128 loader knocking

cj4200 · #1 10-30-2009, 10:15 PM

Well I have a 128 with a homemade loader on it. I love it its a great tractor but it was on lifting duty tonight and started to knock. I got it back in the barn and took a quick look and I think one of the screws off of the chock came off and went through the carb. Its to bad cause it always ran real good. So what do you guys think? What kind of damage could it have done? Where should I start?

Merk · #2 10-30-2009, 10:42 PM

Is it a motor knock or a clutch/driveline knock?

First thing you need to do is double check the screws on the choke plate.

Is the engine oil level ok?

Where does the hydraulic pump get its power from? Can you disconnected the pump? Does your Cub still make the noise?

Remove the spark plug check it. Was the spark plug tight? What brand spark plug?

If the noise is still there I would remove the head and check for a blown head gasket.

Check the cumbustion chamber-surface of the piston and head for any damage.

Let us know if you find anything.

cj4200 · #3 10-30-2009, 10:52 PM

Im pretty sure its a motor knock. The screw is gone and I know it was there just before it started to knock. The knock changes with the throttle. Spark plug is a week old and its a champion h10c oil is good changed about a week ago with spark plug and gap is right. Pump runs off a belt driven pump on front pto.

Merk · #4 10-30-2009, 11:16 PM

Quote:

by cj4200
Spark plug is a week old and its a champion h10c oil is good changed about a week ago with spark plug and gap is right. Pump runs off a belt driven pump on front pto.

chanpion spark plugs are junk (my $.02).
I still would double check the items in my first post.

cj4200 · #5 10-30-2009, 11:23 PM

I plan on doing that in the morning.

danny · #6 10-31-2009, 02:02 AM

i would pull the head after you have done the other things talked about. The screw is ether stuck in the head or the pistion. If it did not score the bore or bend a valve dig it out put in a new head gasket and your in bisines.

cwmcbee · #7 10-31-2009, 09:09 AM

While nothing ingested into an engine is good, this should be a brass screw (isn't always though) and damage should be minimal. Maybe it was time to decarbon anyway, kill two birds with one stone.:biggrin2.gif:

Rhoderman · #8 10-31-2009, 12:00 PM

I'd pull the carb from the engine and look for the screw there first. Can a screw that size get uphill first, and then through the valve gap due to lift?

I can see where if it got past all the above and was causing the piston to tilt when at TDC, it would knock a bit.

I'd suggest pulling the head like the other(s) to do a damage assessment. If the screw is close to the edge, you may have smashed a ring groove. If at the center of the piston, dig it out, put on a new head gasket, and put it back together. You might want to put a new screw in your choke plate and tighten the other, heh.

I thought those screws were riveted in place. It sucks it happened to you, but it may have saved me a future headache since I'll be sure to check mine now.

Cvans · #9 10-31-2009, 02:00 PM

It's been my experience that the screw does very little damage. I picked up a very large Simplicity for cheap because of this same issue. Pulled one head and found the screw stuck under the exhaust valve. The head of the piston looked like a rabid Woodpecker had gone after it. Was only cosmetic tho. No damage to the cylinder or anything else. Replaced the head gasket and my Son is still using the tractor. So I would say pull the head and go from there. You might just get by for the price of a head gasket.
Good luck,
Chris

cj4200 · #10 10-31-2009, 02:38 PM

Well I pulled the head this morning and found the screw smashed up in lots of pieces on top of the piston. The top of the piston has the woodpecker effect that Cvans was talking about also the head has a few marks but cylinder looks fine. I think I will clean it all up put new gaskets on and see what happens.