New to me C-120 Hydro

[TonyToro Jr. 2,138]

This past weekend I acquired this tractor from one of the tractor pulling families. They said it ran 4-5 years ago. (Maybe I believe it) 

Anyway, Over this past week me and @TonyToro have replaced a few ends on the battery cables, new solenoid, good used starter as ants were coming from the old one, all new fuel lines, new ignition switch, carb cleaning, rebuilt the metal Kohler fuel pump, new spark plug and changed the oil.

Today we finally got everything put back on and within a few minutes it fired right up. It also came with a snowplow which I believe is a 48”. Needs a good degreasing and a PB blaster and scotch brite pad cleaning. We did a little on the fenders and it came out pretty good and at least smooth.

Going to run it for a little bit and change the oil again as it was very black.

More additions to come soon as this will mostly be a plowing snow  and dozer blade work tractor.

Enjoy the pictures!

[953 nut 62,131]

Looks like it is very complete and unmolested.                        Hope the hydro works well too.

[ebinmaine 74,525]

Great Catch!

[TonyToro Jr. 2,138]

23 minutes ago, 953 nut said:

         Hope the hydro works well too.

It seems to be one of the best I have so far. But haven’t even really even driven it around much yet.

[Bar Nuthin 1,480]

Can't wait to see the first snow plowing video! 

[pfrederi 18,966]

If the engine oil is dirty I would guess the PO didn't change the fluid and filter in the hydro either.... may want to do that

[peter lena 9,451]

@TonyToro Jr.  ran in a number of  neglected engines , regularly  suggest  , adding 4 ounces of  rislone ZDDP ZINC SUPPLEMENT  to oil changes , really  effective for a  heavily varnished engine , usually a smoker , its the operational  , SMOOTH RUNNING EASE ,  that hooked me on its effect . been using it for years , use this with  rotella 30 wt , only suggest  something that  I have many hours on , also use a heavily treated gallon  of  fresh gas , drop carb bowl , think  a oiled patina  would be fitting , personally  like the  penetrating oil soak  for days or more , then a clean cloth  mineral oil  rub down , have never  scratch padded  any paint  .once its gone its gone . just looking over the pto lever set up , for improvement , and the opportunity  to  detail in a snow plow , they  swing with total ease , build it up on milk crates, roller stool so you can see the gains, remember  the swing quadrant spring  , runs the whole set up , squeeze lever , tells you how its going to work ,  pete      

[TonyToro Jr. 2,138]

9 hours ago, pfrederi said:

If the engine oil is dirty I would guess the PO didn't change the fluid and filter in the hydro either.... may want to do that

Actually looked at the transmission fluid and it’s very clean. Not sure if the filter has ever been changed though. So definitely still going to change both

Edited October 25 by TonyToro Jr.

[TonyToro Jr. 2,138]

22 hours ago, Bar Nuthin said:

Can't wait to see the first snow plowing video! 

Me neither!

[TonyToro Jr. 2,138]

Completely forgot to post pics of the wheel weights but here they are. Could not  find any marks or labels besides a 61

Edited Saturday at 04:51 PM by TonyToro Jr.

[TonyToro Jr. 2,138]

Good evening everyone

So I have been running this engine but as soon as it gets hot she smokes. Like a lot.

Checked the oil, mind you I’ve probably ran it total 3 hours and had the oil filled right to the top. Now, oil is about a 1/4” from the add mark.

So needs rings. I’m willing to put a set it but would like your guys input in a good set. If only I save tractors we’re still around there would be no question and I would get them from Norman.

Please let me know about a good set

Thanks guys!

[ebinmaine 74,525]

22 minutes ago, TonyToro Jr. said:

Good evening everyone

So I have been running this engine but as soon as it gets hot she smokes. Like a lot.

Checked the oil, mind you I’ve probably ran it total 3 hours and had the oil filled right to the top. Now, oil is about a 1/4” from the add mark.

So needs rings. I’m willing to put a set it but would like your guys input in a good set. If only I save tractors we’re still around there would be no question and I would get them from Norman.

Please let me know about a good set

Thanks guys!

 

 

@Sparky had a thread about similar just a few days ago.  

[oliver2-44 10,976]

On 11/1/2025 at 11:50 AM, TonyToro Jr. said:

Completely forgot to post pics of the wheel weights but here they are. Could not  find any marks or labels besides a 61

Those look similar to Sears/Craftsman weights I have. 33lb.

[TonyToro Jr. 2,138]

7 minutes ago, oliver2-44 said:

Those look similar to Sears/Craftsman weights I have. 33lb.

Definitely more then that I weighed those are are about 60 a piece. But maybe by sears I’ll have to do a little more research.

[oliver2-44 10,976]

5 hours ago, TonyToro Jr. said:

Good evening everyone

So I have been running this engine but as soon as it gets hot she smokes. Like a lot.

So needs rings.

Since it sat up a while there is a chance some rings are stuck. Everyone has their magic potion for stuck rings…..

Try running it until it’s hot and smoking. Shut it off and put a couple of table spoons of transmission oil or MM oil down the spark plug hole.  Let it sit several days. FYI it will really smoke when you start it up, but should burn the oil out quickly.   Maybe someone else will share their ideas on freeing up possible stuck rings. 

[Bar Nuthin 1,480]

5 hours ago, TonyToro Jr. said:

So needs rings.

 

I'm sorry you got a smoky surprise - but I'm eager see pics as you freshen it up!

 

I don't have any experience with this seller, but I did see this on his ebay page

 

ENGINE REFRESH KIT for KOHLER M8, M10, M12, M14,K161,K181,K241,K301,K321 | eBay

You have to let him know which engine you have after you place the order.

Make sure you check the piston to see if it's been bored.

Edited yesterday at 04:02 AM by Bar Nuthin

[953 nut 62,131]

You may need more than just a new set of rings, don't order any parts until you have checked it over.  Once the piston is out of the engine carefully remove one of the rings and follow this thread.

 

[ineedanother 1,729]

On 11/4/2025 at 5:21 PM, TonyToro Jr. said:

Good evening everyone

So I have been running this engine but as soon as it gets hot she smokes. Like a lot.

Does it also lose power as it gets hot? Just a thought before you dive in deep would be to pull the valve cover and make sure it's clean and assembled correctly. Lack of oil draining back into the block with exhaust valve issues might also smoke the neighborhood.

Edited 19 hours ago by ineedanother

[TonyToro Jr. 2,138]

4 minutes ago, ineedanother said:

Does it also lose power as it gets hot? Just a thought before you dive in deep would be to pull the valve cover and make sure it's clean and assembled correctly. Lack of oil draining back into the block with exhaust valve issues might also smoke the neighborhood.

Yes definitely looses power.

Also it cranks over way faster then my C-121

[ineedanother 1,729]

Just now, TonyToro Jr. said:

Yes definitely looses power.

Also it cranks over way faster then my C-121

Concur with rings then 

[TonyToro Jr. 2,138]

Just now, ineedanother said:

Concur with rings then 

Yep. Found a set from Lil red barn on eBay I’ve heard are good. Just have to get a gasket set.

@953 nut

I bought the tractor from the original owners and they said they never even cleaned the carburetor so i think we are good on that end but will still check.

[sqrlgtr 1,026]

Had a 312-8 with the magnum 12 that would smoke like a freight train, but still had plenty of power and never let me down. Always cranked right up and mowed it with for couple summers like that . Tore it down and it had a broke ring. New rings and still going today. I didn't even hone cylinder but probably should have.... Gotta luv them Kohler's.