Hey All,

So the other day my glow plug fuse blew so I replaced it with a 50amp, it blew again, so I assumed I must have misread and replace it with an 80amp fuse. When it blew initially the glow plug fuse light turned off. Today the glow plug fuse light was off again, and I checked the fuse but it isn't blown, and the glow plugs aren't turning on. Any help would be really appreciated!

Does a 79 have the loop/filiment type glow plug system or the pencil type Glow Plugs?

You have not mentioned looking for a short circuit like on the wiring or connectors.

If you have the loop/filiment type glow plug it is possible for the short to be inside of the Glow Plug or due to carbon build up.

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84 300D, 82 Volvo 244Gl Diesel

Welcome to the forum! I've attached 2 links to our site's DIY tech articles on the glow plugs. Please let me know if you have any questions or if you need more details, post a Comment just below one of the articles and our master tech will get back to you with specifics. Hope this helps!

Mercedes-Benz W123 Glow Plug Replacement | 300TD 1977-1985 | Pelican Parts DIY Maintenance Article

Mercedes-Benz W123 Glow Plug Relay Replacement | 300TD 1977-1985 | Pelican Parts DIY Maintenance Article

If it has the loop type plugs, I'd replace them with pencil plugs. It's simple and they start much better with pencil plugs. You'll need the retrofit pencil plugs, not the standard pencil plugs. Threads on here with part numbers and instructions.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13