MTFCA Forum

I tried to start my 27 touring recently and checked the battery which had a good charge, but I got nothing when I depressed the starter switch. This was one that I got from Langs some years ago that never gave me any trouble. I checked the input side of the switch with a voltmeter and got 12.6 volts on the input side and 0.01 volts on the output side when I depressed the starter switch. I figured that the switch was faulty and Lang's did not have any in stock so I picked up what appeared to be an exact replacement from NAPA for a tractor starter switch. Before I installed the switch, I checked for continuity with the switch for continuity with the switch depressed and got an excellent reading of 0.01, the same as the two probes from the tester touching each other. I thought it must be a ground problem with the bracket, so I sanded off the paint on the frame where the switch brackets is bolted and put in clean bolts and nuts. Still the same.

I last had the car running last fall and it started and ran great. I have not done anything to the car except rebild the front end, so I am at a loss as to why this will not work. Thanks in advance for any advice.

Have you checked the voltage reading on the battery side of the switch when it is engaged? You may have a bad connection at either battery post or where the battery ground cable connects to the frame. A poor connection at any of these points can allow voltage at the battery side of the starter switch to drop to near zero when the starter switch is engaged. Also, once in a while, a battery cable terminal will not make a good connection with the cable itself. In that case, it won't matter if the cable clamp is clean and tight at the battery post. The starter switch does not need to be grounded where it bolts to the frame.

This switch sometimes includes a mounting bracket. Some designs even have a circular instead of hexagon base. There have been numerous discussions about issues with these switches and most everyone says get an original. https://mtfca.com/phpBB3/viewtopic.php? ... ch#p225125
Lang's, Napa, Tractor Supply, Autozone etc etc all the same
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In order for the switch to work the plunger needs to be depressed straight down for the jumper bar to bridge both contacts. Sometimes a large hole through the floor board allows for some forward movement so only the forward parts make contact. Your problem may also be oxidation of the jumper or posts. You can open the switch by bending the 4 tabs (white rectangle). Also inspect the collar that the plunger slides through to see if anything is bent in that area.
The switch is what it is......

Beware of the "short!"
Switch bent, causing short, causing the switch to weld itself on. NIGHTMARE!
Easy access battery disconnect/kill switch to the rescue.
These switches, see below, are cheaply made and complete junk.
I changed to a 20amp push button starter switch and a 3 pole 6v solenoid(1rst pic).

Now you know why I was amazed that the three original switches on the classifieds were not snapped up immediately. None of the replacements come any where near the performance and reliability of a good original.

Allan from down under.

The way the circuit is designed the total current flows through the switch which is a considerable amperage draw. This can play havoc with the contacts. For that reason I only use the starter switch to activate a relay. Heavy duty relays are available from the vendors. I still use an original starter switch, but wanted to protect the contacts of that switch.

Did you load test the battery? How fresh is it? A battery can show full charge, but fall on its face with a load.

"I thought it must be a ground problem with the bracket, so I sanded off the paint on the frame where the switch brackets is bolted and put in clean bolts and nuts. Still the same."

The switch bracket does not need to be grounded. Check your ground connections at each end of the negative battery cable and both ends of the positive battery cable.

You state that you did a continuity check on the new switch, but only did a check for voltage drop on the old switch. Maybe do a continuity check on the old switch as well. You might also try taking a voltage reading on the input side of the new switch, with the switch sitting as-is and with the switch being depressed. A voltage drop at the input, with the switch depressed, should indicate if you have a problem with the battery, the cables, or the ground.

Can you include a picture of the plunger hole in the floor board from the drivers position. These switches pretty much require being depressed straight down to operate correctly. If you say that you have 12 volts to the input post and nothing on the switches output post, sounds like its in the switch.
The switch spec says "Application: for manual start models, 6V, base mount for 7/8" hole " and your connecting 12v to it.... Better open it up to see whats left.

I overlooked the 12 V part. Unless you have a 12 volt starter, using the stock type switch to apply 12 volts to a 6 volt starter will severely overload the switch. (And the starter and starter drive)

That 6 Volt Starter does not mind using a 12 Power Pack to start the engine.

My 12 Volt Power Pack seemed to mind a lot and will no longer take a recharge.

A 6 volt starter, all else being equal, will draw about twice the current that a 12 volt starter will. A dragging starter, cold engine, draggy clutch, etc, will add even more current draw. A 6 volt starter can take some abuse, but it adds up.

J1MGOLDEN wrote: ↑

Thu Jul 14, 2022 12:06 pm

That 6 Volt Starter does not mind using a 12 Power Pack to start the engine.

My 12 Volt Power Pack seemed to mind a lot and will no longer take a recharge.

The starter motor can handle it, but the Bendix won't for long.