Cub Cadet 1811 - Gas in Crank Case

Wed Jun 01, 2011 5:58 am

Ok, cannot figure this one out. I've got two, twin 1811 tractors, in nearly the same condition, one with 1072 hours and one with 1000 hours. Both show basically the same wear.

The one with 1072 hours had a TON of gas in the crank case. I drained the crank case, then rebuilt the carburetor with a new float, cleaned it real good, and re-filled the oil with a new oil filter. She's holding great. Runs perfect, oil level has not changed, so I'm very happy.

The one with 1000 hours was not over full on oil, but the oil smelled a lot like gas, and was VERY thin. Also, this one was not getting fuel to the carb, so I replaced the fuel pump, and did the same carb rebuild, cleaned it very good and did find a bunch of crud up in the seat of the gas inlet. Checked the float and needle seat and when the float is up, you cannot blow through the gas inlet line, therefore I figured I had the float and needle valve working well. While the carb was off and the oil pan plug was out, I cranked the engine a few times, just to try to get out any extra oil/gas mix that may have remained, and did get a trickle of mix out of the oil pan drain plug. Re-assembled carb, re-filled with oil and a new oil filter. Started and runs excellent. Yippie! Ran for about 5 minutes. Shut her down and checked the oil. Oil looks really thin and smells a lot like gas and is about 1/2 inch higher on the dipstick. I had only put in MAYBE 1/8th of a tank of gas in it before I started the process, and it looks to be about the same level. Is it possible that the float is sticking and the carb leaked that much gas that quickly? It is definitely above the full mark on the dipstick. I guess I need to take the carb apart again, but I still can't believe that it leaked that much gas in such a short time..... Thoughts?


Re: Cub Cadet 1811 - Gas in Crank Case

Wed Jun 01, 2011 1:46 pm


The only two possible explanations I could give you are: Something is causing the float/needle to stick, causing excessive gas flow.

The other: possible bad float. Is the float brass? I know I've bought several new floats (brass) that looked good to start with, but soon (and I mean real soon) were gas logged. I was lucky enough to shake the float in desperation next to my good ear, and I could barely hear something sloshing around in the float.

Parts aren't the quality we used to get our hands on anymore. In fact, I troubleshooted two Troybilt chipper shredders for gas overflow conditions. Guess what? Both had brand new brass floats and both were bad. The new floats I later bought were both plastic, and that ended the problem.

Re: Cub Cadet 1811 - Gas in Crank Case

Wed Jun 01, 2011 5:30 pm

I think you have dirt in the gas tank and a small piece of dirt on the seat lets the gas run right to the crankcase if you don't turn the gas off when not using it.

Re: Cub Cadet 1811 - Gas in Crank Case

Wed Jun 01, 2011 8:49 pm

i agree with SundaySailor...i have rebuilt the carb on my 102 bought the kit at TSC came with the needle float pin both gaskets new needle seat and seal. 10 bucks and it fired right up and runs great now. check the gap on your float also maybe the needle is lifting to high or isnt going down all the way. just a few suggestions

Re: Cub Cadet 1811 - Gas in Crank Case

Thu Jun 02, 2011 10:31 am

This gas effects some of the needles/seats too. My 1200cc seems to stick when its parked if i leave the gas on. It will drain my tank of gas too.

Re: Cub Cadet 1811 - Gas in Crank Case

Wed Jul 13, 2011 12:16 am

These two 1811 tractors are turning out to be real pains in the rear ends. The floats were the problem, but it was because they were not adjusted properly. Think I fixed that.

One of them was blowing oil all over the place in the front. After tearing apart the oil filter lines and replacing them I found that the stupid oil sensor was leaking where it went in to the block. Replaced that with a pipe plug and it seemed to fix the leaking oil, except that it's all over the frame and has ruined a mule drive belt by soaking it with oil.

Now the other one is running lousy, burning oil, and smoking like crazy. LOTS OF BLOW BY. The air cleaner is totally soaked with oil, and has a nice blue cloud of smoke coming out of the breather vent. I was hoping to get through the mowing season, but it sounds like the rings are shot and I'm going to have to tear it down. I ought to just go ahead and do it but I just don't have the time. How long do you think it will go before becoming a real problem?

Tell you what. I thought I liked these higher HP Cub Cadets, but I never had problems like these with the old Kohler single cylinder engines. I've just about had it with these V-twins! Right now it's seeming like one of the worst mistakes I've ever made.

Re: Cub Cadet 1811 - Gas in Crank Case

Wed Jul 13, 2011 8:28 am

The 1811 should have a Kohler MS18 Magnum 2 cylinder (flat or opposed twin, not a Vee twin, the "V" twins were called Command's ) that is same basic engine as the KT-17's, and fuel pumps with internal leaks are known problems. I would suspect a bad fuel pump (even though you changed it) filling the crankcase with gas rather than a float that was not set at the correct level being the one and only cause.

As far as the excessive oil problem, make sure one side of the block does not have an extra "window" or hole in it. Just like the KT-17's, the Magnum 18 can break a rod/piston/cylinder jug on one side and continue to run, run "lousy" like you said, but still run.

Re: Cub Cadet 1811 - Gas in Crank Case

Wed Jul 13, 2011 12:47 pm

You're correct, it is the flat twin. I'm curious, with the fuel tank so high over the engine, why you would even need the fuel pump. I'm thinking of just taking it off and putting a blank over the hole to see what happens. I know that the Magnum engines were used on tons of other applications, even the later model cadets with the tanks back under the seat, thus needing a fuel pump, but with all the gas sitting 6-inches to a foot above the engine, it seems to me like it would never "need" to be pumped to the engine. Just a thought.

Yea, I'm worried about the KT-8.5 syndrome with this engine. However, when it starts, it runs great and will run the 50" mower deck without problem. IT just smokes like a chimney! I'm guessing that it was run with the crank case full of gasoline and it has broken rings on one or both of the pistons. I'm going to try to get my Cub Cadet 1200 together and take it out to swap with this 1811, so I can pull the engine this weekend. I just didn't need another project right now.

On the other, for the meantime, I think I'm going to install a remote fuel shutoff valve that can be actuated from outside the engine compartment without removing the side panels. Something simple with a big ON/OFF sign, so the guys can see it and work it without thinking too much about it.


Re: Cub Cadet 1811 - Gas in Crank Case

Mon Aug 15, 2011 3:15 pm

Well, they did it and blew the engine in the one that smokes. Luckily, I got to it before they did too much damage. It turns out that the piston rings were just broken, and the cylinders are in excellent shape. the bad thing is, the stupid M18 Kohler engine does not have an oil pan. Therefore, the whole block has to be split just to pull the piston and put rings in it. So, I'm sending it down to my buddy who builds custom Harley Davidson engines, and letting him go through it the right way.

Tell you what..... I've totally had it with the newer Cub Cadet tractors. From now on, I'm not working on anything with side panels! If this had been a K-series Kohler, I'd already have it back in the tractor and running. When this one gets fixed, it's going up for sale!

Re: Cub Cadet 1811 - Gas in Crank Case

Tue Mar 26, 2013 3:20 pm

Hey guys i really need help trying to figure out how to adjust the float level im haveing the same problem gas is in the oil i know its to much gas getting in the carb does anyone know the specs on the float adjustment its a plastic float by the way. Its a 1811 cubcadet hydro please help

Re: Cub Cadet 1811 - Gas in Crank Case

Tue Mar 26, 2013 6:26 pm

Tell you what, give up on the float. Adjusting it won't help. I rebuilt my carb twice, and adjusted the float about a dozen times. Turns out there is just too much gravity pressure and once a drip of gas gets started, it won't stop, regardless of the float setting. I ended up putting an in-line gas shutoff valve, located on the dash pedestle just under the choke. Here is what I installed:


You only have to remember to shut off the gas when you turn off the tractor. It's been installed for a year and have not yet had a problem. It's a lousy fix, actually not really a fix but a bandaid, however, other than buying a new carburetor, this is the only way I can figure out how to do it. It's funny, the very next series of Cub Cadets they moved the gas tank back under the seat. Wonder why???

PS. Oh, and by the way, DO NOT RUN THE TRACTOR WITH TOO MUCH OIL/GAS in the engine!!!!! We blew up one of our 1811 tractors doing this. Nobody noticed that the crankcase was full of gas, and it blew the rings right off the pistons. Fortunately, the block was fine and the engine was rebuildable, but it cost a ton to have it rebuilt! These are not like the old K-series engines. There is no oil pan :shock: The block splits in half vertically, and you have to disassemble the whole thing to do anything to it. On the old K-series engines you could pull the head and the oil pan and could put a new piston and rings in the block. Not true on these KT-18 engines!

Re: Cub Cadet 1811 - Gas in Crank Case

Tue Mar 26, 2013 6:48 pm

I think its a float adjustment becouse the carb is letting to much gas in it runs very rich and loads up and i need a float adjustment its a plastic one. Need done tonight thanks dev

Re: Cub Cadet 1811 - Gas in Crank Case

Tue Mar 26, 2013 8:18 pm

Well i got it fixed back the float adjustment out and tuned the carb runs good need 2 plugs and oil and then im good thanks