G knock, again

[JLG]

I didnt know how to bring back my old post. So I'll make a new update.

My styled G has a knock. Sounds like someone tapping on the flywheel with a big hammer everytime it putts, and you feel it in your feet on the floor board.

-first noticed knock a little bit last year, it's progressivly gotten worse

-new pistons, wristpins, rod bearings ~5 years
ago

I've done the following:

-set endplay at .008
-new flywheel bolts, they are definitly tight
-new clutch driver, it's now tight too, and new floating driven disk.
-I've just taken out shims from the flywheel side main bearing to set it at .003 clearance. Book says 2-6 thou.
-I checked and the crank was round, amazingly enough

KNOCK IS STILL THERE!! so now what? Thanks.

 

[2cylpartsinfo]

Remove, cut open and inspect the oil filter for metal (bearing, etc.) shavings. This will give you an idea if you have an internal engine problem.

 

[F-I-T]

Have you looked inside? I can't tell from your description if you have inspected the rods or just believe that they are still good from the previous overhaul, and not that that they are not, it's just that we had a broken rod cap bolt on a '48 "A" that sounded like that.

 

[Brother Yoder]

Could also be something in the crankshaft; hitting the crankshaft??

B. Yoder

 

[Anonymous-0]

check ignition timing. could be spark knock, had that on an A once. sounded like a rod bearing.

 

[BushogPapa]

Does the knock change when the clutch is engaged or dis-engaged..?
Are you sure the flywheel/Crank splines are not worn..?
Is this a "Built" engine for pulling..??
I would sure check the rod bearings and Rt Main too..
Many sounds are peculiar to a JD 2 cylinder engine, but a knock that harsh is not..

Ron..

 

[jd b puller]

I found the old post, see link below.

- Did you let the machinist determine the bore, or did he go by the spec? Does it sound like piston slap?
- Did you check your rods for clearance?
- Did you verify that the flywheel wasn't cracked?
- Did you pull the crankcase cover off and rock the flywheel to look for movement in the rod/piston (or rather lack of when slightly moving the flywheel).
old_post

 

[teddy52food]

Still sounds to me like a loose flywheel. Pull it part way off & check the splines.

 

[JLG]

Thanks for all the suggestions.

Next chance I get I'll pull off the starter and crankcase inspection cover and look everything over, checkout the rod bearings, and look for any obvious sources. I'll cut the oil filter open too.

The knock sounds the same, clutch in or out. Listening at different places with the old hose-to-the-ear trick, you hear it pronounced at the center of the crank at the flywheel and lesser so at the clutch. Engine just has .125 M&W pistons, nothing wild by any means.

Thanks again for all the suggestions. I'll write back with what else I find.

 

[MN JD]

Check the block bolts that they are tight. Bought a B that had a knock, and all it was is the block was loose, doesn't take much to make it knock.