Advice needed for first Kohler engine rebuild

[tntatro 171]

I just installed the connecting rod to the crankshaft and it does not turn over by hand. Is this too tight? I followed the instructions for the cap screw torque specs, which is what I believe I have because it is bolts rather than nuts that thread on a rod. I do not have a torque wrench in inch pounds so I used a conversion calculator online. I don't know if I should move on or loosen it a little. The torque calculated to 23.75 foot pounds. I have it a 23 now and I can barely move the crankshaft by hand.

[tntatro 171]

I figured out the problem, I didn't know the the rod had match marks. It turns over but it's still a little hard to turn by hand but not like before.

[WHX?? 48,815]

Yes the match marks are a must as that's how the rod was machined.   Be liberal with the lubriplate on the crank journal.  Make sure the hole in the rod goes toward the cam shaft when stuffing it in the bore.

[953 nut 55,198]

The only way to be sure the rod/crank fit is correct is to check it with plastigauge.

 

[tntatro 171]

I got the engine mostly together. I guess I'll just put faith in the machine shop that they did a good job and hope I didn't mess it up by installing it wrong the first time. 

[tntatro 171]

How do I start it to test before putting it on the tractor? I have it all together, I just need to go out and get oil, e-clips, screws for the air filter housing and a fuel filter.

 

There is still no wire to the + side of the coil or to any part of the solenoid or starter and the wire that comes out of the flywheel isn't attached to anything. I also don't have a throttle cable on it.

[tntatro 171]

I can't get it to spark, I probably am not wiring it up right. At this point I guess I should have put it on the tractor. Maybe on my next day off.

[tntatro 171]

I tested the points and they did not have a good connection so I sanded them. It still had no spark, then I switched out the coil, plug and condenser with ones off a running tractor and got one weak spark. I think my battery was getting weak, it was on a tractor all winter. 

 

I guess I'll get new points, condenser, spark plug, coil and charge the battery for next time. I'm still not sure I had it wired right. I had a wire running from the positive on the coil to the positive on the battery and ground wire from the block to the negative on the battery and also a wire from the negative on the battery to the starter to ground it and I jumped the starter from the battery.

 

It didn't seem to be pumping fuel when it turned over either.

[953 nut 55,198]

9 hours ago, tntatro said:

get new points, condenser, spark plug, coil and charge the battery for next time.

After all the mechanical work you have done it is a good idea to replace the ignition components too. The fuel pump is good at pushing fuel but not so good at pulling a prime on a fuel line that is full of air. Remove the hose from the fuel pump and let it drain into a container until there is a steady flow of fuel.

[tntatro 171]

I  haven't even got to the carburetor yet. It came with two but one needs a throttle shaft. The other appears to have been cleaned up. Hopefully it is good.

 

I recently picked up this k181 for free. It is completely locked up and probably worth its weight in scrap. I was able to swipe bolts off it that were missing on the k241. I can at least practice honing and valve seat cutting on it if I can get it apart.

[953 nut 55,198]

22 hours ago, tntatro said:

I can at least practice honing and valve seat cutting on it if I can get it apart.

Best to get practice on something you can make mistakes on without costly consequences.             

[tntatro 171]

I put on all the new ignition parts and it started right up. It blew a bit of blackish smoke at first. Then it would just blow smoke when I throttle up fast, then I ran out of gas. 

 

One of the air filter housing screw holes in the carburetor is stripped so I had to use a longer screw and add a few washers so it wouldn't hit the choke shaft. I'm a little concerned about it because if it came off it wouldn't be good. I may try to thread it the next size bigger.

[bc.gold 3,403]

On 3/23/2019 at 12:26 AM, tntatro said:

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.

 

 

Valve lifters wear areas  would have been case hardened, if you were able to file our already beyond the hardened skin.

 

https://en.wikipedia.org/wiki/Case-hardening

 

[bc.gold 3,403]

On 4/3/2019 at 6:44 PM, tntatro said:

I  haven't even got to the carburetor yet. It came with two but one needs a throttle shaft. The other appears to have been cleaned up. Hopefully it is good.

 

I recently picked up this k181 for free. It is completely locked up and probably worth its weight in scrap. I was able to swipe bolts off it that were missing on the k241. I can at least practice honing and valve seat cutting on it if I can get it apart.

 

If the cylinder bore is water damaged probably needs an oversize piston anyhow, the wrist pin will parallel the crankshaft anyhow I drill the piston top full of holes making it easy to break up.

 

Once that frozen piston is out the the way the rest of the disassembly is a snap.

[bc.gold 3,403]

On 4/1/2019 at 1:09 PM, tntatro said:

I figured out the problem, I didn't know the the rod had match marks. It turns over but it's still a little hard to turn by hand but not like before.

 

If your torqued the improperly aligned caps it possible that you have now misshapen the aluminum connecting rod cap and its no longer totally round.When the machine shop resized  that connecting rod to .030 the end cap became much thinner.

 

Improper match of cap and connecting rod could also have created undue internal stress on the end cap as it was being forced to conform to being mated to a round crank journal. The could lead to premature failure.

 

Just my 02 cents.

Edited April 6, 2019 by bcgold

[tntatro 171]

Thanks for the information, I was going to put the motor on the tractor but now I'm not sure if I should yet. I couldn't find any new lifters,  just used ones. As far as the rod, maybe I'll ask the machine shop their opinion, I know they have done thousands of rods. Unfortunately they are closed tomorrow.

 

Does seeing black smoke after a rebuild mean something isn't right? I did forget to flip the choke lever back at first, I thought that might have caused it. 

[bc.gold 3,403]

1 hour ago, tntatro said:

Thanks for the information, I was going to put the motor on the tractor but now I'm not sure if I should yet. I couldn't find any new lifters,  just used ones. As far as the rod, maybe I'll ask the machine shop their opinion, I know they have done thousands of rods. Unfortunately they are closed tomorrow.

 

Does seeing black smoke after a rebuild mean something isn't right? I did forget to flip the choke lever back at first, I thought that might have caused it. 

 

Cast iron is porous then you have all those honing marks that will have taken up fluids during the machining process these fluids  will soon burn off so nothing to worry over..

 

Did you measure the piston ring end gaps and stagger them on the piston.

 

The abnormal wear on the bearings shown below was due to an out of round connecting rod boss.

 

With an all aluminum connecting rod that uses no bearing insert you do not have the luxury of the soft Babbitt, you may not notice any perceivable damage to the end cap but this is the weakest point. Your connecting rod is made from a type of die cast alloy rather stiff and unforgiving cast aluminum breaks similar to glass when stressed.

 

Edited April 7, 2019 by bcgold

[tntatro 171]

Yes, I checked the end gaps and staggered the rings.

 

The connecting rod I have does have a bearing insert.

[bc.gold 3,403]

25 minutes ago, tntatro said:

Yes, I checked the end gaps and staggered the rings.

 

The connecting rod I have does have a bearing insert.

 

Ok now I see what the machine shop did was to machine the stock Kohler aluminum connecting rod to accept bearing inserts, they must have had to remove a lot of material to accommodate those bearing inserts that would have further weakened the end cap.

 

Noticed that connecting rod is an oil dipper, two questions.

 

1. Were the rods notched to accept dimples made into the ends of the bearing inserts. Those dimples prevent the inserts from spinning inside the connecting rod.

2. Did the inserts have an oil hole drilled that would mate to the oilier hole for the dipper.

 

 

[bc.gold 3,403]

Looks like the bearing inserts used on the Kohler engine modification come from the Allis G.

 

[tntatro 171]

The machine shop ground the rod and inserted the bearing, I'm pretry sure it has the dimples. I think they drilled the oil hole but I didn't notice any groove.

 

The guy at the counter said they have done thousands of them so it was probably fine until I installed it wrong and torqued it 20% over spec and loosened then torqued to spec. 

 

I did find some new lifters last night. I found that searching the part number was better than searching the name of the part.

Edited April 7, 2019 by tntatro

[ebinmaine 67,455]

10 hours ago, tntatro said:

ask the machine shop

^^^^^^^^^^^^^^^^^^^^^^^^^^

 

THAT is the best idea

[bc.gold 3,403]

43 minutes ago, ebinmaine said:

^^^^^^^^^^^^^^^^^^^^^^^^^^

 

THAT is the best idea

 

What is your opinion over torquing connecting rod bolt that is a stud threaded into aluminum, at what point do the treads in the aluminum connecting rod become distorted.

 

As for a professional second opinion I totally agree and that sometimes a third is necessary to get the facts beyond reasonable doubt.

 

Kohler connecting rod with visible oil hole the kohler bearing inserts use holes for oil reservoirs. This will vary from one manufacture to another.

 

 

Edited April 7, 2019 by bcgold

[tntatro 171]

I'll call the machine shop tomorrow and see what they have to say and go from there. It will be a week and a half before I can work on it again but after that I'll have a lot of time to mess with it. I saw a nice looking crankshaft and rod for sale online off a 310-8 that is standard size. Claimed that it is ready to use so I might buy it if it's still available if not for this build then for the next 241 that needs it.

[ebinmaine 67,455]

35 minutes ago, bcgold said:

What is your opinion over torquing connecting rod bolt that is a stud threaded into aluminum, at what point do the treads in the aluminum connecting rod become distorted

Definitely a concern.

It's been 25 years or more since I've had the internals of an engine apart so I wouldn't be able to give an opinion.

I do remember that over torque in small aluminum pieces can go bad, quick.