Mercedes-Benz Forum banner

1 - 11 of 11 Posts

·
Registered
'79 300TD - '74 Triumph Spitfire, '86 Alfa GTV6 & Spider
Joined
·
24 Posts
Discussion Starter #1
I had the last couple days off from work, so I spent some quality time with Trudie, my '79 300TD.

First up was to adjust the throttle and transmission linkage. It was WAAAAY off! I don't think I was even getting 3/4 throttle. Followed the online FSM instructions, not too bad a job, just a little head scratching figuring our exactly which setup I had and where things are. I did find that printing it out helped a lot, the pictures are better on paper than on the pdf onscreen.

Second was fixing the fuel level sender. It only worked somewhat from 1/3 of a tank down, and the low fule light didn't work. Hardest part was finding a socket that would unscrew the thing. No getting channel-locks on it in a wagon, the access is through a hole in the floor. Took it out, cleaned the guck off the bottom enough to get the screw on the bottom off, and openned it up. YUCK! Obviously the car was stored all that time with only a third of a tank of fuel - the bottom third of the shaft was shiny, the top two-thirds was NASTY. Furred up with rust to the point that the float couldn't go up and down. I had to use a screwdriver as a scrapper to clean it off so the float could go up and down. Then it was just a matter of cleaning up the lower contacts for the low fuel light and the channels in the bottom disk. Works fine now.

Next was replacing all the underhood fuel lines, replacing the primer pump and upgrading to the new style, and doing a diesel purge from a temp tank. This all went well too - not too much smoke while doing the purge, but she seems to idle noticably smoother. Changed out both fuel filters after.

Last was upgrading the glow plugs to the pencil type, and adjusting the valves. Glow plugs came right out, and I had no trouble using my shiny new way-too-expensive reamer. Probably should have saved my money on that, very little carbon came out. I packed the flutes with grease to catch it, which worked well. Valves were pretty good, only two exhaust and two intakes were tight. I did have a hard time adjusting one of the intakes, I think the valve was spinning with the locknut, but I got it eventually. Not too bad a job, a bit hard on the back!

The payoff for all this is that Trudie feels like a new car! Starting is now instant, and I would say she accelerates as hard starting off in second as she used to with kickdown to first, and the transmission shifts correctly now. No more winding way up in each gear under light throttle. 75mph on the highway is now very easy to maintain, even up hills.

Tomorrow's fun it to upgrade to the new-style fast glow relay and change the oil.

-Kevin
Trudie - '79 300TD 121K miles
 

·
Banned
2003 Mercedes S430
Joined
·
806 Posts
Nice work! I must agree with you that the carbon reamer is too expensive and, in the end, a waste of time. The better approach is to remove the glow plug (which you are going to do anyway), remove the injector and then pull the pre-combustion chamber.

Once that is out, you can decarbonize the entire, and I mean ENTIRE, assy in a few minutes.

That's the only way to fly.
 

·
Registered
2013 MINI Copper S Clubman, '84 300CD-weekend car
Joined
·
10,152 Posts
^ You don't know you have little carbon until you check, do you have a specific tool to remove the pre-chamber? Don't forget, new heat shields too.
 

·
Banned
2003 Mercedes S430
Joined
·
806 Posts
Yes, I have all of the Mercedes diesel tools in the shop from the 70s to current designs. Pulling the prechamber is the only way to go.

The reamer does, in my opinion, very little and does not address the core issues if you have carbon buildup. There is no way to clean out the flame holes unless you remove the prechamber. If you have that much carbon buildup, then you have to address that or the reamer, and time spent, is folly.

Yes, always replace the heat shields, they are cheap.
 

·
Registered
1982 300D 275,xxx
Joined
·
55 Posts
Yes, I have all of the Mercedes diesel tools in the shop from the 70s to current designs. Pulling the prechamber is the only way to go.

The reamer does, in my opinion, very little and does not address the core issues if you have carbon buildup. There is no way to clean out the flame holes unless you remove the prechamber. If you have that much carbon buildup, then you have to address that or the reamer, and time spent, is folly.

Yes, always replace the heat shields, they are cheap.
Do you rent out tools? I'm going to be doing my lower control arms in the near future and will need to rent or borrow the correct spring compressor.:bowdown:
 

·
Registered
'79 300TD - '74 Triumph Spitfire, '86 Alfa GTV6 & Spider
Joined
·
24 Posts
Discussion Starter #10
Nice work! I must agree with you that the carbon reamer is too expensive and, in the end, a waste of time. The better approach is to remove the glow plug (which you are going to do anyway), remove the injector and then pull the pre-combustion chamber.

Once that is out, you can decarbonize the entire, and I mean ENTIRE, assy in a few minutes.

That's the only way to fly.
Well, on an engine with only 120K that is running beautifully, I am loath to take quite that much apart. If I too had a shop full of MB special tools I might be more tempted, but I sure am not going to make that investment at this point.

My problem is my garage has 1 Mercedes, 1 Triumph, 2 Alfas, and one modern Saab in it, too darned many special tools already! I do 95%+ of my own work. I sub out tires, alignments, and anything that needs more specialized knowledge than I feel I can teach myself. And I don't do paintwork that needs to be pretty. DIY is the only way I can afford my little fleet!

If anyone would like to see some pics, go here: Flickr: kevinr1916's Photostream

Cars past and present. Anything that says for sale is gone - need to clean that up!

-Kevin
 
1 - 11 of 11 Posts
Top