Glow plug module connection issues
 

Wanted to get some advice.

I replaced the glow plug module on my '87 300 TD a few years back - but it seems like every year once it starts getting cold I have a short right there at the two wiring plugs connecting to the glow plug module - and hence no glow plug firing. I am assuming this is just oxidation on the wiring connectors.

I am pretty sure last time I used some dielectric grease when I put the wiring connectors back on the module - but it just seems strange to me that this seems to happen every year when it starts to get cold. The glow plug module cover is a little bit of a nuisance to get off - and getting it off to take the connectors off and on to get the car to start is also a nuisance.

Is this sort of thing expected with a 25 year old vehicle - or should be looking at replacing the wiring connectors or something?

Thanks!

I suspect that thermal contraction in the cooler weather is perhaps giving you the issue. You are wise to use any dielectric grease so it probably is not corrosion. I always use it on any car electrics when working on them. I really hate to revisit the same problem area again someday.

I would get a couple of the plugs off a wreck if you cannot retension the current contacts. Or creativly use aluminium foil with dielectric to tighen the connections in some form of creative way. Poor connections or less than optimum may continually degrade if high current is flowing as well.

The cycle till troublesome may just be circumstantial as well. The corrosion may have spread back up into an area of the connector where you cannot see it may also be another possibility. Especially in the area of the wire to prong junction. I might get it running temporarily and take my thermal gun to see if there is some form of abnormal elevated temperature when curent is flowing. In otherwords an unfound or unrepaired high resistance connection.

it could be the dialectric grease causing a short; you have to be real careful with that if there's more than one pin/connector. i don't like to use it at all

I suspect rather than short he is developing an open. I could be wrong. As far as I know a silicone based grease is probably the best bet for a dielectric application. I try to stay away from anything that might attack plastic. Also living this far north in the rustbelt connections can be more troublesome.