Hello all,

I need some help with my glowplug relay...I'm sure that it has been addressed before in this forum, but after checking many of the threads, I can't seem to find my particular problem...here goes...

When cold, I turn the key and the relay turns-on lighting the glow light on the dash...I usually wait until I hear the relay shut itself off... 30 seconds. Then I try a start. It runs smoothly for about 10 seconds and then begins to miss and run rough...very rough....lots of smoke. Not wanting to run the engine for fear of damage, I shut off the engine.

Then I try the same technique again, but the relay shuts itself down in just a few seconds...not the 30 seconds or so like the first start, but in just a few seconds...

I'm sure that a new glowplug relay would probably solve the problem, but the reason I drive a Diesel is because I'm so thrifty (cheap).

I've read the threads on the "Violet Wire", but have yet to try that method. And it may not help because the relay shuts down so quickly on the second try.

Any thoughts?

Thanks,
The Tenor Man

After is starts on the first try, quickly bring the rpm's up to 1500 and hold it there. The roughness should abate quickly due to the higher rpm and greater heat produced.

The '86 can do the same thing on occasion...........as if it drops a cylinder for 10 seconds or so............don't shut it off..........raise the rpm's.

The coldest I have ever been in is about 10 degrees. I found that letting it run through one complete cycle and then starting when the light goes out on the 2nd cycle to be the most comfortable way for me to start. I am not a fan of RPM higher than idle until the engine has warmed. I don't drive off until the heater is making the cabin comfy. I don't see the point especially in diesels as there is no power when they are cold.

It might be you have a bad GP, I would check them to be sure.

What I have stated is my opinion and what I do. I have no scientific basis to suggest what I am doing is correct or someone else suggest is wrong. It is what to me is logical.

__________________
1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it

The diesel is not a fan of running at idle. It has poor combustion characteristics and leads to excess carbon production due to the low combustion temperatures.

Although the engine is down on power, it'll warm significantly faster if you drive the vehicle gently for the first five minutes.

Operating above idle when cold (below 2000 rpm) has no negative effect on the engine.

Sounds like the glowplugs aren't as effective as they used to be.

The "violet wire fix" should solve your problem. Sounds like when the engine starts, the idle won't generate enough heat to keep the cylinders hot and firing. On the other hand, the cycle will still end and GPs extinguish when the relay times out, ... on a cold day this will likely not be enough to maintain a smooth idle and you'll have to rev it a bit first.
How cold is it when this happens? Where are you?

The owner's manual states that you should bring the RPMs up until the engine runs smoothly, as long as you have normal oil pressure a high-idle with no load is going to cause significantly less wear than carbon fouling the rings and washing the cylinder wall oil down with un-burned fuel while idling.

I find myself resisting the standard RTFM response to these, since many responses from loving and knowledgable owners seem to not know the procedure that is stated in the glovebox manual, ... does anyone read these anymore?

__________________

Gone to the dark side

- Jeff

..........ROTF.........


Yep, I'm saving that one..........RTFM

Question is, does anyone HAVE these anymore?

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

And....by what was stated by another....."that you should bring the RPMs up until the engine runs smoothly, as long as you have normal oil pressure a high-idle with no load is going to cause significantly less wear than carbon fouling the rings and washing the cylinder wall oil down with un-burned fuel while idling......."

It seems that over the years WHAT MB says to do has changed. I have the manual for an 80 and 83 and it says no such thing. I realize the original post was from a different year and I don't have that info.

My 83 says...

"Ambient Temperature below 0 C/ +32 F
Depress accelerator pedal to the floor. Turn key in steering lock clockwise to the stop. Release key only when the engine is firing regularly and back off accelerator slowly"

It adds to the sequence.. if lower than -18 C / 0 F depress accelerator 3 times.

In my case both engines run smoothly at start-up and idle without issue. That was not the case when I bought them.

__________________
1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it

I can't remember exactly but I think the manual in my '90 says the same, so the procedure for the 60x is the same. However, I've never needed to do that on my 602. It fires right up on all five when the glow light goes out, even at 15 degrees, the coldest I've had to start it (it doesn't get cold in western WA). The diesel clack is noticeably louder when the engine is cold, but after a mile or two of warming it subsides to the normal sound.

If my GP's are not working (did a little experiment last week), it just plain won't start if temps are in the 40's. I did get it to start without GP's (with a good amount of protest) last summer, but that's when it was 80 out.

__________________
Dale

http://i52.photobucket.com/albums/g1...MG_2277sig.jpg

1990 300D 2.5 Turbo -155k
2000 E430 - 103k
2014 Jeep Grand Cherokee Ecodiesel 4x4 - 11k
2014 VW Passat TDI SE - 7k Bro's Diesel
2006 E320 CDI - 128k Pop's Benz

Pre-glow - A moment of silence in honor of Rudolph Diesel

Thanks to all for the speedy replies...

I live in Western PA, and I generally have the problem when the temperature drops to 20-25 degress F.

Above 30, I never have a problem with the rough starts. My glow plugs haven't been changed in over 5 years. I'll probably check them over the weekend.

The relay is more than likely the problem...the second glowing has been getting shorter and shorter.

Thanks,

The Tenor Man

You might check then the coolant temperature sensor, I believe that is a factor in the glow-light time.

__________________

Gone to the dark side

- Jeff

Thanks to all who have replied...

As far as the coolant temperature sensor, I think my glow plug relay uses the ambient air temperature to regulate the amount of glowing time.

I don't usually drive this car during the winter, but this year I plan to. I think that I'll try this set-up:

http://***************/forum/showthread.php?t=398

I think the parts will cost about $200.

The 1987 300D has no afterglow built into the relay...and I'm sure that my relay is the orginal...and having to purchase a new relay anyway, the only additionl cost is the temperature sensor and some time.

I do have one question...can I use the exisiting glow plugs with the afterglow unit? I believe the plugs that are installed are the Bosch 80006.

Thanks again,
The Tenor Man