Hi I6 Gurus,
I have a 1984 F150 300 I6 w/ 183000 miles. I have had it for about 8 months. The first four months were pretty good but the last four have been really bad! The truck died in the middle of the road 4 months ago...got towed, turned out the roll pin that holds the gear on the dist. shaft sheared. So for $109 the problem was diagnosed and roll pin replaced. Well that worked for about 30 miles and then same thing again, truck dies in the middle of the road. Towed, this time they put in a new roll pin and replaced the oil pump (at $350 +)figuring it was the root of the problem...it made sense to me since the oil pump shaft is tied into the dist shaft...if the oil pump seizes then something has to give. Well, that got me maybe another 100 miles or so and then the truck dies again. They put in a new pin at no cost this time, stating that the previous pin they put in was mild steel, not hardened as it should have been. Well, that pin got me maybe 250 more miles (!) and yesterday it died in my driveway while starting. I took of the dist. cap and while cranking --sure enough the dist shaft was not turning %#$&*$#%#!!!
So, what do ya'll think is the problem?? Could there be something wrong with the distributor itself? A friend said his uncle had a similar problem and said that some of these engine blocks were not correctly bored for the dist shaft--ie bad tolerances and this caused the problem. However it seems hard to believe that this has happened every 100 miles or so for the 183K the truck has on it!
I'm going to have the truck towed up to the same shop again (I know, seems dumb) hoping that they will off to do it for free since they haven't gotten right yet. I'd like to work on it myself but I don't have anyplace to do the work and I am moving out of state in about10 days!!
I need help, suggestions and advice would be greatly appreciated!!!
Thanks, Paul

 

First off............
Welcome to the FTE Forums..............


What weight oil are you useing??
How much oil pressure do you have??
Is the screen on the oil pickup tube clean..
The oil pump seizing or the distributor seizing will cause the pin to shear. I have never heard of the misbored/misalignment thing
It has to be a oil pump or distributor issue.

ftwfred

 

ftwfred,
Thanks for the reply and the welcome.
I am running 10W30...the shop suggested trying 5w30 but they have been the ones changing the oil during each of these events and told me they put in 10w30!
Oil pressure always runs in the "normal range" according to the gauge. It does fluctuate some, moving somewhat higher or lower but always within "normal".
The shop put in a new pickup tube and screen when they changed the oil pump so I assume that it is clean?
Thanks again!
Paul

 

maybe the oil coking on the dis shaft is sweeeling enuff to lock it up when the motor gets hot enuff an shearing the pin . if youve ever taken apart an old motor an take the dis out an tryed to take it apart u know it takes a big hammer to get them apart . some thing id look in to
hope this help ya
mark

 

after it sheared the pin the first time maybe the gear doesnt fit tight enough on the shaft because it should have to be driven on. if it is on there loose there would be added stress on the pin so that could cause it. if i were you since you already replaced the oil pump i would say go with a new distributor. they usually come with a gear already on them so you should be able to drop it in yourself just borrow a timing light off of someone and that should be all you need

 

Here's something to consider (and I hate to mention this after all the $$ you've poured into this problem) if the holes in the shaft and the holes in the gear are not inline..or maybe the pin is slightly too big, then the shear force of pressing the pin in through the two parts is work hardening the pin making it very brittle. Another thought to consider is the dizzy itslelf - is there any excessive slop between the shaft and the housing? $109 is a lot of dough to throw at an old dizzy, I'm suprised the whole damn thing wasn't replaced - They're cheap enough.

 

I agree with tetra...replace that dizzy.

 

Thanks for all the advice guys. I plan on having them stick in a new distributor (hopefully at their cost since prior diagnoses were prob. off). I wish they would have done that too in the first place considering I can get a reman one for $52! They're nice guys and have done me well in the past but maybe they are not putting their full attention into this. I'm a little sick over the whole thing. I enjoy working on vehicles and do what I can with my limited tools & knowledge & time/space. Wish I would have just worked on it in the first place --might have saved a lot of
Paul

 

Paul,
Be sure to let us know what you find. This could be some good info for other members here...

ftwfred

 

Drill out the distributor shaft and the gear and install the next size up rollpin. This has worked for me in the past.

It sorta sounds like your oil pump is binding up. That is what causes the pin to break. That is the whole point behind the design.
If the pump siezes for some reason, the pin snaps and the motor stops, thus saving the motor from damage from no oil pressure

 

I had the same prob once on a friend of mines truck... I towed it in and after beating our heads against the wall for a few hours I finally realized that I could turn the dist. by hand... pulled it, pin was sheared. I had never heard of it before. Lucky for him I carry extra's of everything in the bronco. I had an extra stock dizzy from an old motor that I carried complete with cap, rotor, and wires, just in case. I dropped it in and had had him back up and running in no a few mins... that was 2 years ago and no probs since. I would say that your dizzy is bad... maybe a bad bearing that siezes when it gets hott... or the gear fit could be an issue too. I wouldn't trust it either way... as cheap as that reman is that would be the way to go. If you can get it with a lifetime warranty.. and if it isn't the right fix atleast it will be covered when you shear the pin again.

 

BTW, I'm not sure that just the oil pump sieze is the only thing that will cause pin shear... his sheared because he didn't know how to properly set the timing on his 6 and didn't unplug the sensor wires... after he timed it he drove it to town, it backfired when he shut it off (because the timing was too far advanced) and that sheared the pin.

 

just an idea but the timing gears might be worn causing extra vibration on the distributor gear i don't know if this is even posible on this motor but i know a honda with a loose timing belt will cause the distributor gear to snap back and forth until it's destroyed. don't hold me on this one... just a theory

 

Been there, seen this. Fords and Chevys alike. It is coked-up oil in the distributor. Tear it down, clean thoroughly, maybe even clean up the shaft with some emery cloth. oil up the shaft and re-assemble with new roll pin. Done deal. Just bought a spare dizzy this week for my 351, and found it nearly locked up. This will cure it for ya! BTW, carb cleaner works great for this.

 

Thanks again for all the replies, suggestions, advice, etc. I got the truck back from the shop today. They thought that the dizzy was to blame as well --stated that there was "excessive clearance between the distributor shaft and ditributor shaft gear". Basically a little too much slop. So they put in a reman distributor in. Wow, what a difference...can't say for sure whether or not it will sove the roll pin problem but it sure brought the truck back to life! Over the past several weeks the truck was running worse and worse and seemed to be losing power, just couldn't make it up the hills as well anymore. Thing runs like a champ now! Guess the timing had gotten way off with the old dist. Pulls very strong now! Anyway, thanks again for all the help.
Paul