Mitsubishi MT20 starter

[stnickstoys]

Does anyone happen to have a Mitsubishi MT20 4x4 3cyl diesel that they are parting out? I don't have the engine number handy right now but I will get it. I know I need the solenoid. The starter gear and bendix works but the solenoid doesn't seem to have the ooompf to kick out and get a clean engagement. Makes for some noisy starting action and I don't want to ruin the ring gear teeth. /forums/images/graemlins/confused.gif If someone has a solenoid on hand, I need that for sure.
Thanks
Nick

 

[Anonymous Poster]

Nick,

Just a thought, but doesn't the starter motor current pass through the solenoid? Thereby causing the solenoid to activate and the motor to engage the flywheel?

If that is the case, then there might possibly be something going on with the motor itself, like brushes that are getting short, that is causing the motor to draw lower than normal current and therefore also developing less pulling power by the solenoid.

Just something to consider if it applies to your engine...not sure it applies or not.

 

[Anonymous Poster]

In trying to keep old motors running.......have many times just torn into the solenoid/starters and cleaned and refurbished......one of the easiest chores going...files, emory cloth, and organization as to reassembly........one of the best uses for a video camera is recording close ups of what goes where ........parts are easily obtainable from most alternator/generator/starter rebuild shops...........the most important thing is cleaning up contacts......some seem to be hit with an arc welder instead of just acting as a switch......good luck

 

[stnickstoys]

I took apart the starter, brushes looked good. Yes, the current for the motor does pass through the solenoid. As the solenoid is activated it jerks backward closing the circuit that provides power to the starter motor and kicking out the bendix to engage the flywheel. It does manage to activate the motor but the bendix engagement seems a little sluggish. It kicks towards the flywheel and makes the grinding sound but doesnt seem to kick hard enough to get a good engagement every time. I checked the teeth of the flywheel and starter, both seem to be fine.
Thought a solenoid would be a good place to start.
Nick

 

[Bird]

Yep, Dennis, just last Spring had a similar case. My brother's Suzuki Sidekick wouldn't start and he was going to go to town and see if he couldn't find a new starter. I suggested we better take the old one off first so he could take it with him to be sure to get the right one. So we took it off in my shop building and I wanted to see what was wrong with it before going after another one. We took it apart, didn't even have to do the things you mentioned, couldn't find anything wrong with it, just cleaned it up good, put it back together and put it back on (tested it before re-installing) and it worked perfectly again.

 

[karmakanic]

It's conceivable a shorted winding in the solenoid could cause it to engage with lower force then usual. Depends upon where in the winding the short occured. But usually with a shorted winding, you'll get no movement at all. Also, the solenoid has to complete it's travel before the contacts are bridged to send current to the starter motor. So, if the motor is operating, the solenoid is probably traveling enough to engage the bendix with the flywheel.


I wonder if the noise you're hearing is in fact coming from the one way clutch in the bendix? When that clutch slips you'll get a kind of screeching, whinning sound. Is that what you're hearing.

It's hard to detect this problem on the bench, since you can't come close to duplicating the normal force on the clutch with the starter out of the tractor. You have to recognize the sound. The key is the whinning part of the noise, it's the starter spinning freely after the clutch failed to lock.

Dave

 

[stnickstoys]

karmakanic
It's definitely not a whining noise, its the sound of teeth grinding which was evident by the tips of the starter teeth when I removed it the first time.

Are you saying that if the motor is spinning the solenoid must have gone full travel, so I chould consider replacing the bendix?

nick

 

[karmakanic]

Yes, the solenoid has to go to full travel before the contacts are bridged to the starter motor. Solenoids are designed this way so the starter won't begin spinning until the bendix has been preloaded against or meshed with the flywheel.

If the starter is spinning and the bendix is not engaging with the flywheel, the most commom reason is wear on the edges of the bendix and/or flywheel gear teeth. One or both of these gears will have an engagement ramp cut into the edge of the teeth. Pay particular attention to this area. Look for rounded edges or chips in the face of the ramp(s).

Engines tend to stop on the compression stroke of one particular cylinder, so the most wear on the flywheel will occur to a localized group of teeth. Rotate the flywheel and check all the teeth to locate this area, and use it to judge if you need to replace the flywheel.



HTH,
Dave