Great discussions here.
I’ve pulled quite a number mid ‘70’s zip starters apart recently and I've seen a few that people have “lubricated” these are fixable but work poorly. As has been said above, any oil, grease, silicone spray etc on the friction washers and the mechanism will perform poorly. The washers need to be clean and dry and any lubrication of other parts kept minimal so it doesn’t flow onto them.
Another problem is wear on pawls. The edges wear and are no longer able to bite into the starter cup. The pawls were originally cut from bar stock square across and barely deburred. The sharp corner of the square edge is what grabs the cup. Once this square edge rounds over you get significantly less grip. In addition some of the same over-lubrication that seems to have happened with the friction washers can flow onto the pawls and cup, further exacerbating grip issues.
I square up the edges on pawls to restore grip. On some of the older ones a file won’t work very well because they’re hardened, it just damages the file. If a file does work then the pawls are unlikely to have much longevity. I experimented with using a diamond plate sharpening stone to redress the pawls to a square edge and that’s slow but effective.
On the pawls that squared up with a file I heated them to red hot and dunked them in quenching oil before redressing with the diamond stone. I’m not sure this is a good idea as there’s now no rust proofing on them. They are, however, nice and hard. I should probably zinc plate them or do something for rust prevention.
I do lubricate the large starter spring. However, this is very sparingly. Some of these can have some surface rust so I treat the rust first and thoroughly dry the spring before soaking it overnight in monograde oil. I let the oil drip off and then wipe the spring dry of oil using a cotton cloth. The oil, however, penetrates the blued surface of the spring. This provides some ongoing lubrication and acts as a rust preventative while not encouraging dust to stick to it.
There is a large brass washer on the top of the assembly between the housing and spring. This is a wear component and on many of the older mowers has worn wafer thin, I’ve had a couple of accidental cuts from these when replacing them as they wear sharp around the edge. I smear a very thin layer of lithium grease on the bottom side of the replacement washer that faces the spring before assembly. It’s only a very small amount but I noticed on the best of the old starters that I pulled apart that there was a trace amount of lubricant on this surface and emulated that as it made sense to me.
I’m interested in how others approach the same issues.
Cheers
Ironbark
