Need Input on Starter Failure.

[George7941]

On a five ton truck at work, the starter (Delco 28MT) would spin without engaging the flywheel when the key was turned to START. This would happen a few times and eventually the starter would catch the flywheel and start the engine.

The starter ia a Delco rebuilt unit that I installed a few years ago. The 28MT starter is a conventional unit with a solenoid pulling the drive into engagement with the flywheel. I just replaced the starter with another Delco rebuilt unit and it works well. The flywheel teeth looked normal, with no excessive wear. The starter drive teeth on this problem starter also looked fine (in fact there is hardly any wear on the drive teeth)

I was wondering what part of the starter could cause this problem. A worn out overrunning clutch, perhaps. Excessive play in the solenoid-to-drive linkage, due to wear, could also cause this problem. Erosion of solenoid contacts would not cause this.

Any suggestions? I don't want to take the starter apart since there is a core charge of $180 on it.

 

[Nick R]

I'm following this thread with interest, because the starter on the shadow does the same thing- though with other annoying starting issues which I'll post about later.

 

[bmwtechguy]

Sounds like an intermittent problem with the overunning clutch, that will eventually leave you stranded when it quits holding altogether. Nowadays so many cost-cutting measures are going on and 'low bid' seems to be the guiding philosophy all-too-often in manufacturing these days. The end-user pays the price with shorter-lived components and a less reliable machine that needs frequent repair and sometimes at considerable expense. Hopefully that is not what happened with your rebuilt starter.

 

[beast3300]

Bad Bendix in the starter, the starter isn't kicking out to turn the flexplate.

 

[spasm3]

i agree bad bendix. I also had a flex plate loose a few teeth and there was nothing for the starter to engage if the flywheel stopped at just the right spot!

 

[bmwtechguy]

The starter gear is engaging the flywheel(flex plate) just fine, or you would not hear the starter motor turn. The heavy contacts in the solenoid are making contact because you can hear the starter motor spinning each time. These actions are simoultaneous due to this starter design. This means that the overunning (one-way) clutch is slipping (not holding) and therefore the flywheel does not turn. Notice he said all the teeth were fine. This confirms what I am saying.

 

[George7941]

Originally Posted By: beast3300
Bad Bendix in the starter, the starter isn't kicking out to turn the flexplate.


Correct me if I am wrong but on starters where the engagement is solely by bendix action, there is no solenoid pulling the drive into engagement with the flywheel. Just the inertia of the drive gear makes it spin relative to shaft and the threads on the shaft make the drive gear slide out into engagement with the flywheel.

On solenoid operated drives, the solenoid contacts will not engage if the drive gear has not slid out to engage the flywheel.

I have never come across a bendix drive starter, the one without a solenoid. I thought they were outdated. My 1986 F250(may it rest in peace) starter had no solenoid but it used one field pole piece to function as a solenoid.

 

[mechtech2]

Faulty Bendix.
It's the guy that makes the little starter gear stick out and engage.

 

[George7941]

There is no Bendix drive in this starter!

Here is the Wikipedia article on starters
http://en.wikipedia.org/wiki/Starter_motor

Here is an excerpt from the article

"This overrunning-clutch pinion arrangement was phased into use beginning in the early 1960s; before that time, a Bendix drive was used. The Bendix system places the starter drive pinion on a helically-cut driveshaft. When the starter motor begins turning, the inertia of the drive pinion assembly causes it to ride forward on the helix and thus engage with the ring gear. When the engine starts, backdrive from the ring gear causes the drive pinion to exceed the rotative speed of the starter, at which point the drive pinion is forced back down the helical shaft and thus out of mesh with the ring gear."

See? Bendix drives haven't been used in cars for a long time. Three posters have mentioned Bendix. I don't understand it. Why are we so fixated on the non-existent Bendix?

 

[1 FMF]

correct, there is no "bendix" drive.
one of those hard to die things, I don't believe you'll find a bendix drive on any new model starter which are PMGR (permanent magnet gear reduction)

the solenoids now used on most starters which are pmgr is an electromagnet and replaces the function of the bendix on the old inline straight shaft type starters. Very popular now in the boat industry as they are now on all new gas engines, anyway I have one on my inline 4 cyl. 3.0L and the starter started giving me problems. I can't remember now exactly it was 5+ years ago, but it would click and ping, sometimes engage and turn the engine over, sometimes grind. The sole problem was the solenoid, which i could not easily replace and had to get a whole new starter (they make it so you have to replace the whole starter not just the faulty $10 part). I did and same thing started happening within a few starts, turned out to be the slave solenoid in the electrical system prior to the solenoid on the starter. The starter solenoid draws a lot of juice because it is an electromagnet, and requires it to be controlled by another relay or solenoid 20 amp or greater- you can't just run the start side of your ignition switch to the start terminal on the starter solenoid like on the old straight drive starters having the old delco solenoid where there was a bendix drive pushing the starter pinion. What was happening is my relay solenoid was faulty and not providing full power to the starter solenoid, and it nuked the solenoid on the new starter. Replaced the slave solenoid and was able to obtain a new starter solenoid and have been fine since.
back then though i had researched into PMGR starters by delco and those solenoids, and there are a few ebay stores that sell solenoids for around $20 (marine catalog listed them as $140 and new starter $300), and I have links to some sites where you can get full part diagrams of all the different model starters if you need. The starter itself is very simple and practically bulletproof, you can easily pull it apart and service it, all it ever needs is some grease in the planetary gears, and cleaning the endcap where the motor brushes are. The solenoid is one piece and those you just replace.

bendix drive:

electromagnet starter solenoid which replaces bendix drives:

 

[SS1970chrysler]

My 59 Ford and 62 Buick think otherwise.

 

[mechtech2]

There have always been 2 main types of starter engagement.
I certainly don't keep track of the umpteen jillion various models!
Calling it a Bendix is just pointing to the problem area. I think we are all very well aware of the solenoid type.

Even a Model T had a Bendix. [You bend-ixed your arm to start it!]