Is this normal glow plug wear for 8k miles?

[IDIDIDIhoDhoDhoDO]

I put motorcraft beru glow plugs in my truck when I first got it several years ago. I don't drive the truck much so I've only put about 8k miles on it since I've had it. The truck starts pretty good but lately it had gotten a little slower to start so I check the glow plugs. Cylinder 3 glow plug had infinite resistance, the others around 0.3 ohms. I put a new motorcraft beru plug in cylinder 3 today and the bad plug that I pulled out of there had pitting on the lower half of the heating element. I have read on this forum that having timing that is too far advanced can eat up glow plugs. If you look at the picture of the glow plug does that look like what is going on? That seems like it might be an excess amount of pitting for 8k miles. At that rate I can't see glow plugs lasting past 20k miles at best.

I have a ferret timing meter and I have set the timing at hot idle, with the cold advance off, to 10-10.5 degrees. Cold advance solenoid on is 12-12.5. I don't have a dial back timing light, just a basic one so I used timing tape on the harmonic dampener instead and it can be hard to get a very exact reading, also the timing becomes too erratic at around 1500 rpm with the ferret so I don't know what the timing actually is past that RPM. Also, where I am the altitude is almost 7000 feet so I felt pretty safe with a little extra timing advance.

What do you think? Is that a normal amount of erosion for a glow plug that is around 4 years old and with 8000 miles on it, or too much?

 

[Black dawg]

Not normal for 8k, but how many times has it been started in 4 years??

 

[IDIDIDIhoDhoDhoDO]

Glow plugs are on a push button so they don't get used for hot starts. For starts that use glow plugs, probably 4 times a week. So around 200 glow plug starts a year.

 

[gnathv]

Are you saying your timing is 10-10.5 at 1500 rpm?

 

[IDIDIDIhoDhoDhoDO]

No, the timing is 10-10.5 at idle. It is probably pretty close to that at 1500, it doesn't seem to move much as you rev it in neutral. But the timing procedure of setting the timing at 2000 rpm isn't really doable as it gets too erratic, I think it's the ferret meter pickup on the injector line that does that. If the condition of the glow plug being what it is isn't from over-advanced timing then I'm OK with the timing where it's at. The motor doesn't give off (what seems to me) too much rattle.

 

[The_Josh_Bear]

The only thing I've ever heard that eats quality GP's is advanced timing, though a few degrees shouldn't. (I'm sure nitrous or a crap ton of propane would do it too but that doesn't sound like your situation)

I do know that idle timing can be 3-5° different from 2k timing, so you may be more advanced than you think, but I really don't remember which way it swings.

If the reading is too jumpy at 2k then it sounds like the line isn't clean enough. You need to use sand paper or steel wool to shine that thing up a bit. Obviously the little clamp is tasked with sensing a very tiny change in space and needs all the help it can get. Also make sure you have a fresh 9v battery in the ferret! That tip really changed my life when it comes to timing these engines.

Point is, you're right to wonder about that kind of pitting/element loss. It's unusual.
To put that kind of wear in perspective the set that came with my pickup 120k and 15 years ago and the two sets I've used since then do not have that much wear. (I changed the middle set out prematurely and now it's a spare, they didn't wear out)