my old nemesis: another gummed up distributor

[dlb]

For the third time in my life, I have run into a stuck mechanical advance on a Tercel distributor. This one was working fine when I did a bunch of work on the car about a year ago (I have always checked for spring-loaded advance on them since my first experience with this) but over time I started noticing the engine pinging more under certain conditions. I had been careful about setting the timing when I installed the distributor but figured I must have messed something up so yesterday I finally got around to checking it. Even with the vacuum advance disconnected and plugged, the timing was way advanced. I tried retarding the timing but the furthest back it would go was 15* BTDC. I was baffled that I could have put the distributor in one tooth off but again figured I must have so I took it out, retarded it a tooth, tried timing it again, and now it was too retarded -- the furthest forward I could go wasn't even 0*.

That's when I finally checked for spring-loaded advance at the rotor, and bingo. It was frozen solid, worse than the previous ones I've come across. I removed it again, tore it down and tried a few things to get the base of the rotor where the grease is (I don't know what these parts are actually called) apart so I could clean the old grease out. I remember really wrestling with this in past and chewing things up pretty badly in the process so I wanted to be smarter about it this time. I removed the plastic spacer things on the weights and used a small torch to apply heat to the rotor base thing, I thought that would warm the old grease up and it would pop right off but nope, even after several attempts at this it didn't help much. I found the best thing at first was to simply use a screw driver to pry the rotor thing back and forth. This was really difficult at first but slowly got a bit easier (but always took some umph). Then I held the distributor with the rotor end pointing downward and sprayed penetrant (I'm currently using Sea Foam Deep Creep) at it's base, and held it like that for a while to let the penetrant run into the old grease/problem area. Work it back and forth, more penetrant, repeat ad nauseum. Eventually it didn't need quite as much effort to work it back and forth but it still wouldn't budge when I tried to pull it off with vice grips, so I stuck a small-ish flat blade screw driver between the two parts at the base of the rotor thing and twisted the screwdriver a bunch to push the rotor thing off. Had to rotate the rotor around and get the other side, back and forth. Finally started seeing movement, was able to start using a big flat black screwdriver, and finally after about 2 hours of all this, it came apart.

This was last night so I only had time to clean off the old grease and re-grease it (I used some really old all purpose grease my dad gave me years ago, I think the stuff is from the 70's) and put the rotor thing back on before I had to call it quits for the day. Gonna go finish that now but wanted to document it here so I can reference it in the future, and also as a warning for everyone with running issues to make sure their mechanical advance is operating smoothly. I think that's 3 out of 11 or 12 distributors I have come across with this problem so I'm surprised other people haven't run into it more.

[NWMO]

Thanks David, that’s something to keep in mind.

Chris

[Petros]

David,

it is considered normal maintenance to re-grease the mechanical advance as part of a tune up procedure. if it is kept moving freely with penetrating oil, and an occasional clean and grease refresh, it should never get stuck like yours. I believe this is in the FSM as part of a regular service. when ever I have the distributor cap off I always test the mechanic advance for free movement, and spray penetrating oil on it. I suspect if you did this regularly, it would never require so much effort to get it freely moving again

[dlb]

David,

it is considered normal maintenance to re-grease the mechanical advance as part of a tune up procedure. if it is kept moving freely with penetrating oil, and an occasional clean and grease refresh, it should never get stuck like yours. I believe this is in the FSM as part of a regular service. when ever I have the distributor cap off I always test the mechanic advance for free movement, and spray penetrating oil on it. I suspect if you did this regularly, it would never require so much effort to get it freely moving again

I feel like you don't even read half what other people write sometimes, Peter.

1, I think you missed the part where I mentioned that this is the third distributor I have come across with a gummed up advance. This isn't me neglecting regular maintenance on vehicles I have been driving for years, these are cars and distributors that come to me either already with this problem or well on their way to it. And that's why I posted about it, because if I've come across it three times myself, I'm sure there must be lots of other distributors out there with the same problem.

2, I don't think I did THAT bad a job describing what I was working on but I'll clarify anyway: I looked it up and the part I am talking about removing and re-greasing is called the signal rotor shaft, and it is part of the mechanical advance system. Here it is in the FSM.

srs.jpg

The signal rotor shaft sits on top of top of a another shaft (which is not shown in that pic), and the grease that gums up is found in between this shaft and the signal rotor shaft. Even with disassembling the distributor, there is no good or easy way to get penetrating oil between these part (I described the best way I have found to do that in my previous post here) so I'm not sure which part or are you're talking about oiling but I don't believe it's the signal rotor shaft.

[Paul]

I never gave this much thought before I saw this post. I think I'll pull the rotor off and take a peek behind the grease stopper.

20240406_144721.jpg

[dlb]

I never gave this much thought before I saw this post. I think I'll pull the rotor off and take a peek behind the grease stopper.

As long as you can rotate the rotor counter clockwise a little bit and it snaps back to position, it's ok. And unfortunately even once you remove the grease stopper and screw, you can't access the grease between the signal rotor shaft and the shaft it sits on without removing the whole dang thing.