M18 Problem

[Darrell]

The M18 in my 1811 has started having a problem and i am hoping maybe someone else has had the same problem with an idea to fix it.

After i run my 1811 for about 15/20 minutes or until it heats up really well , the rpm's drop on it. Just by ear , i would say it is like going to WOT and dropping it down to 3/4 throttle or somewhere in between.

Not sure about the hrs. on the tractor.

If you let it cool off and start it back up , the RPM's are fine until it heats up again and it loses RPM's again.

The throttle lever isn't moving , and the clamp that holds the cable is tight.

Maybe the governor ?? ( I hope not !! )

Maybe the coil ?? The few times a Mag went bad on me , the tractor wouldn't start again until it cooled off. I have replaced the coil once with an aftermarket coil , i would say less than 200 hrs on it.

Something getting hot and expanding ???

Vapor lock ????

I am going to be tearing it apart to replace the starter , hydro stuff , rebuild the deck , etc....

Hoping someone has had the same problem and maybe a fix or an idea where i might look. I know it could be several different things , but maybe someone else has had the problem.

Thanks !!!!!!!!!!

[J-Mech]

but maybe someone else has had the problem.

Nearly everyone with a Mag 18.


More than likely a fuel issue. Can't keep the bowl on the carb full.

Standard answer to fuel problems: clean the entire system. Tank, replace the lines, pull the carb off and put a kit in it, I would replace the fuel pump. Everyone always wants to skip the fuel pump..... then they fool with it for weeks on end arguing every day about how it's good till they finally give in and replace it..... then it runs. Bit the bullet and do the deeds. Don't skip anything.

Could be other issues, but this is a good starting point.


Why does the starter need replaced?

[Darrell]

The fuel issue crossed my mind , but from my experience engines lacking fuel sputtered , cut out , run rough , black smoke , etc... , not just RPM drop. The engine runs like a sewing machine before and after RPM drop.

It has been quite awhile since i did anything with the fuel system , so i may just work on that area.

The starter is dragging , kicking out sometimes. I could probably use it as is for awhile , but i want to take the engine out to clean it and do some other work so i am just going to replace it. I have had a new spare starter for quite some time just for this reason.

[R Bedell]

I would suggest, if you are really going to get into it, to include pulling the engine shrouds. Do a really good cleaning of the flywheel fan, air duct and cooling fins.

[J-Mech]

Black smoke is from too much fuel. I think it's going lean. May not cut out, but would limit RPM. Plugged main will do it.

I don't think your issue has anything to do with heat.... I think it's time ran.

The starter kicking out is also a common problem of a Mag/ KT. Usually you need some lube on the starter. A lot of time it's caused from the engine trying to start then doesn't. Again, you can replace if you want.....

I agree with Roland about cleaning it all up. Never a bad idea to do that.

[Darrell]

Pulling the shrouds is the first thing to do. I have owned this tractor six yrs and i am always afraid of mice nests. The mice really seem to like tractors with side panels the best. They like them all , but it seems the side panel tractors they love.

I have another 1811 that i looked at today and there was a dead mouse under it from the mouse poison i set out. Yep , at least going to unbolt the shroud on the Mag side to check for a nest , will probably do both sides.

I may just go ahead and replace the pump and put a Kohler carb on it first to see if it is fuel related and eliminate this first. If you can believe it , this tractor has had an adjustable Walbro carb on it since i bought it and has always run good.

I have put dry lube on the starter a few yrs ago , but it just seems like a band aid fix.