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artbuc
08-28-2010, 01:32 PM
Just discovered this forum. Have posted on several other forums and received some responses but this forum seems to be loaded with Kohler experts!

My engine is on a Gravely 18-H garden tractor (basically an Ariens GT 18 with a Gravely paint job). I use it to mow 1.5 acres and blow snow. It is 18 years old with about 12-1400 hours. The hourmeter broke in the first couple years so I am giving my best estimate. Engine starts and runs great. Burns very little oil. Compression is 100 & 105 psi. The only work I have done so far is one new exhaust valve/seat and new voltage rectifier, both a few years ago.

I wouldn't be thinking about doing anything except crankshaft endplay is excessive at 0.025" compared to the spec of 0.002/0.014". This winter I am planning on tearing her down to install a new thrust washer. I have been advised to replace the governor gear and install new rings. One person suggested a complete overhaul. I will need this tractor for only another 3-5 years.

I would appreciate any tear down tips and/or advice about what I should do when I get in there. Thanks.

Restrorob
08-28-2010, 06:18 PM
These old Magnum engines are far better than any Command, I would go the thrust washer and governor gear and nothing else. This has many more years of homeowner use left in it as is.

I've got two of these 18's myself, One in my ZTR and one I'm installing in a UTV. The Command 25 I have will continue to sit on the shelf.....

artbuc
08-28-2010, 07:00 PM
These old Magnum engines are far better than any Command, I would go the thrust washer and governor gear and nothing else. This has many more years of homeowner use left in it as is.

I've got two of these 18's myself, One in my ZTR and one I'm installing in a UTV. The Command 25 I have will continue to sit on the shelf.....

Thanks. It has been a sweet engine. My local expert Kohler technician suggested rings because he said you will always have hi and low spots which won't match up when you reassemble. However, another guy said you can pull the barrels off just enough to disconnect the piston from the rod and leave the piston in the barrel. I may try that.

artbuc
08-28-2010, 08:04 PM
PS. What causes thrust on the crankshaft? I have an electric clutch on the PTO shaft. When it is not engaged, the clutch brake is pulling the crankshaft towards the engine. When the clutch is engaged, there isn't any thrust on crankshaft, at least not from the clutch. However, a couple years ago I had the electric clutch removed to clean-up the faces. When I reinstalled it, I did not get the plates all the way home tight together and tight against the shoulder on the crankshaft. As a result, when I engaged the clutch it was pulling hard on the crankshaft (towards the engine).

I don't see how inward thrust from the PTO side would wear the thrust bearing. Is it possible that the endplay is caused by wear between the flywheel sleeve bearing and crankshaft? There isn't any thrust washer/bearing on the flywheel side separating the sleeve bearing from the crankshaft counterweight. It seems like the thrust washer will wear out only when the thrust is coming from the flywheel end, pushing the crankshaft against the thrust washer.

I hope someone here will explain this to me. Thanks.

Restrorob
08-28-2010, 09:03 PM
What's the spec number on this engine and the full tractor model and serial numbers ?

artbuc
08-28-2010, 09:23 PM
Kohler Spec # 24548, SN 1630306026

Gravely 18-H , SN 00589431

The Gravely 18-H does not have a Model number on it but based on Ariens/Gravely Parts radar it is a Gravely Model 931035-000101 which is equivalent to the Ariens Model 931033-004346.

It has a driveshaft connected to the flywheel shaft which drives the hydro trans.

Restrorob
08-28-2010, 10:04 PM
OK artbuc,

IMO, Each time you start a engine the starter drive gear pushes it's way into the flywheel with a certain amount of pressure. The crankshaft floats between the steel thrust washer and the brass flywheel end flange bearing, Between starting and the crank floating you will most likely find most of the end play wear on the flange bearing.

So, What I would suggest is replacement of the flywheel end flange bearing then check/adjust end play with the needed thrust washer to re-gain proper spec.

As far as leaving the pistons in the barrels, That's no problem at all. That's the only way to get it back together. The pistons have to go in first then the barrels/pistons held in place to install the wrist pins.

artbuc
08-29-2010, 06:16 AM
Thanks. When you say flywheel end flange bearing, are you talking about the crankshaft sleeve bearings?

This makes sense because I read that the thrust washer is hardened steel. I don't think it is designed to take the wear.

In addition to the starter wear you discussed, I am now pretty sure the electric clutch was the major culprit. Now that I know the sleeve bearing has a brass face to take wear, it probably has taken a beating with the electric clutch applying so much force to it.

artbuc
08-29-2010, 06:37 AM
Thanks. When you say flywheel end flange bearing, are you talking about the crankshaft sleeve bearings?

This makes sense because I read that the thrust washer is hardened steel. I don't think it is designed to take the wear.

In addition to the starter wear you discussed, I am now pretty sure the electric clutch was the major culprit. Now that I know the sleeve bearing has a brass face to take wear, it probably has taken a beating with the electric clutch applying so much force to it.

PS The service manual gives the following specs on the crankshaft sleeve bearing:

1. max out of round .0005
2. Max taper .001
3. Max running clearance (new) .0049
4. Running clearance max wear limit .0059
5. New ID (installed) 1.7439.1.7461

Which of these specs relates to endplay?

Restrorob
08-29-2010, 08:55 AM
When you say flywheel end flange bearing, are you talking about the crankshaft sleeve bearings?



That's correct,

None of the above specs pertain to the bearing flange (end play). Reason being, The average person would have to remove the bearing to get a measuring device on the flange which would most likely cause damage to the bearing.

artbuc
08-29-2010, 09:13 AM
That's correct,

None of the above specs pertain to the bearing flange (end play). Reason being, The average person would have to remove the bearing to get a measuring device on the flange which would most likely cause damage to the bearing.

I can't tell you how much I appreciate your help on this. I'll probably replace both bearings while I am in there.

How would the average person damage the sleeve bearings? They just slide on and off the crankshaft, right?

Restrorob
08-29-2010, 01:20 PM
Well yeah.....But I've seen people do some strange things over the years......

artbuc
08-29-2010, 06:22 PM
Well yeah.....But I've seen people do some strange things over the years......

I can't say anything after the bonehead move I made on my electric clutch. Sliding on the clutch plate with the key still on the shaft was pretty dumb. Now I have to wonder if I did any damage to my hydro trans. All of that endplay was being translated into the trans.

PS. I saw a good color photo of my sleeve bearings. They look like they are made out of a steel sheel with the bore lined with bronze. Hopefully the sleeve steel is softer than the crankshaft shoulder it rides against!

Restrorob
08-29-2010, 08:04 PM
Yes they have a steel inner sleeve that's a interference fit to the crank, Then the bronze flange bearing rides on the sleeve and the flange to the crank to wear the end gap wider.....

artbuc
09-28-2010, 09:02 AM
Yes they have a steel inner sleeve that's a interference fit to the crank, Then the bronze flange bearing rides on the sleeve and the flange to the crank to wear the end gap wider.....

Restrorob,

Here is my sleeve bearing. It looks like the flange that rides against the crankshaft shoulder is steel. It looks like the outer sleeve that is captured by the crankcase is steel and the bore is lined with a bronze sleeve which rides on the crankshaft.

Sorry for being dense on this, but the bearing you are describing seems like it is a different design altogether. What am I missing? Thanks.

http://cgi.ebay.com/NEW-Kohler-Crankcase-Sleeve-Bearing-52-030-10-S-/270592515934?pt=LH_DefaultDomain_0&hash=item3f00921f5e

Restrorob
09-28-2010, 12:09 PM
Sorry artbuc,


It is not you who are missing something, It's me..... Ole age is catching up, It has been quite a few years since I was inside one of these. It was another engine that has the bearing I described..... :hammerhead:

That is the correct bearing you linked, It is a bronze bearing with a teflon type coating that gives it the different color.

Sorry again for the confusion......

artbuc
09-28-2010, 01:28 PM
Sorry artbuc,


It is not you who are missing something, It's me..... Ole age is catching up, It has been quite a few years since I was inside one of these. It was another engine that has the bearing I described..... :hammerhead:

That is the correct bearing you linked, It is a bronze bearing with a teflon type coating that gives it the different color.

Sorry again for the confusion......

Thanks. So what I am calling steel is really coated bronze and the crankshaft shoulder is riding against coated bronze. That explains alot. I am quite sure now that when I split the case, I will find the flywheel end sleeve bearing shoulder to be mostly gone. This is because of the mistake I made assembling the electric clutch on the opposite PTO side. Everytime I engaged the clutch
I was heavily loading the crankshaft, that is, pushing the crankshaft into the flywheel side sleeve bearing.

Restrorob
09-28-2010, 05:50 PM
I will find the flywheel end sleeve bearing shoulder to be mostly gone.


I don't know about mostly gone because there is one on the other end of the crank, But that's the wear area that will cause excessive end play.