If you've been having glow issues and just can't figure out what is wrong after testing everything and all seems good, try replacing your glow plug relay. I replaced all my plugs, redid a couple wires, proper voltage everywhere, good strip fuse, and it all seemed good, but just didn't work quite right. Symptoms were a slight stutter at start or difficult when very cold (running the full glow cycle a time or two), and the glow light would only go on for a couple tenths of a second.

This morning it was 20 something degrees out (maybe single digits overnight), no block heater, turned the key after the glow light turned off (what a feeling seeing that thing actually work for once) and it started right up. Purred like a big cat.

Oh the glory!

Oh yeah, and it's an afterglow relay.

__________________
B
-
1983 300SD

bbeardb,

Before I would replace my GP relay, I would analyze what the problem is. U were lucky that replacing the GP relay solved your problem. It could have been something else and U would have bought a new GP relay and it wouldn't have fixed your problem.

P E H

Hence the reason I said if everything else checks out and it still doesn't work quite right, replace it. According to all my tests, the thing should have been working, but alas, it was not.

__________________
B
-
1983 300SD

bbeardb,

Did U check the GP relay fuse? They have been to known to have a crack in them and conduct current intermittently.

Did the relay click when key was turned to the run position with engine shut off? Did the cabin light dim when the relay clicked (if it did).

P E H

Like I said and wrote in the original post, I checked everything. Relay strip fuse, check. Relay clicks off, check. Resistance checked at the glow plugs, checked, and replaced all 5 anyway. Checked power at fuse, check, but it was already checked, checked again. Checked power to all pins when on glow cycle, check. Check, check check. Everything tested out, expect the glow light would only briefly light up. Only thing that didn't check. So I replaced the relay.

Like I said, if everything seems to be working and you're still scratching your head, just get the new afterglow relay. Works so nice!

__________________
B
-
1983 300SD

bbeardb,

OK U checked, checked, checked. I'm glad U are happy with your new GP relay.

Better keep the old GP. Afterglow shortens the life of the GP.

I can get afterglow by turning the key switch on and off quickly. I use that trick once in a while when I start a very cold engine.

BTW, the GP indicator light has nothiing to do with the GP operating. Its only a timer and indicator of an open (burrned out) GP.

P E H

Obviously it was an indicator of a larger issue for me, as replacing the relay fixed all issues. Tangofox had the same bizarre issue, and he had the same results when replacing his relay: Functionality.

Don't understand the disbelief in the comments. All I'm trying to do is help someone out that might have the same head scratching issue. If everything appears as if it should be in order, but it's still not right, replace your relay.

Best $80 spent so far (beside the dealer alignment, but that was $130)

__________________
B
-
1983 300SD

I'm having the same types of issues. My new GP relay is on its way along with Diesel911's reamer. Did you use a reamer?

John

__________________
Certified Registered Nurse Anesthetist (CRNA)
2002 F250 powerstroke with Plantdrive WVO conversion
1983 300SD 190K miles ,sold
2006 E320 CDI

No, I didn't use a reamer. I would have if I had one, but I'm not sure it's entirely necessary. I think the majority of the people change them without reaming.

__________________
B
-
1983 300SD

bbeardb,

I Odn't pay much attention the GP indicator light.

One I have works all the time but for it stays on much too short a time and engine is hard to start unless I wait longer for GP to heat.

The other one is intermittent and sometimes comes on after engine has been running for a while. So I just ignore it and do my own estimate for how long the GP should be preglowed.

Again, I'm glad U are happy with your new GP relay.

P E H

FWIW, the FSM says reaming should be performed when GPs changed.

John

__________________
Certified Registered Nurse Anesthetist (CRNA)
2002 F250 powerstroke with Plantdrive WVO conversion
1983 300SD 190K miles ,sold
2006 E320 CDI

The one time I changed 'em out, no reaming. I understand that is to remove carbon build up, if any, so the plugs won't short out.

__________________
83 SD

84 CD