First of all, greetings everyone! I hope it's not in poor form or considered rude to register and make my first post just to ask for help. Also, I apologize in advance because I'm leaving town in about 8 hours and won't be back until Monday afternoon. I'll be up in the mountains with no internet and no cell reception, so I'll be incommunicado until I get back.

Anyway, here's a quick explanation of the problem I'm having (I'll go into much more detail below). I have a high-mileage (almost a quarter-million) 1995 Ram 2500 4x4 with a 5.9l (360ci) gas v8. It's been running fine for a couple weeks at a time, but then it will just refuse to start (or even die while driving down the road). When I manually rotate the engine to top dead center and pull the distributor cap, I find that the distributor shaft & rotor have somehow been turned exactly 180 degrees in the wrong direction (the opposite direction of cylinder #1).

In case you're not familiar with what the 5.9 v8 distributor looks like, here's a picture I took. The area circled in red is the end of the shaft that has a tab. This tab sits inside a slot of the drive-gear down in the engine block (here's a picture of what that looks like... I circled the slot also in red). As you can see, the tab and slot can only align on a single axis in two possible directions (180 degrees from each other). If I pull the distributor, turn around the shaft and realign it in the proper direction (the rotor only fits on the shaft in one direction) and put everything back together, it'll usually start and run/drive for a period of time... until the exact same thing eventually happens again.

I thought I had found what was causing the problem. If you look again at the second image I linked to, you'll see some of the rear gasket of the intake manifold circled in green (a few months ago I had to pull the engine to replace the freeze plugs, and I installed new intake gaskets when I put everything back together). I was certain that this must be preventing the distributor from seating properly, and therefore causing the distributor shaft to slip out of place. I used a razor to cut away the excess gasket, re-installed the distributor and put everything back together (after also installing a new cap and rotor, new plugs, plug wires, etc.), and it started right up and things were running great again.

But then a couple weeks later, it again suddenly started refusing to start. It was the same problem with the distributor shaft turned exactly 180 degrees in the wrong direction.

This is the point where I'm stumped. I have no idea why this keeps happening. I was certain the gasket was getting in the way of the distributor, but it turns out that isn't what's causing the problem. The only thing I can think of is maybe my timing chain is loose and is binding up causing problems? I was hoping to get some more input/opinions before I start tearing stuff off the engine to remove the timing chain cover.

I used a screwdriver to turn the drive-gear that drives the distributor shaft. When I try to turn it counter-clockwise nothing happens, but when I try turning it clockwise it starts turning and moving upward. Here's a youtube video of what I'm talking about (I don't know if you can see it in the video, but when the gear turns it starts moving up quite a bit as if I'm pulling it out of the engine block). Does anyone know if this is normal? I can't find much info on this in the service manual.

One last thing: I should also mention that sometimes the transmission will shift in and out of overdrive (it seems to happen less often once the car is warmed up). I'm pretty sure that the overdrive clutch is just worn and needs to be replaced, and I doubt it has anything to do with the distributor problem, but I'm just trying to give as much info as possible. When it shifts in/out of overdrive, it isn't any more abrupt or violent than a normal up/down shift.

 

I believe that your high mileage motor needs a new timing chain and gear set installed to completely solve the issue. If it has never been replaced, there is likely so much slop in your timing chain, its causing the issue of erratic timing.


Also, anytime the distributor is moved, the fuel trim should be checked to ensure that its within spec. This can be done with a good, full function automotive scanner or at the dealer.

 

Something to keep in mind as well is, when the timing marks show TDC, that happens TWICE per one revolution of the distributor. You will have either cylinder 1, or 6 in firing position. If timing was 180, it would spit and backfire horribly. If you can turn the dist 180, and it will start and run again..... REPLACE the distributor.

Behavior of the drive gear is normal.

Trans shifting, if it 'bounces' about 200 RPM, replace the throttle position sensor.

 

That was my best guess, but I was totally just taking a shot in the dark. As far as I know, it's never been changed. Also, when the distributor is installed, there is a little bit of play in the rotor/shaft so you can jiggle it back-and-forth a couple of degrees (wasn't sure if that's normal). According to the service manual, the timing chain should have no more than 0.125" of play, so with a timing chain that is probably a couple feet in circumference, I'm guessing that should translate to almost no jiggling at the distributor shaft (if the play in the shaft/rotor is a result of a loose timing chain).

I'm leaving in a couple hours, so I don't have time to take a look at the timing chain before I leave, but I feel better having some confirmation that it is a possible cause of the issue. I'll check it first thing when I get back.

Well, that's a huge relief.

As far as the transmission, normally when I'm cruising at highway speeds with overdrive engaged, the RPMs are at about 2,000. If I disengage overdrive by using the "O/D off" button on the dash, then the engine will be at around 3,000 during highway speeds. From time to time, this is what is happening on it's own: it will start alternating between 2,000 and 3,000 RPMs as if it's slipping in and out of overdrive (it only happens at speeds of about 45mph or more, which is why I'm fairly certain it's an issue with the overdrive).

Like I said, the poor old truck has almost a quarter million miles, so the tranny could use to be torn apart and rebuilt. For now, I'm trying to just get the thing running reliably.

 

Yep, thats O/D dropping in and out. Not going to be that easy.... Have you check TV cable adjustment?

Any slop in the distributor is going to between the cam, and the distributor itself. You aren't going to turn the cam by turning the dist, unless you have some REALLY strong hands.

 

I hate to disagree with you but if the timing chain was loose it might jump one or two teeth on the gears. There is no way it can jump 180* out. I would guess it has to be something with the distributor.

Of course I could be all wrong too.

 

Yea I agree with this. If it was so loose it could jump half the chain it wouldn't grip at all and would just not run.

It's probabbly just your dizzy itself.

Idk though. You do have two tdcs like hey you said. If it's 180 out it could just be pointing to 6. Idk though I don't have the cylinders on the dizzy memorized lol. Interesting you can just flip it back and it will run. Really interesting. If your fuel sync was terribly off I would think it would show itself immediately. Not run fine for a while.

This is interesting be sure to keep us updated!

 

With that many miles on it, I think it will need both the distributor and a timing chain set swap. Just what I'd do with it if it were mine to fix..

 

I agree with you 100% man. Just dont think the chain alone is the problem.

 

I completely agree.