K241 winter project.

[Snoopy11 5,714]

The only thing we can do to lengthen the life of these engines is to use quality oil. 

 

Don

[Snoopy11 5,714]

Oh, and to further answer one of your questions @Gregor... rod bolts can break, but normally only when they are not torqued correctly. Rod bolts are not like normal bolts. 

 

When you go to torque a rod bolt, the bolt is actually stretching, which locks it into place. It will stay tight forever (proverbially speaking) if it is torqued correctly. If it is torqued incorrectly, 2 things could happen. 

 

1. The rod bolts will back out, and loosen further, leading the rod cap to... do obvious things.
2. However, believe it or not, if it is overtightened, the rod bolts themselves will break. 

If installed correctly, it is VERY unlikely that rod bolts are the culprit. AND, if an engine has been running for years and years without issue, it is even less likely that rod bolts are the culprit. On a brand new engine, if a rod was to fail, the first thing you would think is rod bolts, and justifiably so. 

 

Don

[Snoopy11 5,714]

It is just a very thin layer of oil that is keeping our engines from... imploding... 

 

A millisecond without this oil... all hell can break loose. 

 

Don

[slim67 2,735]

And there wasn’t a lot of oil in the crankcase 

Edited November 29, 2021 by slim67

[Snoopy11 5,714]

Just now, slim67 said:

And there wasn’t a lot of oil on the crankcase 

The good thing is, your oil dipper is still intact. 

 

That is another culprit of engine failure... as without that little stupid-looking dipper, our engines would be toast.

 

Not enough oil in the crankcase is, in my opinion, what caused this failure. 

 

Don

[Handy Don 12,235]

27 minutes ago, Gregor said:

So what do you all think is the main cause of broken rods ? Engine revving too high?  Metal fatigue? Bolt failure? Under designed? Weakest link in the motor?

Thanks for asking this question. Following to become informed but I'll hazard a guess...looseness at the piston or crank journal causes repetitive stress on the rod outside its design parameters leading to fatigue and failure

[Snoopy11 5,714]

17 hours ago, sparkie333 said:

 

so can I jump in and ask a question engine related but no on topic----I need to find a muffler like this one for a 16hp WH do you know where I can pick one up?

Looks like Eric has got you covered Sparkie, but do let me know if you need anything else.

 

Don

[Snoopy11 5,714]

6 hours ago, squonk said:

 

Was the ziptie holding the rod cap on?

 

 

Don

[slim67 2,735]

2 hours ago, Snoopy11 said:

The good thing is, your oil dipper is still intact. 

 

That is another culprit of engine failure... as without that little stupid-looking dipper, our engines would be toast.

 

Not enough oil in the crankcase is, in my opinion, what caused this failure. 

 

Don

Do you mean the dipper on the end of the end cap or the dipstick? The oil dipper on the end of the end cap is broke off. It isn’t much but I did fish the piece out.

[Snoopy11 5,714]

2 hours ago, slim67 said:

Do you mean the dipper on the end of the end cap or the dipstick? The oil dipper on the end of the end cap is broke off. It isn’t much but I did fish the piece out.

Now, the little piece that I have circled... is that part of the oil dipper??? 

 

Don

[slim67 2,735]

49 minutes ago, Snoopy11 said:

Now, the little piece that I have circled... is that part of the oil dipper??? 

You are correct ! I think Stens has a steel replacement but haven’t verified that for sure. I’m sure another aluminum rod will probably outlast me though. I’m good about checking the oil on anything I own or use plus oil changes.

[Horseoholic 169]

On 11/29/2021 at 12:41 PM, Snoopy11 said:

Oh, and to further answer one of your questions @Gregor... rod bolts can break, but normally only when they are not torqued correctly. Rod bolts are not like normal bolts. 

 

When you go to torque a rod bolt, the bolt is actually stretching, which locks it into place. It will stay tight forever (proverbially speaking) if it is torqued correctly. If it is torqued incorrectly, 2 things could happen. 

 

1. The rod bolts will back out, and loosen further, leading the rod cap to... do obvious things.
2. However, believe it or not, if it is overtightened, the rod bolts themselves will break. 

If installed correctly, it is VERY unlikely that rod bolts are the culprit. AND, if an engine has been running for years and years without issue, it is even less likely that rod bolts are the culprit. On a brand new engine, if a rod was to fail, the first thing you would think is rod bolts, and justifiably so. 

 

Don

Got a question on rod bolt torque , I've read from people on other websites about when torquing brand new rod cap bolts that you should "over torque" the bolts if I remember correctly about 20% more than factory specs then back them off and torque them to the factory specs  to mainly do what you mentioned about stretching the bolts , I'm guessing this is to "pre-stretch" the bolts to try to eliminate the rod bolts from backing out ? Have you or anyone else heard of doing this? Last month I bought a Wheel Horse 1057 that was advertised as having no compression , well....... The K241 in this tractor has the exact same issue.... You can look down the oil fill hole and see the rod laying down there in the oil pan , I don't have the engine off and apart yet to see what other issues are there , I just seen this topic and will be following it, just wanted some opinions about the torque procedure I mentioned for when I cross that bridge  with my K241. Thanks.

[Gregor 4,846]

Kohler manuals

Poke Here

 

Page 12.12 Kohler manual

 

[Snoopy11 5,714]

3 hours ago, Horseoholic said:

Got a question on rod bolt torque , I've read from people on other websites about when torquing brand new rod cap bolts that you should "over torque" the bolts if I remember correctly about 20% more than factory specs then back them off and torque them to the factory specs  to mainly do what you mentioned about stretching the bolts , I'm guessing this is to "pre-stretch" the bolts to try to eliminate the rod bolts from backing out ? Have you or anyone else heard of doing this? Last month I bought a Wheel Horse 1057 that was advertised as having no compression , well....... The K241 in this tractor has the exact same issue.... You can look down the oil fill hole and see the rod laying down there in the oil pan , I don't have the engine off and apart yet to see what other issues are there , I just seen this topic and will be following it, just wanted some opinions about the torque procedure I mentioned for when I cross that bridge  with my K241. Thanks.

Very good question. The answer to this question is that, it has nothing to do with rod bolt stretch. What you are doing when you overtorque the rod bolts at first is seating the rod cap. 

 

It is especially important to do this and loosen the rod bolts, then retighten. If you look VERY closely as you are tightening it for the first time, you will see the rod cap gap between the cap and the actual rod portion get smaller. Again, It is an important procedure to make sure the rod cap is seated. You also want to make sure that your rod bolts are lubricated with oil, and that you apply butt loads of molly lube in the rod bearing and on the crank journal. YES, it is a big mess, but you want the molly lube oozing out when you put the rod cap on. 

 

What we notice in engine building, particularly with rods and babbitt bearings is that... taking extra precautions (which is really what this is) never hurts, especially when you invest time an effort into a build. 

 

If you have any other thoughts or questions, buddy, be sure to ask them. 

 

Good question @Horseoholic 

 

Don

[slim67 2,735]

I am happy to say that the inside of the crankcase looks great with no signs of skirt damage or otherwise. Im hoping the bore will be within tolerances and just need honed. I have a few more external items to remove then I can check it further. 

[slim67 2,735]

I cleaned up the block in the parts washer and can say that everything looks good. There is a little scratch being pointed out but that’s it and the scratch is minimal. The crankshaft journal will need to be cleaned of the aluminum.

[RED-Z06 2,221]

Sometimes the dippers break off and seize the big end...but with the rod not darkened black at the big end and no scoring on the crank im inclined to think speed was an issue.  Having said that, not likely a sudden over rev like a broken governor or manual manipulation, im thinking long term fatiguing from running 4100ish, you start getting fastener fatigue, and cap fatigue and eventually it breaks.  A sudden run away will usually snap about an inch below the pin and beat up the block 

[Snoopy11 5,714]

21 minutes ago, RED-Z06 said:

Sometimes the dippers break off and seize the big end...but with the rod not darkened black at the big end and no scoring on the crank im inclined to think speed was an issue.  Having said that, not likely a sudden over rev like a broken governor or manual manipulation, im thinking long term fatiguing from running 4100ish, you start getting fastener fatigue, and cap fatigue and eventually it breaks.  A sudden run away will usually snap about an inch below the pin and beat up the block 

I would agree. However, my understanding of rods comes from Amundsen Research Corporation. Cast rods can handle 5,500-5,800 over longterm. That is, with no load. What starts to create issues is engine lugging. 

 

Engine lugging is more unhealthy than extra rpms... this is what breaks cast rods more often than not. 

 

Don

Edited December 12, 2021 by Snoopy11

[RED-Z06 2,221]

33 minutes ago, Snoopy11 said:

I would agree. However, my understanding of rods comes from Amundsen Research Corporation. Cast rods can handle 5,500-5,800 over longterm. That is, with no load. What starts to create issues is engine lugging. 

 

Engine lugging is more unhealthy than extra rpms... this is what breaks cast rods more often than not. 

 

Don

In most engines, yes.  I turned my Kohler CH6-XKE to 6800 stock..loaded and not,  never had any problems, i take hondas and clones (up to 205cc) to 6200.  Modern short skirt pistons and short rod engines are kind to the reciprocating assembly.

 

The problem is the heavy piston on old engines like the Iron briggs, Kohler L and M...they were a full deep skirt design, and they really put alot of stress on the rod, in Kohler and Briggs schools years ago they had worked out a formula that showed that for every 250 rpms over 3600, rod stress went up like 35%, they showed that rod stress on older engines caused the rods to actually stretch and compress right before failure, that if the piston had any deck popup it could physically touch the head at high revs.  I had a K321 let go at just 4500, was running fine...i was making adjustments on the carb, monitoring speed and temps, governor slipped on the cross shaft and it rose to 4500, i went around to kill it and a few clanks and then silence.  It broke an inch below the pin and the rod bent the cam before it broke off the crank.

 

Ill tune my Commands to 4000 and run the dog doodoo out of them..but old engines, 3500/3600.

[Snoopy11 5,714]

24 minutes ago, RED-Z06 said:

In most engines, yes.  I turned my Kohler CH6-XKE to 6800 stock..loaded and not,  never had any problems, i take hondas and clones (up to 205cc) to 6200.  Modern short skirt pistons and short rod engines are kind to the reciprocating assembly.

 

The problem is the heavy piston on old engines like the Iron briggs, Kohler L and M...they were a full deep skirt design, and they really put alot of stress on the rod, in Kohler and Briggs schools years ago they had worked out a formula that showed that for every 250 rpms over 3600, rod stress went up like 35%, they showed that rod stress on older engines caused the rods to actually stretch and compress right before failure, that if the piston had any deck popup it could physically touch the head at high revs.  I had a K321 let go at just 4500, was running fine...i was making adjustments on the carb, monitoring speed and temps, governor slipped on the cross shaft and it rose to 4500, i went around to kill it and a few clanks and then silence.  It broke an inch below the pin and the rod bent the cam before it broke off the crank.

 

Ill tune my Commands to 4000 and run the dog doodoo out of them..but old engines, 3500/3600.

I agree, I also think sharp increases in rpm don’t necessarily help either… 

 

Don

[RED-Z06 2,221]

6 minutes ago, Snoopy11 said:

I agree, I also think sharp increases in rpm don’t necessarily help either… 

 

 

 

Don

 

The margin for error...when you start to wind one up, goes down.  We used to take stock rods and polish them to remove stress risers like casting lines

[RED-Z06 2,221]

I had a Honda gx200 that i wanted to run in a 200cc open mod class, took the block and had it decked to 0.0" popup, put in an ARC billet rod with inserts, Wiseco 2 ring cryogenic piston, ARC 4lb billet flywheel, ported a 12cc early gx200 head and had it milled to 11cc, stainless swirl polished undercut valves, 1.3:1 roller rockers, billet keepers, 32lb springs, copper head gasket, arp studs in the whole block, Tillotson Double pumper carb bored out so much it had no idle circuit.  Cam was a custom Isky grind.

 

Turned it up to 9600....on Nitromethane, pushed the cylinder off the block, needed a girdle.

[Snoopy11 5,714]

4 minutes ago, RED-Z06 said:

I had a Honda gx200 that i wanted to run in a 200cc open mod class, took the block and had it decked to 0.0" popup, put in an ARC billet rod with inserts, Wiseco 2 ring cryogenic piston, ARC 4lb billet flywheel, ported a 12cc early gx200 head and had it milled to 11cc, stainless swirl polished undercut valves, 1.3:1 roller rockers, billet keepers, 32lb springs, copper head gasket, arp studs in the whole block, Tillotson Double pumper carb bored out so much it had no idle circuit.  Cam was a custom Isky grind.

 

Turned it up to 9600....on Nitromethane, pushed the cylinder off the block, needed a girdle.

HellHorse turns around 7,650.

 

Started with 457cc Duromax. Flat-top piston, ARC rod (had to bore out the wristpin journal myself with a die grinder… as the 420 ARC rod does not fit the wristpin on the 457).

 

Billet flywheel, 65lb valve springs, 1.3 ratio rockers, billet hot cam, Mikuni with tuned jets, and several other mods.

 

That thing puts out some serious hell. ARC told me that an engine just like mine got put on the dyno. It made 51 horsepower.  

 

Don

[RED-Z06 2,221]

14 minutes ago, Snoopy11 said:

HellHorse turns around 7,650.

 

 

 

Started with 457cc Duromax. Flat-top piston, ARC rod (had to bore out the wristpin journal myself with a die grinder… as the 420 ARC rod does not fit the wristpin on the 457).

 

 

 

Billet flywheel, 65lb valve springs, 1.3 ratio rockers, billet hot cam, Mikuni with tuned jets, and several other mods.

 

 

 

That thing puts out some serious hell. ARC told me that an engine just like mine got put on the dyno. It made 51 horsepower.  

 

 

 

Don

 

I had a local guy put my Honda on his dyno, it was an odd setup, used water pressure to load it down but it had shown accuracy...the 196cc honda made 23hp on a too small Mikuni Flat slide and 27.2hp with the big Tilly.  It was something watching the bugle pipe cherry up on the dyno.

[Snoopy11 5,714]

2 minutes ago, RED-Z06 said:

I had a local guy put my Honda on his dyno, it was an odd setup, used water pressure to load it down but it had shown accuracy...the 196cc honda made 23hp on a too small Mikuni Flat slide and 27.2hp with the big Tilly.  It was something watching the bugle pipe cherry up on the dyno.

My Tillotson that I sold made 25.

 

Don