Glow Plugs for 78 300D....

[TurboDawgs]

What do you recommend I replace these plugs with??? It has the standard glow system on it.. Pretty slow on cold days and right now I have to glow it about 3 times to start it.. Won't start in cold unless heater plugged in. This is a good running little car.. My Son dealed with our Mechanic to buy this car on his 12'th birthday.. Hopefully by the time he turns sixteen, it will still be running and he can drive it... Though he really wants the Jag...

I don't mind the slow glowing plugs at all..Just want something that is going to help her start..

[Luke]

Well.... Cold starting should not really be dependent on glow plug type, but engine condition, proper maintenance, proper winter fuel and oil (in EXTREME climates) and so on. That said, either plug style gets the prechambers as hot, but the pin style plugs heat them in less time. The loops have a reputation for being more robust. The rare series loop plug failure can be a bummer, though, since they are in SERIES, and when one fails: no glow. A parallel pin plug failure will at least leave you with some glow. The general consensus is that pin plugs have a higher - perhaps even routine - fail rate. I'll encourage you to do a search of this forum, key words "cold start" for a wealth of information on the matter from folks who live in really, really, cold places. I'm in northern California.

[coldwar]

I just got my '76 300D back from the shop last night- had my old series loop GP setup changed over to parallel 12V pencil (or pin) type. Incredible difference! Not only is glow time reduced from 45 sec to 10 sec, startup happens on the first crank. Right now we're having a "heatwave" (30 degrees F), so I'm waiting to find out what my new go / no-go temp is going to be (It was +20 F before- pretty bad). Keep in mind that the pencil GP's extend deeper into the pre-chamber, so there is a lot more glowing there for the fuel to hit.

I also found out there are some variations in wiring to do this conversion, depending on car. The fastglow kit sold on Fastlane would not be correct for a '76 300D according to Phil, so I opted for bypassing everything in the old setup and wiring all new from the keyswitch, through a generic relay activated by a pushbutton switch under the dash. I have to hold the button and count the seconds, then crank. (Mechanic did this for me- I'm not a DIY-er)

Also I do have a fastglow kit coming- courtesy of a kind member on this Forum as Fastlane doesn't ship outside the U.S. I'm in no hurry, but I could use this kit to eliminate my pushbutton by custom wiring the kit's relay. Phil was right- it's not a direct "plug in" for a '76, but I believe he said that it would be for the early W123's with series circuit.

The night and day difference I'm experiencing is also helped by the fact I had my valves adjusted too- they were too tight on 3 of the 5 cylinders. Still, I'm convinced the conversion to pencil type plugs is the way to glow. Even if they do have a higher failure rate, they're easy to check and replace, and not expensive.

Dave

1976 White 300D W115 "Pearl"

[coldwar]

Originally Posted by mespe

I have a feeling that your go/nogo temp will be about the same.

Our heatwave has ended- temperature this morning was +7 F. After sitting all night outdoors with no block heater, the car started first time after 15 seconds of glow. This is a tremendous improvement in my go / no-go temperature. I will grant you that the valve adjustment would be a big part of the improvement- the down side is that the car now has a lot less power. I'm wondering if the valves might be too loose now.

Dave

1975 White 300D W115 "Pearl"

[WANT '71 280SEL]

A '78 SD was the first to have the "new" pencil type plugs. Does the GP light flash for about 45 seconds after starting? If the light does then you have 1 GP out. If it doesn't come one at all, either you have 2 or more GP's out or the relay is bad. You know the valves have to be adjusted every 15k miles right? Where are you located at? What kind of ambient temps are we talking? 15F? -15F?
Thanks
David

EDIT: I see you're in Richmond, VA...Sorry.