Possible to replace gaskets without removing engine?

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
nathancitox
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Possible to replace gaskets without removing engine?

Post by nathancitox »

My 1947 G3L have some oil leaks that are getting worse.

I would like to replace them, but I'm not sure if the valve cover and cylinder can be removed without first removing the engine from the frame as I see the space is tight from the top of the engine to the frame.

Gaskets I would like to replace: Valves cover, Cylinder head, if possible cylinder base.

Also I don't find any info about torque for the bolts, is it possible to tighten the bolts without a torque wrench?

Any suggestions will be greatly appreciated!! :beer:
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Rob Harknett
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Re: Possible to replace gaskets without removing engine?

Post by Rob Harknett »

You recently asked about a carb. & were directed to where you could get books for your bike. Look in the books. You should have no problems removing the rocker box, head and cylinder with the engine still in the bike. I have never used a torque wrench to tighten bolts, only used the small spanners.
nathancitox
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Possible to replace gaskets without removing engine?

Post by nathancitox »

Thanks Rob, I've read the manual, but it wasn't clear for me, as it said one of the footrest needed to be removed. English is not my main language and that could led me to the confussion.
But I do have most of the manuals and books listed in the archive.


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Rob Harknett
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Re: Possible to replace gaskets without removing engine?

Post by Rob Harknett »

I have not checked Johnathan. I don't know why a footrest should be removed, unless it needs to be removed to get the exhaust pipe off.
Your English is good, so you should not have any trouble removing the top end of the engine OK.
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REW
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Re: Possible to replace gaskets without removing engine?

Post by REW »

All the top end can be removed and gaskets replaced with the engine in the frame. You will see the other parts that need removing to make this possible - tank, carb loosened and pulled back, exhaust and so on - do what is obviously needed and no more.

I used a slightly thicker cylinder base gasket than the thin paper originally used and I used O rings to seal the pushrods - search this site for info. If re-using a copper head gasket heat to red and quench in water to soften it.

As for torque settings, no, there are none officially and I urge you to use sensible "feel" with small spanners rather than tighten to a specific value with a huge torque wrench! You can always tighten a bit more with a spanner but not back off a stripped thread.
Ron

1951 Matchless G3L thumping round the Durham Dales.
nathancitox
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Re: Possible to replace gaskets without removing engine?

Post by nathancitox »

Thanks gentlemen, I'll follow your suggestions!


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clive
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Re: Possible to replace gaskets without removing engine?

Post by clive »

My torque settings, medium spanner head bolts and cylinder base nuts. small spanner rocker box cover!

To get the rockerbox off you have to leave the rearmost bolt in after loosening and slide the unit out with the bolt still in place. Remember to replace the bolt before replacing the rockerbox.
clive
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Rob Harknett
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Re: Possible to replace gaskets without removing engine?

Post by Rob Harknett »

clive wrote:My torque settings, medium spanner head bolts and cylinder base nuts. small spanner rocker box cover!

To get the rockerbox off you have to leave the rearmost bolt in after loosening and slide the unit out with the bolt still in place. Remember to replace the bolt before replacing the rockerbox.
That figures Clive, the smaller spanners are shorter, so you cannot tighten so much. A clean joint is important. I usually paint a thin coat of red hermatite gasket cement, on the paper gaskets with a small paint brush. Note on the gasket both sides, not on the engine part.
nathancitox
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Re: Possible to replace gaskets without removing engine?

Post by nathancitox »

Hi, i was able to replace the rocker box gasket. New problem! The rod that lift the exhaust valve touches the rocker box itself, not sure if I' m explaining correctly, but I can't adjust the exhaust valve. I'm sending a pic.

Thanks
Image
Image


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Rob Harknett
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Re: Possible to replace gaskets without removing engine?

Post by Rob Harknett »

Have you swapped the push rods. Have you re adjusted the tappets. That exhaust tappet looks like it is adjusted up very high compared to the inlet tappet. You must adjust the tappets. Turn the engine over until both valves are shut, check the tappet adjustment. If you have not done this, maybe you swapped the push rods, Now the exhaust is too tight and the inlet too loose.
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