I have an annoying leak from the head joint.
so started a strip down but having removed the sleeve nuts ..... cannot now free the head from the barrel. ...its an alloy barrel and appears to be stuck with some sort of goo...maybe wellseal or similar
Any advice , tips etc welcome.
thanks
Compression?
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George, thanks for reply…
George, thanks for reply...already tried kicking over but it didn’t work. As both barrel and head are alloy heat no good either.
john
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I've heard of...
... people setting it at BDC, feeding a length of rope into the combustion chamber then rotating the engine and pushing the head off. Sounds bit unlikely to me but people swear they've done it. Wouldn't do any harm anywayespecially if the rockers are off so valves closed.
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Ian, thanks for reply. I’d…
Ian, thanks for reply. I’d forgotten that dodge....but it doesn’t work as the barrel and head both move so joint not broken.
john
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Can you whack a wooden drift…
Can you whack a wooden drift up against the exhaust port?
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Michael thanks for reply yes…
Michael thanks for reply
yes a gentle whack but the barrel moved with the head.....need to hold barrel down
john
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If you enjoy excitement…
If you enjoy excitement..replace head bolts. Slacken them back 1/16". And fire it up! Problem might be stopping it if you have a magneto...?
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David, thanks for reply…
David, thanks for reply
thats too much excitement for me....and yes it’s magneto
john
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Length of rope…
...was how I got Doris's head unstuck.
No external violence required!
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Alan, thanks for reply. was…
Alan, thanks for reply.
was Doris a single ?
john
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Head removal.
Hi John,
All the methods of string and compression will only work if you have a bolted flange barrel, so not feasible in your case. Michael's advice is best using a piece of wood and hammer in both ports alternatively, but you need a friend to hold the barrel down. Also try tapping the head in a rotational direction as the barrel studs will stop the barrel turning. Whatever you do, do NOT try a tyre lever between the fins, I have lost count of how many broken barrel/head fins I've seen where this has been done.
When you do get it stripped down, double grind the head and barrel joint and don't fit a head gasket.
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head removed
Richard, thanks for reply.
yes, without the barrel secure the whole plot moves when tapped. Appreciate the broken fin problem....but I have taken care !
got a couple of narrow flat steel plates and placed between joint with as much contact as poss....sleeve bolts back but eased off a little...... .pushed down on these plates to hold barrel down then some gentle taps in safe places and bingo separation achieved.
NOW...another issue. The head joint had been ground although personally I’m a gasket man.
always thought that lapping in this joint should give a smooth Matt finish just as when grinding in valves......BUT the grinding looks like circular tram lines.....
I will flatten these down a little and then it Hylomar and head gasket.
john
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The instructions are to use…
The instructions are to use coarse grinding paste on the broad surface and fine on the spigot. Then when it is cleaned off there will be a slight gap on the broad surfaces when the head is back in place, and the spigot will be in close contact. There is no reason to desire or expect a smooth grey surface on the broad face.
Why use a sealant? It's not specified or required. You have already found the problems they can so easily cause. And when and if you ever remove it again, you'll have the same problem. There are no water galleries to worry about, and the assembly is so symmetrical that a sealant isn't necessary.
Some sealant might help around oil drain holes. Some fit O rings there.
Can some ES2 experts assist? As far as I remember, prewar bikes had no oil return galleries, but post war ones do have them - on the broad face. So they must need an o ring? Is that one reason why postwar OHV singles had gaskets?
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Head removal
Hi John
A few years ago on my M50 Mike Pemberton did my engine for me and we decided to remove the head gasket, so he machined a shallow area round the drainage holes in the barrel to enable some small 'O' rings to be fitted, and then ground them in, as previously suggested by David.
No sealant was used, or required for 20k hard miles until I got a slight weep from one of the 'O' rings. I have since replaced them with some Viton ones, and this time re-used a head gasket, for another reason than a leak.
Regards John O
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Head joint.
Hi John,
Looking at your photo, I can see this is a 350 head opened up for a over-bored 500 barrel. As David says you should use the fine past on the spigot joint as this is where the gas tight seal is required to be perfect. The coarse paste will give a very small gap on the outer area which is correct for a gas tight spigot joint. By using an aluminium head gasket you immediately nullify this seal by making a corresponding gap in the spigot, just where you need the perfect seal. Also, the gasket is too malleable and as the castings expand with heat the gasket can be squeezed out of shape and fail. Sealant should be used on the outer faces to seal the oil drain holes, with or with-out "O" rings. If you want to check the quality of the "O" rings, put them in some new engine oil and leave them in you domestic oven at 200c for an hour.
Hi David,
Yes you are correct that no pre 1948 OHV engines had positive rocker lubrication as they were only oil mist lubricated. Pre-war these engines didn't use head gaskets and were a ground fit. This was a time consuming task and the use of gaskets later was to save money and speed up production. Just anecdotally, I have run this type of engine at up to 12.5 to 1 compression ratio, without a gasket of course!
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Richard, or should I say Mr…
Richard, or should I say Mr Holmes.....your observation is correct.
I have followed the collective advice and ground/lapped the head and barrel with fine and coarse paste and have good joint on the spigot. decoke done and both valves ground in so ready for reassembly.
i have O rings from my central heating boiler spares that are a good fit so they should be OK heat wise....plus some hylomar round the edge.
NOW just to play devils advocate and highlight annomolies.....why do some twins have spigots when the heads cant be ground....just to locate the head ??
WHY do all 1957-1966 single gasket sets include head gaskets ???
Just the sort of reason that these forums are so useful
Thanks again to all for input
regards John
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Worth trying kicking it over with the plug in (lead off!) and see if that will free it?
Otherwise heat from a heat gun can be your friend.
Good luck,
George