Archive through April 24, 2013

[kostendorf]

Doug, I'm kinda new to working on cubs and learning real fast on this forum with all the knowledge you guys are putting out there. That said it sounds like you checked all the technical stuff. It might have been a hair line crack in the oil dipper that made it break off and not sling oil on the crank.

 

[dlbarnett]

Gary I. fortunately the only thing broken was the dipper. when it seized the rpm was low so no grenade effect.

Keith O seems like if the dipper broke first there would be other oil starved components in the engine as the engine relies on splash for lubrication. I inspected the pan for signs off interference with the dipper but found none. I suppose that the rod my seize before anything else as it is under the most load.

 

[jdiederichs]

When the dipper fails on a rod, 99% of the time it is due to a ding, a scratch etc. in the aluminum, which creates a stress riser. Found this out when I was in warranty dept.

Here's another strange example, although not on topic: Snowmobile warranty work, techs pressed off defective track drive sprockets after scribing a slight witness mark so new sprockets could be installed in the same spot. All the drive shafts subsequently broke at the scribe marks, even though they were barely visible on a 1.25" diameter hex aluminum shaft! Each looked as if it was laser-cut, the break was so clean.

Back on topic, we saw many, many dipper failures due to a slight mark caused by:
a) manufacturing process
b) handling in packaging
c) mechanic installation causing a small ding.

 

[nbextermueller]

If the dipper broke. And keep in mind even that oil dipper weighing only a few grams, see's literally 100's of g-forces as it is constantly changing directions at a very high rate of speed even at idle. If it had a fault, cracked and broke off, it would take less than 30 seconds for the rod to seize without oil.

And your right, the rod, piston and wrist pin are under severe load. Keep in mind an idle of 800rpm, those pieces are changing direction 13.3 times a second. At WOT of 3600, that's 60 times a second. Say "1 Mississippi" your piston just moved back and forth 3"+ 60 times. And a .015in or so film of oil is all that's keeping 100's of lbs of forces apart in the rod end.

Amazing all it takes is that little tiny hole and a splash of oil. Every other surface in the engine puts the oil in shear. A much worse condition. But even the lifters are only seeing 30 or 40 pounds of pressure on the oil. Nothing like what the rod is seeing because of its massive weight and rate of acceleration.

 

[pbell]

Doug
I don't know if your other Cub Cadets get as much use or hours as your 149, but the Kohler "K-Series" engine manual only recommends 5W-30 oil (or any other multi viscosity grades of oil), for use below 32 degrees F. Above 32 degrees it only recommends straight 30W meeting service class SR or SG (or higher). Since I don't know what temp's your tractor was used in, I'm not saying the use of 5W-30 oil is the cause of your engine problems, but I would think it could be, or at least be a contributer.

 

[nbextermueller]

I'm not trying to bring up the age old oil debate again, but Paul indirectly made another point. Using a multi grade oil designed to meet current automotive requirements barely have enough of the ZDDP (the slick stuff) in the to meet the design requirements our 40yr old kohlers require. I would also recommend using an oil designed for small engines in the correct weight. And keep in mind new small engines are also emission regulated. So even the new small engine oil is lacking what could add years to your little engines.

Although, it's only my opinion. I use Lucas Oil 30w Plus in all my machines. It designed for our application and has up to 4 times the ZDDP of regular, say Vavoline 30w for cars. In the summer I also swap 20% of the oil for Lucas Synthetic Oil stabilizer. And run the Upper Cylinder Lube in every gas tank. And yes there is a very noticeable difference in engine performance.

 

[rrjohnson]

David P. Regarding snugging up the cam follower in your steering box, if the frame on your 122 is anything like the one on my 125 you can line up the slotted screw with a hole in the frame just by rotating the steering wheel one way or the other and not have to use a pain-in-the-neck offset screwdriver. It's fairly easy to hold a screwdriver in the hole while dealing with the jam nut and keep the pin from turning. Sometimes you can even crank a bit of a turn on the screw without loosening the jam nuts if you can get both hands to grip the screwdriver. As for determining where the slop is. if you turn the steering wheel and the drag link doesn't move the slop is in the box. If the drag link moves right away the slop is down the line in the roll pin, ball joints, and axle. In your case it's probably a little of all those parts adding up to major steering slop.

 

[hydroharry]

Doug B - geez, as others may be implying that 5w30 doesn't seem appropriate to me. Temps here are hardly ever below 30, and if you're mowing grass up your direction I suspect you're talking 50+ degrees minimum, except maybe Oct. I ran it a few time in CT when temps were below 30 and with my 14hp 1450, after about 15-20 minutes run time the oil looked nearly like water and would just run off the dip stick. I quickly switch back to running straight 30W but I kept my unit in an unheated partially insulated garage attached to the house that was probably hardly ever below 30 even when it was zero outside. Would that contribute to the dipper breaking off? Seems unlikely and more possibly due to the scratch, ding, fine line, etc, mentioned by others. Question - since this is the 2nd time the rod failed did the dipper break "both times" or was it just the last?
Now, with regard to your pics that Kraig requested, I vote for some of your wife, but they should be posted over in Geezer's Garage (which requires special request access, but you gotta have the head, guts, stamina, to take any and all comments).

 

[lhinds]

Doug if you use the tractor going around a slope like mowing a ditchline a lot, that can starve a splash system for oil. The other thing that comes to mind is overspeeding the engine. It should operate at no more than 3600 RPM. I usually set my mower engine at 3400 with mower deck in gear.Just my 02c

 

[kide]

David P...
One thing about your steering gear not mentioned is that the groove in the worm that the pin rides in will most likely have wide spots worn in it. If you tighten the lash adjustment up with the pin in the worn area, it'll bind in the rest of the worm groove...

Luther :
Not to start another debate, but most small engines are actually designed to operate best at a specific speed, typically the spec is 3600 rpm.. If they're actually balanced, it's going to be best at a specific RPM or a multiple of it. IIRC, the K motors are specced at 3600. I know that my 129 has several engine speeds at which the shake and vibration is much more pronounced ...

Also wanted to comment on the ZDDP issue - a comment was made that it was " the slippery stuff" in oil .. Uh, if that were true, the entire mechanical world would come to a stop. Rather than define it's role here, I suggest anyone interested google ZDDP and read volumes about it and the problems lack of it will cause.......

 

[pbell]

The service class of the oil for the "K Series" I listed below should read SF or SG, not SR like I posted (<font size="-2">I blame it on fat fingers and the keyboard keys being to close together. That's my story and I'm sticking to it</font>)

 

[hydroharry]

Hey Gerry - in most post I did mention David P would have to check for binding or backlash if he tightened the cam follower screw 1/4 turn. In my experience you may get a little binding at a few spots in the rotation, and maybe a little kick back at one or both ends of the rotation, especially if you're setting it up while you have it out of the tractor. I've even replaced the cam follower screw with new ones and still had some of these slight binding spots. I don't know of anyone actually replacing the worm gear shaft. I suppose new replacements may be available (didn't check) but most likely a used shaft would be used and likely have almost the same result (because of 30-40 years of wear). I think it best to final test the box when installed. Most of the time a little binding and maybe a little kick back, will not even be noticeable in normal use, and has a good chance wear away and provide good service for another 10+ years. (I'd probably put a used box or shaft on the top of my cabinet shelf at high reach in case I needed it before 10 years). Lets hear from some of the others on hear. Wayne, you must have gone thru alot of steering boxes. Don T, you have several units to.

Paul B - I believe several of us posting on hear have gone to using "senior" keyboards with oversize buttons.

 

[dlbarnett]

Thanks all for your input on the rod failure. at this point it seems that most likely the dipper failed first, causing the rod to seize. And yes in both cases the dipper was broken off. I did use the 149 the weekend before to mow the 300 ft. of ditch in front of my house, normally I use the 169, so it would seem that if I oil starved the 149 I would have oil starved the 169 a long time ago. I will switch back to 30w oil, although it would seem a good multi grade synthetic blend would more than do job. The 149 does see more hourly use per week mowing but the 169 would be close second and is used for chipping & tilling

 

[mconway]

Alas...have to do a little PM on my built in June '72 109. Came out today and smelled gas, only things near was my truck and the tractor. I knew the truck was ok and lo and behold, the grass under the engine on the tractor was black...aha...found the problem. Will take the bowl off carb and inspect the float 'cuz I'm thinkin' it might have a hole and didn't close the needle off. Updates will follow....love this forum

 

[dplogman]

Thanks all for the steering slop suggestions. I've copied / pasted them into one document so I can read them carefully as I get in there to tinker. I dont need this old girl to steer like she was when new, just like it better than it is. She is after all, a worker. If the steering is a little notchy that would probably be ok. I do think I'll do the roll pin replacement first.

About 7 years ago I cut the top off the cap and welded the cap to the top of the axel shaft. Worked great for about 5 years until I crashed into the side of my backyard deck and broke the axel- took that last turn a little too wide! Dave

 

[hydroharry]

Doug B - one question you asked before was how many times the Kohler crank can be ground. I always thought it was only once if you were going to use Kohler parts. They only have one undersized rod (.010 under). I understand there may be an aftermarket .020 rod, and/or some shops that might adds bearings to a new rod for use with a more undersized crank. Hope others on here can provide details and outcome stories.

David P - sometimes the cap wallows, and sometimes the spindle, and sometimes it's both, and sometimes it's just the roll pin. The standard hardware store roll pins don't work well for this application. You need an IH spring roll pin (sometimes called a Spirol pin, or I call them a sorta double roll pin).
As for the steering, if you ain't messed with it before I suspect a 1/4 turn on the cam follower screw will give you alot of improvement, and sure help you avoid those scary moments when you turn the wheel but the tractor don't, and you crash into backyard decks or other such things.

Mike C - more likely a sticky needle in that carb. Just get yourself a new needle and seat kit with new gaskets first. Make sure you screw in the seat all the way and snug it (you'll need a small 1/4 drive socket to remove and install). You can replace the float if you want. I'd just check it by shaking and listening for fluid slosh, and looking for holes. If the needle and seat doesn't resolve the leak then replace the float, but this is just how I do it.

 

[wshytle]

I personally would just go to the trouble and remove the steering box. There are several variables here all of which are fairly easy to address but that's when it's on the bench. If you have to do it in the tractor I'd also remove the small cotter pin that locks the bottom plug and see if it can be tightened a bit. Grease is another major concern and if it hasn't been attended to the top bearings are most likely dry. The races can pit if moisture has ever gotten in and this makes the ball bearings work that much harder. I usually change out the bearings anyway. I bought a "lot" of 100 (I think) a while back of chrome plated steel 5/16" ball bearings.

The steering box has become something I just go through routinely when going through a tractor. I even go to the extent of cleaning and painting the inner rod that came unpainted from IH. It's usually nasty and can be heavily rusted. Removal of the steering wheel seems to be the hardest thing in this project for me (but it hasn't stopped me yet).

 

[kide]

Harry - my 129's steering worm gear had surface that was actually wavy (IIRC, I posted a couple of pics at the time).. I'm not sure how deep the hardening is on that surface, but I can tell ya that a new follower pin didn't make that much difference when I got it adjusted, center of the travel is still loose about 15 degrees....

Sorry about missing your mention of the binding issue - I usually save your posts for when I have lots of time, like, uh, "library duty".....

 

[dplogman]

Harry- could you clarify your comment about the axel in the axel channel? not following that part.

It was steering fine when I crashed, I just went too wide and didnt hit the brake fast enough! I bet that pin tighten up will help a lot. D

 

[kide]

He probably was referring to the axle channel in the frame ... see this Faq on how to tighten..