LT40HDG24 Onan trouble

Chuck White · October 21, 2009, 06:41:00 PM

This problem has been pestering me for a couple of weeks now. >:(

When the blade exits the far end of the log/cant and I disengage the blade, the engine as normal, drops to idle, but then slowly loses RPM's and will die.
What I usually do is pull on the Clutch/Brake handle to increase the RPM and then it will be ok, unless I run one of the hydraulic systems.
NOTE: I have a voltage gage installed under the control panel.
If I run one of the hydraulic systems, the voltage will drop immediately from a little over 14 volts to slightly less than 12 volts, unless I hold the throttle open to a point just shy of the blade engaging.
As soon as I leave the hydraulics alone, the voltage goes right back up to 14+ volts, but again, if I leave the engine alone at an idle the RPM's will start dropping within a minute or so and will then die! :-\

Anybody got a foggy idea what's going on with this engine?

ladylake · October 21, 2009, 07:18:56 PM

The voltage drop is normal when using anything electrical that take a lot of juice. Maybe try turning the idle mixture adjuster screw in a little, sounds like it running rich. Is your air cleaner clean. Steve

MartyParsons · October 21, 2009, 07:24:01 PM

From reading your posts you saw frequently? I have two LT40HD Onan engines in the shop today. One a 87 and one a 94. I removed the top of the carb on both of these engines and found messy stuff in the carb. I also remove the fuel pump and clean it. They run much better after the stuff is removed. You should not need any gaskets if you are carefull. Remove the air cleaner. Clean the top of the carb with cleaner then remove the top of the carb. There is a small jet that you should try to remove. Make sure you have the correct size scew driver if not you will damage the jet! There is a plug on the mast side of the carb remove it and drain the stuff out. If you want you can remove the main jet. I did not need to remove the jet everything looked ok. We always dump all contents out of the gas tank also and check for water. One of the mills today looked like orange juice instead of gas.
Both of these mills would stumble when the clutch was disengauged. One had a piece of dirt on the pick up in the fuel tank.
The alternator needs to be turning at rpm to charge. Hope this helps. This should take you less than 1 hour to do this.
Marty

Jim_Rogers · October 22, 2009, 01:55:22 AM

Chuck, this sounds like a similar problem I had once. And you may think this is wild, but it could be just your battery is too old.

You see the battery uses lots of electricity making the hydraulics run. And it cycles up and down a lot. I was having problems keeping my mill running and called tech service. I explained that the mill wouldn't run right and they talked me through the events of what was happening and I told them that it couldn't be the battery as it was only 2 years old on a 5 year battery.

They said: "you got two years out of your battery?".... "wow, we'd never heard of that before.....usually batteries only last a year or so due to the deep cycling nature of how it works in the mill." "We suggest you buy a deep cycle marine battery."..... which I did and got a good long life out of that battery as well....

Now this all happened several years ago,,, don't remember exactly when, but since that deep cycle marine battery, I got another one and it was a regular one and they said the these new regular batteries are just as good as the deep cycle marine batteries.

I got a battery load tested once time and have used it to see if batteries are truly ok. Knowing the voltage is good and your gauge will tell you that, but if the battery can't hold the voltage then it's no good.....

I maybe way out to lunch on this, but you could try checking this out, by using a load checker, before you go and by a new battery on my say so.....

Good luck with your problem, and I hope you get it fixed up....

And if you can, when you figure it out, post the solution here so we'll all know.

Jim Rogers.

PS. I think we meet years ago at Gould Farm... barn sawing......

petefrom bearswamp · October 22, 2009, 06:50:22 PM

Hi chuck,
I had a similar problem with your mill about 6 or 7 years ago.
Called Dave Scott and he suggested a remedy which was cleaning a jet. (perhaps the one Marty suggested)
The mill ran great after that.
Jim.
I had chucks mill for 8 years.
I replaced only one battery on that mill and this was because I shorted the old one out by lowering the head when I had the jumpers on the old old battery which cooked it.
Chuck,
See you next week, I'll call when I get to DeGrasse
Pete

woodmills1 · October 22, 2009, 07:28:00 PM

yes and yes and yes

on onan powered mills make sure the alternator belt is tight

use mid grade gas

take the top off the carb and clean out the vast quantity of junk

replace the battery

and maybe just maybe the red wire from the alternator is rubbing every time you pull up the motor

I loved my no name was bob's now not mine owned by firefighters LT 40

MotorSeven · October 22, 2009, 10:34:32 PM

My vote is also for gunk in the carb. This isidious ethanol in all the gas these days is giving all of my small engines fits. In less than a month, the fuel gells into a kinda off white cottage cheese that carbs hate. After a carb cleaning, treat the fuel with a etahnol targeted treatment(Phaser 3000 or Starbright StarTron).

Corn should be eaten....not made into fuel :

.

RD

VictorH · October 22, 2009, 10:41:05 PM

Around here the mid-grade is the ethanol. the low grade and premium is straight gas. Which should I use in the mill I go to get on Monday ;D

Chuck White · October 24, 2009, 07:08:07 PM

Thanks for all the pointers guys.
I went out this afternoon and puttered with the mill.
There was a lot of sludge and stuff in the float chambers as well as dirt in the throat of the carb.
Removed the plug on the side and sprayed the whole area out with carb cleaner
TIP: I placed a dry shop rag on top of the engine, just below the drain plug and tight to the bottom of the carb to absorb any gas, etc. that came out!
Marty had it pretty-well nailed in his suggestion.
I did get the small jet out OK and I sprayed carb cleaner down into the jet. I believe you meant the one that has the little pipe and it has several perforations on the part that goes down into the bottom part of the carb.
Took me just a little over an hour and I had the mill all buttoned back up, and running again.
Seemed to run nice, I even moved the head back to the front of the mill and ran the log loader several times and that didn't kill the engine!
I have a customer bringing in a large hemlock log in a few days, that he wants a couple of live-edge 3 inch slabs out of. When I saw it, I'll know if I really have the problem solved!
Thanks again for all the help!

Dave Shepard · October 24, 2009, 08:20:51 PM

Good to hear you've got it running well again!

Victor, I run high test in all of my small gas engines, ATV, chainsaws, etc. They don't use enough to worry too much about the cost, and I know the two-stroke manuals recommend at least the mid-grade.

VictorH · October 24, 2009, 09:27:14 PM

Thanks Dave. I run high test in my powered parachute and was leaning that way.
Victor

MartyParsons · October 25, 2009, 08:36:51 AM

I think Jim Rogers post would also cause the same problems. Glad we helped! The little jet most times is not plugged but I have seen it. Little brass tube with three holes.
Marty

Chuck White · October 26, 2009, 05:32:24 AM

Quote from: MartyParsons on October 25, 2009, 08:36:51 AM
I think Jim Rogers post would also cause the same problems. Glad we helped! The little jet most times is not plugged but I have seen it. Little brass tube with three holes.
Marty

You're right Marty, Jim had it too. I thank all of you guys for your inputs!
INFO: My battery is less than a year old, and still going strong!

Chuck