New poster here, just joined the forum after lurking for some time.

The truck- 94 extended cab with 22 Re (4cylinder)

The backstory- Timing chain noise for some time during warmup. Son was driving home and truck died. After quick on the road diagnosis, no spark, rotor not turning in distributor. (This had happened once years earlier and dealership replaced pin/gear on distributor shaft).
Towed home and into garage to thaw out (we are in AK). Pulled valve cover and distributor gear had slid down shaft and seized up. Timing chain still intact but guides looking very worn. Good time to replace timing chain, I figure. Distributor won't come out of the head and I end up up using a punch and destroy the distributor. No big deal, I find a correct OEM replacement on e-bay.

I go through the entire timing chain replacement (with dropped oil pan) and get everything buttoned back up. When I install the replacement distributor it will only slide in partially leaving about a 1/2 " gap between base of distr. and the head. Hmmm. I rotate the engine clockwise and distributor drive gear draws it in the rest of the way. Engine at TDC, everything looks good. Truck fires right up and runs for about 30 seconds then emits a loud metallic "snap" and it dies. I pull valve gasket and the distributor gear has done exactly the same thing and slid down the shaft and seized up!

When I inspect the distributor drive gear on the end of the cam shaft I find excessive wear and chunks missing in different places. I also can feel a groove in the bottom of the slot in the head that the end of the distributor seats itself in. I kick myself for not inspecting when reassembling! So now I have ordered a distr. drive gear and second used OEM distributor.

So here is the question- does it seem plausible that the worn gear at the end of the cam shaft could cause this all to happen? Is this why the distributor wouldn't seat itself properly? Any suggestions as I put things back together a second time so I don't keep repeating my mistakes?

 

Shame on you for not looking at this when you pulled the cam gear off.

As the gear on the distributor rides in the gear on the cam .

If the one on the cam is worn and has missing teeth the fact it ran at all is amazing !!

Since you don`t mention mileage I can only guess this is the second or third timing chain.

My question is what caused this abnormal wear ??

 

If I have the picture correctly, the worn seat in the head allows the cam gear to push the distributor gear out of alignment. If that's the case, I don't see any fix that doesn't involve replacing the head.

 

And a new gear on the cam shaft. If teeth are broken or chipped on either gear, the mating teeth can jam against each other instead of sliding between each other. The same can happen if, as scope suggests, the worn slot is allowing the distributor gear to move sideways and ride up onto the cam gear teeth instead of mating properly with them.

When that happens either everything instantly stops (not likely with the engine running at any reasonable speed) or something breaks - in your case one of the gears.

It's likely the worn slot caused the initial gear mis-mating, and that caused the chipped teeth. At this point you have a system that simply won't work.

This sort of thing happens frequently with worn starters and flywheels, but because the speeds are so low, the usual result is just a locked up starter that won't turn the engine over. Here the results are more catastrophic.

 

Thanks for all of the feedback! When I tore into the engine it appeared to me that timing chain had not been replaced, unless shop replaced original with another plastic guide. Is that possible for a timing chain to go 240,000!!??

When I looked back through my service records, I found the techs notes from the previous fix- "Dist gear support hole needs to be honed; Dist seized in hole; tech honed dist. support hole; replaced drive gear."

I believe that either the distributor seized up in the hole again or the distributor froze up due to oiling channels getting clogged. The truck has 240,000 and this was the original distributor. The previous time problem occurred was 185,000, so the techs fix worked for almost 60,000 miles

I have sourced a good used OEM distributor and am waiting for distributor drive gear. But this does not solve the problem of the Dist. support hole. Talking to a guy at the local machine shop he suggested finding a bushing that fits the distributor and honing out the support hole to fit the bushing. Seems crazy to have to get a replacement head just to address the issue of the support hole!

This sounds like an effective fix to me, what do you all think?

 

Depends just what kind of price your quoted a new loaded head could very well be cheaper.

 

Fully assembled head from Enginebldr is $ 348 plus shipping to AK. Either way I needed replacement distributor. $65 from local pick and pull. $25 for distributor drive gear.

Bushing fix seems like it would come in substantially lower. The question I keep asking myself, have I correctly sourced the original problem!!??

 

I have the same problem on my 84 22R with 144,000 mi, any ideas on how to hone the hole in the head, access is tight. I really dont want to replace the head due to a seized dist. It seems like we would have to remove a lot of material to insert a bushing (brass?) I would much rather hone it if it would last longer than 60k. I am unsure why the dist support seized it appeared well oiled however the dist and the support hole seem to have shared some metal and seized up I wonder if this is due to wear of the gears putting extra load on the support hole? My dist is also original, anyone know of an affordable better than stock replacement?

 

Rust Bucket,

Here's what I ended up doing. We took the bad distributor and cut a lengthwise slot with a hacksaw on both sides, not deep at all. This created a mini edge to hone the hole. Then we inserted the shaft into the support hole and worked it round and round spinning the rotor. At first it was very stiff and would not insert very deeply but over time we honed down the burrs until it was moving freely and inserted all the way in easily. Make sure to oil the shaft to improve the process. It is essential to replace your distributor drive gear as well because if your diet. seized then it messed up the gears! I found mine on e bay for $25.

So far so good. Now I need to fix my oil pump oil leak!

 

Thanks for the tips, I had to use a pipe wrench on the end of the distributor to get it worked loose and out. Then I used a dremel honing attachment on an drill bit extender with some brasso on it to hone the hole. Slipped in the new dist. with the drive gear out to check the fit and it was good. Back in action!