glow plugs

Voltage loss is because the high resistance of the glow plugs is drawing the battery down. Kinda like leaving your car lights on. Did you purchase the tractor new? How old is your battery? Sounds like it could be a little weak.

Also, the wiring to the glow plugs is marginal on these tractors.  Better to install a relay and a heavier primary wire to the plugs.   Saves the switch contacts and gives the glow plugs full voltage.  I'd recommend nothing smaller than 10 gauge for the glow plugs – 8 gauge would be better.

What Rich said is true, however nothing really needs to be re-wired. Simply remove the existing (blue?) wire from the bus bar and use it for the relay coil feed. Run a new 10 gauge wire from the battery terminal on the starter solenoid to one leg of the relay contacts, then run another new 10 gauge wire from the other relay contact leg back to the glow plug bus bar. I recommend using a 40 amp relay. This same mod is recommended for use in the starter solenoid circuit. I have done both mods and it makes a world of difference. Performing these mods prolongs the life of the key switch by keeping high amperage loads away from it.

The blue wire comes up from the starter hot lug to the 40 amp relay. The black wire from the relay to the solenoid.Another black wire from the solenoid to the glow plug buss bar. The yellow wire is the original wire from the starter switch to the glowplugs, it’s now only energizing the solenoid which uses very little current saving the starter switch and giving you plenty of juice for the glow plugs. Same thing Bob said with a picture.

What I called a 40 amp relay is in fact a circuit breaker, I can't seem to edit text, the text didn't show up when I hit edit, just the picture

Sorry for the confusion

Tinbender raises a good point, one which I forgot to mention. If/when you install a relay, it's a good idea to also install a 5 amp fuse or circuit breaker on the relay's contact coil feed wire.

Yep, if you have a wrecking yard nearby just about any Ford truck will have one mounted up by the battery, mine came out of a Honda that was being junked at the time we were putting the tractor together. I used these for hot leads for trailers many times before too,with the energizing wire going to the ignition on circuit. That way if the trailer is hooked to a parked truck it can't run the trucks battery down.

To further clarify: A solenoid is an electro-mechanical actuator, usually mounted on the starter motor to pull out the Bendix drive, engaging the flywheel. A relay is a “switch”. The starter relay Tinbender was referring to will work just fine, the generic relay I was referring to is rated for 40 amps and will work just fine also – it's what I used for starter and glow plugs. You may use either. Your call.

I’ve had mine since 2008 without any problems, and it ran in a Honda for 20+ years before that. That’s a good sized switch for the amount of current going through it, Think about it, it's made for starter current, not a little 10 or 12 gauge wire for glow plugs, and sometimes folks crank on the starter for 20 seconds at a time. I wouldn't worry about it.

Dogdoc,

If you purchased a starter relay (no such thing as a “starter solenoid switch”) , your tech support guy isn't very knowledgeable. Typically, a starter relay is rated for well over 200 amps momentarily, and because their designed service is momentary they don't have a continuous rating. Your glow plugs are only going to draw 25 amps max. and that diminishes as they warm up. I assume you will only use your glow plugs momentarily anyway.

If you want to get into continuous duty relays then you are talking latching relays, and I don't do those here.

Semantics are very important when it comes to understanding technical issues. Oftentimes meanings and descriptions get lost, bastardized, or clouded by using colloquial and slang iterations.

Btw, all of those links are dead.

It's all good. Good luck.

Bob is right about the solenoid/relay thing.  All my Ford pickups (and my 72 Dodge, for that matter) had a relay on the fenderwell that energized starter and solenoid. The solenoid is actually a coil with an internal steel rod that gets pulled into the coil when current flows, throwing the starter gear into the flywheel. The coil energizes, creating a magnetic field. The steel rod distorts the magnetic lines of force, which like rubber bands want to be as short as possible, so the rod is pulled inside of the coil. When current stops, the lines of force go away, and there's a spring that pushes the rod out of the coil, waiting for the whole thing to happen again.  The Chevys I remember (ain't had one in a long while) had an integrated relay and solenoid, just like the Jinma.

There's plenty wrong in that quoted article, although it's good enough for the average Joe. It glosses over a whole lot of detail.

Bob IS wrong in his post #2 where he talks about the high resistance of the glow plugs drawing down the voltage. It's the LOW resistance (and hence high current draw) that does that. I bit my tongue until now, 'cuz I know he knows what he's talking about and just mis-spoke.

Tom

Biggerten wrote:

“Bob IS wrong in his post #2 where he talks about the high resistance of the glow plugs drawing down the voltage. It's the LOW resistance (and hence high current draw) that does that. I bit my tongue until now, 'cuz I know he knows what he's talking about and just mis-spoke.

Ur right Tom. I know I was thinking the right thing but it came out backwards somehow. Gad! I hope I don't do that at work.

It wouldn't be a bad idea, I'd use a 40 amp. Something would have to short out to blow that, that's why I used a 40 amp circuit breaker (behind the switch/relay in the picture). I used this for if a momentary surge did require 40 amps (not at all likely) it will shut the relay, and when cool, it will reset. That and I have a catchall drawer in my toolbox with several of these laying around.