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I have a 2001 model Hustler Super Z with the Kawasaki FH721V. It started leaking oil slowly early last season then by the end of the season it was leaking like a sieve. I cleaned it and the best I could tell it was the output shaft seal. I pull the engine, and there is oil everywhere. So I'm second guessing my assessment. BUT. I've pulled off the crankcase cover and will be checking the bearing tomorrow. If the bearing is still good I plan on replacing the following: crankcase gasket, output shaft seal, governor shaft seal, pcv valve and gasket (not sure about the breather foam block thing??), oil cooler o-ring. Thoughts? engine and mower has <900 hours on it...but they are 21 years old this next season.

So let's assume more is wrong with this thing than I've listed above, e.g. crack in the case/block, bad output shaft bearing (which requires the crankcase cover to be replaced to the tune of another $200). What's a good current model alternative replacement Kawasaki engine for this thing? Personally, I love this engine, it runs/ran like a champ. This mower has been really good 2 me, and so has the engine. So I did read a few months ago about a good replacement, but I can no longer find that thread or website. suggestions?

So. sorry for asking 2 questions in 1. But... thoughts on my repair? suggestions for a new engine?

You’ve got a good engine there, so my recommendation is to replace the seal and crankcase cover gasket. With that many years on the engine it‘s not uncommon for the seal to go bad. If for some reason those two parts don’t resolve your problem, then I would consider replacing the engine, but only after a second look at what might be wrong.

Replace both crankshaft oil seals. Also replace the governor shaft oil seal.

StarTech said:

Replace both crankshaft oil seals. Also replace the governor shaft oil seal.

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Both the top crankshaft seal and the governor seal look like a pain to replace. have to pull the crank. and looking at the governor, it looks fun.

So if I remove this crank, do I just need to mark the direction and piston the caps come off of and make sure I reinstall on the same piston and direction and be sure to retorque to spec or is there more to it than that? I would plan on just pushing the pistons up in the cylinders to slide the crank out. I already have the flywheel off. I suppose... I could try and pull that seal up without removing the crank with some seal pullers or? it looks too small to put some screws into it and use a slide hammer?

The governor seal, any suggestions there? I do have the Kawasaki service manual. Will see if it offers anything helpful as well.

Rivets said:

You’ve got a good engine there, so my recommendation is to replace the seal and crankcase cover gasket. With that many years on the engine it‘s not uncommon for the seal to go bad. If for some reason those two parts don’t resolve your problem, then I would consider replacing the engine, but only after a second look at what might be wrong.

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Thanks for the info. I know this engine has been a workhorse for me. I'm the second owner on the mower, I know personally the person who owned it before me. They put about 350 hours on it in 10 years. I've done about 550 in 10 years. The only major work I've done to the mower is I rebuilt one of the hydraulic motors myself. Cost about $60 to put the output bearing, thrust bearing, high pressure seal, and low pressure seal in it. I've put 5 seasons on it since rebuilding that motor. So I did something right. I really need to do something right with this engine! Thanks for the help!

I’ve replaced a lot of seals without pulling the crankshaft, only remember one where it didn’t work. It can be done, depending on your patience and time. Not really that hard to do. Only need one special tool which you can easily make. If you would like to try, I’ll try to put together the steps I go through.

Rivets said:

I’ve replaced a lot of seals without pulling the crankshaft, only remember one where it didn’t work. It can be done, depending on your patience and time. Not really that hard to do. Only need one special tool which you can easily make. If you would like to try, I’ll try to put together the steps I go through.

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I would be interested in your suggested tool. otherwise, will likely pull this crank out tomorrow.

driveguy said:

I would be interested in your suggested tool. otherwise, will likely pull this crank out tomorrow.

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BTW, I mic-ed the ID of the output bearing and it was within spec. Spec being 1.581" and we measured both output bearings at 1.5765" and 1.5760"

driveguy said:

Both the top crankshaft seal and the governor seal look like a pain to replace. have to pull the crank. and looking at the governor, it looks fun.

The governor seal, any suggestions there? I do have the Kawasaki service manual. Will see if it offers anything helpful as well.

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It is a pain to get out if done while engine is still together but once the crankcase cover it should be a lot easier. I done had to do three while the engine was still together. As I said a real pain to do that way.

StarTech said:

It is a pain to get out if done while engine is still together but once the crankcase cover it should be a lot easier. I done had to do three while the engine was still together. As I said a real pain to do that way.

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that's what I'm thinking, simply mark the rod caps and rods (one dot, two dots) remove 4 bolts, crank is out. pop old and press new seal, install crank, match up dots, torque to spec. I'm getting too old to keep doing this stuff. lol.

Ok, I’ll try to remember each of the steps in order. I’m assuming you have removed the engine.
1. TAKE YOUR TIME AND HAVE THE PATIENCE OF YOUR MOTHER.
2. List of tools. Sharp scratch awl, large and small flat head screwdrivers, ballpeen hammer, rough and extra fine abrasive paper, plastic wrap, (I use something different, but this works in the field) assembly lube, and special tool, (I’ll get into this later)
3. Remove the shroud and flywheel. Take a picture of each seal to reference how deep to drive the new seal back in.
4. Tip the engine over and support it so the crankcase cover is up. Might want to clean the cover before doing this.
5. With the rough abrasive paper clean the PTO end of the crankshaft until shiny And smooth. Repeat with the extra fine abrasive. You want it as smooth as a babies bottom.
6. Wipe clean with soft cloth and what ever cleaner you prefer.
7. Take the scratch awl and pound a hole into the metal portion of the seal.
8. Drive your small screwdriver into this hole and leverage the seal out. Think of a seesaw and lever, might need to find something to put under the screwdriver to act as a fulcrum. Also, might have to switch to a medium or large screwdriver. This is where patience comes in, as some seals can get very tight. Your seal has been ruined so don’t worry about more damage to it. YOU WANT TO AVOID DAMAGING THE AREA OF THE COVER WHERE THE NEW SEAL CONTACTS.
9. Once the seal is out wipe the crankshaft clean and now resand the shaft again with fine paper. Wipe clean again.
10. Now wrap the area of the crankshaft, wear the New seal will come in contact with, with plastic wrap. ClingWrap works best, ask your better half.coat this wrap liberally with assembly lube. I like assembly lube because it is halfway between oil and grease, but messy.
11. Now the special tool, I made. I took a piece of galvanized pipe, 1” ID and cut off an 8” length. Completely demurred both ends, inside and outside, until it wouldn’t catch a piece of Kleenex. I want it smooth. Once you have completed this you now have a bearing and seal driver which will fit over the shaft.
12. Coat the new seal liberally with assembly lube and slide it down the shaft. The lube and wrap will protect it for being cut it you’ve done everything right and go slow. Push down by hand until it stops and then drive it into place with your driver and hammer. Once it is in place slowly and carefully remove the wrap and wipe the area clean.
13. Repeat on the other side.

Like I said earlier, I done it this way more times than I want to count. I’ve probably got a dozen different drivers I’ve made for different size seals and bearings. Sometimes this is the only way it can be done. Whether you decide to try it is up to you, and I won’t feel hurt if you decide to open the engine. Because I’ve done it so many times, I no longer think about try to open things up and driving the seals out, take to much time. Good Luck in your decision and I’ll now wait for someone to tell me I’m stupid for trying this hack job. If you have more questions about this feel free to ask.

Just had good you are at replacing the following seal while the engine is still assemble when you only have 3mm or less of space to work with?

Is this an April Fools joke? Even you know a governor shaft seal that size cannot be done using my method. I can count on one hand the number of times I’ve had to replace that seal. Nice try though.

I only replaced about 12 in the last five years here.

And for two crank seal I would something with an OD nearly large as the seal OD. One is 48mm and the other 62mm on FH721V. And I am pretty sure 1 inch ID is 25.4mm so it wont fit over the nearly 35mm journals of the crankshaft.

Ok, did you read my entire post? I said I have maybe a dozen different size drivers I’ve made. When I get a chance I clean the outside of each driver and label them with the appropriate ID size. I would figure if you’re experienced enough to tackle this job, you’re smart enough to change the size of driver needed. Are you trying to be Korik and get under my hide. It’s my method for replacing seals, if you don’t like it don’t use it. The OP asked how I did and I posted it for him and anyone else who might want to try it. By the way, instead of ClingWrap, I use a microfiche card, but most people have no idea what that is. Is there something wrong with that too?

No problem and no your not stupid; just wise. It just read more like you were suggesting using an one inch pipe for his project. Now of course he will find out it wont work if he don't check the journal before trying. And yes I am constantly making my own arbors too.

Rivet, you got to remember one thing I am currently very busy as my Spring start up seasoon is early this year so if you can forgive me if I am irritating for I don't mean to be.

And boy I haven't seen microfiche film in years. Just telling off just how old you made me feel. What was suggest to me was to use electrical tape to wrap the shafts. But I don't think that will work on the step shaft.

Usual method for doing it in situ is to drill 2 or 3 very small holes in the seal being careful not to scratch the crank or drill into the crankcase
Then put some long self tappers into the holes and use them with a claw hammer to pull the seals out .
Once out polish the shaft will well lubricated steel wool 0 , 00 or 000 grade ( from the wood work section )
Wrap the shaft with cling wrap when putting the new seal in to avoid cutting the lip on the sharp edge of the keyway

I don’t have the time to look up shaft sizes, so just figured a 7/8” size. That’s why I posted that I have many drivers. Even have one for 3” seals on a tractor PTO. My little brother machinist makes them for me. I have used tape in the field, when it was all I had on an odd size seal. Messy cleanup. You think you’re old, when I started we didn’t even have microfiche, had only the 3” thick IPL books. At times I wish I still had them, only have about a dozen back at the shop I retired from. I‘m happy the owner allows me to borrow them when ever I need them, which is about 6 times a year. Yes, I love to work on the old stuff, two years ago I had fun getting a Briggs Model 6 running again. Should have seen the grin on the guys face, felt guilty charging him anything,

That all I ever had access to until about 12 yrs ago when things went to Acrobat files.

As for pullers I made my own as the crappy ones from the local auto parts store fail the very first time I used it.

well. i went the adventurous route (i.e. the cam and crank are now in bags sitting on the workbench). It only took about 2 hours to break the whole engine down. I will be ordering all the gaskets and seals this week.

Any suggestions on how to get the oil cooler mounting "joint" off? it's pretty stuck. anyone know if it's 25mm or 1" or ? reverse or regular threads?

It should be RH threads and considering it is a Kawasaki it should a metric size. But off the top my head I just don't know the actual size. I haven't taken one off in a few years but this why I have a complete set of Metric wrenches from 8mm to 30mm available to use if needed.

And seems I always needing to buy more wrenches and sockets every month. Now I got get a 22mm impact socket just to change the wheels on my truck. Nearly 10K in tools and I still having to buy more.

Well. just a heads up for anyone who reads this. The fitting nut for the oil cooler is 1". And the nut is so narrow I had to machine off the taper/chamfer on a $9 socket to get enough engagement with the nut. otherwise I just round the very outside edge off of it. I've been too busy with work and taxes to work on it much BUT the grass is growing, and I expect to have it done in 2 weeks. Will update then.

Well. weeks later it's almost there. work, taxes, family. and more work. So. does anyone have any good pictures of the front and back control panel connections as it relates to the governor arm, spring, shaft, and throttle linkage. I feel like something isn't right. I set it per the manual which states:

Turn the top end of the governor arm counterclockwise to fully open the carburetor [G] throttle valve and hold it there.
Turn the governor shaft counterclockwise fully to the end of its travel.
Tighten the clamp nut.

Which I did, and the arm lines up with the shaft exactly where it did before disassembly, because I do have a picture of that. The linkage is installed correctly as well. I believe the governor spring is, but maybe the arm on the control panel that rotates isn't in the correct orientation or sequence or???

So the problem. When I try to rotate the throttle arm on the control panel it tries to open the throttle more and starts to flex the linkage from the governor arm to the throttle. Maybe I'm confused on how this works. When I manual move the governor arm down (clockwise) the throttle will move down (clockwise), which I assume is closed (clockwise is closed, rotates the throttle toward some kind of stop screw), (counterclockwise is open...per the manual even.... and it rotates the throttle toward a hard stop). At this point I'm scratching my head.

Any pics? thoughts? guidance?

have a friend whose dad has the exact mower and same engine +/- a year or 2. Looked at his. I had the governor and linkage correct, but when I tightened the clamp it would shift the arm just a hair. So had to be a little more aware of keeping the governor arm from moving. and the answer to my question is, yes I was confused on how governors work on these small engines. So learning something every day.

driveguy said:

Well. just a heads up for anyone who reads this. The fitting nut for the oil cooler is 1". And the nut is so narrow I had to machine off the taper/chamfer on a $9 socket to get enough engagement with the nut. otherwise I just round the very outside edge off of it. I've been too busy with work and taxes to work on it much BUT the grass is growing, and I expect to have it done in 2 weeks. Will update then.



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That is something I do to a lot of my smaller sockets for the same reason. Shallow fasteners heads.

Alright. last update for a while. It's together and running. Sounds great. no leaks so far. I will be watching it closely the first few weeks. So here's all that I did:
Replaced:
Top and bottom shaft seals
Governor shaft seal
Crankcase gasket
PCV Valve and cover gasket (left the stop and breather foam thing)
Oil Cooler o-ring
Valve cover gaskets
Adjusted valve clearance
and of course intake and exhaust manifold gaskets
Dipstick tube o-ring
Spark plugs, oil filter, fuel filter
Cleaned the hydro cooling coils

I have about 10 hours on it already and so far so good. I'm really glad I broke the engine down this far and replaced everything I could. I feel like I would be right back at it in another year or 2 otherwise. I learned so much about small engines doing this. I never did get a price from a dealer on a full seal replacement, but the couple I called wanted $450-$600 for just the bottom shaft seal. So I'm guessing it would have been $1200 or more to break this engine down. idk. At least that's what I'm telling my wife, so I can go spend $1000 on something I want! lol. I think I have $175 into it including the drive pulley I bought.

Ok. I'm back for a quick update. Have about 60-70 hours on it since the seals were replaced. Zero leaks. Zero issue. Runs like a champ. Makes me feel great to take on a new and different challenge.