Correct nut type and torque for K341 rod

[ecsi635j 34]

Hello All

Question for any K341 engine builders here, In an effort to prevent a catastrophic engine failure I wanted to confirm that my K341  did not have the factory installed balance gears upon inspection I was relieved it did no have any balance  my engine is a K341 16HP AQS spec.# 7120.So also while I still had the oil pan removed I  decided to check the condition of the connecting rod and found the big end rod surfaced had no scoring or unusual wear pattern. When I went to reinstall the cap and nuts I found what looked like regular nuts with no locking fasteners. So I went ahead and installed the original nuts and tried torqueing them to spec. which going by the manual  is 285 inch pounds which works out to just under 25 FT. pounds.Well,the nuts would not torque to spec  and I could feel they where startein to strip so I stopped tightening at that point. What I found was what looked like fine thread grade 5 nuts so decided to replace these with fine thread 5/16" grade 8 nuts and retorque to spec. but  again I install them as I found them without lock washers of any type . Been running the engine like that since. my question is .is this assemble correct in regards to using plane fine thread grade 8 nuts with no locking devices of any type and would it be safe to torque to 300 inch pounds / 25 Ft. pounds. really sorry for the long discorse any help is greatly appreciated

[Snoopy11 5,718]

Hello sir,

 

Absolutely no problem... glad you mentioned everything you have done. 

 

So, here is the thing. The washers that are on there are not for locking... they simply act as spacers. Some people thing that they need to use loctite or similar product to help keep the rod bolts from coming loose. However, this is unnecessary... as rod bolt stretch is what locks them. So, if you torque them to spec, they will lock fine. This is what happens when you torque the rod bolts to spec, the bolts stretch, locking them in. However, if you keep removing the same bolts over and over, they fail to stretch... thus why it is best to use new bolts each time you remove the rod. I use ARP fasteners in my rods... but that's just me. 

 

Now... are you saying that you did not use washers at all? I think you would be fine in that case... but the washers do serve a purpose.  Here is a picture of the K341 rod with washers...

 

 

Have you thought about buying a new rod... just to get around these issues? They are only 40 bucks...? 

 

Regards,

 

Don

[pfrederi 18,649]

Most K341 used Nuts (Posilock).  interesting the same rods used in Magnum 16 service manual says used/reinstalled rod torque only to 200 inch lbs  (260 new)

 

as does K seizes for posilock  i think you may have misread the torque chart.

 

What is spec number of you r engine (7120 is not enough digits

Edited November 6, 2021 by pfrederi

[Snoopy11 5,718]

2 minutes ago, pfrederi said:

Most K341 used Nuts (Posilock).  interesting the same rods used in Magnum 16 service manual says used/reinstalled rod torque only to 200 inch lbs  (260 new)

Interesting... as I cannot seem to locate a replacement posi lock rod.

 

All I can find it non-posi rods...

 

 

Coincidence?

 

Don

[Snoopy11 5,718]

Had to dig around for this... but this K341 looked like this before I buttoned it up... with non posi rod bolts...

 

@pfrederi... do the posi lock nuts have bendable tabs on them... locking them in? I have never seen one with those... so I am very curious!

 

 

 

Don

[ecsi635j 34]

3 hours ago, pfrederi said:

Most K341 used Nuts (Posilock).  interesting the same rods used in Magnum 16 service manual says used/reinstalled rod torque only to 200 inch lbs  (260 new)

 

as does K seizes for posilock  i think you may have misread the torque chart.

 

What is spec number of you r engine (7120 is not enough digits

Pfrederi, thanks   My mistake, you're right,  I went back to take another look  I saw 2 different torque values one for Posilock= 260 new  and the other CAP SCREWS =285 inch pounds. What I found originally,  were what looked like regular plain 5/16"s fine threaded nuts  with out any type of washer and not CAP SCREWS ,So could have these been POSILOCK nuts that looked like plain jane regular nuts? just thought a POSILOCK nut may have looked like a NYLOCK nut.

Also spec# turned out to be 71246a

[Snoopy11 5,718]

Out of all the engines I have worked on, I have never heard of any of this. 

 

I am pleased to be here... 

 

Can you take pictures of what you are looking at @ecsi635j...?

 

Don

[ecsi635j 34]

4 hours ago, Snoopy11 said:

Hello sir,

 

Absolutely no problem... glad you mentioned everything you have done. 

 

So, here is the thing. The washers that are on there are not for locking... they simply act as spacers. Some people thing that they need to use loctite or similar product to help keep the rod bolts from coming loose. However, this is unnecessary... as rod bolt stretch is what locks them. So, if you torque them to spec, they will lock fine. This is what happens when you torque the rod bolts to spec, the bolts stretch, locking them in. However, if you keep removing the same bolts over and over, they fail to stretch... thus why it is best to use new bolts each time you remove the rod. I use ARP fasteners in my rods... but that's just me. 

 

Now... are you saying that you did not use washers at all? I think you would be fine in that case... but the washers do serve a purpose.  Here is a picture of the K341 rod with washers...

 

 

Have you thought about buying a new rod... just to get around these issues? They are only 40 bucks...? 

 

Regards,

 

Don

Thank you Don ,There were no washers of any kind upon initial inspection so I reassembled them as I found them. I thought that was kind of strange as well. the rod in you're picture looks like it uses CAP screws with washers guess they ran two different types 

[Snoopy11 5,718]

Just now, ecsi635j said:

Thank you Don ,There were no washers of any kind upon initial inspection so I reassembled them as I found them. I thought that was kind of strange as well. the rod in you're picture looks like it uses CAP screws with washers guess they ran two different types 

Evidently sir, you are correct. I have never worked on a Kohler with anything but rod bolts... so... I am actually very interested to hear more. 

 

Don 

[ecsi635j 34]

1 minute ago, Snoopy11 said:

Evidently sir, you are correct. I have never worked on a Kohler with anything but rod bolts... so... I am actually very interested to hear more. 

 

Don 

Don, unfortunately the engine is completely assembled and running . But I was thinking about droppomg the pan again to make sure every thing is right . I don't want to blow up this engine

[ecsi635j 34]

Might some one have a sample of what a POSILOCK nut looks like?

[WHX?? 51,732]

Interesting  topic what's your take on this @richmondred01 ? 

He does builds the right way ecsi....

[pfrederi 18,649]

Not  great pic I will try to get a better one later.  This is a posilock rod.  The nut has a bit of a flange on it.  From kohler web site it appears you engine had posilocks whether it had the old piston or the newer Mahle.  They do not list a part number for just the nut.

 

Did you strip the nut or the threaded shaft??

[pfrederi 18,649]

Incidentally according to Kohler your engine came with balance gears.... Guess someone was in there before you 

[ecsi635j 34]

pfrederi, Thank you for the picture. I can see the  nuts have a flange and appear to have a black phosphate color to them. The type I found on the rod from my engine do not look any thing like yours  Mine just look like regular 5/16 fine threaded nuts. I guess some one may have been there before and did not replace the Posi-locks.

In regards to stripping the threads I stopped tightening the nuts when I felt the threads in the nut start to pull.

Not sure where to find these special nuts if Kohler does not show a part number.

I really would not like having to replace the rod with a new one being the engine runs very well  not burning oil and runs very clean.

[pfrederi 18,649]

For reference... the nuts are the posilock from a K341  The bolt (or capscrew as Kohler calls it) with flat and lock washer are from a K321

 

 

[pfrederi 18,649]

25 minutes ago, ecsi635j said:

pfrederi, Thank you for the picture. I can see the  nuts have a flange and appear to have a black phosphate color to them. The type I found on the rod from my engine do not look any thing like yours  Mine just look like regular 5/16 fine threaded nuts. I guess some one may have been there before and did not replace the Posi-locks.

In regards to stripping the threads I stopped tightening the nuts when I felt the threads in the nut start to pull.

Not sure where to find these special nuts if Kohler does not show a part number.

I really would not like having to replace the rod with a new one being the engine runs very well  not burning oil and runs very clean.

 

 

I suppose you could sell the other 98..  But these are dimensionally the same as Kohler posilock

 

 

[Gregor 4,847]

I just buttoned up a K341 yesterday. It's running very well. I'm ashamed to say I cannot remember if it had bolts or nuts. Getting old really ...........! Whether it had nuts or bolts, I can assure you I used red thread locker on them. I always do. Most here will disagree with that practice, but I have not had one fly apart on me yet. I have only rebuilt 5 or 6 four cycles, but I have rebuilt at least 15 two cycle lawn mower engines. It looked to me as though the rod bolts/nuts simply backed off on many of these motors. I didn't want it happening to me.

Here is a pic of a Kohler Magnum 16 I recently rebuilt. The rod had let go. Again, it looks to me like the nuts simply backed off. Neither the nuts or the studs were stripped or broke.

[richmondred01 2,307]

14 hours ago, WHX?? said:

Interesting  topic what's your take on this @richmondred01 ? 

He does builds the right way ecsi....

Pfrederi has this topic covered well. 

Edited November 7, 2021 by richmondred01

[ecsi635j 34]

Pfrederi , and every one, thank you so much for all the help. I completely forgot about MC Master Carr they have every thing

Also as Gregor mentioned I do like the idea of using a dab of red Loc tite  just as added security .can't see how it would be a detriment to any thing.

Thinking using the McMaster supplied nuts and maybe toqueing to the higher 260 in.lbs. spec.

Edited November 7, 2021 by ecsi635j

[Handy Don 14,054]

39 minutes ago, ecsi635j said:

Pfrederi , and every one, thank you so much for all the help. I completely forgot about MC Master Carr they have every thing

Also as Gregor mentioned I do like the idea of using a dab of red Loc tite  just as added security .can't see how it would be a detriment to any thing.

Thinking using the McMaster supplied nuts and maybe toqueing to the higher 260 in.lbs. spec.

@pfrederi and @richmondred01 and @Snoopy11

 

Red requires substantial heat (over 500º F) to break it down to permit separating the "lok-ed" parts (once it has cured).

 

To me, there are two important challenges to the "dab of Red":

First is that when used where none is expected, a later disassembler may damage a part not realizing it is being held by Loctite.

Second is that at temps not far above 500º, aluminum (and to a lesser degree, steel) can begin to have their composition affected.

 

I tend to use Blue where my goal is a bit of extra protection for an otherwise well-secured fastening and save Red for extreme cases.

Edited November 7, 2021 by Handy Don

[Gregor 4,847]

41 minutes ago, ecsi635j said:

Also as Gregor mentioned I do like the idea of using a dab of red Loc tite  just as added security .can't see how it would be a detriment to any thing.

As a word of caution, some contend you will not get a TRUE torque reading with Locktite on the threads. Just so you know.

[Snoopy11 5,718]

3 hours ago, Handy Don said:

when used where none is expected, a later disassembler may damage a part

 MONEY!!!

 

Don