Frozen Chain Trencher

Digger 258 · Mar 14, 2016

I bought my used PT-425 back in November along with a trencher. Clearly the trencher had been sitting outside for years unused, as it had a bit of rust on it. trencher didn't look heavily used before it was parked outside, as the teeth weren't beat up or bent.

This weekend I decided it was time to start on the thousands of feet of trench I have to dig for drainage. Hooked up the trencher, flipped the PTO switch and . . . nothing. Trencher is frozen.

I sprayed everything very liberally with spray lube and beat on the thing with a heavy plastic dead blow and tried again - just a slight jerk when I flip the PTO on, and nothing else.

Sprayed some more, waited 24 hours, loosened the tensioner up all the way. Still no spin of the trencher. Right now I have it sprayed in more lube. I'm thinking I might need to take the chain off of the trencher and beat every link with a hammer to work some movement and then reinstall.

Surely some of you have a trick I haven't tried yet. Any thoughts?

woodlandfarms · Mar 14, 2016

It sounds more Hydraulic. would be surprised if it is the chain (the forrce of the motor should break it free, I mean the thing is breaking up rocks and everything).

Does the engine bog down when you turn on the PTO? If it doesn then I would remove the chain to make sure the motor is turning. If it does not bog down then you got a bad motor that is bypassing or....

Digger 258 · Mar 14, 2016

The engine bogs down when I turn on the PTO, and the chain bumps (like it's trying to move) a couple of millimeters or so, and freezes. Engine definitely changes it's tune when I put the PTO on - it doesn't die out or anything. I assumed the hydraulic motor on the trencher bypassed fluid if it was so rusted as to not be able to turn it. I guess I'll try to remove the chain and see if I have a spinning motor . . .

woodlandfarms · Mar 14, 2016

The motor could be worn out. you never know on these things. Front sprocket could be frozen.

Heat and wax is a VERY good way to get in as long as there are no plastic or bearing oriented parts. heat the heck out of it, and then push a white candle into the gap, wax melts and gets into the rusted parts.

Marks481 · Mar 14, 2016

Sure you don't have a stone caught in the teeth somewhere you can't see? Every now and then I get one lodged in really good and everything stops until I break it up with a chisel.

MossRoad · Mar 14, 2016

Yeah, I was thinking maybe a rock is binding it somewhere.

As others have mentioned, look for obstructions.
IF no obvious obstructions, then try removing the motor (or chain) and seeing if the PT can spin the motor with no load.
IF motor doesn't spin, motor problem.
IF motor spins, chain or track or sprocket problem.
Start at the beginning and move along down the line until you find the issue..

I love IF, THEN troubleshooting. :laughing:

Digger 258 · Mar 14, 2016

I got out of work too late to do anything tonight, but I'll look for rocks and obstructions. I would have thought I would see one while I was lubing every link in the chain, but was not specifically looking for that - even though that's probably what I should have looked for first! I'll also try the candle wax idea, (that sounds like it could be fun). If no joy there, I'll try taking the chain off or the motor off, whichever seems easier . . . Probably be Thursday before I can get to it but I'll let you know what I find. Thanks for all of your help so far. I've put 50 hours on the PT since November, and if it weren't for that pesky job getting in the way, I'd surely put more. It's just so darned convenient . . .I had no idea what I was missing before the PT.

BobRip · Mar 15, 2016

Sometimes the chain will jam on one of the sprocket teeth. You can tap the chain with a hammer and clear the jam. I always carry a hammer and cold chisel when using the trencher. Rocks get caught in the sprocket and chain interface. Chisel and hammer will clear this.

johara1 · Mar 17, 2016

Why can't you run it back wards, if something caught it will free up….. jim

Digger 258 · Mar 17, 2016

I thought about that, but in my novice mind the only way to do so would be to switch the hoses at the motor, and I guess I am not sure if running the motor backwards will hurt the motor at all. Does switching the hoses pose a serious risk of contamination of the hydraulics with dirt or introducing air that would hurt anything? I'll take any ideas . . . Hope to get working on it tonight, and if not I've got Saturday. I'll let you know what progress I make.