New stump grinder

[coolbrze]

We've got a 2003 Carlton 2500-4 stump grinder w/ 27 Hp Kohler gas motor & one of the guys called me this a.m. & said it's blowing a BOATLOAD of blue/gray smoke. It's an '03 but only has 500 hrs on it & we've been good w/ oil changes. Going to look at it this evening when they get back but any ideas as to what may have happened?

 

[earlthegoat2]

First off, check the oil. Make sure it is not too high....or low.

Kohlers were so well known for blowing head gaskets and burning copious amounts of oil in their engines of that era that I am surprised they are still in business.

What is the exact model series? CH740? I think that model was rated for 27 back then. Nowadays they are 25 though. What kind of air filter does it have? Flat and circular or cylindrical? Pull the spark plugs and check for deposits on them. If there are then you are burning oil like the rest of the Kohlers did then.

There was a time I had 3 of these engines all on turbine blowers. In 5 years I had to put in new short blocks on all of them for problems related to oil consumption.

 

[stumper63]

That sure wasn't my experience with Kohler. Had a 2003 SC252 with the 25hp Kohler. Had over 4,300 hours on it when I sold it and was still running good. Never did a thing to that engine except all the routine maintenance. Started to use some oil at about 3000 hours, but prob no more than a cup between oil changes.

Hope you get it figured out.

Stumper63

 

[earlthegoat2]

If the OP googles Kohlers smoking and/or burning oil, he is going to have quite a lot of reading on his hands. it seems that if it was a Kohler with two cylinders for a while, they were oil burners. Vertical shaft or horizontal shaft even. They had updated head gaskets you could get and those helped but did not solve.

A little more info on my experience is that I got these equipments with the Kohler engines on them two years after they were purchased. I don't know who did the maintenance or what kind of maintenance was actually done. Also, these were on turbine blowers that were used for grounds maintenance and were run at full throttle for 4 straight hours. Then sat for an hour for lunch and were run again for two hours five days a week and then for 3 hrs on Sat and Sun.

I ask about the air filter because after I installed the cylindrical Donaldson style filter setup they quit burning oil as bad. What's messed up is that the Kohler factory spec for oil consumption on these engines is 1 oz per cylinder per hour. That is 72 oz of oil per week times three machines. Kohler would not help me out because they were all going through oil within spec!!

Two of them carboned up a combustion chamber which caused a hot spot that caused pre ignition and fragged a piston. The other one had so much carbon build up in the combustion chamber it got into the valve seats and cracked a valve. There was also significant damage to that piston and the rings were fused into the grooves exacerbating the oil consumption problem.

I'm not against the engines but I am leery of them. The more modern ones don't seem to have that problem. Then again, they all do have the Donaldson filter setup.

 

[coolbrze]

Didn't get a chance to really look at it until today & noticed 2 things. First, the front spark plug boot was off so I'm guessing the front cylinder wasn't firing. Second, & which worries me more, is that there was a lot of gas in the oil. I changed the oil & filter and fired it up. It started right up but started smoking again after a minute or so...

 

[Mowingman]

Gas in the oil means you have a carb. flooding problem. That is how the gas is getting in the oil. Get the oil changed right away, as it is thinned out by now.
Also, I recommend Kohler brand oil in Kohler engines. I was a Kohler servicing dealer, and, also ran a large fleet of Kohler-powered commercial mowers. It may seem like hype, but I found by experience that the engines ran better, quieter, and lasted longer with less issues, when I used Kohler oil in them. I can not tell you why it works better, but from my experience, I recommend only Kohler oil in Kohler engines.

 

[earlthegoat2]

@Mowingman makes an interesting observation.....could be at least a partial cure to the problems I had.

If the engine you have has a fuel stop solenoid on it, then that may be malfunctioning and causing the gas to get into the oil. This is most definitely what would cause the smoking. The gas gets into the oil and causes the oil to thin out BUT it also causes the oil/gas in the crankcase to rise. It can rise high enough that the oil control ring on the pistons cannot completely get all the oil off the cylinder walls because there is just too much of it and that will cause excessive smoking. I have seen this very thing happen on Briggs Vanguard twins which are also equipped with a fuel stop solenoid that was malfunctioning.

If it does not have a fuel stop solenoid then the needle valve in the carb is getting stuck open after the engine has been turned off. May need a carb kit. Also, are you experiencing any "oil leakage"? What will happen is as the gas fills the crankcase it will start leaking out of the main seal and you will have a gas/oil pool under the engine.

 

[coolbrze]

Thanks everyone! It was a float stuck in the carb & the fuel pump was leaking also. I used SAE30 oil as our temps are in the teens now & Carlton said that was OK to use w/ this motor although they recommended 5w20 or 5w30 in the manual. Changed the oil & oil filter twice just to make sure everything was purged.