirt sleeve" (as my metalwork teacher used to say!)

Based on the information in the replies, I have matching tappet blocks, pushrod tubes and head (looks like if I had a mismatch in any of these it wouldn't even bolt together).

I can only assume the head has been skimmed at some point.

Can the seals be cut down effectively or is that unlikely to work? Thicker head gasket?

Thanks all again for your advice.


1963 3TA (TwentyOne) Half Bathtub
1968 T120 Bonneville
(Long gone - 1975 Puch VX50, 1976 Suzuki BZ120, 1983 Honda CBR125 TDC, 1991 Honda CBR600)
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Hi Peter, I’ve successfully sliced the seals on the lathe, using a socket in chuck that seal fits on snuggly. Spin it up & slice with new razor blade. Not so easy to get consistent results.

End of day it’s probably best to buy all the thickness you might need & have on hand.

Who knows what they did at factory? We know they leaked.

Production tolerances at Triumuph were pretty lax.

Regarding head thickness who knows. Triumph gave no spec. I’ve measured a few heads carefully. All over the place. I bought my bike new. Skimmed head .009”. Head still thicker than most. I had it skimmed just now again to improve surface. .008”.

Do I dare bring this up?? Two parts to this. Combustion chamber volume is reduced. From skimming, but also rocker arm geometry. Skimming brings rockers closer to cams. Push rods stay the same place. This brings adjuster screw end closer to valve stem. However stem height must be accounted for. Perfect geometry centers adjuster screw on center of stem at 50% opening. Thicker head gasket certainly compensated for skimming depending on how much was removed & how thick the gasket.
Head swimming yet? Nothing is simple on a Triumph!

What to do? Here’s what I would do. Get the selection of seals. Trial fit with normal head gasket. If you find thinnest seal too thin, then do math & get thicker head gasket. If valve adjuster screw doesn’t run of tip of valve stem closed or fully open, don’t worry about it. Mine were biased after installing.080” thick head gasket. I’ve seen many biased. Bikes worked fine. Guides seem to last fine also.

Looking like next step is order a selection of seals. Thing is a shop has all this in stock. They get a selection off shelf. Charge out the ones that fit, restock the others. This is common shop practice. Luckily seals are not too costly.
Don


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Cheers Don.

Yes, makes sense to get some other seals rather than bodging the ones I have.

I have had a proper look at the head and there doesn't seem to be much of a "foot" where the gasket sits. In places it is almost flush with the bottom cooling fin. in other places there is probably a couple of mm of metal. Not sure if this is a sign of a previous skim or whether they came out the factory like this.

Bit concerned now that the head may be no good. That's a problem as only second hand ones available in the UK (I guess everywhere), so no guarantee any other one is going to be any better.

Starting to wish I had just put up with the leaky base gasket and left well alone! :-(


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Quote
They are E3547 at the top and E4752 at the bottom, which the part book shows as correct. However, the resultant gap between head gasket and head, 


E3547 top seal is the "thin" one .... OD: 1+1/4" (31.5mm)... ID: 15/16" (24mm).... Thickness: 1/16" (1.6mm)

E4752 bottom seal is thicker ... 7/64 thick . ( these a book measurements real washers may be different )

Assemble the engine with head gasket and head ... and bottom of push rod assembly ...
( but without the top 1/16" seal . )... everything in place and finger tight except the top pushrod seal .

Ideally the pushrod tube now ... would rattle up and down and you would be able to measure a 1/32 gap
between bottom of tube and top of bottom seal .
If the top 1/16 gasket were in place... the 1/32 gap would be filled ... and the other 1/32 of gasket would provide the crush .

If you don't have 1/32 gap ... the bottom washer needs to be thinner... or the copper head gasket thicker .

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Hi Peter, So was running fine before just leaks. I’d measure old head gasket. Get one that thick.
Get a selection of seals if don’t already have thinner on hand.
Then get thicker head gasket as needed.
Don


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Thanks Quinten & TR7TVMan,

I have ordered a selection of seals and a thicker head gasket. Will try the approaches suggested to get as close to 30 thou. as I can.

I also ordered 2 pushrod tube cups for good measure from Feked. They are different to what I have. The ones from Feked are a simple "cup" shape that the profile would be an "L" if you sliced trough it. The ones I have already look like a cup inside a "wedding band". If you sliced through these the prifile would be "|-". They look like they are made that way but it is possible they are a cup pushed inside a "wedding band". Anyone seen these before?

One other question I have. From the Lowbrow video above, I can see that my Inlet rockers have been installed incorrectly. They have the Thackery washer against the rocker and the rocker has a slot in it. The guy in the video references a Service Advisory. Is it possible to get hold of these advisories from somewhere. My manual still says install it the way it has been installed.

Thanks again.
Peter


1963 3TA (TwentyOne) Half Bathtub
1968 T120 Bonneville
(Long gone - 1975 Puch VX50, 1976 Suzuki BZ120, 1983 Honda CBR125 TDC, 1991 Honda CBR600)
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Hello Peter,
The rocker question has been done to death on this and other forums, but THIS will help. Probably searching on "thackeray washer" on this and RAT will give you enough to put you to sleep for the night.
Cheers,
Mick.

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That is a very good link from TinkerToo. It is from The Bonneville Shop and includes the bulletin plus a description of the rocker washers.

Dave

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Done a test build with E3547's (thin) seals top and bottom and a thicker head gasket and it all looks much better. Difficult to accurately measure the gap (Tried Quinten's suggestion but one of the tubes is quite tight in the head, so I can't pull it up and down to see the gap). However, I have a gap when the head is sat on the tubes and I can push the head down onto the gasket with moderate hand pressure. Will give it a go and hope I don't get any leaks from the tubes.

I found that the original cups had been siliconed inside the wedding band type rings. I have now just used the new cups I bought with no wedding bands (the bands would be loose and rattle without any silicone to stick them to the tappet blocks or cups)

Thanks TinkerToo for the link. I have printed that off and added it to the workshop manual.

Hoping I might get everything back together this week in time for a ride at the weekend.

Thanks all for your advice and comments.
Peter


1963 3TA (TwentyOne) Half Bathtub
1968 T120 Bonneville
(Long gone - 1975 Puch VX50, 1976 Suzuki BZ120, 1983 Honda CBR125 TDC, 1991 Honda CBR600)
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My final comment on this thread, as I like to see these threads concluded :-)

All back together and done a few miles (between rain showers) and it all looks pretty good.

No leaks from the push rod tubes. No leak from the base gasket. No leak from the rocker shaft.

I was expecting I might need to re-torque after the first run but as everything seems ok I will leave well alone.

Having done this now I think I have "a feel" for how much "squidge" you need. It is pretty much common sense - not enough and it'll leak, too much and it'll deform the seals / tubes and it'll leak. Once you know all the variables you can pretty much judge what is right (IMHO).

It does look like my head may have been skimmed in the past given the need for a "thick"head gasket, but as long as it doesn't leak / blow then I'm happy.

I have some other, unrelated questions, but will start a new thread if I can't find answers.

Thanks for all the tips.
Peter


1963 3TA (TwentyOne) Half Bathtub
1968 T120 Bonneville
(Long gone - 1975 Puch VX50, 1976 Suzuki BZ120, 1983 Honda CBR125 TDC, 1991 Honda CBR600)
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Hi Peter, That's great news!!

The head gaskets settle in.... Very, very important to retorque the head after the first road test. Then again in a few hundred miles or so. Again in about 4-500 more miles. Not a bad plan to check torque before routine valve adjustments. After each torqueing the valve adjustment should be checked. Head gasket compression is double to the valve lash. So if gasket settles down .001" after torque the valve clearance closes by .002". At least remove rocker caps & feel that you still have at least some clearance.
Don


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Thanks Don.

I consider myself "advised"! :-)

I have some wiring that I am going to tidy up (put decent connectors on). I will need the tank off for that, so I'll give it a re-torque then.

Thanks
Peter


1963 3TA (TwentyOne) Half Bathtub
1968 T120 Bonneville
(Long gone - 1975 Puch VX50, 1976 Suzuki BZ120, 1983 Honda CBR125 TDC, 1991 Honda CBR600)

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