Advice needed for first Kohler engine rebuild

[oldredrider 2,548]

If your measurements about bore size are close, you've got a 10hp engine. Standard bore on a 12hp is 3.375".

Many 10hp blocks are labeled "K301". You've got room to machine that block. 

Have a machine shop check the crank pin to see if it can be saved or if it will have to be built up and turned to proper spec. You may be able to find a rod for a .020 oversize crank.

[tntatro 171]

What part is the crank pin?

[953 nut 55,264]

The crank pin is the portion of the crankshaft that the connecting rod attaches to. They tend to become egg shaped over time, you will want to take it to the machine shop too.

[tntatro 171]

I took the block and crankshaft to a machine shop. I didn't hear back from them today so hopefully Monday. I guess I'll be rebuilding chainsaws this weekend instead.

[tntatro 171]

I went to the machine shop today to check on the engine block and they bored it .020" over. They said the crankshaft was already .020" under so they can do .030" and fix a connecting rod to fit it. They should have it done in a week and I'll start back on it in about a week and a half.

 

I decided to get a used Sunnen cylinder hone off ebay so I can try doing the next one myself. I also picked up a Neway 31/46 valve seat cutting tool.

[ebinmaine 67,540]

10 hours ago, tntatro said:

decided to get a used Sunnen cylinder hone off ebay so I can try doing the next one myself. I also picked up a Neway 31/46 valve seat cutting tool

That right there is awesome.

Cool tools.

[Howie 886]

I like those Neway seat cutters, have the 15/60 degree cutter also along with a couple

of smaller diameter cutters for smaller valves. Also have my late father-in-laws that I

should sell.

[Tractorhead 9,064]

Didn't know the sunnen cylinder hone, but i reworked in the Past myself a 4,2 Liter Diesel Engine from a 40 year old Mercedes.

The reason for rework was weak fireup and lot of oil burning.

A very heavy job at this Truck, because the house over the Engine can not be tilt as on actual Trucks.

 

All my measuring at the Engine was in tolerance compared with Mercedes Data Values so far at that Old Lady, 

Just the crosscut was completley "like glass". It burned a lot of Oil (about 5 Liters at 100Km)

The Engine has Rep Stage 1 on Cylinder, means they seemed to be reworked allready at about 500.000 -700.000 Km i guess.

 

Only the Valves and their Seats last's complete out of tolerance, so i decided to exchange the Cylinderhead to a reworked one in exchange, because of the good condition after 980.000 original Km in stage1 of the Cylinders (bougth it with 950.000 Km on Tacho) 

 

About all that issues, i just decided to rehone the Cylinders carefully a bit, give them a new crosscut, insert new Crankshaft bearings and 4 brandnew 5Ring Pistons and that's it.

 

 

 

I drove that Old Lady myself until 1.320.650Km and sale it to a Fella, who's need it for his collection of Mercedes.

The Engine fireup immediately after 4 Cranks at - 21Deg. and is also still in Service continousely.

The Oil consumption is now at about 0.1liter/1000Km.

It was the first direct injection without Glow Plugs...😎

 

 

I used a Flexhone for the crosscut, a very handsome tool as i found..

http://www.brushresearch.com/brushes.php?c1=2

 

the main thing i learned at this job was a lot of Oil to wash out the honecut

and low speed at the hone rotation and lift.

Goal was at about 72deg. Crosscut, that seems to be the best value.

[953 nut 55,264]

23 hours ago, tntatro said:

Sunnen cylinder hone off ebay so I can try doing the next one myself. I also picked up a Neway 31/46 valve seat cutting tool.

             You must be planning on going into the business!

[tntatro 171]

34 minutes ago, 953 nut said:

             You must be planning on going into the business!

I guess I'll have to do a lot of blocks to justify the purchases. I generally do some compulsive spending around tax refund time. The Neway kit was $120 shipped and looks hardly used, the Sunnen AN was $195 but I had to get new stones. I have two more K series Kohlers to do and a couple Briggs and Stratton off late 90's/early 2000 mowers that I might rebuild. 

[tntatro 171]

I got the block back yesterday. I checked the bore and piston clearance and according to my tools it's .0105", the manual says it should be between .007" and .010". My cheap tools may be off a little or my skills not so good but it seems to be at the high end of the specs on that.

 

The ring end gaps are under .030"

 

The camshaft end play is .015" with the existing shim installed so I ordered a .010" shim.

 

So far I have only installed one bearing and the governor gear. The manual says to reuse the bearings if they appear to be okay so I guess I'll do that.

 

I have read that it's good to replace the plastic governor gear with a metal one, is that highly recommended or are the plastic ones generally fine to reuse?

 

I still have to check the valve guides, I forgot to get a split ball gauge so I just ordered one.

[tntatro 171]

Is this right for the timing on the camshaft and crankshaft?

 

Also, I got my used Sunnen cylinder hone and the shaft that goes down the middle is a bit worn. Anyone know if that will affect its performance or accuracy?

[tntatro 171]

Since I'm waiting on parts I cleaned and flattened the cylinder head.

 

The valve lifters had pretty deep dimples in them. I measured the difference and one was sunken .0055" and the other was .0045". I flattened them with a file and then sanded them smooth.

[squonk 41,129]

On 3/9/2019 at 7:46 PM, tntatro said:

I went to the machine shop today to check on the engine block and they bored it .020" over. They said the crankshaft was already .020" under so they can do .030" and fix a connecting rod to fit it. They should have it done in a week and I'll start back on it in about a week and a half.

 

I decided to get a used Sunnen cylinder hone off ebay so I can try doing the next one myself. I also picked up a Neway 31/46 valve seat cutting tool.

Interesting. I had a 341 at a machine shop a few years ago and the guy told me my crank was already .010 undersize and couldn't be turned anymore. A new crank was going to be $350 by itself.

[tntatro 171]

He said they had to fix the connecting rod to make it work. He said they have done a lot like that and it works, only other option was to replace the crankshaft.

[tntatro 171]

I got the split ball gauge but still waiting on shims for the camshaft. The measurements I got for the valve clearances were both around .002" both with the new valves and the old ones. I guess the valve guides didn't wear out much or I measured wrong.

[richmondred01 2,237]

On 3/9/2019 at 7:46 PM, tntatro said:

I went to the machine shop today to check on the engine block and they bored it .020" over. They said the crankshaft was already .020" under so they can do .030" and fix a connecting rod to fit it. They should have it done in a week and I'll start back on it in about a week and a half.

 

I decided to get a used Sunnen cylinder hone off ebay so I can try doing the next one myself. I also picked up a Neway 31/46 valve seat cutting tool.

 

Make sure prior to getting the crank turned you can get a .030 rod.

 

[953 nut 55,264]

7 minutes ago, richmondred01 said:

 

Make sure prior to getting the crank turned you can get a .030 rod.

 

This is how Brian Miller takes care of it.

Install STD size, .010", .020" or .030" undersize Replaceable Bearing Inserts in Connecting Rods for Kohler engine models K241/M10, K301/M12, K321/M14, K341/M16, K361 M20 and MV20. Rods for the before mentioned engines can be bored and notched to accept bearing inserts. Even severely burnt, scored, or rods with a mismatched cap can be bored for installation of bearing inserts. Only USA-made Clevite 77, Federal Mogul or Sealed Power bearing inserts will be installed. No low quality Chinese-made bearing inserts ever installed. All A-1 Miller machined connecting rods include ground-out notches to prevent bearing rotation in rod and drilled oil hole for proper lubrication. Please indicate diameter of crank journal for size of bearing inserts. (STD size, .010", .020", .030" or .060" undersizes.) Also, rods can be center-bored for top of piston to come flush with deck, or bored .020"± offset for a .020"± piston pop-out at no extra charge.

• Clevite 77, Federal Mogul or Sealed Power Bearing Inserts. Available in STD size, .010", .020", .030" and .060" (limited quantity) undersizes. $20.00 each, plus shipping & handling.
• Bore and notch your rod only (customer supply and install own bearing inserts): $25.00 labor, plus return shipping & handling.
• Bore and notch your rod and install our bearing inserts: $45.00 ($20.00 for bearing inserts + $25.00 labor to bore rod), plus return shipping & handling.
• Purchase one of our rods, bore and notch rod and install our bearing inserts: Price of rod $? + $20.00 for bearing inserts + $25.00 labor to bore rod = $? total, plus return shipping & handling.

NOTE: If a crank journal is worn beyond specs or badly scored/burnt,it will need to be reground to the next undersize to match the appropriate size bearing inserts. And if you want me to bore a rod for you, please let me know if you want the bearing insert centered in the bore of the rod (5.300" rod length; piston flush with top of block), offset .020" (5.320" rod length; safe to use with a milled OEM Kohler stock head and stock head gasket) or offset .060" (5.360" rod length; use with a non-milled OEM Kohler head and stock head gasket) to pop the piston out of the cylinder (see below Ê) to raise the compression and help improve airflow within the combustion chamber for more power and torque. The bearing inserts I install in Kohler 10-16hp flatheads and 18hp OHV K361 connecting rods can be used for general lawn and garden use, stock or high RPM competition pulling engines. The rod will need to be bored exactly 1.625" for correct bearing to journal oil clearance.

NOTE: Being virtually all Kohler K241/M10 pistons come within .020"± from the top of the block, which lowers the compression ratio. (The factory made them this way for reasons unknown.) I prefer to bore the K241 10hp rods .020" offset so the piston will come flush with the top of the block. This will allow the engine to produce a little more power. It won't effect the longevity of the engine or cause any problems whatsoever. But sometimes with the .020" offset, the piston will pop out of the cylinder a few thousandths of an inch, which will still hurt nothing. And the bore can be offset .040" for a .020"± piston pop-out.

FYI - Before I machine a rod for installation of bearing inserts, I use a metal "plug" alignment tool that I fabricated to precisely align the big hole of the connecting rod with the centerline of the spindle in my milling machine. Then while the plug is in the rod, I firmly clamp the rod to the milling machine table and after leaving the big hole centered or moving the table so many thousandths of an inch offset for piston pop-out, I lock the table so it won't move in any direction while boring the rod. But for reasons unknown, sometimes the cutting tool will bore the hole in the rod slightly off-center toward one of the bolts or studs. When this happens, I simply grind a small notch on the outside of each bearing shell so they'll clear the rod bolt. I've talked to other machinists who bore Kohler rods also about this and they tell me sometimes the same thing happens to their rods. But as long as the outside of the bearing shells are notched for clearance of the bolt or stud, the off-center of the bearing inserts poses no problems whatsoever.

And bearing inserts for the 10-16hp Kohler engines can be installed in Kohler engine models K482, K532 and K582 STD size connecting rods, but the crank journals would need to be reground exactly to 1.500" to match the inside diameter of the bearing inserts when installed in the rods. And for your information, STD size crank journals for the K482, K532 and K582 engines measures 1.6245"

[richmondred01 2,237]

Yep Brian may be the only way to go. He’s outstanding.

 

[tntatro 171]

They ground a rod and put the bearing insert in. I had them order a new rod for it but I probably could have saved money by using the old one. 

[richmondred01 2,237]

That’s good. Always go with a new one

[tntatro 171]

I figured since it's reground and rebored with new piston and I also got new valves it's best to get a new rod also.

[Howie 886]

I sent two rods to Brian Miller and had them bored for the bearing. Used a couple that were worn and

not overheated or anything. They are fine that way. Old machine shop here used to do that but shop 

closed. That bearing is for a 4 cyl Continental engine or something like that. Have one in my Raider 12

and put one in a Cub Cadet. Shop in Kokomo would cut the cap and rebore to size no insert, not very

cheap though. 

[tntatro 171]

I finally got the shim I needed for the camshaft. I think it is good now but when I put on the bearing plate I ended up ripping one of the shim gaskets for the crankshaft end play. I needed that one to get it in spec, without it there is no play at all. I ended up gluing it together with a little liquid gasket maker but I don't know if I should leave it that way. It probably won't leak because there is no compression there and it won't be submerged in oil.

 

In the manual it says to rotate the piston rings 120 degrees apart at the ends. On this piston the bottom ring is three pieces. Should the ends to all three pieces line up or should they also be staggered some how? The piston kit did not come with any instructions.

[Howie 886]

No they do not line up together on the oil ring. I always put the rails to either side

of the center of the expanded center portion. if that makes sense.