I'm new to the old diesel thing, so i'm struggling a little bit.

I've got a 1983 6.9 F250 that im fighting with cold starts. once its running its perfect, and it starts right up with even a little heat in the engine, either from the block heater or running as little as 45 seconds. it's just the initial startup thats fighting me.

I've replaced the Glow plugs, but I don't have a great understanding of this first year glow plug system, as most of the threads I find are on the newer system.

so I turn the key to on, and the "wait to start" light illuminates for around 8 seconds, then shuts off with a distinctive click. At this point, I get no clicking from the relay, and it'll still crank for forever before it'll finally start.

My understanding is the relay should be clicking and cycling the glow plugs for the next 1-2 minutes while the key is still in the on position right?

The old plugs were no doubt bad (buldged, burnt, and covered in thick soot) and I had assumed that was the issue. Should I start with replacing the Relay or the controller next?

 

Have you confirmed that you are actually getting power to the glow plugs when they are supposed to be on ?

 

I have not, I don't have a test light, but I'll be getting one soon as I have time.

The next question for me becomes, even with working glow plugs, and good batteries, is the old school direct drive starter even capable of giving good cold starts?

I plan to swap out that starter for a gear reduction style one, but theres about a hundred other things I need to do to it also so i'm trying to weed out all the things that aren't emergencies so I can get it on the road part time soon.

 

I have actually been able to start my 7.3L diesel at near -40 not plugged in with the old style direct drive, it is a far more reliable starter than the later gear reduction units.

You need to confirm to if you are actually getting voltage at the glow plugs before you go any further. Check both banks of the engine and all the plugs for power. Or check one on each bank then check for continuity between that one and the rest on that bank.

 

Do you have a sound clip of your direct drive? i'm wondering if this ones worn, cause it seems to crank pretty slow even with two good 850cca batteries.

Ill get a test light and check the power on the plug wiring before I go any further

 

No I do not. And the stater may be due for a rebuild. If you don't have a test light I would pick up a DVOM (Digital Volt Ohm Meter) just a cheapie will do for what you are doing and it will allow you to check actual voltage and do continuity tests.

 

Also, make sure you only use motorcraft or international glowplugs. They will have Beru written on them and are made in Germany. With any other brand glowplug you risk them swelling up and then breaking a piece off down inside the engine.

That old glowplug controller you have is famous for sticking on and ruining the glowplugs also. I would make sure you get a new controller, or if it were me I would just put a manual pushbutton on it. That's what I have on mine, and the glowplugs glow as long as I hold the button down. Works just like a piece of equipment or a old tractor.

 

 

I suggest eliminating the controller and running a pushbutton. Wire it to deliver +12v to the low current terminal on the solenoid that activates it. Hold button for 7-10 seconds depending on temperature, glow plugs not required if it has run recently.

I had starting issue with my 6.9 the first winter I had the truck. It had old mismatched batteries and rattle cables. Below freezing if I fired the glow plugs too long it wouldn't crank, not long enough it would crank but not fire and I only got about 2 revolutions out of it before it wouldn't turn anymore. That got old real fast so I picked up a pair of group 31 stud tops along with 2/0 for grounds and between batteries and 3/0 to teh starter and some ring terminals which I crimped and soldered, heat shrink and liquid electrical tape to seal. The next winter it started just fine without being plugged in down to negative single digit temps. That was with a planetary gear reduction Mitsubishi style starter. I'm not aware of any direct drive starters for these trucks, but if you actually have a direct drive ditch it and get a gear reduction. Mitsubishi plantary reduction is fine but very long and tough to install, I prefer Nippondenso offset gear reduction as they're much easier to install and put the terminals in convenient locations. Granted you can get replacement solenoids and parts more easily for Mitsubishi starts so pick your poison.

Go over all your cables, solenoids, etc. and veryify your glow plugs are actually working. If you keep the controller try cycling it twice on a cold start.

 

If you have the direct drive keep it. Not only will out last either the Nippendeso and the Mitsu starters. The direct drive Delco Remy starters spin the engine faster, but do suck more amps so you need to keep your batteries and cables in good shape. In cold weather you need all the cranking speed you can get. And the only thing that wears out in them are the brushes that are like $3 to replace and can be done in situ. The Delco Remy 27MT starter was designed for for way heavier applications than the IDI's
If you want to go to a gear reduction unit forget the Nippendeso or the Mitsu units and get a Delco Remy gear reduction 29MT or 37MT family , they will last longer and spin the engine faster than either the Nippendeso or the Mitsu. Compared to the Delco Remy units the Nippendeso and the Mitsu starters are throw away junk.

 

 

Here's a link to a 86 diesel's glowplug system. It's later than yours but it still uses that older controller like you have that screws into the engine. Like I said, if yours looks original, make sure you replace it, they are known to go bad.

http://www.garysgaragemahal.com/star...---diesel.html

Your first year diesel is also known for cracking the engine block around the block heater.

 

 

It doesn't matter which way the current flows through the coil of the relay. If one of the ends of the coil was grounded, and the relay was bolted to a ground, then it would matter. From the diagram it looks like the relay has two small terminals, both above ground, so it should not matter.

If you wanted to experiment a little bit, you could take that purple wire off and tape it, and then run a temporary wire into the cab, to a pushbutton switch, and then to a power source. You should hear the relay thunk when you push the switch, and the plugs should be glowing. If you happen to have a volt meter in the dash (my later truck does) you can see the voltage of the batteries drop way down, and that is a sign the plugs are pulling power from the batteries. Don't glow them over 10 seconds and you should be fine. If this works reliably, I think you can say the plugs and the relay and that wiring are good, and there is something wrong with the controller.