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4 hours on newly rebuilt k241 and rod siezed to crank


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#1 newcaseowner OFFLINE  

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Posted July 02, 2016 - 04:19 PM

i rebuilt my k241 because it was burning oil.

 

it was running great every thing i did was by the kohler repair manual.

 

piston clearance is .0075 - ring gap .010 - rod clearance .001 - engine is full of straight 30 weight oil right at the full mark and timing was set with a timing light .

 

after a total of 4 hours running as near as i can tell the rod seized to the crankshaft.

i was cutting my lawn a 3 hour job it slowed down and quit right after it started blow huge amounts of white smoke out of the crankcase breather.

 

the rod is a saint bird brand do you guys think it was a bad rod to begin with as i have never worked with that brand rod before.

 

the rod was installed with match marks together and oil hole toward the camshaft as per manual.

 

block was cleaned well before assembly to remove grit from honing

 

the rod is .020 under as the crank needed to be turned down to .020 under .

 

ideas guys the more the better.


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#2 HANKG ONLINE  

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Posted July 02, 2016 - 04:29 PM

Sheet happens, could very well be a faulty part, sounds like you know what your doing.

#3 boyscout862 OFFLINE  

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Posted July 02, 2016 - 04:30 PM

Did you use plastigauge? Did you over torque and then retorque because it is a new rod? Did you change the oil after the first 1/2 hour? Post some postmortem pics. Good Luck, Rick



#4 powerstroker00 OFFLINE  

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Posted July 02, 2016 - 04:57 PM

Been there done that. What I figured out was that I used the wrong torque specs on the rod. Mine lasted about 5 minutes. It was the first one I had rebuilt.

#5 EricFromPa OFFLINE  

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Posted July 02, 2016 - 05:00 PM

I change oil twice on engines after rebuilding.1st change is after 1/2 hour to 45 minutes of running between 1/4 and 1/2 throttle.Then pull the oil pan spray out with brake clean.When draining it you will see a good bit of shiny metal in the oil.This is normal,Oil will almost be gray in color till the rod wears in and rings seat.

 

Start up again and run for 2 hours at 3/4 to WOT then change the oil again.Oil should have very little metal in it by this time.After that it should be good to use normally.

 

It usually only takes about an hour or so for rings to fully seat and for the crank to run in.But they do shed a good bit of fine metal shavings while they're breaking in.If you don't change the oil and keep the metal shavings out and away from your crank journal it will score and Gaul your connecting rod fast to your crank.Luckily it didn't snap the rod and throw it through the block.

 

You can clean the aluminum off safely by soaking it in muriatic acid.It will eat 100% of the aluminum off and leave your crank journal untouched.


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#6 Rustysteele OFFLINE  

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Posted July 04, 2016 - 07:41 PM

I hope you didn`t have the connecting rod backwards, so the oil dipper wasn`t pushing oil into the hole in the rod cap. Just an idea.



#7 newcaseowner OFFLINE  

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Posted July 11, 2016 - 05:47 PM

update the con rod is the only thing that went bad every thing else in the engine is just fine.

 

there was plenty of oil and every thing was getting oil.

 

i looked for any funny wear on other parts and found nothing.

 

so the big question is why did the con rod go bad when every thing says it should not have.

 

the con rod looks like it was not getting oil but i had the oil hole toward the cam shaft and match marks were lined up  and it was full of oil to the full mark on the dip stick..

 

the rod was torqued to the specs sent with it which are 260 in/lbs with a click stop torque wrench.

 

the only thing i can see is there had to something wrong with the rod that i did not see or it could have been something you could not see.. 

 

and before i forget the engine could be turned over by hand 4 hours before it fried the con rod..


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#8 DougT ONLINE  

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Posted July 11, 2016 - 07:48 PM

When the crank was cut, was the radius at the edges right for the rod? I had  Kohler K181 crank cut .010 under once and within a year it had a rod knock. Took it down and the crank was worn bad and the rod not hurt. Machine shop said the .010 must have taken it past the hardened part of the crank. Hope you have better luck with the .020.



#9 cmn135 ONLINE  

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Posted July 11, 2016 - 09:55 PM

Could just be a faulty rod. The only thing that jumped out at me is the Kohler manual recommends torquing to 20% over spec, then back under a little, then torque back to spec. But perhaps the aftermarket Saint bird rod has different instructions.

#10 Alc ONLINE  

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Posted July 12, 2016 - 05:30 AM

Chris I've been reading this thread since you started it and started at the beginning again today, not wanting this to happen to myself or others . I noticed you said you had .001 for the rod clearence , was that a typo , if not how did you get that size ? One of the spec I found said it should be .0035" . Did the machine shop do the sizing for the rod ?

Edited by Alc, July 12, 2016 - 05:31 AM.

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#11 newcaseowner OFFLINE  

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Posted July 12, 2016 - 05:23 PM

tractorholic    the .001 clearance is from the kohler manual  unless the manual is wrong

 

but then when i looked on Brian millers web site it says the same .001 to .002 clearance and he builds pulling engines.

 

so i conclude that clearance is right as i measured the crank and the new rod and had about .0012 clearance.

 

after taking the rod out i find the the big end is warped out of round by quite a bit.

 

i cant bolt it back together by hand i have use a wrench when it was new the bolts went in easy by hand.

 

i am beginning to think it was a weak rod and the big end warped while running and then fried it self.


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#12 newcaseowner OFFLINE  

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Posted July 12, 2016 - 05:30 PM

Could just be a faulty rod. The only thing that jumped out at me is the Kohler manual recommends torquing to 20% over spec, then back under a little, then torque back to spec. But perhaps the aftermarket Saint bird rod has different instructions.

the specs that came with rod said torq to 260 in/lb and nothing about over torquing and then re torquing it.

 

but then the instructions they sent could be wrong  after all the rod was made in Taiwan..


Edited by newcaseowner, July 12, 2016 - 05:33 PM.


#13 Alc ONLINE  

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Posted July 12, 2016 - 07:33 PM

Your right the manual reads .001"- .002" the .0035" I found doing a search this morning .

#14 newcaseowner OFFLINE  

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Posted July 16, 2016 - 10:56 PM

i have some pics of the rod that went bad now to see if i can get them to post.

 

a little about the rod - when i went to unbolt the rod it was loose even tho i had torqued it to 260 in/lbs as per the instructions that came with the rod..

 

i put one bolt in finger tight so the rod is together on one side and the other side has a gap.

 

if i am correct the rod bolts loosened then the rod cap bent and the rod burnt to the crank.

 

you cant see them well in the pics but the match marks are together ..

 

 

well when i can figure out why i am getting this with  jpeg photo's i will post pics (You are not allowed to use that image extension on this community)                     



#15 Brucepts OFFLINE  

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Posted July 18, 2016 - 09:11 PM

I always torque my rods up in steps, maybe something like 50, 150, 200 then 260. This makes sure the cap seats evenly.

 

What did you use to prelube your bearing surface? Did you get extra in the oil hole and it did not allow oil to lube the rod? I always use a light coat of white grease so if the engine sits for sometime before it gets run the prelube doesn't run off. I run my engines till warm and then drain and refill with fresh oil.

 

Just some thoughts . . .






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