Starter not turning over on M35A2

[Procyon256]

When I press the starter button on my M35A2 with a 1975 Continental M/F engine I get a click. I'm getting voltage down to the soleniod and can hear and feel it operate. The ground reads continuity.

Before I take off the starter and buy a new one are there any suggestions on what ealse it may be?

Know of a good place to buy a starter and about how much I can expect to pay for it.

Thanks

Dan

 

[Blood_of_Tyrants]

Check all the connections to make sure you don't have a corroded or loose terminal. The solenoid takes very little current while the starter takes massive amounts.

 

[cranetruck]

..... The ground reads continuity.....

How and where did you measure this?

The connections from the starter ground to the battery should have no more than 0.001 ohms resistance as should the supply cable connections.

You have two clicks in quick succession, the starter relay, which feeds the solenoid (on the starter motor) and the solenoid itself.

The proper order of things is like this, first the start button, then the relay, then the solenoid egaging the "drive gear" and lastly that same solenoid closing the contact to the starter motor.

You may have a bad relay contact, bad solenoid contact or too much of a voltage drop in the system to turn over the starter motor.

As far as current drains:
Start button: Less than 1/10 amp
Starter relay: Up to 80 amps
Solenoid motor contact: Normally 200 amps, but could be 400 amps or so.

This should give you a starting point in the troubleshooting.

 

[OPCOM]

These checks should help find the problem before you have to buy anything. Step 6 actually might be the likely thing, if I read your post correctly.

1. check for 24V constant on wire 2 of the bendix. Tests the lead from the battery.
2. check for 24 constant on wire 14 at the start relay. Tests the smaller lead from the bendix to the relay.
3. push the button and check for 24V at wire 214 on the start relay and at the other end at the bendix. Tests the relay contacts.
4. push the button and check for zero volts at terminal 4 on the bendix (GND) Tests that the bendix ground path is good.
5. check with the ohm meter between terminals 1 to 4 of the bendix, this is the actuating coil and should be less than 1 ohm. Tests the bendix coil.
6. push the button and check for 24V at terminal 3 of the bendix. this is the terminal that feeds 24 volts DC to the starter motor. It will have a big, short strap as the wire, usually. Tests the benxix contact. It can be burnt and the bendix will engage but not turn the starter on.

 

[Procyon256]

Thanks

I'll take heed to your recommendations.

Although I had no luck starting the Deuce yesterday, I just went out and gave it another try.

The first attempt yielded but a click. On the second attempt she started right up.

I'll run through the tests and checks that you all recommended before proceeding with a new starter.

Thanks again,

Dan

 

[Big Mike's Motor Pool]

RE: Thanks

mine was clicking and it turned out to be loose terminals

 

[WillWagner]

RE: Thanks

Sometimes the mechanical parts in the starter get dry or rusty if you run in alot of water, If you get stuck somewhere and it does the click, click thing, you can give the starter some love taps with a hammer and it will get you up and running again.

 

[m16ty]

My truck has the relay bypassed. The start wire goes straight to solenoid. I think the relay is bad is the reson it's bypassed. Is this too much load on the start wire?

Cranetruck, 80 amps sounds like a whole lot just to kick the solenoid in.

 

[cranetruck]

...
Cranetruck, 80 amps sounds like a whole lot just to kick the solenoid in.

That's the approximate max current that the realy is expectaed to be able to handle, in actual life it may not ever exceed 50% of that.

 

[cranetruck]

FWIW, this is the start relay for the xm757 (multifuel engine), rated at 50 amps.

 

[OPCOM]

oooohhh!! Cutler-Hammer!! the good stuff! Mr. Haney gave (er.. sold) me a box of similar relays, many are 30-50 years old, and not one has been defective!

 

[cranetruck]

Definitely a quality product. Keep in mind that this series of relays are not "sealed" and must be protected from the environment. Used a lot on aircraft according to some references.
It's also important to include contact protection circuitry, for a long life, something soorely neglected in automotive power relay installations for some reason. This one (above image) has a burnt contact and is no longer 100% reliable.....I have another relay here, also Cutler-Hammer, which is hermetically sealed, so it doesn't need so much in weather protection. I'm also experimenting with contact protection devices for it...

 

[OPCOM]

Try some protection from STMicroelectronics, the company I work for. These solid state devices can absorb a 5KW pulse.

The LDP24A is designed for load-dumping on a 24-28V system. When the contacts open and the arc begins, well, it won't be much of an arc because the thing will be totally clamped at 33-40V depending on the energy available to the device. Additionally placing a 1uF/250V plastic cap across the contacts helps reduce the peak current further.
http://www.st.com/stonline/products/literature/ds/6116/ldp24a.pdf

Also consider a Transil. It too can swallow a 5000 watt transient.
http://www.st.com/stonline/products/literature/ds/2973/bzw50.pdf
The one for protecting a 28V system is the BZW50-27B. It clamps at 30-40V both polarities -good for across the contacts.

These things work great (and just so I am not advertising, our worthy competitors make like items..) and can really take a wallop. Instead of the arc across the contacts being a couple hundred volts @ a few amps, just squash it with one of these. I have not tried to measure the opening-contact voltage or arc current on any of my contactors, never gave it much thought, but if they are failing, it might be time to investigate that. I do not have a high frequency current probe.

 

[OSO]

One thing nice about this site , there quite a few guys that really get down to the correct voltages and amp draws on the electrical systems . Gives guys like me something to work with . When dealing with electrical problems, and other problems that crop up on older trucks and equipment. Thanks for all the help!!!

 

[cranetruck]

My truck has the relay bypassed. The start wire goes straight to solenoid. I think the relay is bad is the reson it's bypassed. Is this too much load on the start wire?

Cranetruck, 80 amps sounds like a whole lot just to kick the solenoid in.

Yes, it's too much for the starter bush button, on closer examination the pull-in current is 35 amps initially plus the usual in-rush current on top of that...

 

[Kakashi]

My M35A2 had a problem like that before. I was on a hill so I rolled it backwards and popped the clutch. She then started right up, and after that she started with the button several times. Then she started sticking. The starter would try and kick every time the accessory switch was turned on and wouldn't stop until it was turned off. I found that tapping the start button housing made the relays inside free up. The hitting with a hammer will do the same thing but if on a hill and you can roll then might as well give it a try.

 

[yustie]

Greetings all; I have a question and need help...I have a 1971 M35a2. Just completed total restore. Two years ago changed out multi-fuel with new engine. Started great and instant. However, shortly ago, and after sitting about three weeks, I started engine. While driving, I noticed smoke coming into the cab. When I pulled over and shut-down, smoke cleared and find nothing wrong. Re-started and returned home. Checked everything again; nothing found. Sat again for a few weeks, and when I attempted to started the engine, all there was were "clicks". I tried several times and got the same thing. I tried tamping the starter and nothing. Batteries checked and are perfect (they are one year old). The starter came with the new engine. I have current to the silendo. What are your thoughts before I consider replacing the starter? Thank you for your time and thoughts in this matter. Blessings to all.

 

[gimpyrobb]

Sounds like you have more than one issue. Was the smoke coming in the cab exhaust smelling or electrical? If you have voltage to the starter but it isn't kicking in, its time to pull it apart.

 

[DieselBob]

If you haven't already you might try cleaning and tightening the ground cable (10) for the starter. Just a thought before you start pulling things off although the "smoke in the cab" thing doesn't sound good.

 

[yustie]

Greetings, starting problem. Started with whitish smoke in cab, no wiring problems found. When cab filled with smoke I heard what sounded like a breaker tripping and resetting. Thereafter m35a2 would not start. Batteries read 12 and 11 volts. Solinode was getting current. Recharged batteries and engine would not start, only clicking sound. The starter was replaced and new batteries installed. Before I move forward should I be concerned about the starter relay, and does any of this sound like the relay is involved with the clicking sound and smoke. Thanks to all that offer assistance. Blessings. Yustie