Sheared Distributor/ aux shaft gears

[Farmerrye]

hello friends,

305k on this old 1988.. we have been through a lot in a short time..... bad electrical, mysterious timing belt incidents, seized belt tensioners, and now the latest.. the distributor gears were sheared off on one side and the rotor wont turn. i replaced the dizzy tree and ran it for 50 miles then snap! the dizzy gear is eaten up (not as bad as previously) so i took it out and said a prayer and put it back in and turned the engine over to TDC and the rotor was catching. i put the cap on and reset the wires and nada. im assuming the aux shaft gears are done for..... i will pull the dizzy again and inspect the gears but im assuming they are too far gone .... I did some research about the causes then proceeded to get lost in the debate over oil pumps/strainers/screens, gear materials, and mods to the dizzy to get more oil in there.

not sure where to begin, i know there are some 2.3 at the local boneyard but i would like to have some what of a plan before going into it... any thoughts from you guys??

thanks

ryan

 

[Mark_88]

Well...I think the only way to tell what you need is to actually pull the engine remove the pan and have a look. I'm sure if you drained the oil and dragged a magnet through it you'd come up with plenty of metal shards...but that only tells you some of what you already know.

There may be bearings or excessive wear in the shaft that you could only determine from the tear down and look see...

I've had a distributor gear shear before...which was partially due to the lock pin from what the mechanic told me...but never had the auxiliary shaft lock up.

Can you turn the aux gear by hand with the timing belt removed or is it locked up now?

 

[tomw]

I think I would check the pump for hangups first. The load is mostly pump, not turning the distributor rotor & 'shutter'. Verify by rotating the distributor shaft by hand, removed from the vehicle. If good, smooth bearings, not 'catches', check the pump.
You can use a 6-point socket to rotate the oil pump shaft. Be sure to affix the socket to the extension so it won't go for an oil bath. If it does, it won't hurt anything rolling around in the pan as it for sure won't fit through the pickup screen.
One would think that the oil pump should be the best-lubricated thing in the engine. I do. That's why I suspect something else.
On to the aux shaft. I would want to check it for free rotation. Then put the distributor in place, and check for 'lash' by rotating the aux shaft back and forth. Note the degrees of rotation before the distributor rotor starts to turn. It should not be much.
You can pull the aux shaft and check the bearing and journal condition. All the above should rotate smoothly and freely. In addition, the aux shaft should not be able to be wobbled up and down. If the 'rear' end of the aux shaft is movable, I think that would cause mis-mesh of the gear and possible jamming. But, would that cause the gear to shear? Break teeth, yes, but shear the pin? I dunno. Gotta think on that for a while.
If you shear the roll pin that aligns the gear, you have a real bind occurring. In addition to the roll pin, the gear is a 'press fit' onto the distributor shaft. It is not easy to remove nor easy to install. It is really the friction of the press that holds it in place, I think, not the roll pin, given how hard it is to R & R from the shaft.
If you really want to know... do the engine pull & pan drop. Short of that, aux shaft inspection would be a first.
tom
tom

 

[Farmerrye]

I think I would check the pump for hangups first. The load is mostly pump, not turning the distributor rotor & 'shutter'. Verify by rotating the distributor shaft by hand, removed from the vehicle. If good, smooth bearings, not 'catches', check the pump.
You can use a 6-point socket to rotate the oil pump shaft. Be sure to affix the socket to the extension so it won't go for an oil bath. If it does, it won't hurt anything rolling around in the pan as it for sure won't fit through the pickup screen.
One would think that the oil pump should be the best-lubricated thing in the engine. I do. That's why I suspect something else.
On to the aux shaft. I would want to check it for free rotation. Then put the distributor in place, and check for 'lash' by rotating the aux shaft back and forth. Note the degrees of rotation before the distributor rotor starts to turn. It should not be much.
You can pull the aux shaft and check the bearing and journal condition. All the above should rotate smoothly and freely. In addition, the aux shaft should not be able to be wobbled up and down. If the 'rear' end of the aux shaft is movable, I think that would cause mis-mesh of the gear and possible jamming. But, would that cause the gear to shear? Break teeth, yes, but shear the pin? I dunno. Gotta think on that for a while.
If you shear the roll pin that aligns the gear, you have a real bind occurring. In addition to the roll pin, the gear is a 'press fit' onto the distributor shaft. It is not easy to remove nor easy to install. It is really the friction of the press that holds it in place, I think, not the roll pin, given how hard it is to R & R from the shaft.
If you really want to know... do the engine pull & pan drop. Short of that, aux shaft inspection would be a first.
tom
tom

thanks for the reply, the gears stayed on the distributor tree but are chewed up but the pin is not sheared. im hoping its just the gears on the aux shaft. also i dont think the aux shaft is binded be cause it still turns over. im gunna pull the timing belt off and spin the shaft by hand and verify the several tests on the the aux shaft u mentioned. hopefully i just need to pop a new aux shaft and new bronze? gear for the distributor. i think the oil pump is okay because when i pulled the dizzy the second time there was oil on it....
i can change the oil and see whats inside of it... ive been running cheap 10w-40 and probably synthetic before that.. lol is pulling an engine anything that anyone wants to do .

 

[Farmerrye]

I think I would check the pump for hangups first. The load is mostly pump, not turning the distributor rotor & 'shutter'. Verify by rotating the distributor shaft by hand, removed from the vehicle. If good, smooth bearings, not 'catches', check the pump.
You can use a 6-point socket to rotate the oil pump shaft. Be sure to affix the socket to the extension so it won't go for an oil bath. If it does, it won't hurt anything rolling around in the pan as it for sure won't fit through the pickup screen.
One would think that the oil pump should be the best-lubricated thing in the engine. I do. That's why I suspect something else.
On to the aux shaft. I would want to check it for free rotation. Then put the distributor in place, and check for 'lash' by rotating the aux shaft back and forth. Note the degrees of rotation before the distributor rotor starts to turn. It should not be much.
You can pull the aux shaft and check the bearing and journal condition. All the above should rotate smoothly and freely. In addition, the aux shaft should not be able to be wobbled up and down. If the 'rear' end of the aux shaft is movable, I think that would cause mis-mesh of the gear and possible jamming. But, would that cause the gear to shear? Break teeth, yes, but shear the pin? I dunno. Gotta think on that for a while.
If you shear the roll pin that aligns the gear, you have a real bind occurring. In addition to the roll pin, the gear is a 'press fit' onto the distributor shaft. It is not easy to remove nor easy to install. It is really the friction of the press that holds it in place, I think, not the roll pin, given how hard it is to R & R from the shaft.
If you really want to know... do the engine pull & pan drop. Short of that, aux shaft inspection would be a first.
tom
tom

So I loosened the bolt on the aux gear and am about to get a puller to get the gear off. The gear spins freely as long as the dizzy(with broken teeth) isn't in there. It also doesn't hVae much play up or down. Maybe <1/16 of wiggle. Is there as gasket back there i need to replace?

 

[tomw]

I believe a bolt holds the sprocket to the aux shaft. Remove the bolt and the sprocket can be pulled off. Behind should be a retainer that insures the shaft will not walk out the front of the engine, and behind that should be a seal to keep oil inside the crankcase and not drooling down the front of the engine. As far as I know, the seal and then the shaft should be pulled. Reverse for installation.
I would inspect the aux gears for problems. Look closely at the teeth for evidence of lack of lube, such as scoring on the sides of the teeth. Do the same for the remaining distributor gear teeth, to determine the cause of the double(triple?) failures. Something is definitely wrong. Check the fit of the distributor shaft at its end where it rides in a hole in the block, at the bottom. It should fit snugly, to keep the pairs of teeth meshed properly. If the distributor can flop around too much, the teeth can get into an interference position. The shaft will be kept pretty well aligned by the distributor, but a bit of motion is possible at the bottom end.
This problem is one that I have not seen or heard of before. Turning the distributor shaft by itself is not much load on the gears, adding the oil pump changes the amount of effort(torque) necessary. I would get a socket & extension, chuck it into an electric drill, or hand crank somehow, and turn the oil pump shaft trying to determine if there is damage. It doesn't make sense to me as the pump is the first thing lubed whenever the crankshaft, etc start to rotate. To my mind, 3 things can affect an oil pump. 1)deposits, 2)gear teeth wear, and 3) gear support shaft wear. How can it do that when oiled 100% of the time? I dunno. Deposits on the stationary shaft one gear rotates on could make the gear 'sticky', but I don't see that happening. Lost. I bet on aux shaft teeth wear or play in the aux shaft allowing 'mis-mesh' of the teeth.
tom

 

[Mark_88]

Personally, if it was my truck and my time...I'd suspect that the aux shaft is turning and otherwise functioning...but there may be foreign materials (like the chewed up teeth) in the oil that is somehow getting tossed back up into the shaft/gear and jamming it.

I recall that there was a bit of up/down slop in my distributor shaft that was normal...when the hold down bolt was not in place.

Once the hold-down bolt and U shaped hold down bracket was in place there was no movement in the distributor...at all...other than rotation.

If there is up/down motion then it is possible that the gears on the distributor would bind and being the lesser in strength compared to the aux shaft (not sure about that) would get chewed up.

When you tighten down the bracket for the distributor is there any up/down play at that point? Do you feel the bolt tighten and find it as tight when you loosen it or is there a possible thread issue with the hold down bolt itself?

I've had my alternator bracket literally ripped off the side of the engine because the bolts I was using were not the right ones...too short...and they were just grabbing by a thread or two and felt tight...the slightest force on the fan belt caused them to pull free...and there I was with no alternator...

Anyway...just reread your post and saw a few possibles...carry on!

 

[Farmerrye]

so i replaced the aux shaft and new dizzy and it happened again in 500 miles max. the only thing i can think of is metal scraps getting into the gears. or the oil pump failing. not sure. i cant locate the oil pump where is it?

thanks
ryan

 

[Farmerrye]

dizzy was tight and hodl down bolt was very tight, no movement up or down......

Personally, if it was my truck and my time...I'd suspect that the aux shaft is turning and otherwise functioning...but there may be foreign materials (like the chewed up teeth) in the oil that is somehow getting tossed back up into the shaft/gear and jamming it.

I recall that there was a bit of up/down slop in my distributor shaft that was normal...when the hold down bolt was not in place.

Once the hold-down bolt and U shaped hold down bracket was in place there was no movement in the distributor...at all...other than rotation.

If there is up/down motion then it is possible that the gears on the distributor would bind and being the lesser in strength compared to the aux shaft (not sure about that) would get chewed up.

When you tighten down the bracket for the distributor is there any up/down play at that point? Do you feel the bolt tighten and find it as tight when you loosen it or is there a possible thread issue with the hold down bolt itself?

I've had my alternator bracket literally ripped off the side of the engine because the bolts I was using were not the right ones...too short...and they were just grabbing by a thread or two and felt tight...the slightest force on the fan belt caused them to pull free...and there I was with no alternator...

Anyway...just reread your post and saw a few possibles...carry on!

 

[Mark_88]

so i replaced the aux shaft and new dizzy and it happened again in 500 miles max. the only thing i can think of is metal scraps getting into the gears. or the oil pump failing. not sure. i cant locate the oil pump where is it?

thanks
ryan

Sorry, didn't see read this one before replying to the other one...

Chunks of metal can certainly be causing the problem...changing the oil and running it through a screen will probably show you if that is what is causing it...or just a magnet in the oil will pick up any metal. I have one of those magnetic sticks that I've used for similar searches.