My weird to me glow plug situation . . . - Page 2 - PeachParts Mercedes-Benz Forum

Shawn T. W. · #16 09-29-2009, 12:53 PM

Quote:

Originally Posted by Biodiesel300TD

I've never had luck testing the resistance to tell if they were any good. I always pull them and give'm 12v on the bench and see if they glow bright orange or not. NOTE: they get REALLY hot so be carefull when handling them after glowing.

Usually a faulty GP light is the sign of bad glow plugs. I'd pull each one and bench test it.

I'll test hem when I get them out, it they glow cherry, than I'll keep them for a spare . . .

tangofox007 · #17 09-29-2009, 01:17 PM

Quote:

Originally Posted by fruitcakesa

If the glow plug light comes on normally does that necessarily indicate that all the glow plugs are working? Or can it light even with a bad plug?

The light is controlled by a relay which measures the balance of the current to the #1 glow plug versus the combined current to the remaining plugs. Except for the #1 plug, it is possible that one failed plug will not be detected. According to the FSM, the failure of the #1 plug or any two other plugs is guaranteed to provide a proper light indication.

Shawn T. W. · #18 09-29-2009, 02:11 PM

Quote:

Originally Posted by tangofox007

The light is controlled by a relay which measures the balance of the current to the #1 glow plug versus the combined current to the remaining plugs. Except for the #1 plug, it is possible that one failed plug will not be detected. According to the FSM, the failure of the #1 plug or any two other plugs is guaranteed to provide a proper light indication.

Hmmmm . . .that kinda makes sense, but on my setup, I'd think it was #4, not #1, as 1-3 seem all connected together in the relay harness . . .

Read my original post . . . could it be differnt on the 240/616?

Shawn T. W. · #19 10-01-2009, 08:35 AM

Very HAPPY with QUICK service from Phil, I got my package yesterday! So Friday I need to make time to get this done.

Shawn T. W. · #20 10-02-2009, 09:57 PM

I didn't have much time today . . . while cleaning up the backyard I discovered the main water line from my meter to the house was leaking . . . !

I did manage to take out #4 plug and hooked it to 12 volts, . . . nothing, hooked up a new Beru, RED HOT! So I put in the Beru, and hooked it up, started up better, light stayed on for a bit . . . was 84 degrees out by then, and car had already run down to the hardware store . . . I drove it to the school where I work, and took the old plug apart, and drilled it out to 9/32" (which is .28125") I measured the plug before I butchered it so I'd know how long to make it, I decided to end up with an extra 1/16" in length, and flat ground the end, welded the other end, (got a bit hot . . .

)

But this is what it looks like . . . I was surprised how dirty the "new" plug was in the 60 miles I had driven . . .

Greased it up . . .

Reamed it out, went in with a little resisnance, I had to wiggle it a little before the threads could engage, I got it all but the last thread in by hand, then used a wrench for the last bit . . .

I decided to clean off the reamer, and regrease, and do it again to see if any more would come out . . .

Tomorrow I hope to do the other three . . .

fruitcakesa · #21 10-02-2009, 10:20 PM

That looks like it does a good job. I will have to add it to my winter project list. My 81 needs the GP's checked as it is not starting as quickly as before.

Shawn T. W. · #22 10-02-2009, 10:25 PM

Only took me about 15 min to make, not counting driving down there . . . after that I drove up to "town" for groceries . . . 27 mi oneway . . .

Shawn T. W. · #23 10-03-2009, 09:23 PM

I got the other 3 reamed out today the old ones glowed red, but I'll keep them for spares, and I put in the new ones.

Works GREAT Now!

unkl300d · #24 10-03-2009, 09:35 PM

Hey Shawn was your relay OK??

I lived with a relay that was causing my glow plug light to flicker periodically for years.
Finally my glow plug fuses started to burn up. My plugs had to be replaced because one went bad, but later I had to replace the relay.

Now its perfect.

bobodaclown · #25 10-03-2009, 11:34 PM

Did you remember to put some anti-seize compound on the threads?

Shawn T. W. · #26 10-04-2009, 08:32 AM

Quote:

Originally Posted by unkl300d

Hey Shawn was your relay OK??

I lived with a relay that was causing my glow plug light to flicker periodically for years.
Finally my glow plug fuses started to burn up. My plugs had to be replaced because one went bad, but later I had to replace the relay.

Now its perfect.

Yes, Relay was/is good, Thanks!

Shawn T. W. · #27 10-04-2009, 08:39 AM

Quote:

Originally Posted by bobodaclown

Did you remember to put some anti-seize compound on the threads?

No, The old ones came out with my fingers after I initially lossened them, turned my reamer in by hand, when they stopped, I put a wrench on it, and only got another 1/6th of a turn!

I have a cast iron head . . .steel threads on the glowplugs . . .

kerry · #28 10-04-2009, 10:09 AM

You got a lot less carbon on the reamer than I got when I reamed my 116. Reaming improved cold weather starts for me (below 10 degrees).

Shawn T. W. · #29 10-04-2009, 04:19 PM

Quote:

Originally Posted by kerry

You got a lot less carbon on the reamer than I got when I reamed my 116. Reaming improved cold weather starts for me (below 10 degrees).

We don't usually get that cold . . .

shopstone · #30 02-10-2010, 07:06 PM

I've got an '84 300SD and my car straight up won't start. It turns over, but the GP light doesn't ever go on. Someone told me to see if the fuse was blown, but I really don't know what that looks like. Is the fuse anywhere on the relay (would it be one of the parts in that top pic)?