Alternator pulley destruction (1 Viewer)

[dcruiser666]

Had a pretty terrifying breakdown yesterday and curious if anyone has experienced this before. Was driving on the highway when what’s displayed in the image occurred. Started with a loud pop and then dash lights coming on. I was able to shut the engine down by disconnecting the battery, because it wouldn’t respond to the key.

Couple questions

What's the probable cause of a pulley ending up like this? The alternator is a denso 100amp that was rebuilt a couple months ago (poor rebuild job, belt tension too tight, wrong pulley size?)

The temperature rose to just below the red before I got it shut down. The engine ran for 3 minutes at most after the incident. Is it possible that any overheating related damage could have occurred during this time? Haven’t restarted since, but there was no obvious signs of overheating like steam or coolant boiling out everywhere.

What’s the best way to shut the engine down in an emergency like this? Much more familiar with the OM616 which has a manual shutoff lever w/"STOP" printed on it and it would not shut off by disconnecting the battery. Is there something like this on an 89 3b2 (no edic)? Pressing the throttle lever backwards did not shut it off and If the terminal had been tighter I don't know how I would have shut it down without pulling off a fuel line - I don't think Toyota would have designed this engine with those as the best options for emergency manual shutdown.

 

[CharlesHS]

With the picture you posted above..... I can imagine the alternator bearing(s) ceasing up; the power of the crank shaft continuing to drive the belt destroying the alternator pulley which ended up looking like that...
A pair of vise grips pinching down on the rubber fuel line should stop the engine.

 

[coldtaco]

just stall the engine. when you are stopped put it in gear and let the clutch out fast, make sure there is nothing in front of you to hit first

 

[dcruiser666]

Thanks, both good ideas. I’ll keep a set of vice grips in the glove box from now on too, In case I don’t have room to stall. Regarding the bearing seizure, that sounds logical to me. I’ll have to check out the alternator again to see if there is evidence of that. Could I fault this to the rebuilder? Trying to decide if I should fight for a refund.

 

[AndrewHadji]

I would think you could put a in line manual valve that you could shut off after the fuel filter. This wont help you if you are turbo and runaway condition happens, only thing that will help you there is shutting down the airflow to the engine....

 

[dcruiser666]

I would think you could put a in line manual valve that you could shut off after the fuel filter. This wont help you if you are turbo and runaway condition happens, only thing that will help you there is shutting down the airflow to the engine....

That actually sounds like a fun mod to work on. Might go that route. It's not possible for a non-turbo to runaway? I never knew that.

 

[Nas90tdi]

Absolutely possible for a turbo or non turbo diesel to run away. Just more common with turbo because often the fuel source is blown turbo seals. Hope you never see it either. A true runaway is completely terrifying and nearly impossible to stop unless you have something to slap over the intake.
And, word of advice if you ever see one, don't try to put a rag or your hand near the intake. It will not stop it and is likely to do some serious damage to you. A board flat over the intake is about the only thing to stop a true runaway. I have heard a fire extinguisher aimed at the intake will kill one, but never seen it.

 

[CRSWA]

Wait a minute... An engine can continue to run away even when the fuel is cut off? How is that possible? What's fueling the combustion?

 

[dcruiser666]

Wait a minute... An engine can continue to run away even when the fuel is cut off? How is that possible? What's fueling the combustion?

I believe a runaway is caused by an uncontrolled unintentional fuel source getting in the combustion chamber like the vapor from heavy blow by recirculating through the breather. Basically a feedback loop. Blow by vapor might not be accurate though, it’s something along those lines. It’s always been my philosophy that if your engine gets to a runaway state, you’ve probably missed or ignored signs that it needs a rebuild. Don’t know if it can happen to a healthy engine.

EDIT, did a quick wiki search

"In many vehicles, a crankcase breather pipe feeds into the air intake to vent the crankcase without releasing raw hydrocarbon vapors into the atmosphere. In a highly worn engine, hot gases, including unburnt fuel can blow past the piston rings and into the crankcase. This creates an excess oil mist, which is then drawn from the crankcase into the air intake via the breather. A diesel engine will readily burn this oil mist as fuel, since engine oil has similar energy content and combustion properties as diesel fuel. The extra fuel causes the engine revolutions to increase, causing still more oil mist to be forced out of the crankcase and into the engine, and a positive feedback loop is created. The engine quickly reaches a point where it is generating so much fuel from its own crankcase oil that it can sustain operation even with the normal fuel supply shut off, and it will run faster and faster until it is destroyed "

 

[Nas90tdi]

Wiki is correct. A diesel will run on it's own oil and the problem is exponential. As it feeds, it build RPMs thereby pulling more oil equaling more RPMs and so on until it grenades.
Yes and no on the healthy engine. They can certainly do it from any any number of unforeseen events in an otherwise ok engine. But, letting things like turbo seals and crank ventilation get in a poor state will make it much more likely.
Mercedes has a couple of engines that if you put the fuel shut off in incorrectly it will run away on it's own diesel. And, the key does nothing because you put the shut off in incorrectly. It's a sort of tricky maneuver to seat it right. My nephew learned that one the hard way. Made a hell of a mess when it started spraying black sooty oil all over. I laughed for days at the pictures. He was covered and so was everything within 20 feet.

Watch some videos on YouTube. You will get the idea. Everything from our little trucks to a locomotive will run away. The big engines are really something to see.

 

[dcruiser666]

Sounds hilarious, hope he saved it. First time I did that replacement on a w123 a mechanic friend told to keep a phone book handy just in case.

So what about the heat? Last unanswered question, and I know it's a difficult one. I have luckily never experienced an overheating issue in any vehicle and am honestly still a little traumatized. I've yet to restart the truck as I'm waiting for the alternator replacement. Should I just put it back together, start it, and see if anything is unusual? Really just looking for the best course of action, in other words "what would you do?" This is a beautifully running motor and I don't want to overlook any possibly checks I could do.

Again, it did not quite make it to the no-no zone, 3 minutes max with no water pump. No smoke, no steam, no boiling, coolant is clean, but definitely hotter than it has ever been.

 

[coldtaco]

Maybe mention what engine you have? Since I for one don’t know.

 

[dcruiser666]

Maybe mention what engine you have? Since I for one don’t know.

Sorry, it’s in the first post, 89 3b2

 

[ALEXY]

I had a fuel cutoff between filter and IP. It does take 20-30 sec to stop the engine once you shut it, its not an instant stop.

 

[Nas90tdi]

Best guess is, you are fine. Obviously the only way to tell for sure is get it fixed and crank it. But, a couple of minutes of no water flow unless you were already pushing the engine hard is not likely to create any serious issues. If you weren't boiling the coolant already in the engine it is unlikely that you got the head hot enough to hurt anything.
Good luck with it.

 

[dcruiser666]

Best guess is, you are fine. Obviously the only way to tell for sure is get it fixed and crank it. But, a couple of minutes of no water flow unless you were already pushing the engine hard is not likely to create any serious issues. If you weren't boiling the coolant already in the engine it is unlikely that you got the head hot enough to hurt anything.
Good luck with it.

Thanks, new alternator comes today so I'll just put it together and start it up. Probably just being overly neurotic but feels like there is so much at stake with a healthy non-domestic Toyota diesel.

I also went with a new old stock 60amp for a 22r, I think 100 was overkill since there aren't any crazy accessories. I'll report back on fitment of the new one, I haven't seen any examples of people using this as a replacement.

 

[dcruiser666]

I had a fuel cutoff between filter and IP. It does take 20-30 sec to stop the engine once you shut it, its not an instant stop.

This doesn't sound ideal in an emergency. Have you heard of anyone installing a kill switch on the IP?