M119 distributor related issues

[link]

One of my cars has had a long term problem. In brief if let to sit for several days it started okay and ran sort of okay for about 10 minutes then ran terribly thereafter, with a pronounced miss and hesitation on accelleration below about 2000 rpm. I’ve taken it to 3 places and none have provided a useful solution, but all have charged me for their disservice.

I did a bunch of reading about this kind of problem with the M119 and decided to have a look myself. I pulled the distributor caps. Haven’t done anything like this in 20+ years.

The driver’s side distributor was visibly pristine. All appeared fairly new and shiny and in great shape.

The distributor cap on the passenger’s side had a bunch of fractures and, in addition, the rotor was shot. Using my ohm meter on the rotor I found there was zero conductivity between the center of the rotor conductor and output conductor. The inside of the passenger side distributor was filthy and there was some sticky residue on the inside of the distributor cap.

In addition to above, each distributor of the M119 has what is called a dust cap. This is the rear portion of the distributor and is dirt insulator but also primarily an electrical insulator. I read that this can wear and develop tiny fractures (the car is 20+ years old), and as a result it will allow current to pass through and short the cap. The dust cap also has an O ring that compresses against the distributor cap.

I completely cleaned the inside of the distributor areas with isopropyl alcohol and lint free cloths, then replaced both of the dust caps and and O rings. Surprise – the dirty one had large crease in the O ring.

After replacing the parts, the engine has started fine and runs better than it has in years. I’ve let it sit for a few days and it still starts and runs fine after that. This is a huge improvement.

Could the previous rotor have failed in a day or two and caused the other problems noted above? I didn’t find any debris on the inside of the cap but I have no idea if the forces inside the cap could have melted the rotor and caused the sticky residue and other crap inside the cap.

Given that the plugs connected to this distributor have been receiving a lot less than typical voltage, for quite some time, would you replace the plugs (all 8 that is) or will they clean themselves?

TIA

[Ferdman]

link, I would replace both distributor caps, both rotors, all spark plugs and the ignition wires also, especially if they are 20 years old.

You need to find a shop with skilled techs to service your vehicles. Difficult to believe that 3 shops could not diagnose/locate the problem with your engine.