Run away 240D engine, very scary! - PeachParts Mercedes-Benz Forum

79-240d-project · #1 03-08-2004, 02:16 AM

What a day!

I replaced the vacuum shut off valve on the IP because the 240D would not shut off. I also rebuilt the the vacuum pump. After I got the valve's adjusted and put in the new radiator everything was ready to go.

After reading the mishaps of some of the forums other members with regards to the critical nature of the proper installation of the vacuum shut off valve I took the following precautions.

1. Left off the air cleaner assembly.
2. Had a phone book handy.
3. Had 17 mm wrenches at the ready.

I was very careful when I re-installed the vacuum shut off valve. I was sure I got it correct, espically after reading all the warnings. Please excuse the liberties in the terminoligy. I had the "L" in the shut off valve firmly seated in the notch in the rack of the IP(did I say that right?). I tested the new shut off valve with the hand held vacuum pump. Everything seemed ready to rock and roll.

Thank you know who for being paranoid. When I started the motor, you guessed it, it ran away. I was alone and as soon as I realized the beast had been released I jumped out of the car and slammed the phone book over the bare intake. The motor shut off quick. It only ran wild for a few seconds. Scared the #### out of me. After my heart stopped beating below 1000 bpm and I changed my shorts I started to look into the cause.

After a quick call to a very good man, the trouble shooting began. I rechecked my install of the shut off valve. It was in the slot. I noticed some strange behavior in the throttle linkage. It would not return to slow idle with the shut off valve installed as I imagined. Now this car, ran just fine, except it would not shut off when I bought it so I was very sure the IP was in fine shape. Something I had done cause this problem. My ace in the hole was a super mechanically smart friend of mine, a MB diesel die-hard. When he arrived we went thru much discussion and tried several things. With the phone book handy we had a couple of failures, none as wild as the first one, much easier with a second set of brains and hands. We removed the shut off valve and left it off and the engine ran just fine. The shut off valve install was cause of the problem. When the shut off valve was installed with the 'L' in the rack linkage the throttle linkage would not return to slow idle most of the time. When we installed the shut off valve with the 'L' forward of the rack, not in the slot, the engine ran and shut off just fine.

Did I miss something?

All input would greatly appreciated!

79-240d-project · #2 03-08-2004, 04:10 AM

Bump! Sorry, I think this one is important!

#3 03-08-2004, 08:39 AM

To keep this from happening next time when replacing the shut off, apply vacuum to it after installing and see that the stop lever moves when vacuum is applied.

I'm glad you saved your engine.

I now feel that by embarassing myself to death, maybe it saved someone elses engine. I assume that you read my post.

Have a great day,

kerry · #4 03-08-2004, 09:26 AM

For people reading on this topic, don't forget the post from last week which proved that you can stop a runaway MB engine by removing or cutting the fuel line. It's not necessary to loosen the injectors as has been discussed in the past when a quick move with a pair of sidecutters will solve the problem.

TomJ · #5 03-08-2004, 10:15 AM

Quote:

Originally posted by kerry edwards
For people reading on this topic, don't forget the post from last week which proved that you can stop a runaway MB engine by removing or cutting the fuel line. It's not necessary to loosen the injectors as has been discussed in the past when a quick move with a pair of sidecutters will solve the problem.

From what I've heard, there's enough fuel in the IP and injectors lines to destroy an engine, so not sure if cutting the fuel line will do it? Don't know though, never had one run away, an hopefully..., learning from Larry's tearful experience, I won't!

BTW, maybe we should all start a fund that we donate to for Larry's destroyed engine. Every time we "almost" didn't check, or "almost" had a runaway, but we saved it because we remember Larry's caveats, we donate a few $'s???

kerry · #6 03-08-2004, 10:21 AM

The post last week proved the speculation about fuel in the IP incorrect. A member had his engine run away, he pulled off the fuel line and it stopped within 1 second.
I can't remember the title of the thread, but the poster was asking about turbo parts since his turbo flew apart when the engine ran away.

#7 03-08-2004, 02:31 PM

Since it takes over a thousand lbs of pressure behind an injector to make it release, I would think any disturbance in the line would stop fuel from making its way into the firing chamber.
Nice job stopping that engine. Another diesel saved.

#8 03-08-2004, 10:12 PM

The thousands of PSI is on the injector side, not the fuel infeed side. I don't know from first hand experience if pulling the soft line will work, but it has nothing to do with the thousands of PSI on the injector side.

I really wish that I could say from first hand experience that it worked.

Have a great day,

kerry · #9 03-08-2004, 10:41 PM

Larry:
I can't find the thread anymore from last week about the runaway engine and the broken turbo, but I know I did not imagine that thread. Perhaps it has been deleted but it definitely was a first hand account of the effectiveness of removing the fuel line to stop a runaway. It didn't save the turbo, but it saved the engine.

#10 03-08-2004, 11:05 PM

Another way to stop one of the silly things when it runs away is with a common shop tool that we all should have around. That would be a fire extinguisher, but not just any fire extinguisher it has to be a co2 one. They effectively kill the engine by starving it for air and as soon as the co2 clears away everything is back to normal. Beware! Do not do this with a dry powder extinguisher they WILL ruin the engine. It must be co2.
Hudson

79-240d-project · #11 03-08-2004, 11:12 PM

I still have the oddest feeling about this situation.

I was sure that the 'L' at the end of the shut off valve was supposed to fit in the notch in the rack. After reviewing lots of old posts on the subject, I was really sure I got it correct the first time.

I spent the day running the car, all is well but I still have that feeling.

One other thing I noticed was the tension spring for the throttle linkage on the firewall. I only have one and I was told I should have 2. Could this be related? Might the lack of the spring to return the throttle have caused the run away?

I was sure that the 'L' angle on the shut off valve was to be in the notch!

Anyone?

TomJ · #12 03-08-2004, 11:14 PM

Here's how to test. Easy.

Start your engine and pull the primary filter while it's running.

Worst you'll have to do is bleed the system to get it started again.

If the engine shuts down right away, then it should in a runaway.

If it takes a little time, it still could shut down the amount of flow it takes to keep a runaway going.

If it takes a LOT of time to run down, then it's probably a given that it'll blow before the fuel runs out.

#13 03-08-2004, 11:47 PM

Here is the thread you are looking for.

#14 03-09-2004, 03:30 AM

I was not disputing the accuracy of the statement. I was only saying that unfortunately I cannot testify personally to this being a workable shutdown method. If I COULD, then I would not have lost the engine in my daughters car.

If I had a good running diesel, I would NOT rev it up just to try the method.

I still contend that if the air cleaner is not off the engine, having a 17MM open end in your hand is the best way to go.

If I only had it to do over again.

Have a great day,

Ken300D · #15 03-09-2004, 05:16 AM

I think you should be prepared to cut the line between the spin-on fuel filter and the injection pump. If you cut the fuel line at the pre-filter, then the engine still has the fuel supply in the big spin-on fuel filter.

You'll get more of a mess of diesel fuel because the fuel pump will still be able to pump fuel through the spin-on filter. But the engine should stop sooner.

Ken300D