1979 301AQS

[oldtin 0]

Spins free when not engaged!

[tunahead72 2,424]

Spins free when not engaged!

Okay, but your problem comes when the PTO is engaged, correct? Have you tried backing off the trunnion on the PTO rod one or two turns, just to see if it makes a difference?

I'm not sure where Terry (TT) was going with his suggestion to try removing the mower drive belt and then engaging the PTO, but you said it still slowed down. I think that points to the same thing I'm thinking, which is that the PTO clutch may need to be adjusted.

Another thing to check -- is your mower drive belt properly tightened, and not too tight?

Your symptoms could be the result of a combination of these two things, certainly easy enough to check out and fix.

Help me out here, guys, you've already mentioned anything else I could have thought of. It just seems like the bogging only occurs when the mower is engaged, maybe we should investigate that action more closely.

Or maybe I'm just way off base? :woohoo:

[Duff 206]

I'm not sure where Terry (TT) was going with his suggestion to try removing the mower drive belt and then engaging the PTO, but you said it still slowed down. I think that points to the same thing I'm thinking, which is that the PTO clutch may need to be adjusted.

Ok, I'm going to take a wild stab at this, only because I was working on the PTO clutch on one of my tractors last night and was thinking about this thread.

If I understand how the PTO clutch works, when it is disengaged the pulley/clutch plate (not the friction disk, because that's attached to the engine pulley) sits still (if the PTO brake thingy is working) and the drive shaft from the engine just spins inside the large needle bearing that's pressed into the clutch assembly.

When you engage the PTO clutch, the clutch plate and friction disk on the engine pulley are forced into contact and the pulley/clutch assembly spins up (hopefully!) to match the engine speed and transfer drive power to the attachment belt. At this point the big needle bearing isn't "bearing" anything, but only acting as a spacer to hold the parts in alignment.

With the PTO clutch engaged the second, smaller (needle?) bearing inside the pulley/clutch plate assembly that supports the stub shaft is now spinning its little heart out because the clevis that engages the whole shebang is pinned through the stub shaft holding it from rotating. Anybody still with me?

So.....if the smaller bearing for the stub shaft spins only when the hoop applies pressure to the clutch assembly and this bearing is failing, it may create drag. This may be what TT was thinking about.

And one other possibility: if the main pulley off the engine to which the friction disk is bolted has loosened up even a hair and that pulley has slid toward the engine block, there is a chance the pulley is dragging on the block once the PTO clutch is engaged since this pushes everything toward the engine. This may or may not make a noise, but I would think eventually it would begin to howl as dry metal rubs dry metal (initially a little left-over oil on the side of the block might provide just enough lube to keep things quiet). I think, without benefit of my Service Manual here at work, they recommend 1/8" clearance between the back side of the main drive pulley and the engine block.

Whew! That made my head hurt....and who knows if I'm even close to the right ball park, let alone in it!

Duff :woohoo:

[oldtin 0]

I backed off the trunion and checked the pulley and nothing changed. I am totally confused because when I engage the clutch the motor starts to bog,but I can pull my Swisher pull behind and the motor doesn't miss a beat. Just got done mowing 2 acres of grass with the Swisher and The WH did fine,but every time I tried to engage the deck the rpms started to drop!! :woohoo:

[TT-(Moderator) 1,131]

This may be what TT was thinking about.

No.......... I was actually thinking about the possibility of a safety switch malfunction.

If the engine still "bogs" after removing all engine driven accessories and engaging the PTO, the next thing I would do is bypass the safety switch(es) and/or relay (where applicable) to determine if it's restricting full power from reaching the ignition coil.

[Save Old Iron 1,566]

or the PTO lever may be grounding out the electrical system thru a chaffed wire :woohoo:

[rmaynard 15,520]

or the PTO lever may be grounding out the electrical system thru a chaffed wire

Would that not cause it to die as soon as the "short" occurs? He says that it bogs down, then dies if the PTO is not disengaged.

[WH nut 553]

It may not be making constant contact. Like SOI mentioned, I would try running a jumper right the the + side of the coil and see what it does..

If that doesnt help I would be thinking a slighty plugged muffer, the extra load on the deck would be more that pulling the other mower around and it might be just plugged enought it cant breath

[Save Old Iron 1,566]

Would that not cause it to die as soon as the "short" occurs? He says that it bogs down, then dies if the PTO is not disengaged.

when you turn off the ignition switch , magneto or coil based, the engine does not instantly stop - I guess you could use the phrase "bogs down" before it coasts to a complete stop. One can easily keep the engine running by turning the ignition switch back on before the engine coasts completely to a halt - similar to momentarily lifting up off the seat and engaging the kill function of the seat switch - sit back down quick enough and the engine continues back to life.

I think the "bogs down" phrase is confusing the issue here.

I'm going to say final answer here for SOI.

Remove the PTO bell completely - get all mechanical issues out of the way - no decks, no belts, no bearings, no trunnions, grunions, whatever - everything mechanical off the crankshaft.

Start the tractor and push the now very loose PTO lever forward - Dies ?? - it's electrical. We can outline some quick steps to make an ohmmeter check of the wiring.

[rmaynard 15,520]

...but every time I tried to engage the deck the rpms started to drop!!

Please elaborate. When you engage the deck, how long does it take the engine to bogs down to a complete stop?

While driving along with the engine at the throttle setting that you would normally mow, and the PTO disengaged, turn off the key. Does the engine do the exact same thing that is does when you engage the PTO?

[Save Old Iron 1,566]

Like SOI mentioned, I would try running a jumper right the the + side of the coil and see what it does..

Yeah , I don't recall if we got a real firm answer on that post.

But still, if the 12 volt line is being temporarily grounded, it would "bog" - but you would expect the fuse to blow - if there is a fuse.

I think we are reaching here, over-thinking the problem.But it is possible.

Gotta love long distance blindfolded troubleshooting - hence my avatar.

[Save Old Iron 1,566]

Like SOI mentioned, I would try running a jumper right the the + side of the coil and see what it does..

and I might even put a finer point on that suggestion

to eliminate the possibility of the PTO lever grounding out wiring or possibly physically moving wiring and disconnecting a wire from the back of the ignition switch,

disconnect the + wire to the ignition coil (removes grounding as a cause) - insulate the wire terminal to prevent touching ground.

jumper the + side of the ignition coil DIRECTLY to the battery + terminal (removes the possibility of the ignition wire being physically removed from the ignition switch)

start the tractor (battery jumper cable directly to the starter terminal, then remove)

and engage the PTO lever

what happens :woohoo:

[oldtin 0]

I'll try that tonight when I get home from work! Rmaynard,It bogs down to stop running with the pto engaged,If I turn the key off it just shuts down!

[rmaynard 15,520]

So what you are saying is that it is not acting like you've turned off the key. It just slows down until the engine stalls.

Do you have a video camera or a digital that will take videos?

[oldtin 0]

OK guys another update. Made a jumper from the batt to the coil and it made no difference. NOW some good news! Been wracking the old brain to remember when all this started,like I said I plowed snow all winter with no problems and cut the grass a couple times in the spring. Then I shredded the belt from the PTO to the deck so I went to my local TSC store and got me one of those Huskee blue belts,because I go through at least 3 Dayco belts a summer and figured I solved the belt problem. So today just for giggles I got another Dayco belt and put it on,started the tractor and engaged the PTO and started to cut grass in 2nd gear and cut for about 10 minutes and it started to bog down so I shifted to 1st gear and it cut great till I finished the yard. Not cured but a step in the right direction. I was troubleshooting the wiring like SOI said and I found I also had a fried post on the ignition switch and the plug is melted around the green wire. Still got the barking from the muffler which sounds like a motorcycle with straight pipes when they downshift. So now I know I need a rectifier and plug and an ignition switch and plug! Still need to figure out why I can't cut in 2nd gear without bogging the engine down. THANKS for all the help so far! :woohoo:

[rmaynard 15,520]

As I said in the beginning, and I'm saying it again, the problem is in the deck or the mule. If you are shredding belts, you've got something that is not right.

[can whlvr 993]

ya 3 belts a season is way too many,something aint right there

[Save Old Iron 1,566]

I found I also had a fried post on the ignition switch and the plug is melted around the green wire.

Thanks for hanging in there with us on eliminating wiring / chaffing as an issue.

Looks like you found a few issues in the electrical system (fried terminal at the regulator and ignition switch) which would have given you problems in the near future.

If you can get access to one, an infrared non contact thermometer gun may help in pin pointing any "hot spots" localized to a particular pulley or bearing/pulley combo which may be locking up.

[oldtin 0]

I guess I should have not have used the word shredded for the belts failure. The belts have a mold mark on them and after awhile they seperate and come apart at this mark. All the pulleys are fine and are spinning free.

[rmaynard 15,520]

Belts don't come apart for no reason. Even the cheap ones.

[WH nut 553]

Still got the barking from the muffler which sounds like a motorcycle with straight pipes when they downshift.

As mentioned before, baffe can loose plgging muffler? :woohoo:

[oldtin 0]

Going to check muffler this weekend!

[tunahead72 2,424]

Just a bit of a bump here...

This problem has come up more than once recently, does anybody know if this particular issue was ever resolved completely?

Thanks!

[Anglo Traction 761]

I reckon Andy (wheeledhorseman) is close to the issue, especially as many options offered so far have been checked . Symptoms show signs of a bad seated Exhaust Valve and or Carbon build up. Can significantly affect Power/exhaust noises etc. Have you ever had the Head off of it Oldtin ?.

[rmaynard 15,520]

I don't believe Oldtin has been on since the original RedSquare crashed. I too would like to see how the problem was resolved.