VIDEO: K301 12HP running bad after rebuild.....HELP!!!!!!!!!!!

[Fordiesel69 271]

Well guys, problem has been diagnosed unfortunately.

I did not even need a measuring device to tell the cam is shot. I have a magnum 14 hp laying in the garage, the ex valve opens quite far. On this engine. The ex valve opens only half as far. So per the Kohler book, the 12/14hp engines have the same cam.

This means the entire engine needs to come back a part to swap the cam. What a bummer. In my years of rebuilding small engines, I have never seen a cam worn out before. I have seen some 8hp kohlers cracked in half, but never just worn out. I wonder if Low oil level, or just the wrong oil like an SA rating dollar store oil.

[squonk 44,519]

I mentioned the lobe being worn. Working on Chevys in the 70's I saw a lot of "pressure" being blown back into carbs. Did you look at the cam the first time you had it apart?

[Martin 2,133]

just read your diagnosis. yes the cam lobe wear is something that many of us overlook. in some reading about acr problems earlier, that was one thing that also came up quite often. ive never worried about measuring the lobes myself, but on an engine with lack of maintenance and a lot of hours, wear could be a problem. usually i will check the lobes and followers for abnormal looking wear, (sharp edges on the followers or edges of the lobe is a real giveaway) but not often do i measure them...... i guess ive learned a little more now as well. i was leaning more towards the valve guides/breather diagnosis. i really would go over the engine with a fine tooth comb, checking all your measurements and clearances, since you are going to have it apart. there has been a lot of good discussion and suggestion on what to look out for, use all the info to your advantage while its apart.......

 

what was done on the 'full rebuild'?

 

engine bored to match piston?

decent rings used? gaps in spec?

valve guides reamed to match new valves? or in clearance?

etc, etc....

Edited May 13, 2013 by Martin

[Fordiesel69 271]

I never did because I have never heard of a failure other than reading about it.  The engine did not blow up so I assumed it was OK.

 

It looked OK, but I never measured the lobes to see if they were in spec.  You can bet I will in the future.

[squonk 44,519]

While your at it check the guides ans make sure the seats are round.

[MarkPalmer 81]

If your plan is to swap the cam with the one in the M14, make sure the one in the M14 has the lobe for the points pushrod as Kohler started leaving it off sometime during Magnum engine production.  I have not ran in to a Kohler engine with excessive cam lobe wear, but I imagine it can happen.  I remember SBC 305's wearing out cam lobes in the late '70's and early 80's big time  

 

-Mark-

[Fordiesel69 271]

I am getting a cub cadet k301 cam off eBay so it should be a perfect fit. The valve guides feel normal. I lapped the valve seats by hand and they came out nice.

[rmaynard 16,549]

Don't forget to measure that Cub cam before installing it. I would like to know the difference in height between the two.

[squonk 44,519]

If that cam is as worn as you say you better replace the tappets/lifters or the new cam will be junk in no time.

[racin_ny 25]

Just got back home and had a chance to look through this thread.  How was/is the condition of the valve guides? These is a lot of valvetrain noise that new valves and tappet adjustments didn't correct, plus the positive pressure and exhaust gasses coming out the intake, both conditions indicate badly worn guides.   

 

Are you absolutely sure the breather is on the right way, with the reed valve facing the outside of engine, small hole on plate down? 

 

-Mark-

 

I agree with Mark this is a valve train issue. I had one like this and the guides were just shot. I had a friend put guides in it and it has been running great for some 18 years now. Before we did that work it acted like this and vibrated so bad it loosened the nuts holding the carb to the block.

[Anglo Traction 761]

Well it's good to know you got to the problem in the end. Shame you have to tear it apart to fix it. In addition to the good advice of replacing the Followers/Lifters, put new Valve adjusters in them.

Many a worn adjuster face is the cause of inaccurate valve clearances. If you use old ones, clean of any ridges with an Oil Stone and polish so the 'Feeler Gauge' blades don't ride over the top of the worn recesses.

Look forward to hearing you got it running good.

[Fordiesel69 271]

Thankfully the new cam comes with its matched tappets and pin.

[MarkPalmer 81]

Thankfully the new cam comes with its matched tappets and pin.

 

That is a very good thing.  If forced to buy a used cam without the original tappets, the tappets have to be replaced with brand new ones to stand a chance.  When you inspect your new (used) cam, you'll find the exhaust valve lobe should measure considerably taller than the intake.   

 

-Mark-

[Fordiesel69 271]

Now onto another problem.  When the cam / tappets arrive, how can I tell which is exhaust and intake?  Mark my words the seller will not have them labled,.

[MarkPalmer 81]

Because the intake/exhaust tappets are interchangeable on the big block Kohlers, about the best you can do if they didn't mark them at disassembly is to look for a common wear pattern between the lifter shoes and cam lobes- not often easy to do. 

 

-Mark-

[illinilefttackle 399]

Just my humble opinion, but after all the trouble you have gone thru with this engine-why not take the time to get new valves and matched valve guides? I find it hard to believe an engine ,with a cam in this condition, goes not have abnormal wear other places too. Good Luck-Al

[Fordiesel69 271]

Just my humble opinion, but after all the trouble you have gone thru with this engine-why not take the time to get new valves and matched valve guides? I find it hard to believe an engine ,with a cam in this condition, goes not have abnormal wear other places too. Good Luck-Al

 

 

For two reasons: 

1.) Local machine shop requires you to strip the block to have them do work on it.  I cannot and will not do this a second time.  They can make the tough rules and loose thier customers as far as I am concerend.  I saw them do the job and they could do it in the tractor no problem. 

 

2.) When I checked the valve stems, they measure fine, and I polished them with some crocus cloth with it chucked in a drill.  Valve face was grooved, but was nice and even.  I felt the play in the valve guide to stem and it felt nice.  So it would be a waste to spend the time.  I also swapped in my M14 valves in which they were like new as the engine had low hours.  I only had (1) K181 with aq bad EX guide and it was worn sideways on the seat and face.  It was $60 back in 2001 to have this done which included a new guide, and a seat regrind, and a valve face regrind.   

[squonk 44,519]

I would ask them since they were in the engine once, would they replace the guides with the engine in the tractor. They make the tough rules to protect them selves. They don't want a bad rap because they made a mistake. I know several machine shops and they all have the same rules. They are all swamped so they aren't lacking for customers either. Those guides that feel nice today might not be so nice in 6 months to a year.

[Fordiesel69 271]

With how worn the old cam is, would it be any good for the folks to use for modifiing for tractor pulls.  To my knowledge they weld it up and regrind it to move the power up higher in the RPM.  Thought instead of throwing it out, that someone could use it.

[Fordiesel69 271]

Got the new (used) cam, and the tappets were not marked as I expected.  On the tappet face were it rides on the cam lobe, I notice one has a little wider shiney pattern vs the other.  I assume this is the exhuast one as the ACR tab probably wears it just a little more.  Would this be an accurate assement? 

[MarkPalmer 81]

I would say that is accurate for a couple of reasons.  First, most wear occurs when starting, and that is when the ACR finger is up making an additional wear pattern other than the cam lobe.  Second, the exhaust valve lobe has more lift than the intake, which can make for greater wear. 

 

-Mark-

[Fordiesel69 271]

Well guys here is the good news................................it runs perfect now.  I got an ebay cam with tappets for $14.99 + shipping.  What a deal!!!  It was like new and measured within spec.

 

Here is a side by side comparison of the exhaust lobes.  Bad cam on left, new cam on right:

http://i891.photobucket.com/albums/ac117/Fordiesel69/Temporary%20Pics/IMG_2497_zps5999a091.jpg

 

Now onto some theorys.  In looking at the cam pin, there is no scoring, as in lack of lubrication.  There is also no sign of damage to the tappet bores.  So I conclude that the metal was simply misformulated, or the owners had rebuilt the engine too many times and the cam has tons and tons of hours on it.  They removed the air cleaner assy as a result of the carburetor blow back.  It probably soaked the air filter.  This contributed to cylinder bore wear. 

 

I have also done sone reading over at www.bobistheoilguy.com and there has always been a lot of discussion on newer oils API SL or newer having very little ZDDP in its formula, thus making any engines with flat tappet cams really wear.  This is all in effort to save catalytic converters / emissions.  It is better to run a HDEO such as Delo 400, Delvac 1300, or Rotella T all with DUAL commerical / passenger ratings.  An example would be Delo 400 which is CI-4+/SJ rated.  This type of oil meets diesel ratings which typically have flat tappets, in addition to meeting passenger car requirments.

 

A 15w-40 weight oil would have added benfit during cold starts with better splash lubrication, and also be able to hold the viscosity in very hot engine temps due to its 40wt upper end.  I personally think we can look past mono grade oils if we simply keep an eye on the oil level.  Oil companys do not put the R&D into mono grades as they do in state of the art diesel oils.  Would anyone disgree?

[MarkPalmer 81]

Whoa, I've never seen a Kohler cam lobe worn down like that before!  WoW!  There was some sort of issue with the cam/exhaust valve in the past, likely an incorrect tappet adjuster setting. 

 

I mentioned it in a thread a while back about the zinc being removed from modern oil, and how important it is for the Kohler solid lifter setup.  You can get the needed ZDDP by just adding a little bit (2-3 ounces) of STP oil treatment (or the Wal Mart Super-Tech oil treatement works fine too) to your regular 30W oil whn you change it.  Multi-viscosity oils down to 10 or 15W tend to burn off in the Kohler engines during warmup, which you try to avoid to prevent carbon buildup, and really have no benefit unless you run the engine in the winter.  One bottle of STP lasts a lot of oil changes, so no need to spend a lot of money on synthetics or diesel engine oil.  I have been using the Super-Tech HD30 oil with a bit of STP in all my small engines for as long as I can remember, changed every 15-20 hours. The engines run great, they are mechanically quiet and the oil drains fairly clean.   

 

-Mark-

[Fordiesel69 271]

Oh, I forgot to mention, there is far less vibration now.  Somthing with that old cam made this thing almost want to jump off the tractor.

 

I chose to leave the balance gears out as they were way to loose on the stub shafts.  These would have blown a good motor at some point.

[tunahead72 2,581]

This has been a great read, guys!

 

Fordiesel69, I'm glad you were able to get this engine running properly after all the work you put into it -- just wondering, where's the video?

 

And MarkPalmer, I've seen your references to STP Oil Treatment in other threads, one of these days I'll actually remember to start adding that or something similar to my oil changes.  There's also a product out there called ZDDPlus that I believe is close to what could be called "pure" ZDDP, I'll start a thread on that soon.