So pretty much I got this 83 f-250 from a friend 351w 4x4 auto. It hadn’t run in 10-15yrs. Bought it for cheap but have invested $500-600 doing basic tuneup stuff, needed new starter, plugs, cap, rotor, blah blah. Got it going, ran like crap, found out it was a bad vac leak cause he tried to remove all the emissions crap but didn’t finish the job.... I did. Comparatively had it running pretty well. I am currently running an edelbrock 1406 carb because the Holley on there was garbage. In the course of repair I had changed all the coolant hoses due to leaks and of obviously all the fluids. Anyway, I had kinda a funny thing happen. I had been playing around and running it ect doing some further tuning maybe 50miles pretty good! I let my kids drive it and then wham they’re stuck, now the car won’t start at all I tow back to my house and SUPRISE! no water anywhere no coolant whatsoever dry babay. So idk if it was losing just a bit at a time but bottom line I think I cooked this puppy pretty good. With no coolant on the sensor don’t think it was registering anything, snafu all normal Lol 😂 Think I’m just going to pull the heads and see what’s going on (not my first choice), but I guess my question is... if you had the ball, what would you do? To add insult to injury I had tried to crank several times, no fire, pulled a plug (looked not out of ordinary) hooked up comp tester and got up to 90ish psi but then batt dead pretty much while it was building pressure💀 omg I’m a clown sometimes embarrassing really like how can I be a mechanic and not realize all the coolant is gone?!?! Who would expect? There was no visible leaks UGH 😩

 

I would put water in it and troubleshoot it first. See if you have spark and fuel.

 

Yes of course I put more water in. There’s fuel all day... I hadn’t checked for spark specifically, guess that’s another question. It has that funky ford ignition module, does that receive input from a temp sensor?

 

Here's my experience losing all coolant in a 351W. Five years later, still running strong:

https://www.ford-trucks.com/forums/1...-a-bullet.html

With any luck, your engine fared as well. There's a very good chance the innards are still okay, so don't convince yourself otherwise.

As far as your compression test, CHARGE THAT POOR BATTERY! If you do a cranking compression test with a low battery, the results are meaningless. It could easily lead you to condemn a good engine.

The no spark? No idea, but I can't make any connection to an engine overheat. You'll have to run some basic troubleshooting to figure out why.

 

Ford had a lot of funky ignition system boxes.I would think yours being an 83 it would have the duraspark II module on it, a big silver box on the driver's side inner fender. But if it was from California, it may have came with the TFI module which is mounted on the distributor itself, and had a computer system driving it. But even though the TFI has a computer with it, it does have a limp mode and will produce enough spark to run without the computer. I guess it could also have a EECIII, it will look much like a duraspark box.

Harbor Freight sells inline spark testers.

 

I read that other thread... maybe it is spark, yes the battery is on the charger now. Just odd because it was turning over just fine but not even a sputter like trying to start. Seems obvious now but that’s sometimes how troubleshooting is, when you’re in the moment you kinda lose your mind and don’t check the simple stuff. Maybe it’s just a coincidence and the module died at the same time.

But I still want to know does the temp sensor influence the ignition module or is it not that sophisticated?

I’m going to fool around later and check for spark. The oil doesn’t seem burnt looks clean and fresh not coked.

 

Yes I think it’s the duraspark module it’s on the fender not dist. I believe the car was originally Canadian so doubt it’s the Cali emissions.

 

If you have a duraspark system, it's simple if it has blue plastic where the wires come out. It's only duties are to create spark, no other influences from any sensors. If the plastic is another color, then it might have a sensor for baro pressure or something, but it only affects the timing curve not the spark generation.

 

Cool, So does it have advance weights/springs in the distributor somewhere or is that just preset in the module? I think I may have just answered my own question because it does have vac advance so it must just be underneath the rotor ect.

 

Yes, if you have vacuum advance, it's all mechanical in the distributor. The module and the pickup inside the distributor just take place of the points to turn the coil on and off to create spark.

 

Right, good, I've been told these modules are prone to failing maybe that's it. I was wondering if I could fix that curve but thought it may have been controlled by the module. Another stupid thing was the truck was down on power in the mid rpm range so without knowing I could go to a lighter spring I decided to give it some more initial to see if that would help. Think that probably contributed in part to the overheating, beyond having no coolant whatsoever Lol. I promise I wasn't intent on torturing this truck!

 

Why did the battery die so quickly as you lead us to believe ?

Is there oil in the pan ?

Or were you spending a lot of time cranking the engine over trying to find out why it wouldn't start ?

 

The modules are not really prone to failing. And they usually give you a warning , they will quit when and when they cool off they will work. They rarely just up and quit. if iyt was run for any length of time with no coolant the engine is probably junk as cylinders will be warped as may the heads. You may get it running again but will likely lose a head gasket shortly afterward and it will be an oil burner from here on out.

For the no spark do the usual stuff check for power at the coil during start and run and the module (red and white wires) ohm out the coil and ohm out the dist pick up, if all that checks out then suspect the ignition module. The modules do not typically fail of all the ignition issues that get posted on the board coil failuers have been far more common than ignition modules.

 

The battery deal is unrelated. Prob just from cranking a lot, charging system maybe not so good and old batt. Put another in that was charged and it’s fine cranking ect.

yes there’s plenty of oil and it’s in fair shape no water, gas, or looking suspicious.

 

Did compression test and I’ve got one cylinder low about ~120psi and the rest are just a tick under 150psi and hold pretty good.

The good


The bad #7

I took out a plug and it was sparking for a bit then it was kinda hit and miss. The coil is brand new. What was odd is that it was almost like when cranking it wasn’t sparking then I’d kinda get a spark at the end it was odd. Anyway that module was one of the few items I didn’t replace so I pulled it and am going to replace it.

From what I can tell right now even with one cylinder low on compression it should be firing off. I really don’t think I’ve done that much damage because a motor this old and tired to be pushing ~150psi even after this “incident” is pretty good. My plan right now is replace that module, see if I can start, but ultimately likely a burnt valve or something on cylinder #7 so the heads are coming off and we’ll see what’s going on.