k241 has noise when hot

[Martin 2,133]

as i posted in my 1054 rebuild thread, the k241 has a noise when it gets hot or been running about 10-15 min. its not loud unless you get up real close. seems to be coming from the upper half of the engine, but not 100% sure. tried to pin point using a large screwdriver like a stethoscope and its most prominent from the head area, loudest when touching the head bolts. the first video below is up close so the noise is louder than if you were just standing next to it. almost cant hear it when sitting on the tractor. this problem really put a dampener on a exciting day getting this thing operational..

this engine is an older rebuild and seemed ok before i tore the 1054 apart. it was running fine although i didnt have a lot of seat time on it in one go. more time was spent getting it running good. all ive done engine wise is gaskets and clean it up. engine looked clean inside, nothing looked out of place and all fasteners were at factory specs.

im wondering if valve clearance could be a suspect, they were set to factory clearances. otherwise not sure where to begin looking. any ideas? what does bearing noise sound like on these, same as say an automotive engine?

am i being too paranoid about this?

any and all help/suggestions appreciated.

click on pic for video.

heres the other videos on the rebuild post where the noise doesnt seem to be noticeable..

[Cody 277]

Check the points and make sure they are set to .020. If they are then it sounds like it could possibly be the connecting rod causing it to knock. Beautiful restoration by the way. It was a pleasure to watch you restore it piece by piece.

[Martin 2,133]

thanks for the comments cody.

points were the first thing i double checked today. as the point gap affects timing, maybe too much advance was causing this. it did seem to help a little by closing the gap. the points are set at .020. now and its a little better. points were filed some so i might just go ahead and replace them and see what happens.

would closing the gap retard the timing?

im going to go searching for TTs static timing post and read up alittle.

might also try some different gas too.

[Kelly 1,033]

Set the valves, I've fixed a few rod knocks by doing that, people swear the engine was going to blow up it had a knock, turned out to be a simple valve adj. ok not so simple you do have to pull the carb, some throttle linkage, and the valve cover and breather, but not real hard, on yours pull the grille.

[MikesRJ 558]

After checking the valves, I would also suggest setting the point gap this way. Much more accurate than using straight gap measurement:

http://www.mywheelhorse.com/graphics/file/...ngineTiming.pdf

[Martin 2,133]

After checking the valves, I would also suggest setting the point gap this way. Much more accurate than using straight gap measurement:

http://www.mywheelhorse.com/graphics/file/...ngineTiming.pdf

mike, thats the post i was talking about. i was wrong with the author though, it was T-Mo and not TTs post. thank you......

[JC 1965 1,532]

:ROTF: I must say, I had my doubts about the static timing when I first read the post about it. Then I decided to try it and I am amazed at the difference it made in my tractors. Just goes to show, you don't know until you try it. Thanks for the post T-Mo. Much appreciated!! :woohoo:

[rmaynard 16,333]

Pinpointing sounds is very difficult. The fact that the sound seems louder when the engine is hot makes me think it is exaggerated by the thinning of the oil as it gets hot. The sound heard in the video is the same as what I had in my K241AS. It had a worn connecting rod and crankshaft. The longer the engine ran, and the hotter it got, the louder the noise got.

I never rebuilt that engine, but used the internal parts in rebuilding another.

I was told by the machinist that turned my crankshaft, that as a crankshaft wears, the top of the crankpin (the area where the rod contacts the instant the plug fires) flattens out a little over time. Changing the timing changes the point of contact between the connecting rod and the crankpin ever so slightly. That is why changing the timing can in some cases reduce the noise.

[Martin 2,133]

update. had a small amount of time this afternoon to check the timing. i must say the static way is very easy to get right and no guessing if you are unfamiliar with feeler gauge 'feel'. as it was, just setting to .020 the timing was retarded some. about half way between the spark mark and tdc mark on the flywheel when it started to change resistance on the meter. i like the static way, very easy once you work out whats going on. one important thing is to wedge the points bracket well when tightening otherwise it can move, even just a little.

just for interest sake i checked the gap afterwards and it was slightly easy on .028 and tight on .030.

conclusion: timing is good, runs smoother but the noise is still there. infact it seems slightly louder. guess the valves will get checked next and that doesnt fix it then im tearing into the engine. hope the crank is usable, someones done some work on it before, has a .020 piston in it and the bore looks good. just would be good to turn the crank thats in it and put in a new rod. we will see..........

[tunahead72 2,546]

Martin,

I'm reading your thread with a lot of interest right now. My K241S sounds very similar to yours, although as Bob (rmaynard) pointed out, it is hard to judge from a video, and then compare that noise to what I'm hearing on my machine in the shed.

I'm curious about a few things that have already been mentioned:

• [*:tdmfwjpp]I haven't seen an answer yet to your question about whether closing the points gap retards the timing. This seems logical, based on the little I know about engines, and if it's true then you actually advanced the timing by setting your points at .028"-.030", which I think would explain why your noise is now louder (if it's actually a knock).[*:tdmfwjpp]Your final points gap seems really high, but only because I don't have a lot of experience with the static timing method. Is it normal to have that much of a difference from spec, in an engine that's basically sound, or does it indicate something else?[*:tdmfwjpp]Using a higher grade of gasoline can also help engine performance, so I'm interested in hearing how yours runs and sounds after you change grades.[*:tdmfwjpp]I own a couple of early '80's Honda motorcycles, and every manual I've ever seen for those machines emphasizes that the valves should be set properly first, before you make any changes to the timing or even adjust the carburetor. I don't know if that advice applies to these engines as well, but it wouldn't hurt to check your timing again after you adjust your valves -- you know, before you tear the engine apart. Mike's (MikesRJ) post seems to suggest that also, if I'm reading him correctly.

Good luck with this thing, hope it works out well for you!

[Martin 2,133]

i wanted to start with the simple stuff and see if any changes were evident. i thought about the gap/adv/retard issue and it seems logical that if the gap is larger the points are open for a longer duration (earlier and later) than if the gap is smaller. since the plug starts to fire earlier it is advanced more than a smaller gap would be.

which brings up a point bob stated about the flat spot on the crank(if that is my problem) it maybe firing on a worse position than before. i feel the timing is better set the way it is now, the engine runs better, although i have noticed it takes longer to start, now two or more revs before firing instead of the 'instant' fire the way it was.

valves are going to get checked next. im really hesitant to tear into this thing, but it needs to be addressed. i dont feel good about it as is.

[Martin 2,133]

ok, heres the latest...

i was thinking about the gas issue, whether it was bad (siphoned fresh from my wifes suburban that day- think she filled a day or so before) and whether she had filled up on the cheap stuff....... also wasnt ruling out detonation just yet with the way that the noise got worse when i did the timing and it was obviously using more advance. anyway got some fresh shell 93 and drained the gas tank and line and ran some 93 through it. started up quiet.......ran different, adjusted the low speed mix and got it running sweet.... the noise slowly came back. so gas didnt really solve the noise problem, but it did make it run better. i ended up using the gas i drained in the 875 to mow tonight and it ran like crap every now and again, maybe bad gas, maybe just tired 875 too........

enough dribble, onto the valves.....

pulled the throttle linkage, grill insert, air cleaner, gas line to carb, and managed to wiggle the breather assembly out of there......

looked at clearances, little on the loose side of spec ..011 to .012 on the in and .020 to .021 on ex.

(man says in .008-.010 ex .017-.019)

i adjusted them down to .008 in ( .008 slides with a slight drag, .009 goes but is tight.) and .017 ex.

anybody have any thoughts to kick around here? where do you guys run them, on the high side, low or in the middle.

i know the risks of burning valves with too tight a clearance on them, and usually they are noisy when too much is present. i did my fair share of flat tappet cams back when i was in my twenties. its been a while, though.

[rmaynard 16,333]

I set my K241S valves to .009 and .018. I figured that middle of the range is a happy spot. However, I don't think your noise is in the upper portion of the engine. It sounds typical of a rod knock. I was going to suggest piston slap, but that usually improves as the engine gets hot. So I'm sticking with the connecting rod/crank pin.

[Martin 2,133]

i understand your theory bob, i had a little more time to listen tonight and it seems more upper than lower. the video tells us its lower but i can hear the noise travelling in the shroud from up above as well. the screwdriver stethoscope shows more noise from the head bolt area than down low around the crankcase. it is also showing up at the front of the motor up high.moving the valve lifter up and down by hand touching the valve stem is producing the same but quieter noise as im hearing while its running....... the jury is still out though. one thing at a time. will get the breather and linkage back on tomorrow or sat and fire her up and see. im hoping it will end with that, but who knows.......

thanks for your comments though.......

[rmaynard 16,333]

Engine diagnosis via the internet is almost as bad as trying to diagnose a pain via WebMD.

[Martin 2,133]

Engine diagnosis via the internet is almost as bad as trying to diagnose a pain via WebMD.

we will get there eventually. id rather not be dealing with this at all, but im learning more about these tractors as we go along.

i guess without problems life would be pretty boring.........

[tunahead72 2,546]

i guess without problems life would be pretty boring.........

Yeah, I don't know about that, I can always find SOMETHING to do.

--------

Martin, I definitely like your "change one thing and see what happens" approach, and I'm curious to see how it runs now that you've adjusted the valves. And if you're still not satisfied, I would still suggest checking the timing again, just to see if the combination of the two changes makes a difference.

One other thought. You mentioned the possibility of detonation, which is something I've considered also. I have a 1996 Dodge Ram pickup which pings occasionally, sometimes often. I know from a bunch of research that the root cause is probably a bad plenum gasket, a known problem area in this truck, which I just don't have the money to fix properly. I've tried several "band-aids" over the years to reduce the pinging -- using better gas helps, as do regular doses of Techron in the fuel, but the most noticeable improvement came at my last tune-up when I switched from Champion spark plugs to the next colder range Autolite plugs. Maybe changing brand and/or heat range of your plug would help?

Of course, we could both be wrong, and Bob could be right that it's really just a rod knock. <_<

EDIT: I meant to ask -- Am I reading your post correctly, did you actually manage to adjust your valves without removing the carb?

--------

And Bob, for my own benefit, what do you mean exactly by piston slap -- is this side-to-side movement in the bore, or something else? What does it sound like? And why would it improve as the engine gets hot?

:woohoo:

[Martin 2,133]

i guess without problems life would be pretty boring.........

Yeah, I don't know about that, I can always find SOMETHING to do.

--------

Martin, I definitely like your "change one thing and see what happens" approach, and I'm curious to see how it runs now that you've adjusted the valves. And if you're still not satisfied, I would still suggest checking the timing again, just to see if the combination of the two changes makes a difference.

One other thought. You mentioned the possibility of detonation, which is something I've considered also. I have a 1996 Dodge Ram pickup which pings occasionally, sometimes often. I know from a bunch of research that the root cause is probably a bad plenum gasket, a known problem area in this truck, which I just don't have the money to fix properly. I've tried several "band-aids" over the years to reduce the pinging -- using better gas helps, as do regular doses of Techron in the fuel, but the most noticeable improvement came at my last tune-up when I switched from Champion spark plugs to the next colder range Autolite plugs. Maybe changing brand and/or heat range of your plug would help?

Of course, we could both be wrong, and Bob could be right that it's really just a rod knock. <_<

EDIT: I meant to ask -- Am I reading your post correctly, did you actually manage to adjust your valves without removing the carb?

--------

And Bob, for my own benefit, what do you mean exactly by piston slap -- is this side-to-side movement in the bore, or something else? What does it sound like? And why would it improve as the engine gets hot?

ed,

changing only one thing at a time is the only way to go. i want this problem to go away, but i also want to know what change made it go away.

the timing will be checked once again to make sure it is still ok.

detonation is still on my mind as well. im not sure how much was removed from the head at any time in the past to true it up, i know i took a bit off by hand with 400 on a flat surface to get it right this time. i guess without cc'ing the chamber i wouldnt know. thats why i tried the different gas. the plug has got me thinking though...........

i didnt want to remove the carb, just one more gasket to replace, and the breather plates can slide out of there ok, just got to get them past the governor arm first and then you can get them around the carb bowl. take the breather off one piece at a time and it will come out of there. the hardest part is the back plate.

i hope for my sake that bob ISNT right about the rod noise, but i guess time will tell.

i think that what bob is saying about 'piston slap', is looseness of the piston in the bore. as the piston goes up and down the piston skirt rocks and 'slaps' the side of the bore. as temps rise, it is reduced because the bore and piston expand... is that right, bob?

[rmaynard 16,333]

You definition of piston slap is correct.

[tunahead72 2,546]

i didnt want to remove the carb, just one more gasket to replace, and the breather plates can slide out of there ok, just got to get them past the governor arm first and then you can get them around the carb bowl. take the breather off one piece at a time and it will come out of there. the hardest part is the back plate.

Good tip, I may give that a shot next time I check the valves. That's one SERIOUSLY clean engine!

i hope for my sake that bob ISNT right about the rod noise

Likewise.

--------

And guys, thanks for explaining piston slap. I assume that would cause more wear on the piston and bore the longer it continues, and maybe everything below as well, can things actually break if it goes on too long?

[varosd 1,185]

I need to pull my breather of my K-181 but thought I had to pull off the carb and governor! How did you do it? The carb bowl seems to be contacting the breather(at least on my 8 hp). my little "small block" is leaking oil from there so not sure if the weep hole is blocked or engine is due for rebuild. Your resto job looks great!!

Don V

[Martin 2,133]

I need to pull my breather of my K-181 but thought I had to pull off the carb and governor! How did you do it? The carb bowl seems to be contacting the breather(at least on my 8 hp). my little "small block" is leaking oil from there so not sure if the weep hole is blocked or engine is due for rebuild. Your resto job looks great!!

Don V

if i remember correctly, you will have to at least pull the carb on the k181. i did the breather on my 875 and the breather plate is a different shape, larger than the k241 plate. the plate goes up and behind the bowl.

[Martin 2,133]

heres the latest, with some vids as well......

alright, got the engine back together last night, was itching to start it up but was hesitant and so i used the excuse of wanting the ultra black on the breather gaskets to set up before running it......

well i also had a new set of points that i hadnt installed yet(not that there was anything wrong with the others, other than the adjusting area- that you use for moving them, had worn considerably) so i installed them and set the static timing again. this time the gap ended up about .026......

so here comes this afternoon and i decided to pull it out of the garage and see if anything was different with the noise.

engine started fine and idled rough a bit at first, so played with mix a little, got it better. no noise..... still not running right so got out the timing light and checked timing to see where it was at. mark not even visible in the hole. had a dial back light so it was easy to find the mark on the flywheel....30 degrees on the dial back..... played with the gap, had to close it up some to get it right. very easy to do. so got that done, idle dropped some but was a ton smoother. redid mix screws. better.

engine running about 1/2 hour can just detect noise but a heap quieter. top of engine is a bunch quieter so valve adj worked there.

bob is probably right about the location of the noise, but im not going to tear into it just yet. maybe im expecting too much from this engine. dont really have anything to compare with other than a smoky k181 in the 875.. so i guess i will just have to wait until kellys bash to get with some other k engines to compare.

heres what ive learnt during this whole experience.....

both valve adj and timing accuracy have an effect on how noisy this thing is.

doesnt run nearly as hot with timing right.

my static timing procedure was a bit screwy, it got me closer to being right than point adj when just turning over the engine by hand...but checking with a light is essential when its running. (strange how gap started at .020, static changed it up to about .026 and now after running with the light and getting the timing spot on with the flywheel mark, checking the gap gives me .018....) i guess just setting with the gap alone on this engine was actually closer to being right than static by hand.

the valve adj and timing adj have smoothed this engine out higher in the revs, its still has vibration but not as bad.

kelly was right that the valves needed adjusting. much, much, quieter on the top.

i still need to confirm if bob was right about the rod noise.the 'bottom end noise' is much quieter.......

i like messing around with these old kohlers.......

i still need to finish the battery hold down.....

rs is awesome.....

i need more

well the last one is just a given......

heres 2 vids of it running now, i think still room for improvement, i guess untill i get it next to some nice runners and some rattly, smelly ones and work out where its at, im leaving it as is.......

[squonk 43,880]

How did you adj. the valves? Don't you have to grind the valve and seat to close the gap or am I a dummy. :ROTF:

[Martin 2,133]

it shows you how in the manual. there are adjusters between the valves and the cam followers.

scanned it out of my paper copy...

looks like on k91, k141, k161, k181 you need to grind. so you were right on the grinding for the smaller engines. but only if the clearance is too small.

on the k241, k301, k321, k341 they are adjustable by holding the lower part of the adjuster and turning the upper screw......