78 300D Runnaway!! help - PeachParts Mercedes-Benz Forum

81kgb · #1 12-23-2009, 12:26 PM

i have been delegated to get a 78 300D running that has been sitting in a barn under 2 tarps for at least 15 years, i figure no problem, my better judgement tells me, dont try to start it, change fluids etc first, well i check the oil, its ok, way overfull, dunno why, but there was oil, put a batt in it, lights work, etc etc, turn the key to see how much fuel is in it and check to see if it will turn over, i wasnt paying attention to the fact that the glow plug light didnt seem to go out, so they had cycled for longer than needed. turn it over and the damn things starts right up, almost **** myself, belt was squeelin so i look under the hood, a c pump, ok go to get in to shut it off, away she goes,runnaway, smoke everywhere from the belts, luckily im a benz owner and know the stop lever well. and i think i reached it before catastophic failure,? my question, could the extremely high oil level be the reason, and possibly only reason for this runnaway? im assuming the owner would add oil just for ****s and giggles as the car was sitting all theses years, not knowing better, thinking he was doing good. HELP

toomany MBZ · #2 12-23-2009, 12:35 PM

I doubt too much oil would be the culprit, a problem with the fuel system is more likely, maybe linkage issues.

Codifex Maximus · #3 12-23-2009, 12:38 PM

Quote:

Originally Posted by 81kgb

i have been delegated to get a 78 300D running that has been sitting in a barn under 2 tarps for at least 15 years, i figure no problem, my better judgement tells me, dont try to start it, change fluids etc first, well i check the oil, its ok, way overfull, dunno why, but there was oil, put a batt in it, lights work, etc etc, turn the key to see how much fuel is in it and check to see if it will turn over, i wasnt paying attention to the fact that the glow plug light didnt seem to go out, so they had cycled for longer than needed. turn it over and the damn things starts right up, almost **** myself, belt was squeelin so i look under the hood, a c pump, ok go to get in to shut it off, away she goes,runnaway, smoke everywhere from the belts, luckily im a benz owner and know the stop lever well. and i think i reached it before catastophic failure,? my question, could the extremely high oil level be the reason, and possibly only reason for this runnaway? im assuming the owner would add oil just for ****s and giggles as the car was sitting all theses years, not knowing better, thinking he was doing good. HELP

Since you hit the STOP on the linkage, there is evidently some issue with the fuel delivery. If the car was smoking badly then I'd say the extra oil might be a factor but not the deciding one.

81kgb · #4 12-23-2009, 12:54 PM

Quote:

Originally Posted by Codifex Maximus

Since you hit the STOP on the linkage, there is evidently some issue with the fuel delivery. If the car was smoking badly then I'd say the extra oil might be a factor but not the deciding one.

i think all the smoke was from the a c pump being locked up and the belts running over a pulley that wouldnt move, plus it stunk like a belt,????

81kgb · #5 12-23-2009, 12:55 PM

what i didnt get..is that it was idleing for a min or two fine, i wasnt worried about the belts cus i assumed they would need changed anyways, so i was so in awe that it started, i just let it run for a min, and it rannaway?

BodhiBenz1987 · #6 12-23-2009, 01:11 PM

Quote:

Originally Posted by 81kgb

what i didnt get..is that it was idleing for a min or two fine, i wasnt worried about the belts cus i assumed they would need changed anyways, so i was so in awe that it started, i just let it run for a min, and it rannaway?

It could be the linkage, if you want to start with checking the simple things first. I had the spring pop off the back of the IP where it attaches to the linkage and had intermittent "running away," where the car would idle fine but if I hit the accelerator a bit it would suddenly race up to red line and stay there, until I hit the stop lever. If your stop lever is working, than it isn't running away soley on oil ... in that case it would keep running even after you shut the fuel off. However, definitely remove some oil and get it to the correct level. In fact, I'd just go ahead and do an oil change, filling with the correct level.

Impressive that it started ... hopefully some of these guys can help you get it back on the road!

81kgb · #7 12-23-2009, 01:39 PM

thank you very much everyone for the fast posts, i failed to mention all of this happened in the pitch black ohio dark, so i wasnt able to check springs, and was honestly a little shaken up and didnt think of it, but i do recall hitting the accelerator when i got back in it while it was running,awkward to get into after owning only a 126. and that is right before it started free revving, so you may be right! im gonna have a look today though, very impressive car, needs alotta sheet metal, but i think its worth it, only has 100 k on th clock! im just hoping to god its something simple

LUVMBDiesels · #8 12-23-2009, 02:09 PM

Just a second... by running away, do you mean it just would not shut off from the key or that it spun up to high revs and would not slow down?

From what you described it sounds like a typical shut off valve vacuum issue... Check the vacuum lines going to the valve on the IP.

If it was a true runaway the STOP lever would not do anything.

Just my 2 cents

81kgb · #9 12-23-2009, 02:17 PM

Quote:

Originally Posted by LUVMBDiesels

Just a second... by running away, do you mean it just would not shut off from the key or that it spun up to high revs and would not slow down?

From what you described it sounds like a typical shut off valve vacuum issue... Check the vacuum lines going to the valve on the IP.

If it was a true runaway the STOP lever would not do anything.

Just my 2 cents

honestly im not even sure if i used the key, i got so freeked out, cus the car isnt mine, but it just started free revving, red line, my 81 has a shutoff issue, it simply wont shutoff, this thing went crazy on me, and with the lever it wasnt wanting to shut down, i had to push the **** outa it, my car, press the lever, off it goes, this thing needed some force, but it did bring the revving down right away, just didnt want to shut off unless i pressed harder.

LUVMBDiesels · #10 12-23-2009, 02:38 PM

Sounds like what theother posters said -- linkages.

If the engine was running on the oil from the overfilled sump the lever would have been futile and the only way to stop the engine would have been to deny it air. Even if it revved up high the governor would keep it from doing damage. I bet the engine is fine. You probably need to take off each piece of linkage and soak the ends in trans fluid....

Diesel911 · #11 12-23-2009, 03:59 PM

Quote:

Originally Posted by 81kgb

i have been delegated to get a 78 300D running that has been sitting in a barn under 2 tarps for at least 15 years, i figure no problem, my better judgement tells me, dont try to start it, change fluids etc first, well i check the oil, its ok, way overfull, dunno why, but there was oil, put a batt in it, lights work, etc etc, turn the key to see how much fuel is in it and check to see if it will turn over, i wasnt paying attention to the fact that the glow plug light didnt seem to go out, so they had cycled for longer than needed. turn it over and the damn things starts right up, almost **** myself, belt was squeelin so i look under the hood, a c pump, ok go to get in to shut it off, away she goes,runnaway, smoke everywhere from the belts, luckily im a benz owner and know the stop lever well. and i think i reached it before catastophic failure,? my question, could the extremely high oil level be the reason, and possibly only reason for this runnaway? im assuming the owner would add oil just for ****s and giggles as the car was sitting all theses years, not knowing better, thinking he was doing good. HELP

A Stationary “Italian Tune-up”!

81kgb · #12 12-24-2009, 01:08 PM

i still havent had the chance to look into it, the holidays have me running like crazy, i just wish i could do it in my benz, but the fact that i live in ohio makes me not want to ruin my first year body style 81 126, thats perfect. so im s o l, so im hoping to check into it tomm or the day aft, you people have been wonderful, and im thinking that you guys are right, like i said i just kinda lost it, cus the car isnt mine, and the orig owner passed away and his son wants me to get it running and try my hand at doing the sheet metal.

brownrice78 · #13 12-24-2009, 03:12 PM

I would cut the AC belt off. You could always replace it later if you want.