Perkins 4.108 Delco 20MT Starter Info Here

[forsailbyowner]

While rebuilding the starter on my 4.108 I came across this info from a variety of sources and I thought it might save somebody some time if I put it in one place. The 20mt starter is a far superior starter to the 28mt osgr starter that precedes it.The cranking speed is much faster and in cold weather starts much easier , definately worth the effort to track down the parts and rebuild it yourself. I will include some places with the best prices I've found to get replacement parts.

Info: Delco 20MT 1107587 5E 21
Dry Clutch, , Direct Drive, 4 terminal cap,DD series,3spline 12 tooth CW rotation HD Roller drive

Part. Oem#
Roller Drive. 1940134
Field Coil. 1960853
Armature. 1949190
Brush Holder. 1988414
Brush. RX95
Solenoid. 1114356
Soleniod Cap. Snc1161c
Kit(1). EC3057
Kit(2). EC3517
Drive Housing. 1968769

Drive end Bushing .627 O.D. .505 I.D.


USA Auto Elec. Repair Kit. Product I'd RK12011
Brushes and holders,Felt Brake washer,brush springs Bushings,screws etc...
866-415-6770
Fleet Starter and Alternator.
Drive. 4-282
New Alternators and Starters from Fleet Alternator Starter

[phorvati]

Thanks,
I've been on the hunt for a used spare one, something I can rebuild, or have re-built.
But a spare parts kit might be better.

[forsailbyowner]

As long as were on the subject why not go over fault finding and repair procedures? So far these are the failures I've had with my starter.

Starter soleniod clicks and doesn't turn or turns with a series clicks. After checking the more obvious causes which would be a low battery or resistance(dirty or loose) in the connections, remove the soleniod cap and resurface or replace the copper bolt and the copper ring it contacts under the cap. I've found this to be necessary every couple of years with daily use.

If the starter spins without cranking the engine suspect the drive ratchet mechanism. It can either fail to engage resulting in freespinning or if it freezes up it will give a screech when the engine starts. This won't result I'm immediate failure but its vitally important to address this asap. By the time I got to mine the drive end bushing wore out which allowed the armature to contact the field coils.

More to come......

[philocat]

Located across the pond from you guys but is the 20MT reasonably common to hunt down? I've seen on another thread that another option is using a geared starter but understand this could be overkill although nice to have.

FSBO, looking forward to more to come.

Actually you have given me a hint. Got a very stubborn to start perkins; almost starts on first couple of cranks but then stubbornly refuses thereafter. I have been suspecting either fuel or the cold start manifold element as likely culprits with a poor starter condition as runner up. However sometimes the starter doesn't turn on first push of the switch but always the following try- so perhaps the solenoid also needs attention in addition to the more usual commutator problem.

I have noticed that there appears to be many different starters around some with 13 and maybe even 10 teeth from memory.

[forsailbyowner]

Here's a good article on testing starter field coils also mentions r&r steps.

Starter components and their function, part six - Phoenix Auto Repair | Examiner.com

[forsailbyowner]

Originally Posted by otya

Located across the pond from you guys but is the 20MT reasonably common to hunt down?

Woods auto. In UK has a large web presence and lists the starter and parts in its catalog, that's where I got many of the part numbers



I've seen on another thread that another option is using a geared starter but understand this could be overkill although nice to have.

The starter you mention is the 28mt osgr (offset gear reduction) IMHO these starters are throwaway junk. I bought one and had cold start problems from then till I fixed the 20mt and reinstalled it. The difference was going from a 1 second start with the 20mt to cranking for 10 seconds, letting the starter cool, then getting a fire on the next try. In the mean time the undersized motor is quickly wearing out from all the cranking. Parts are crimped together on the 28mt making repairs and rebuilds complex, the price difference is around $350 for a 20mt and $120 for the 28mt.

Actually you have given me a hint. Got a very stubborn to start perkins; almost starts on first couple of cranks but then stubbornly refuses thereafter. I have been suspecting either fuel or the cold start manifold element as likely culprits with a poor starter condition as runner up. However sometimes the starter doesn't turn on first push of the switch but always the following try- so perhaps the solenoid also needs attention in addition to the more usual commutator problem.

My cold start problems went away with starter problems. Faster crank means faster start.



I have noticed that there appears to be many different starters around some with 13 and maybe even 10 teeth from memory.

From what I've found the Delco starter listing for the marinised perkins 4.108 is the 1107587. There are many other starters for bobcats and other machinery that uses the 4.108. Another desirable starter that was used was the Lucas Helix drive. It has a large motor for fas cranking and is very low maintainence. Very expensive often listing for over $500

[forsailbyowner]

One thing I should mention is the 20mt is a general classification for the motor part of the starter and was used on many applications that don't apply to perkins. Or in other words just because it says 20mt doesn't mean it will fit your 20mt. On the yoke or the iron case motor part look for the stamped "Delco" then starter model number which will have 7 digits. Use this number for ordering parts. If it is the 20mt it will be 1107587.

[forsailbyowner]

Found the service and installation manuals courtesy of Delco.

Service Manuals - Starters | Delco Remy

[forsailbyowner]

Ordering Bushing sets for the starter. When you call in your starter number looking for parts you will find out that your starter will have numerous different bushing sizes available. The drive end housing and center supports especially. To avoid having to order 3 times like I did try this(requires calipers) measure the hole size the bushing fits into. Then measure the armature where the bushing rides. Subtract the difference and divide by two. This is the approximate bushing thickness. I've seen .030, .060 and .080. Measuring other ways or trying to order from hole sizes can be misleading because "crush" is figured into the dimensions and will change the size with assembly.