Hello all, I dug and dug for a thread on this issue and was not able to find something quite as specific as the problem I am having. That could be my elementary knowledge of forums and computers so please point me in the right direction if I missed it. Here is my situation:

I picked up a 1979 F100 from an old man who had it sitting in his front yard at least since I moved to the area in 2014. The inspection sticker is from 2011 but he claims it was running as recent as fall of 2021.
the truck as a 351M that looked to be in generally good condition. The truck it turns out had been taken down to the frame by owners son and rebuilt prior to 2011 and was his daily driver. My first attempt to rotate the motor proved difficult but after pulling the plugs and spraying in PB Blaster over a week I was finally able to get it to break it loose (going backwards) prying on the flexplate gear. I thought I was in the clear, but when I went up front to turn it from the crank bolt I am not able to get a complete rotation of the crank. It will rotate maybe 180 or 270 and stop, then I can back it off the other way the same amount and it stops again. Anyone seen this and tried something I have not below?

• backed it up and tried to use the starter to break past what I assumed was maybe a rusty ring where the cylinders were sitting in the bore- didnt work
• put diesel in the bores and waited- didnt work
• pulled the valve covers and tapped on the valves with a dead blow looking for stuck valves, none noted. Also didnt see any glaring push rod issues while I was there
• used an endoscope to check for debris on top of the piston preventing any from reaching TDC-nothing
• pulled the distributer- thought maybe the oil pump rod or helical gear might have been jamming up the cam, thus the crank- no signs of this

Aside from pulling the heads next, my only other thought might be the timing chain is buggered up? Anyone know if I can check that on a 351M without pulling the water pump?

 

Unlikely the timing chain would cause it. and if it was out of time you wouldn't move it as far as you are before it came up solid. is it coming up and sticking where it stops or coming up solid but backs up pretty easy ? a broken rod would come up hard and solid.

You've covered all the obvious stuff so most likely it's one of the things you've checked nut you missed it. and whatever it is will probably be the reason it got parked.

The only thing I can think of it you might check the bolts or nuts on the torque converter to make sure it's not coming around and catching.

 

I assume the plugs are still all out? (which eliminates hydrolock issues)
I would get a cheap borescope and see if all the pistons move while you are moving the crank...if one of them isn't moving correctly, that would indicate a broken/bent connecting rod.
I don't know that a fuel pump can lock up and cause , but you could remove it which would also give you a place to insert a borescope and inspect the timing components somewhat...

 

@440 sixpack Thanks for the response, I would say it is coming up and sticking. There is no thud, or vibration when it stops; it just stops. I can then back it off and it moves pretty freely around the other way until it stops again. I have tried to muscle it past the stop in both directions but didnt go "full 6' cheater bar" on it in case there was something hitting and I damage it, or twist off the crank bolt. It is just frustrating the crap out of me.

I haven't checked the torque converter, but its all sitting complete in the truck. I think I'd have to drop the transmission or pull the motor to check that, correct?

 

@dlburch yes sir, spark plugs are out. I have the borescope, have not yet tried watching the pistons with it while turning the motor. Sounds a little tricky to do by myself but I think its a good suggestion and I will see if I can get a buddy or swing that by myself.
I mentioned the oil pump (not fuel pump) only because this feels like something mechanical stopping it so I was just thinking of anything in there that moves and might be jamming me up and that came into mind, but I dont think its the culprit.

 

Behind the inspection cover there should be 4 bolts , or nuts I haven't messed with a Ford automatic in years I don't remember. they are the ones you remove to remove the flex plate from the torque convertor and they are easy to get to. if they are bolts they can come around and hit the block..

If you're binding up hard enough the starter can't overcome it the chances you're not going to have to pull the engine apart to fix it are slim. if it was me I'd probably just pull it and find go through it. at the very least it probably needs rings, bearings and gaskets replaced anyway and being a 335 series probably bottom end work.

If you're not ready for that yet see if all the pistons move. and check again for a stuck or broken valve.

 

X2 dlburch. Working by yourself, put a wooden dowel in each sparkplug hole and you can watch while turning it over.

 

@coyoterun51 you sir, might be a genius. thanks for the tip!

 

Pull the valve covers and watch the valve train while you rotate the engine, what amount you can. My thought was the same as 440 sixpack on a stuck or broken valve.

 

Well, I figured I would post an update. Turns out a few days sitting with ULSD in the bores might have made the difference. I rotated the crankshaft to about 4 positions within the 180 degrees I could get the crank to turn. At each position I would tap on each valve with a dead blow in case any valves were stuck. I was ready to pull the rockers and push rods when I thought to try the crank again. I would rotate it clockwise until it stopped then give a couple of extra tugs in that direction and felt like I was getting a little extra movement. I made a mark on the crank pulley so I could verify this and sure enough I was moving about 1/4-1/2" more each time backed it off and tried this again. I kept at it until Finally! it went 360 degrees clocks wise. I spun if a few extra times for good measure and hooked up the starter to it and its now spinning all the way around with the starter so I was over the moon. Now on to why there is no power to the coil. thanks for all the help and suggestions.

 

It sounds like you have some rust in a cylinder that you pushed through. it's hard to imagine it hasn't done damage you're going to have to take care of. but trying to get it to run isn't going to hurt anything.

You can trace the coil feed wire back as far as possible and see if it has a break in it. anytime you have problems with the durashart ignition changing the ICM is a good place to start.

 

thanks for the follow up. Yes I plan to eventually get the engine gone over once I get this thing to the house and can start digging into it more. I am just trying to get it running to make the 1 mile drive at this point. Quick update on the spark issue: went ahead and just replaced the coil and the ICM, figured I would throw the kitchen sink at it, still not starting but I have a good list of things to try next (thanks youtube). hopefully I can find the right combination to get this think firing!

 

If you still don't have power to the coil it won't start. check that and if you do see if you have spark. if you do then look at fuel problems.

Once you get it running and have time a compression check might reveal a lot.

 

You don't have another vehicle and some straps to just flat tow it to where ever you gotta go? I've flat towed a vehicle with a ride on mower before, it's slow but it works, probably not great if you live in hilly areas...

If it was running in 2021...there was probably something mechanical internally binding it up, there's no way it rusted bad enough to jamb it up like that in that short of a time. If it did rust that bad, I'd be really worried about the rest of the insides. You've probably already scored the cylinder walls by using the starter to spin it, so there's nothing to lose trying to get it to run at this point, it's probably gonna need a full rebuild.

If it wasn't rust and there is an internal binding and you do get it running ..there's always the chance that on the drive back it seizes up.

Check in the bellhousing for any debris. I once had an intermittent lock up issue i thought was a spun bearing and tore the oil pan off a 400 to check them outs, only to find out afterwards there was part of the starter nosecone that broke off in the bellhousing that was randomly jambing it up, but the starter still worked. Another time it was a giant mouse nest that managed to lock everything up.

When you put a breaker bar on the crank nut and rocked it back and forth, did you hear or feel any clunking in the bottom end, or could you see any slop in the valve train?