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Noisy tappet that keeps loosening


minicooper
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I have an exhaust valve noisy tappet that loosens after adjusting and driving for a couple miles. It is loose enough that I can turn the adjuster screw with my fingers - it loosens up to around .024. It seems that to fix I need to pull the valve and spread the fingers, or replace the self-locking adjuster screw (if I can find one). I read a thread where using a wicking thread locker, like Locktite 290, will hold. Anyone had luck with using thread locker on these adjuster screws? This is a 4 year old complete rebuild.

 

-Roland

1952 B3C 218

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The lower portion of the tappet adjusting screw is split down the middle and slightly spred apart. This causes the screw to bind in the tappet body.

I think this is why minicooper is calling it " fingers".

Thread locker will work on clean dry threads...not sure on oily threads.

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Edited by Dodgeb4ya
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Thread locker may work if you can get the threads dry enough.  Both male and female.   Brake parts cleaner and compressed air would help.   Maybe changing only the screw may work if the female part is OK.

 

Mopar and Y-block Fords with the mushroom lifters make a lifter change a big deal!

Edited by kencombs
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I recommend not doing anything that would render future adjustments impossible.  

 

I doubt you could unscrew that without removing the valve (and head). You also won't be able to get it clean enough (and keep it clean) to use thread locker, while assembled and readjusting.

 

Perhaps try unscrewing it as far as possible and wrapping a few turns with PTFE thread tape, that might help bind it up a bit. 

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Maybe, just maybe you can 'damage' the threads enough to make it lock again.  Unscrew to expose as many threads as possible.  Grind a small chisel to the correct width to span from the top of the lifter body to the first thread exposed when properly adjusted.  Using a light but firm touch with a smaller hammer on the chisel to cut a groove in the threads vertically.   If the chisel is hard and sharp enough you should see a small groove form with the cut threads slightly deformed.  If the first try works do several more around the screw.  Now try adjusting.  If this is successful you should be able to feel some resistance when turning it.  Only you can tell if it is tight enough not to move.

 

Last ditch effort here, and will require some 'feel' and technique to make it work.  But, there aren't many alternatives that don't require major dismantling of the engine.

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I had in 2008 the same problem in my #4 exhaust cylinder WWII jeep and tried many times to use "Locktite" and did not solve the problem.Only in 2016 when I restored all the engine.The tappet threads was damaged.Good luck.

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 I used a small (hand held) propane torch and heated up enough to burn the oil off, then when cool, squirted some paint thinner followed with alcohol, then heat again. When finished, flushed with MM oil and another oil change. I had the inner fender, tire and manifold off as there was not enough access to get #4 on my truck. 

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 Just wanted to add as you know the dangers of an open flame. I recently bought an induction heater for removing nuts frozen to studs. If you can barrow one or purchase, they really are a nice tool to create heat without a flame. I would have used this back then but didn’t know such a tool existed that could be controlled in small areas.

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If you compress the spring and push the valve all the way up, isn't there enough room to remove the lifter? I've only disassembled one motor, and it was awhile ago now. Can't remember how tall the lifters are.

 

Loctite and teflon tape probably won't work. I'd try wrapping a small strand of copper wire inside the threads and then screwing it back together. The copper should deform and fill any gap. If you try Ken's method, don't form too much of a ridge, or you just cut more metal away. It's not a bad idea, it's actually how some lock nuts work.

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10 hours ago, lostviking said:

If you compress the spring and push the valve all the way up, isn't there enough room to remove the lifter? I've only disassembled one motor, and it was awhile ago now. Can't remember how tall the lifters are.

 

Loctite and teflon tape probably won't work. I'd try wrapping a small strand of copper wire inside the threads and then screwing it back together. The copper should deform and fill any gap. If you try Ken's method, don't form too much of a ridge, or you just cut more metal away. It's not a bad idea, it's actually how some lock nuts work.

These are "mushroom" lifters, bigger on the bottom and must be removed from the bottom.

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