The weakest link?


New member
Hamilton, ON
Solenoid comparison.jpg
Last winter, 25 C below freezing, three feet of fresh Canadian Snow, and for the first time, I could not start the FLU 419... No click from this solenoid. I decided it had froze inside, and spent 2 hours thawing it out with a combination of a plumbing torch and a camping infrared propane heater placed in the footwell. After much heat, and liberally applying WD-40 and PB blaster, it finally resumed operation as usual, and as long as the engine was warmed up, or last summer when it was warm out, it would function almost every time, or no click a couple of times and then clang back into place. It seems moisture will always find a way in either past the O-ring or through the crimp on the back. First good freeze up this year, and I had a return of the same problem.
I have pulled it in 3rd high gear with a one ton chevy in order to bump start it, but it was definitely not ideal, and it's not always parked in a way that allows for it. I once parked it on a barn hill, thinking that I could get it rolling and bump start it, but it would take a long steep hill to get this Mog moving anywhere near fast enough, and I would have to tow it there with the one ton anyways.. So a Mog that won't start has a weak link. This solenoid. pictured on the bottom in the photo above.
Pictured on the top, is a Bosch 24V solenoid with almost the same part #, that I found a limited supply of NOS(new old stock) at an industrial warehouse nearby. Differences between the Original, and the Industrial, are;
1. the connections at the back are not compatible for a direct swap. (I will try decrimping the industrial one and removing it to see if that will be possible in the future should the magnet coils ever fail in the original.)
2. the return spring inside the industrial one is way stiffer and has a bronze bullet slider inside it. I will be sticking with the original spring, but maybe the heavier spring would be better at reducing wear on the gear teeth? Or even preventing a possible stuck on starter situation? I have had this happen on old cars once the gears got worn, bolts got loose, and even with a new chinese gear on a rebuilt starter once.
3. the plunger has 4 slots in it, and 4 UHMW sliders that fit loosely in the slots. The plunger does not contact the inner walls, and has some additional clearance that is taken up by the sliders.
4. The industrial one did not come with an O-ring, and the original is due for replacement.
5. The industrial one has bolts in the housing, and I have not yet removed them to see if they are threaded the same as the original.
My solution is to use the Industrial plunger, and leave the rest as Original. I will liberally coat it with WD-40, lube it up with Lithium spray grease, and use a new O-ring.
If anyone would like to have the same for their FLU-419, message me directly, (pm) and I should be able to ship just the plungers from as many as I can find, (20-30 available for sure) for about 50 bucks apiece. A new Original solenoid is anywhere from 90-250 online, plus shipping, and will eventually fail in the same manner.
FLU-419's have many failure points of course, and please start new threads for each one, after arguing about which one is the true weakest link here ;-)Solenoid plunger.jpg
What you would get for the 50 bucks, in order to save on shipping. If you want the entire NOS industrial solenoid, Let me know your ZIP and I will get a shipping estimate due to the increases size and weight.
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