I just got a 300SD with 202 thousand miles. Its a great car. I love driving it, expecially on road trips. Just today I couldn't get the engine to start, so I am learning as much as I can about what might have caused the problem.

First off, I put RoadMaster XL premium diesel fuel from cenex (Fuel Info Link) into it last week. Does anyone know what additives are harmful for the diesel engine? The manuel mentions that the trap-oxidizer could be damaged by certain additives, but the local dealer didn't know which additives could cause that. Perhaps this is the issue.

Does anyone know how to drain water out of the fuel line? We just had a rainstorm here in Missoula, MT and it might have gotten into the fuel line. Could this be a possible culprit, preventing the engine from starting? My dad, who I got the car from, thought so but I didn't find anything about draining the fuel line in the manuel.

Lastly, I have read a lot about glow-plugs going bad. I noticed yesterday that the pre-glow lamp wasn't coming on unless I turned the key off and on a couple times. It started fine then, BUT now it will not start, even though the pre-glow lamp is operating normally.

Just can't get the engine to fire. Oh, and it is a warm summer day outside, so the air temp is not a problem.

Any adivce is helpful. Love the car! Glad to meet some people with similar interests.

-Travis

I dont think that your additive has much to do with it.

Its probably bad glow plugs, search here and you will find lots of info on testing glowplugs easily.

It may be water in your fuel line, but if this is the case you may have ruined your Injection Pump

How do you think you got water in your lines?

I was guessing that water might have condensed in the fuel line... but that is just what my dad thought had happened. I am really just guessing. He said you could drain the fuel system to get the water out, but that might not be something I should mess with.

I do not beleive that there could ever be enough condensation inside of your tank (or lines for that matter) that could ever amount to enough to make your car not start...

Anyway, how would moisture from the air condense into the fuel if there is no air in the lines? or are they open to open air?

I would say test your glowplug system. Also, make sure your battery is charged and your starter is turning over fast enough to start the car.

You need to test your glowplugs, for this you need an ohmmeter or multimeter if you have more than 1 ohm of resistance or no resistance you need to change that gp.

Use the search feature, it helps a lot!

Listen to Sady and check the glowplugs first. Don't blame the Cenex Roadmaster Premium fuel. I've been burning it for years. It's good fuel. Does your Cenex fuel come from Laurel, MT? Mine does. All I add to the Roadmaster is 2oz. of Howe's fuel conditioner every fill. Twice I made 30 mpg. with my 83 using Cenex and Howe's.

__________________
1983 300-D turbo
1985 300-D turbo
1959 Harley Panhead chopper
1929 Ford coupe restored
I hang out with Boneheaddoctor at Schuman Automotive OBK#5
All liberals are mattoids but not all mattoids are liberal.

Wow, awesome. Yea I am in Missoula, so that fuel is striaght out of Laurel.

Reading more on the forums has me thinking that I might have fried the starter by trying to turn it over for too long.. but only after I test all the glowplugs will I know for sure.

It looks like if the glowplugs are OK, then I should charge the battery and if it still won't start I should look into putting in a new starter.

Thanks!

-Travis

85 300SD 202,000 miles

Whoa, slow down there! M-B diesel starters are quite rugged and hard to kill.
Well, charge the battery. Don't be so quick to blame the starter UNLESS it is turing over really slow even with a fully-charged battery.

There could be other issues, such as air in the fuel system due to a primer pump. Working this problem one step at a time is a lot less expensive than throwing parts at it.

The pre-glow lamp may come on with one 'bad' GP. With two it probably won't. Your original symptom was a 'funny' GP light, work that problem first!

Test the glow plugs and let us know what you find.

Best Regards,
Jim

After you have checked your glow plugs, and if that was the problem, your next step IMHO would be to address the trap oxidizer issue. Do a search on trap oxidizer and read all the posts. Then you call MB and give them the vin#. Ask them if they have repaired the thing.

__________________
1983 300-D turbo
1985 300-D turbo
1959 Harley Panhead chopper
1929 Ford coupe restored
I hang out with Boneheaddoctor at Schuman Automotive OBK#5
All liberals are mattoids but not all mattoids are liberal.

OK I checked the plugs with a multimeter and three out of five are showing infinite resistence at 200K. There is the problem, which explains why it is not starting.

Currently doing some searches to see how to replace the glowplugs while I wait for the Haynes manuel to come in the mail. If anyone knows of a pretty good thread on glowplug changing for an 85' 300SD that would be grand

Other than that, I will just make sure the battery has a full charge and then give it a whirl after changing the plugs.

-Travis

Don't replace just the bad ones, put them all in. You will save time, labor, and money in the long run. Save the good ones for spares to use in a pinch.

__________________
1983 300-D turbo
1985 300-D turbo
1959 Harley Panhead chopper
1929 Ford coupe restored
I hang out with Boneheaddoctor at Schuman Automotive OBK#5
All liberals are mattoids but not all mattoids are liberal.

valve adjusted OK? you go boy!

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD

sounds like you have a problem, i'm sure there are a few people here who would be gladly take your car off of your hands for you

On a serious note, I would check the battery, starter, and glow plugs. Also make sure your battery cables are in good condition...

Yes having only 2 of 5 functional GPs can produce hard starting.

See 'Sticky' thread #7 (DIY Pages) at the top of this forum, and follow the link in Post #4 for Glow Plug Testing and Removal. It is a W123 basis, but same engine as you have.

Basically, if you can change a spark plug, you can change a glow plug.

Best Regards,
Jim

Interesting update....

OK so I changed all 5 glow plugs and the engine started like a champion. Victory! For now at least. But there is a problem.

I tested the resistence again with really similar results, meaning that three out of five of the wires are still showing a 1 (infinite) resistence when I test them. The other two are showing under 20Ohms, so that is fine. But could the wires from the controller to the plugs be corroded? What would cause three out of five of the plugs to still show no resistence?

Also my car is an 85' 300sd, so I BELIEVE (although I might be wrong) that my plugs are parallel and not in a series. The number 1 and number 3 are the ones that work, all the plugs on the left side of the controller test infinite.

Any ideas?

-Travis

They are parallel, and each wire/plug combo should test less than 1 ohm (but not 0). Otherwise, you may have a broken wire(s) issue.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.