Here is how you can tell easily.
Open the door, turn the key to position II. When the glow plugs shut down the dome light will get brighter. It usually takes 30~45 seconds.
On my 300SD, I would glow twice - start once when the temperatures went below 32f. On the SDL I did the afterglow modification so I full cycle glow once, glow twice, wait for the indicator light to go out and start. The glow plugs will keep glowing until they time out. This has really helped smooth out the engine now that the morning temps are in the teens...

In a way, I suppose.

I originally stated that my glow light goes out in about 10 seconds and the relay clicked off in another 30 seconds. I asked you how I could "just leave the gp circuit engaged for a TIMED 60 seconds" since my relay cuts the glow off at 30 seconds. I was thinking that I was only getting 40 seconds of glow and stated that I immediately switch off the key and restart the glow procedure to get more glow time before starting.

I didn't think it would be helpful to let my car sit for 20 seconds between glow cycles so that's why I was trying to work through all this with you guys. It turns out that I was correctly hearing the glow plug relay clicking and I am benefitting from my two glow cycles.

Hopefully this explains my intentions to you and you don't think I'm trying to be a smart-@ss.:)

I did not think that.. I just was not sure if you thought you were saying something different... which WOULD require the FSM smackdown procedures to be initiated...LOL

:beerchug: Cheers sir. I enjoyed our exchange and having a reason to open my complete set of FSMs.:D

http://www.peachparts.com/shopforum/...&pictureid=485

Stick around...you ,me and jt20 are in the minority around here... owning PAPER manuals ... and reading them... we could really be a force if we ganged up on unsuspecting people who are just making up their answers out of whole cloth...
LOLOL

HA! I'll start writing the credo.

First I never stated that the FSM was wrong, now did I? You are basically stating that the FSM spent millions of dollars on testing cars with 300,000 miles, then aren't you? Don't think so. :rolleyes:

I find it amusing how people know someone else is incorrect when they have never tried it themselves. Have you ever timed your glow plug relay?

The GLOW PLUG relay definitely kicks off at 33 seconds. I have the hood up and can hear the click coming from the glow plug relay box. NOT a light relay, not anywhere else. Try it yourself and see.

I have never tried letting it glow for 60 seconds before a start. So far this winter I have done one double glow at 30 seconds a glow (probably unecessary at the temp but did it anyways). I will try the stated method and see how it works on a cold start. Then next time I have the same temperature on a cold start I will try it with a double glow.

Can you point out where you got the impression the FSM advise was written for new cars only ?

The way I found out about the FSM recommendations was the first 50 degree morning I owned my 1981 Turbo Wagon...I knew it ran well... all I had to do was leave the glow plug on longer and it started down to very low temperatures.... but it did not start with when the glowplug light went off...

For the record, I just timed the glow plug relay on my 85TD. It was about 40 degrees outside and I had driven it to operating temperature about 2 hour prior. Relay stayed on 28 seconds.

By sound, or voltmeter / ammeter?

Sound and brightness of interior light.

OK. I promise to revive this thread on Thursday with my multimeter. I cant agree that that solution is effective.

It takes less energy to keep the plugs glowing once they are lit. The interior lights only show load on th battery.

What would show a definitive change in battery load 28 seconds into their glow cycle besides the glow cycle ending?

hard starting in winter reduced
 

I noticed you didn't mention the block heater. Don't you have one? Or don't you use it?

I started using mine this weekend and was amazed at the results.

I actually agree with you, Kerry. I have noticed the same thing, I am just an adherent to the scientific method.

Directly, I was trying to suggest that the load changes, or fades once the plugs have peaked at some temperature. It is the difference between acceleration and constant velocity.