Changed CDR valve and now trouble...

[Rupert8]

Hello,

I recently posted a separate thread regarding changing out the CDR valve on my 1986 F250 6.9. Job done, and the truck ran fine yesterday, ran very well, even, with the new CDR valve installed.

I went to start it this afternoon and it turned over for a long time and just wouldn't start. Weird, because this truck always fires right up. On the fourth attempt, after letting the starter cool off and with my foot down on the gas pedal it finally started but then ran at crazy RPMs until I cut it off with the key.

It did this twice.

Since the only variable here is the new CDR valve, could this be the culprit of a) not starting and b) super high revs once going?

If so how would this work? My understanding of the CDR valve is patchy.

Would my starting it with the gas pedal depressed cause it to run at high RPMs even after my foot is off the pedal?

And is there a chance that the engine will runaway if I try to start it again? If so, what is the best way of stopping it? Do these 6.9s have a fuel cutoff switch?

That truck was loud in all it's fury...

Thanks as always.

 

[Rupert8]

Ok. This is embarrassing.

Rechecking under the hood, I found a vacuum hose had somehow gotten stuck under the throttle assembly, holding it open, and making the truck rev. A lot.

Thing is, humiliating as this is to write, I have no idea how it got under there. I didn't go under the hood after I drove it yesterday, when it ran fine. So it clearly wasn't under there then. It is one of the hoses that clips to the side of the air filter housing, I guess I didn't secure it well. But it wasn't causing any problems yesterday, which is the puzzling thing.

So the high RPMs are explained. And I'm guessing this was also not helping with the rough start, either. Although I'm not sure why. (As a learning opportunity, any ideas?)

So, moderators - perhaps this thread is a candidate for deletion since it is panic-posting clutter. Or perhaps it serves as a warning to others: Watch vacuum hoses near the throttle. And double check before posting on Oil Burners.

(I'm still curious how to stop a runaway 6.9, in case I'm ever in that situation...)

 

[XOLATEM]

Whenever I had a diesel that would not stop with the key or by disconnecting the power wire to the fuel shut off valve I would ball up a shop rag and stuff it into the air intake....

You cut off the air...

With these larger diesels...you would need something bigger than just one shop rag...probably a bunch of them or an old after-shower towel.

Maybe you have an old bud lite beach towel that you no longer care about...

 

[Rdnck84_03]

The fastest and only guaranteed method to stop a runaway is to block the intake.

Cutting the fuel supply will only shut it down if the runaway is caused by the injector pump.

If it is caused by unmetered oil from a bad turbo seal or a malfunctioning cdr, the engine could still be running away with the injector pump not even on the engine.

James

 

[SkylabTech86IDI]

Whenever I had a diesel that would not stop with the key or by disconnecting the power wire to the fuel shut off valve I would ball up a shop rag and stuff it into the air intake....

You cut off the air...

With these larger diesels...you would need something bigger than just one shop rag...probably a bunch of them or an old after-shower towel.

Maybe you have an old bud lite beach towel that you no longer care about...

I’ve heard of people using a block of wood trimmed down to size

 

[Rupert8]

Fascinating. So we are talking about removing the air filter and blocking the air intake at that location? (All done while the engine is running very fast?)

 

[Rdnck84_03]

I would yank the intake tube and stuff a shirt or jacket in the filter intake first, may not shut it completely down depending on how airtight the housing is but should definitely slow it down considerably. Thankfully I haven't had to shutdown a runaway yet.

James

 

[Old Goat]

I read years ago, a Halon Fire Extinguisher would shut down a run away. Probably has been band.

CO2 would shut one down.


Goat

 

[Brian VT]

I read years ago, a Halon Fire Extinguisher would shut down a run away. Probably has been band.

CO2 would shut one down.


Goat

I wonder if a Chimfex would work.

Chimfex®

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[Greenie]

Here's my runaway diesel story... My day off, my assistant with an small inmate crew is cutting trees and winching them out with a farmi winch on a 35 HP Kubota tractor. The inmate knew better but winched a tree at a 45 degree angle to the tractor. Tractor tips over and starts screaming - black smoke. They shut off the key. They disconnect the battery - still running until it used all the motor oil it could burn. We get the tractor back on its wheels, fill it with oil and cautiously start it. It runs normal. Twenty hours or so we drain the oil and have a sample analyzed by Blackstone - comes back fine. That was 15 years ago and that Kubota tractor is still running to this day. It's never needed any motor work and doesn't make any funny noises. That one incident really sold me on Kubota motors.
I would not shoot anything down the yap of a runaway diesel. The air cleaner would need to come off and heavy canvas or something that will seal around the hold down tap would work best.

 

[KansasIDI]

Only times, I’ve ever been around a runaway diesel, was one time there was a train on fire, that apparently had run away, of course I was not involved in that, but, out on a job in Wyoming, the client, had an old Mack dump truck. Probably built in the 60s, maybe 50s. Unsure what engine it had. Not in great shape. Well he was hauling rock with it, and when we pulled up to the jobsite in the pickup, he hopped out of his dump truck to come talk to us. Well just about as soon as he slammed the door, the thing revved up faster than I’ve ever heard any engine rev up, and really damn high, crap loads of smoke, and we all kinda just stood there like a bunch of dumb dogs for a couple seconds, then without any words said, we grabbed coats and tried to shove them into the air intake. Kept a screamin. Eventually quit it when we cut the fuel line. Key didn’t shut it off. Well after he worked on it for about an hour then he tried to fire it back up. Spun slow, but when it fired up it went right to redline and then made a noise kinda like an angle grinder, only way louder, and died. Punched a hole in the cylinder, clear through the block. Almost a perfect square. Never heard of an engine doin that… but then again, engine failures can be bizarre. Never figured out why it did that all in the first place… too bad…

 

[XOLATEM]

That one incident really sold me on Kubota motors.

In my humble opinion, they are ok...a lot of stuff seems to be powered by them...it is just the using of aluminum for a rear axle housing that I would never spend big bucks for...

...especially if you plan on pushing salty snow with it...had to free up too many things attached to and dependent on the housing not being crudded up...

I have to have good 'ol iron for my axle housings...adds weight and durability to the back end of a tractor...

Have you guys ever seen a Ford 5000 from the back...? Those things have a back end that you just wanna slap....

Have a look...you'll see what I mean...

On the runaway engine thing...I saw an orange tractor...fairly new...but I think that the engine had been freshly rebuilt...and the mechanic had plumbed something not quite right...

Well...it was sitting outside the shop and running and all of a sudden ran away...that thing became enveloped with smoke so bad you could not figure out which end was which so finding the air cleaner housing was impossible...

It quit when it had no more engine oil to burn...

They took it back apart and...best I remember...( I did not want to make a big thing about finding out the details why it ran off to begin with...the guy was embarrassed enough...)...the engine was fine...no damage...

Like I said...in my opinion...kubota engines are ok...I just prefer something else for my equipment.

I will never buy one...work on them..? Ok...but spend money on them...MY hard-earned money..? Hell, no....

 

[Rupert8]

These runaway engines tales are like the best bedtime stories.

And my takeaway from all of these is to cut the air supply in the case of one happening. Small chance of it happening, but valuable knowledge.

 

[XOLATEM]

I would yank the intake tube and stuff a shirt or jacket in the filter intake first,

I wonder if anyone has any shredded shirt or jacket stories to add to to this discussion...?

You know how clothes fads come and go..?

Wearing a shirt or jacket that has experienced a runaway event may just be seen as a diesel lovers badge of honor...?

 

[Rdnck84_03]

Don't have any from shutting down a runaway diesel, I did however wear a carhartt coat for several years that had some interest burn marks on it.

Had a friends dad back around 03 that bought 3 67-72 ford trucks in a package deal, the 67 was drivable but he wanted to get the other 2 running so he could sell them to more or less pay for the cost of all of them.

Anyway we decided to tackle the best condition of the other two, no idea how long they had been sitting. Probably 10 plus years. Everything seemed to look usable so we decided to give it a little gas down the carb to see what we had.

It was sputtering and trying to run, after several attempts with small amounts of fuel he decided to dump a little more in it ( probably about 2" worth in the bottom of a cutoff beer can). This attempt it started for a split second and coughed the entire amount burning gas out on top of the intake.

The only thing I could find close to smother it with was my brand new coat.

James