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Discussion Starter #1
I'm doing a valve adjustment on my 998. Vertical cylinder was all in spec but on the horizontal cylinder all of the openers were too tight and all of the closers were too loose. So I pulled the cams, removed the opener shims, and miked them. All easy enough. I can't get the closer shims off though. They seem to be seized on the valve stem so that I cannot slide them down to expose the half rings.

Has anyone else run into that and what did you do to get them loose? I did a search, didn't come up with anything. I can't be the first person to encounter this though! I guess one idea is to try that trick where you stuff a bunch of rope into the cylinder and use that to hold the valves closed. Then maybe I could crack the shims loose. :confused:

thanks,
Debby
 

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There are a couple of ways to get them off. First, I would secure the valve stem with some forceps coated in latex, or something safe like that. This way the stem will not spin. Now, with your cams removed, pull up on the closing shim and twist it a little bit to re-seat the half rings a bit and offer a new smoother avenue of removal. Be sure you have your opener shims removed and your opener rockers are out of the way...I would assume this is done since you've removed the cams. Now, gently, put the end of a smaller diameter end driver or phillips screw driver (or your finger on the testastrettas) through gap behind the closing rocker and use it to pull the closer rocker forks down the shaft so it is plenty far away from the seat of the shim. Now try to twist and force the closer down from its location on the stem. Sometimes gently snapping the closer shut on the seat of the shim helps to jar it loose. If this proves to be too difficult, I would gently take a deep well socket and rubber mallet and place it over the stem and shim and VERY gently tap it down. Be sure to have a magnetic pickup ready to aid with the removal of the half-rings. If you have MBP collets, I would highly recommend the socket method. All in all this isn't that tough. Be sure to use some particle free grease (no graphite, molybdenum, etc) to hold the rings flush to the stem upon reinsertion- this allows them to stay put. I like to use a dab or red engine pre-lube since it dissolves well in oil. Good luck!!

Forceps, extension cord, or fray-free nylon rope is ok to put into the spark plug hole to hold the valves up. Be careful not to force the piston into the valves.
 

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How many miles are on this motor? When I pulled my 996 apart with 16k on it, the combustion chambers had a shed load of carbon deposits, enough that the squish was almost filled. What I'm getting at is- maybe pulling the heads will end up being the best choice. Not only is the valve train work much easier, but you can clean and inspect your chambers. BTW, I had a few closer shims that gave me problems too, with the head off it was just a matter of backing the valve with a block of wood and using a socket as a drift like ZoomZoom suggested.
 

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I have encountered this problem and have simply moved the closer shim down the valve stem and took a little sand paper and sanded the top edge of the stem (all around) to remove the burr. Sometimes the top of the valve stem mushrooms out due to the pounding of the opening shim from the opening rocker.

Mike
 

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1. Remove the spark plug
2. place the piston at BDC
3. push as much curtain cord as you can down into the cylinder (about 2 yards should do it) (don't lose the one end off the cord down the hole...)
4. carefully turn the engine to bring the piston up as high as it will reasonable go (packing the cord up against the valves inside the combustion chamber.
5. use a small brass punch to lightly tap around the circumference of the closer shim until it breaks loose of the retainer.
6. be prepared to replace some retainers (the stuck closers on my 999 had broken retainers under them)

 

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Discussion Starter #6
Thanks guys. I'll take another stab at it today. If I can't them loose with forceps on the valve stem it will be time for a visit to the hardware store to see what they have in the rope department!

I'm guessing the half rings are all broken but I won't know until I get the shims off.

Debby
 

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Discussion Starter #7
I got them all out. I had to break them free by tapping gently with a drift. Getting the half rings off was difficult though. They were stuck tight to the valve stems and just using the magnetic pickup tool didn't work. I actually had to dig them out with a dental pick. It took a while because the valve stem wants to spin (a third hand sure would be useful). I lost a couple of the half rings in the process, they just went flying across the garage and vanished. I know, pretty inept. I'll have to be more careful next time.

So I guess I'll be buying new half rings and checking the clearances again when the half rings bed in. Oh well, the more you do it, the easier it gets...

Debby
 

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I got them all out. I had to break them free by tapping gently with a drift. Getting the half rings off was difficult though. They were stuck tight to the valve stems and just using the magnetic pickup tool didn't work. I actually had to dig them out with a dental pick. It took a while because the valve stem wants to spin (a third hand sure would be useful). I lost a couple of the half rings in the process, they just went flying across the garage and vanished. I know, pretty inept. I'll have to be more careful next time.

So I guess I'll be buying new half rings and checking the clearances again when the half rings bed in. Oh well, the more you do it, the easier it gets...

Debby
Take a real close look at the half-rings. if they were THAT stuck, maybe they're aftermarket.
 

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The half rings do get pounded by the shim and will stick in the valve on occasion.It is time for the MBP collets so you only have to do it once!
 
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