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Oil Soaked Plugs

#1

W

White Oak Dave

Hello,
I have been working on a Kohler Command Pro CV23S 23 HP twin cylinder in a L130 John Deere. I got the tractor for free because the previous owner blew one of the rods but did not appear to hurt the case or the cam. I replaced the crank, rods, rings, coils and head gaskets. It fired right up but after several minutes it started to stumble under load and blow some blue/white smoke. It now smokes when you start it for several seconds, as if to clear oil that is built up in the cylinder and still stumbles on acceleration. Both spark plugs (new) are wet with oil. I mic-ed the bore and pistons and they are well within tolerance and the end gaps are good on the rings. I also have a 150lbs of compression on both cylinders.
The last thing I have ordered to replace is the seals for the intake valves in the event they are sucking oil in.
Does anyone have another suggestion for the source of the oil in the cylinders before I button this up again and try it? Any advice is appreciated.
Thanks,
Dave


#2

sgkent

sgkent

Assume you cross hatched the bore for the new rings?


#3

H

hlw49

Might check the crank case reed valves. There is one on each cylinder between the lifters.


#4

W

White Oak Dave

Good morning, I did cross hatch the bore, but not sure if I was aggressive enough. It appeared the walls were almost smooth again after the hour of running that I did before tear down again.

As for the reeds, they are in place and laying flat in each lifter bore. I could not find a test or specs for them but did pull each out and ensure they we intact.

Thanks for the quick response.


#5

StarTech

StarTech

Did you check the cylinder at twice at three levels (top, middle, and bottom of the piston stroke) and at 90 degrees of each mic check? Otherwords mic'd the cylinder in six places. This done to check for both ovaling and tapering. On top honing should be done with a rigid hone as a flex hone can just make things worst.


#6

W

White Oak Dave

Thanks! Yes, I did check top middle and bottom and side to side. All are very close to the 3.149. I will look into the rigid hone. It would be a good addition to the shop. Mine is the flex one that goes in a drill motor and the stones are worn.
Since you folks are so helpful.... I can't seem to get an accurate reading on the valve guides. The ball gauge I have is showing tighter than the stems and the valve stems are right on the money. They seem fine, not sloppy or anything in the guides.
Also, the piston itself is tapered? It only says to measure .25 from the bottom on the skirt and nothing about the top measurement. I am showing a uniform taper of about .017 on both and have read that aluminum pistons are tapered for heat expansion at the top. Just confirming, because both pistons have a slight back and forwards rock to them but not parallel to the wrist pin.


#7

sgkent

sgkent

clean the valves, oil the stem and put it in a guide sitting up about 1/2". Wiggle the head. If it is tight then they are Ok, if it is sloppy then they are worn. If it rattles around they are really worn. When a guide is replaced on any motor the hole will be slightly different than before so pay close attention when lapping to be sure that the whole seat is contacting and not just one side. There will be a bit of play but it should not be loose side to side. Example, new would be a rock of maybe .003: to .004" but if the valve head say rocked .005" or .006" side to side I would consider that worn but workable. If it rocks .020" to .040" side to side it is really worn.

Pistons are usually wider on the bottom or the sside just above the wrist pins. If the skirts taper in they are collapsed and will rattle a little. If the skirt has a tang on it so part of the skirt is cut away, and they are collapsed you can use a rawhide mallet to gently tap them back out a bit to the same as just above the wrist pin. Check the ring lands to be sure they aren't worn out.

All my training comes from being an automotive machinist but small engines should be similar.


#8

W

White Oak Dave

Great advice on the valves. I will try that tomorrow. I should get my new hone from Amazon as well. Thanks to everyone for all the great help. My first time on a forum, this one is awesome.
I post back my results.


#9

W

White Oak Dave

sgkent said:
clean the valves, oil the stem and put it in a guide sitting up about 1/2". Wiggle the head. If it is tight then they are Ok, if it is sloppy then they are worn. If it rattles around they are really worn. When a guide is replaced on any motor the hole will be slightly different than before so pay close attention when lapping to be sure that the whole seat is contacting and not just one side. There will be a bit of play but it should not be loose side to side. Example, new would be a rock of maybe .003: to .004" but if the valve head say rocked .005" or .006" side to side I would consider that worn but workable. If it rocks .020" to .040" side to side it is really worn.

Pistons are usually wider on the bottom or the sside just above the wrist pins. If the skirts taper in they are collapsed and will rattle a little. If the skirt has a tang on it so part of the skirt is cut away, and they are collapsed you can use a rawhide mallet to gently tap them back out a bit to the same as just above the wrist pin. Check the ring lands to be sure they aren't worn out.

All my training comes from being an automotive machinist but small engines should be similar.
Click to expand...
Great advice on the valves and there is very little side to side movement.

Quick question about honing. I received a new hone today with 4" 220 grit stones. I plan to hone this weekend. Is is okay to use the new rings that I ran in the engine for 30 minutes or so when the honing was not done well enough? Have I ruined them? They are still well within spec as far as the end gaps.


#10

sgkent

sgkent

I think you will be ok. try to get the crosshatch lines at 45 degrees to one another. You do so by controlling the speed. The stones should go about 1/3 past the end of the cylinder on both sides. Maybe 3 or 4 passes, then check it. If that looks even, stop.


#11

W

White Oak Dave

sgkent said:
I think you will be ok. try to get the crosshatch lines at 45 degrees to one another. You do so by controlling the speed. The stones should go about 1/3 past the end of the cylinder on both sides. Maybe 3 or 4 passes, then check it. If that looks even, stop.
Click to expand...
Thanks!


#12

R

Rivets

Don’t get too aggressive with that hone and make sure you use plenty and a very light lubricant. Maximum of 30 seconds, then wipe clean and recheck all 6 measurements. If you don’t think you have a good crosshatch, repeat. When you get what you want, make sure you wash the block at least twice, then wipe the entire block with Kleenex, which should look as white as new when finished. Any coloration wash again, you don’t want any residue felt in the block. Any grit or dirt can easily ruin all your work. If you didn’t clean it properly last time the residue may have resulted in ruining the rings and causing your problem to reoccur. Also, I’m assuming that the block is bare, no valves, coil, or anything attached.


#13

sgkent

sgkent

keep in mind that as you remove metal you widen the bore. Check the ring gap when done to be sure you didn't widen it too much. I used to bore automotive engine blocks for a living, and 5 or 6 seconds isn't a problem. Doing 1 or 2 minutes will widen the bore way too much. All you need it is to break the glaze and replace it with a cross hatch. Also when you break the engine in, don't just run it a half hour at full load when you first run it. Let it idle 5 or 10 minutes then change the oil. One other thing crossed my mind. Be sure the drain holes in the valve area are open and not plugged with pieces of RTV or something.


#14

W

White Oak Dave

This is all great information. Thanks for taking the time to give details. I'm learning a lot with this project, some the hard way, but.... Thanks so much. Will post when complete.


#15

Craftsman Garage

Craftsman Garage

the new Kohler aren't like the old shaking ones, one life lesson: NEVER BUY A KOHLER COURAGE ON ANYTHING, but the command is a much better engine, courage engines make an unending knocking sound and have lots of problems to be addressed ;)


#16

R

Rivets

Cast iron sleeves used on Kohler engines are not as hard as automotive blocks. That’s why I say “Don’t get aggressive “ when attempting to hone. I also forgot to mention that as soon as you get done washing the block for the &#2:9? time, spray the cylinder walls with a light lube (WD-40, power lube, etc) to prevent rust forming. This can start in as little as 10 minutes.


#17

Craftsman Garage

Craftsman Garage

just look at how many people have the knocking problems:
https://lawnmowerforum.com/threadloom/search?query=kohler courage&tab=3963
and many more to come :(


#18

R

Rivets

This is nothing new with the Courage engines, been going on for many years. There’s even a service bulletin on this. All the techs on this site know that when they hear the knocking on a Courage engine, the first thing they do is pull the shroud and tighten the crankcase cover bolts.


#19

Craftsman Garage

Craftsman Garage

Rivets said:
This is nothing new with the Courage engines, been going on for many years. There’s even a service bulletin on this. All the techs on this site know that when they hear the knocking on a Courage engine, the first thing they do is pull the shroud and tighten the crankcase cover bolts.
Click to expand...
amen to that ;)


#20

B

bertsmobile1

lanerdude9 said:
just look at how many people have the knocking problems:
https://lawnmowerforum.com/threadloom/search?query=kohler courage&tab=3963
and many more to come :(
Click to expand...
I doubt there will be many more.
It only happened to a few engines & most were unafected which suggest 1 mould on a casting machine was a little crook .
Kohler identified the problem and corrected it
The counterbalance was another problem that took a while to sort out as well .
The original Kohler krack only happened to a small number of the total production run of these engines.
I have a lot of them in my service run as Husqvarna dumped the potential suspect mowers down here at a discount.
So there is a disproportionately high number of the suspect engines down here .
I have welded 3 of them early on , but have not had any problem with the remaining 30 odd engines.
The bolts were removed once I knew about the problem & refitted with a drop of blue loctite , problem solved
I check them but not one has moved in the past 6 years .


#21

W

White Oak Dave

Success! Sorry for the delay but my project was interrupted by the church's tractor needing some maintenance before the season started.

Looks like I have a solid running engine now. Things I improved on the second re-build, with your folks help; good honing, ring orientation, replacing the intake valve oil seals and I replaced both pistons with lightly used pistons with rings.

Fired the engine up today with no smoke at start up, did the recommended break in from the manual, 2-3 mins idle then 5-6 mins between idle and mid range. Let the engine cool and re-started 2 hours later and there was no smoke at start up as before and the plugs are very dry and clean.

Thanks so much for the useful help and advice. You all were awesome!

Thanks,
Dave


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