4020 12 volt relay

tnfarmer67 · Apr 10, 2011

i have a 1968 4020 that i converted over to 12 volts 3 or 4 years ago and now it won"t crank with the button.i don"t even hear a click when i push the button, i can jump out the solinoid and it starts fine, it has this denso 182800-3820 on the side of the starter thati believe is bad where can i find one locally (like napa).and has anyone else had this problem?

tim s · Apr 10, 2011

There should have been a relay installed between the push button and the starter relay, I put them under the cowl on the left side by drilling and taping a couple of 1/4" threads to attach it to the cast frame there, I use a "flat" back one for an older Ford truck (S5049Z part # from O'Reilly's) run a hot lead from the batt. terminal at the starter to one of the large post of the new relay, then run a wire from the other large post down to the trigger terminal on the starter relay(removing the one that is there now) them run the wire from the push button to the trigger terminal on the new relay(this wire should be the one you removed from the starter small terminal), try to keep the safety switch in the loop,,for "Safety's sake"...it is possible that your push button is burned out by know also, they will not handle the starter without the extra relay very long..

Bob · Apr 10, 2011

Are you talking about a little "Bosch-style relay" that has been installed near the starter to activate the main starter solenoid?

<img src = "http://www.repairconnector.com/product_images/h/347/5590x1__29289__16214_zoom.jpg">

If that is what you are looking for just about any auto parts store, tractor dealer or hot-rod shop should be able to help you as they are a pretty generic part.

If that's NOT what you are looking for, post back.

Also, are you SURE the problem isn't in the neutral safety switch(es) or wiring connectors or harness?

tim s · Apr 10, 2011

That is not the style relay that I am talking about, and yes the safety switch could be the problem, but you still need a relay between the switch and the starter, the Ford style works the best..

tnfarmer67 · Apr 10, 2011

if you go to ebay and search 182800-3791 and thats what i have on.

Jon Hagen · Apr 10, 2011

Those little cube relays are usually have 30 amp rated contacts while the Delco diesel starter solenoid draws about 50 amps. I tried a little 30 amp cube relay on a conversion and had it fail after about a dozen starts, contacts burned up.
I replaced it with a Ford car / pickup type solenoid which can handle 1000 amps. That has been operating for years and is very similar to the factory 69 ? and later 12V diesel's cowl mounted relay used by JD.
That cranking aux relay is factory installed on the late 12V 4020D and is almost a must have on a 4020 diesel converted to 12V, as the start / nuetral to starter wiring is too light to supply the needed 50 amps for a 12V starter.

David G · Apr 10, 2011

I had the same problem. The solenoid pulled too much current for the safety switch. Add a relay like the others say.

4020_1966 · Apr 11, 2011

What you need is a Ford car/truck starter/ignition solenoid. the round one on the firewall the key engages to send power to the starter. power the one side from the battery hot, the output side (engaged) to the starters solenoid to engage it when you hit the button. The key and button only have to pass a small amount of current to activate the small solenoid, the truck solenoid passes as much as the starter solenoid wants. JD's directions have you use a a large worm gear clamp and strap it down on top of the starters own solenoid so all your wires are short. It does not interfere with the side panels or anything. This will fix it and fix it right.

4020 12 volt relay

tnfarmer67

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tim s

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Bob

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tim s

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tnfarmer67

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Jon Hagen

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David G

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4020_1966

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