743 Grinding Noise When Attempting Start

[onepoket]

So, it has been a while since I've posted.
My 743 restoration has gone great. I rebuilt everything but the transmission, got the engine running great, rewired the whole dash, new gauges, sensors, everything was working as expected.
On Tuesday I started it up and put my bucket away and put the plow box on and backed it in my garage ready for snow. I should note, that when I turned the machine off I thought it made a weird grind noise as it stopped, but I didn't think much of it until today.
Today I went to start it and it would not start. It makes a horrible grinding sound when it tries to turn over. Also, during the start up it is as if the drive is engaged even though the sticks are neutral and the brake is on. The sound is coming from under and behind the seat, in the vicinity of the U joint. I had my wife turn the key while I looked in the back with the fuel line off. The engine cranked fine, no grinding noise or anything, exactly what you expect.
I then got in the machine and tried to start it again with her there and it made the grinding noise again.
My guess is that it is the u joint or the transmission, possibly the rotating group(s). I hand cranked the engine and thought I would hear some grinding but did not. Is that because it needs to spin much faster to hear it? Also, why when cranking with no fuel would I not hear grinding?
Hopefully someone can point me in the right direction. I had planned on pulling the engine next summer and doing maintenance on the pumps/trans/plates and rotating groups. If I have to do that now it will be tough, I dont have a lot of room to move in my garage in the winter.
Thanks for any info!

 

[onepoket]

Any thoughts on this? I just took a bunch of pictures of the u joint with an inspection camera put down through the shroud. Not great quality but I don't see any broken parts, I spun the engine by hand to see all the sides of it. Could it be that the engine slid and is not aligned or maybe pulled the coupler off the pump shaft a little? Or would it sound like that if the u joint needed grease?

 

[flyerdan]

Any thoughts on this? I just took a bunch of pictures of the u joint with an inspection camera put down through the shroud. Not great quality but I don't see any broken parts, I spun the engine by hand to see all the sides of it. Could it be that the engine slid and is not aligned or maybe pulled the coupler off the pump shaft a little? Or would it sound like that if the u joint needed grease?

You mention snow - if it's below freezing any water that might have gotten into the hydraulics could have prevented the pumps turning and stripped the drive coupler. If you can see it turning and there are no grenaded parts, that would account for the noise. A u-joint needing grease tends to squeak when it turns, as you would expect from anything lacking lubrication.
There are several 743 books in the manual thread, you might grab one of them and see if there is anything in the troubleshooting section, or at least it shows all the parts and how they go together.
I can't recall without going looking, but I think there might be a stub shaft on the Vickers pumps that can be replaced without taking the whole thing apart, should the coupler strip it.

 

[onepoket]

You mention snow - if it's below freezing any water that might have gotten into the hydraulics could have prevented the pumps turning and stripped the drive coupler. If you can see it turning and there are no grenaded parts, that would account for the noise. A u-joint needing grease tends to squeak when it turns, as you would expect from anything lacking lubrication.
There are several 743 books in the manual thread, you might grab one of them and see if there is anything in the troubleshooting section, or at least it shows all the parts and how they go together.
I can't recall without going looking, but I think there might be a stub shaft on the Vickers pumps that can be replaced without taking the whole thing apart, should the coupler strip it.

Yeah no chance of water, I keep it garaged and haven't even plowed yet this season.

So, if it was a u joint problem I would either hear squeaking when turning by hand or have seen some sort of blown out parts?

Is there any chance this is something in the pump itself or your guess is on the coupler? And do you think it would typically be the coupler that is stripped or the shaft, not sure which metal would win.

I guess at this point the only way forward is going to be pulling the engine (ugh). Never done it, I do have a hoist but I have limited space in my garage, can't move the machine, and can't fully open the cab.

Has anyone ever had a problem where the engine mounts loosened enough for the engine to slide back and partially decouple the u joint from the shaft? I'd love for a fix to be just pushing the engine in and replacing the shock mounts, which I have on hand.

 

[[email protected]]

Yeah no chance of water, I keep it garaged and haven't even plowed yet this season.

So, if it was a u joint problem I would either hear squeaking when turning by hand or have seen some sort of blown out parts?

Is there any chance this is something in the pump itself or your guess is on the coupler? And do you think it would typically be the coupler that is stripped or the shaft, not sure which metal would win.

I guess at this point the only way forward is going to be pulling the engine (ugh). Never done it, I do have a hoist but I have limited space in my garage, can't move the machine, and can't fully open the cab.

Has anyone ever had a problem where the engine mounts loosened enough for the engine to slide back and partially decouple the u joint from the shaft? I'd love for a fix to be just pushing the engine in and replacing the shock mounts, which I have on hand.

check the starter and the flywheel

 

[onepoket]

check the starter and the flywheel

Tom, what am I looking for? Broken teeth?

Also, if it was a starter/flywheel issue wouldn't I have heard it when my wife cranked it with the fuel line off? It sounded normal when we tried that.

 

[foton]

Tom, what am I looking for? Broken teeth?

Also, if it was a starter/flywheel issue wouldn't I have heard it when my wife cranked it with the fuel line off? It sounded normal when we tried that.

I would look at male splines ( they usally go first), I have never fooled with this part so this is just a suggestion , but is there enough room you can disconnect the engine mounts and seperate things just enough to see if there is wear around the u joint coupler connections? I have read in the past of the splines failing.

 

[onepoket]

I would look at male splines ( they usally go first), I have never fooled with this part so this is just a suggestion , but is there enough room you can disconnect the engine mounts and seperate things just enough to see if there is wear around the u joint coupler connections? I have read in the past of the splines failing.

I'm going to try and get my inspection camera in from the front and see if I can get a look at the pump shaft.

In one of my pics from the top fan shroud, it looks like the u joint is not in very good alignment. It could just be the angle of the pic. But I know that the engine shock mounts are smushed, my wishful thinking is that is causing some u joint / shaft alignment that can be fixed by replacing the mounts.

Tomorrow I will see what I can see and decide from there.

Thanks for the info!

 

[onepoket]

I'm going to try and get my inspection camera in from the front and see if I can get a look at the pump shaft.

In one of my pics from the top fan shroud, it looks like the u joint is not in very good alignment. It could just be the angle of the pic. But I know that the engine shock mounts are smushed, my wishful thinking is that is causing some u joint / shaft alignment that can be fixed by replacing the mounts.

Tomorrow I will see what I can see and decide from there.

Thanks for the info!

So, Im reporting back as I have the machine working again.

Maybe this is a little embarrassing but it turned out to be sort of a perfect storm of things that went slightly wrong at the same time.

I put the camera in through the front and everything looked fine, so I got in there and greased the u joint heavily. The engine did indeed move I think because the fins of the fan ground a slot in the front of the air shroud.

So, the sound I heard I think was part u joint squeaking/noise, part fan blades rubbing the plastic and the last part was the machine creeping with the brake on. The brake surprised me because I had the neutral dialed in so well and had been fine for so long.

After I greased the u joint I loosened the engine mounts and tried to pry it up to replace the shock mounts. I couldn't rock the engine enough to get the clearance I needed so I gave up and just used the old ones but slid the side that was touching the shroud back as much as I could.

I started it up with the brake off and got it going. It sounds better than before, probably because of the greased u joint but Im sure the shroud not getting hit helps too.

Anyway, thanks for all the comments, I'm sure I will be back when I pull the engine in the spring to rework the pumps.