Where can I find one? I havent the foggiest idea of how its done, I've only owned a gas car once and never had to change the spark plugs on it so I dont even have a reference point.

Tony

And before someone mentions it I DID search the forums for a good guide, I did not find one.

I have it, but I have no doubt it is missing valuable tips.

Try the Haynes manual for the W123 Diesels.

__________________
2001 Dodge Ram 2500 Cummins Turbo Diesel - 4x4, auto, 3.54 gears, long bed
-------------------------------------
'92 300D 2.5 Turbodiesel - sold
'83 300D Turbodiesel - 4 speed manual/2.88 diff - sold
'87 300D Turbodiesel - sold
'82 300D Turbodiesel - sold

Hi Tony,

This is an easy job, made tricky only because there is plumbing in the way.

Your glowplugs are a couple inches long, threaded to seat in the head of the engine. Attached to the exterior end of the plugs is a current wire. On mine (1985) there is one wire attached with a 8mm nut if I recall. You take off the electrical connection, then using a deep socket or box wrench (12 mm on mine) you unscrew the glow plug itself. Take old one out, put new one back in, re-attach current source.

If they are difficult to remove because of deposits, you should ream the opening with a special tool. But if it comes out, the new ones should go back in.

It is easier than sparkplugs, because there is nothing that has to be done to the plugs. It is challenging because there is a bunch of plumbing RIGHT UP NEXT TO the plugs. If you have a 1/4" socket set (with extension and wobbler) and a set of metricd wrenches, you should be able to figure it out. If you have big hands, find out who has removed the plumbing, and listen to them. Either way is not a hard job. The good news is that they should be good for a while once you're done.

Good luck. Get a manual, they're good to have, but this job ain't one you need a manual for!

Peter
1985 300TD

__________________
Peter
1985 300TD 4-speed 212K
1992 400E 343K
2001 E320 72K

Ok I will be sure to follow what you said. I have the haynes manual, btw. (some reason my reply to him was put in as if I posted before he replied)

I'll let you know how it goes.

Hey guys and gals,

Glow plugs are easy in theory but a knuckle buster in practice. You can get it done without taking off the fuel lines but I will never do it that way again. Removing the fuel lines and and covering the injectors with plastic will prevent foreign bodies from getting in there. Place the spider web in a clean surface and cover also. Putting them back on is not that hard you just have to be gentle and not force it into place. I was suprised when I changed out my injectors that the spiderweb was not hard to deal with. If you do remove the web it is a good idea to change your fuel filters as you have to prime it again anyway. IF you elect to remove the web you will have much less obstruction and most likely save a couple of hours playing around with those glow plugs. Also change the 2 dollar fuse that is located in the glow plug relay, driver side under the hood beneath a black box.

Also allow your glow plug to glow for at least an eight count when starting, eventhough the light went out they are still on for about 15 to 30 seconds depending on the temp. A good glow plug gives easier starts which is great for your starter.

good luck

bob

PS I would not universally recommend taking off the spider web to anyone. If you have some mechanical game I would try. If not I would at least seek the support of someone who does. I would not want to screw up the fuel line. I did not have any trouble with it but that is not saying much. Maybe other folks can let us know how it went for them.

Without removing the fuel lines I would use a 12mm ratcheting "dogbone". It is still time consuming, but this way you don't fuel spilling all over the place. This is what I used on my SD. I have yet to change the plugs on my TD

__________________
1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

I don't understand why the fuel lines make glowplugs hard to access. Correct me if Im wrong (I bet I am) but the fuel lines are 5 small metal lines running a short distance on the driver side of the engine from the (injectors??) to the glow plugs (??). There are 5 injectors (??) and 5 glow plugs.

If thats true the fuel lines arent in the way on my car.

Anthony,

I think you may be confusing the injectors with the glow plugs.

The glow plugs are underneath the injectors and are not connected with metal fuel lines. They are connected with electrical wire, which energizes them.

Take a closer look.

__________________
Ed
1981 300CD (Benzina)
1968 250 S (Gina) 266,000 miles!
1983 Alfa Romeo GTV6 (Guido)
1976 Jaguar XJS-saved a V-12 from the chevy curse, what a great engine!
1988 Cadillac Eldorado (better car than you might think!)
1988 Yamaha Venture (better than a Wing!)
1977 Suzuki GS750B
1976 Yamaha XS 650 (sold)
1991 Suzuki GSX1100G (Shafty Gixser)
1981 Yamaha VX920RH (Euro "Virago")
Solex Moped
1975 Dodge P/U camper


"Time spent in the company of a cat, a beer, and this forum, is not time wasted!"

Hi all,

I changed my glow plugs last night. I had been having a hard time starting the car and finally metered the glow plugs by using a multimeter on the lowest resistance setting, connecting one lead to ground and the other to each connector on the glow plug relay connector. WITH THE SWITCH OFF. At least 2 showed infinite resistance (open).

It was a pain in the butt. I did not remove the injector lines. The socket sizes are indeed 8mm for the nut that secures the wire and 12mm for the glow plug itself. I had a 1/4 inch drive regular socket set and the plug would push the ratchet out. Got a deep set but they would not fit in the tight spots. Had to use an open end wrench which I immediately and repeatedly dropped down in between the injector pump and engine. Definitely get one of those dogbones mentioned previously. That will make a world of difference and should cut you beer consumption in half.

I changed 4 of the 5 and will change the last one (near firewall) after I purchase a different wrench or more beer. Starts right up!!

On my 300SD the glow plugs are below the injectors. The glow plug relay is on the front of the driver's side wheel well hump. Black plastic box. You can turn the key to the glow position and wait about 30 seconds and you will hear it click back off. You can follow the wires from the box to the glow plugs.

Hope this helps.

Matt

__________________
Matt Camara
'83 300SD
'85 Celica
'98 Harley Springer Softail

There is a special tool for this job which you can get from Mercedes. It's made by Hazet and basically it's a 12mm deep socket with a ball swivel built right in. Makes the job a cinch.

__________________
Regards,
Aaron