Hello everyone, I am new to the forums, and the diesel world. I recently purchased a neglected 1990 F-250 4x4. I decided to flush the radiator since it was running a little hot. After the flush, I was planning on using Prestone radiator cleaner. Fast Forward... the water is running clear. I let the radiator completely drain out, then hand-tighten the drain **** as best I can. Start the water back up to fill the radiator (required for the cleaner) water starts to empty out of the drain. Stop the water. Maybe get an eighth-more turn out of the drain ****. Start water. Leakage. Not just a drip-drip affair either. Full-on pouring out. What do I need to do??? Is there a special tool? New radiator drain ****? Tow top a shop? I feel like the bull in a bull-fight; very confused, pissed off, and helpless!

 

EarthPig, welcome to te forum, I hate to do this to you, but did you tighten it all the way, or did you open it all the way? Try turning it all the way in the other direction to se if thats the problem, the drain will actually move away from the rad to close off, and move toward the rad to open.

 

ahem... thank you very much for the reply. I have just finished the change of fluid.

 

No problem buddy, I still get confused sometines with left VS right, let alone having to reach a contraption that you have to turn into a pretzel to reach!

 

EarthPig,
Welcome to FTE and the IDI diesel forum.


You are working on your own truck.
That puts you in the same class with everyone else here, we all do it because we like it.

I don't care how many times you unscrew something, if you do it from enough different positions you will try to turn it the wrong way every once in a while.

 

Thanks for the encouraging words, guys. I have another (probably) simple problem that has come to light as a result of the radiator flush. As I was attempting to reach the engine block coolant drain plug, my socket brushed across the terminals of the starter! luckily, I was holding it on the handle, and the current mostly passed through the head of the socket (leaving a nice melted spot!) I decided the dirty coolant in the block just wasn't worth the trouble (even after disconnecting the batteries to try to move the starter wiring out of the way). anyways, after everything was put back together, I decided to take the truck out for a spin to get the transmission cleaner, the fuel conditioner, and the radiator cleaner circulating around. It was dark at this point, and I noticed the headlights wouldn't turn on. Everything else in the electrical system is fully functional (Blinkers, Parking Lights, Cabin Light, Gauges, Starter, Etc.) so I reasoned I had merely blown a fuse. Here's where it gets strange... My Haynes Manual says the fuse box is under the dash on the passenger side. Right were they say it should be, there is a trailer brake, installed by the previous owner... but no fuse box. After looking around under the dash, and a cursory glance in the engine compartment, I can't seem to find a fuse box anywhere! Could the trailer brake housing also be the fuse box? There are quite a few wires running into it for just a brake. I dunno, do you?

 

The fuse box is on the driver's side up against the firewall under the dash. You might also want to check the wiring on the pasenger side inner fender to look for any signs of burned wiring.

 

O.K. found the fuse box... (should've looked at that big "fuse layout" sticker as a hint) unfortunately, fuse #4 is fine and dandy. I can only assume that I must've overlooked a connection whilst re-connecting the batteries. I'll have to check everything over tomorrow when I have some sunshine (I'm what you'd call a literal shade-tree mechanic) not that I can really tell, considering how many random wires are just hanging around the engine compartment . On an even *****tier note, while fiddling with the fuse box, I noticed the floor seemed rather... spongy. Peeling back some of the vinyl floor covering revealed the door frame almost totally disconnected from the cab floor! I guess that means I need to find a new cab and a new bed, or aquire some patching/welding skills soon!

 

does anyone have a wiring diagram for a 1990 F-250 diesel? The Haynes manual I have only covers Gasoline wiring diagrams. Would one of those be similar?

 

The wiring is for the most part the same.

If you have Haynes manual "Ford Pick-ups and Bronco 80 thru 96"

Actually if you look at each page very carefully there will be notes for specific engines that were available in that year.

For instance look at page 12-48 down column 28.
You will see the insturment panel with two diesel specific notes, "engine warn ind mod" (diesel) and Plugged Fuel Filter (Diesel)
In column 30 at the bottom of row A is the coolant temp sensor, below that is the diesel version in row B.

On page 12-45 Row A Column 19 has the IP cold timing advance solenoid and cold idle solenoid and the fuel line heater.
Same column row B has the glow plugs.
There is also a note that there are two 14 ga green fusible links at the starter relay that protect the glow plug system.

One of the bad things about the Haynes manual that makes it almost worthless for wiring problems unless you scour over all the drawings for your truck year.

I would have easily given 10 or 15 dollars more if it had engine specific complete diagrams.

Check for fusible links over on the passenger side behind the battery.
I know there are several there on my 86, just don't remember how many right now.
The starter relay positive post is a power distribution point on most of these trucks.
Look for the side that has several wires all on the same terminal.

The links should be between the relay and where the wire goes into a harness.

Looking on page 12-41 it looks like you have 9 fusible links near the starter relay.

 

thank you for the thorough response, Dave. I found the chassis wiring diagram in the haynes manual. There seems to be some discrepancy between the colors of the wires. This what I've checked so far:

Pulled out fuse #4 to check voltage - read 12 V across terminal

used manual to determine the TAN/WHT was the headlight output of the fuse box into the MAIN LIGHT SWITCH. The manual says that the RED/YEL wire is the output of the MAIN LIGHT SWITCH into the DIMMER SWITCH. This isn't the case in my truck, and it is my belief that this isn't the case in any 1987-91 ford F-Series or Bronco. The dimmer is probably just a rheostat or pot inside the switch itself. What the manual should show, at least in my case, is the RED/YEL wire going out of the cab via that large, white, circular feed-through plug-thing. After that, I can't really make out what is going on in that rat's nest of a wiring harness without doing some serious dismantling to find out where the RED/BLK and the LT GRN/ BLK wires of the headlamp assemblies actually are connected to the RED/YEL wire from the switch.

Anyways, I ended up checking voltages between the TAN/WHT wire and the RED/YEL wire to check the functionality of the MAIN LAMP SWITCH. These are the results:

OFF position: 12V
PARKING AND INSTRUMENT LIGHTS position: 12V
HEADLAMP position: 0V

This is telling me the switch is working the way it should be. This also tells me that the RED/YEL wire is the switch output to the headlamps

I also checked the fuse continuity, the filaments on the headlamps, the headlamp ground to neg battery terminal for continuity, and voltage across headlamps with the MAIN LAMP SWITCH in the HEADLAMP position, which read 0v. My reasoning is that a connector must've gotten wet when I was flushing the radiator yesterday, and is shorted out (although I am pretty sure a shorted connection would've blown the fuse). The only other connections I haven't checked (correct me if I am wrong) are where the RED/YEL wire meets with the RED/BLK and LT GRN/BLK wires for the headlamps, and where the two sets of RED/BLK and LT GRN/BLK wires split up to go to their respective headlamps. To check those, I would have to find them first, which would require tearing the wiring harness apart. Talk about a pain in the ***..

I din't think of fusible links as the culprit, becuase all the other electrical systems on the truck are fully funtional. WOuldn't a blown link take out other systems as well?

 

e/p as all old trucks become a rats nest in elec. dept my 86 incl. hdlt switchs ussually have internal cb for hdlts befor doing intense labour be sure lamps recieve 12+ volts at connection point with sw all the way out & lamps arnt burnt out. your hi/lo sw is on floor or direction ind arm?

 

OK mine is an 86 so it might be a bit different.

Red/yellow wire runs from the headlight switch down to the floor mounted dimmer switch.
My red/black and lt green/black wires come from the floor mounted headlight dimmer switch.
They run through the firewall and split left of the steering column.
The left headlight wire is in the harness that powers the windshield washer pump.
Also in that harness are the park light and blinker wires and a wire for one of the horns.

Before you dig into the harness, you may want to remove the wiring connector from the headlight switch.
They are known to cook the switch and the connector.

I did this mod to my headlights years ago, and am very happy with the results.

https://www.ford-trucks.com/article/...ay_System.html

I also changed out my headlights to Silverstar bulbs in aftermarket APC housings.
What a difference in what I can see at night.

 

p s does hi beam ind work?

 

I figured it out! I was also posting on the powerstroke forums, and one of the guys there told me that was the dimmer switch on the floor! I had no idea what purpose that little silver thing in the floor served. I just assumed that it was a modification put in my some previous owner. So I think that switch needs to be replaced, or a loose wire is down there, because as soon as I clicked it, the high beams came on. SO I'm stuck using high beams for now (which is no big deal, considering I've been using them this whole time, apparently). At least I can drive at night now. Thanks for all the help.