Two glow cycles required to start.
 

Hey everyone!

Just wondering, my 78 240 has a hard time starting on a "cold" engine. By cold I mean ambient temperature. The glow light works and I keep the key to 'on' for a total of 45sec. or so and then crank, but usually it dies right away and requires a new glow cycle. Could this be a glowplug, fuel, or much more serious problem?

Thank you

Could be a bad plug or poor compression.

How long does it take for the glow plug relay to open after the key is moved to the "run" position? (You should be able the hear the relay click open.)

tangofox,

I haven't really paid much attention to listen for the 'click' as the annoying buzzer is going off. Should I be able to hear it from the seat or should I have to move my ear toward the pedal area. The light coming on must mean the relay is opening no??

after 30 or so seconds you should be able to hear the click of the relay as it opens (turns off) you should have your seat belt on by then, thus turning off the buzzer...

If I don't hear an audible 'click' as the relay opens, which I don't remember hearing, what is at fault the relay?? The glow light does work.

Thanks again to all!

My relay does not click. It's more of a "thunk" like from a heavy sprung throw breaker.

Follow the dieselgiant.com tutorial for the W123 to test your GP circut.

Are you using the original loop style plugs or the upgraded pencil type?

They are the loop style by have been replaced by the PO last fall I believe.

when was the last time the valves were adjusted? it certainly helped my cold start problem on my 300D

There might be a fuel component to your issues.

I recently found out that my car is a lot harder to start on D#2 than B99. It takes a longer glow cycle and has more startup stumbling when started on D#2 than on B99. Found out when I went out of town for a week and filled it with D#2 because I thought it would be sitting undriven all week. Little did I know.. got reports from the wife about how difficult it was to start and how sometimes she had to start it twice before it'd stay going. :)

I'm sure the fuel isn't to blame for my starting issues, it must be exposing some other issue that I'll be tackling this summer. It is just an interesting data point.

Well, went to start the car tonight and it took 3 tries to get it running. According the the dieselgiant site, the relay is suppost to disengage when moved to start. I do not hear the relay click off while waiting for the glow cycle to complete. Could there be another problem causing like a dirty prefilter or secondary filter? Valves haven't been checked for adjustment yet. I hope to do the pencil style upgrade this summer, and wonder if anyone here has done it the same way dieselgiant has done it.

Does it seem logical that power would be cut to the glow plugs would be cut during start?

Remember, glow "cycles" do not help. your first attempt to start a diesel is going to be your best chance. crank that starter for up to 30 seconds let it cool for about 30 seconds and go back at it.

Check your compression, and make sure your valves are adjusted. check to see if your getting power to each plug as well.