2B just blew up. Why??

[jcolvin]

Ok, the 2B in my BJ41 just blew up . Hole in the crank-case with a rod sticking out, the whole sheBANG.

The tank had been filled with gas by persons unknown, which explains why it wouldn't start.

Drained the tank and lines as best we could (but not the fuel pump). Primed it, pulled off the injector lines (but not the injectors), cranked it a little till the lines were spurting, reconnected the injector lines, and she fired up a but but running very rough for only seconds at a time. Kept cranking her expecting it would run better once the fuel cleaned up, there was a large bang and there's a rod sticking out of the side of the crankcase .

I didn't know you could blow up an engine this way. Is it the gas that caused it? Should we have removed the injectors so there is no compression and cranked it a lot longer to get every bit of gas out of the system? What happened?? Has this ever happened before?

 

[rutbeer]

If I had to guess, let's say there was residual gasoline in the cylinder as it comes around on the compression stroke. The cylinder will reach gasoline detonation psi long before it hits the top of the stroke and max psi for diesel injection. You would basically be fighting the pistons upward movement. Just a guess though. I don't know how there would be that much gas vapor still in the cylinder though. Wow, that sucks. Sorry for you.

 

[mac]

Gasoline is much more volatile than diesel and if your combustion chamber is fed a pure dose of gasoline as opposed to a diesel/gas mix you can create a bomb. The gasoline does not "burn" as the diesel will, it "explodes" and it can do so well before the piston has reached TDC, so on the upstroke. This forces the piston and rod to retreat in the opposite direction regardless of what the crank is doing. If your bottom end is the least bit weak, somethings gonna break. This doesn't usually happen when people put gas in a diesel because there is usually enough diesel to quell the mix resulting in only a poor running engine. But, it can happen- it's not the 1st time.

 

[crushers]

hummm, so the connecting rod broke...
so i am wondering wher it broke. both replys makes sense but if the wrist pin was weak to begin with this might have pushed it over the edge...
i would contact the garage that filled the truck with gas and see what they are willing to do about it... get ready for a fight though...

running rough... rod already cracked and then once it fired it pushed through the block?

that sucks, soory to hear...

 

[jcolvin]

hummm, so the connecting rod broke...
so i am wondering wher it broke. both replys makes sense but if the wrist pin was weak to begin with this might have pushed it over the edge...
i would contact the garage that filled the truck with gas and see what they are willing to do about it... get ready for a fight though...

running rough... rod already cracked and then once it fired it pushed through the block?

that sucks, soory to hear...

No, it was running fine before it was filled with gas. Running rough on the gas/diesel mixture. It wasn't actually me that blew up the engine; it was the mechanic who I took the truck to to find out why it wasn't running (who shall remain nameless). Should the mechanic have done something different? I'm wondering if I have cause to bitch at him.

 

[crushers]

J,
here is my take on this. take it for what it is worth.

i had a FJ40 here that had no power, burned a bit of oil...nothing serious. the owner wanted me to install a H55F from Manfree into it. long story short i will not buy anything from Manfree.
anyhow, i get the tranny installed and the "rebuilt" t/case is screaming so i call the owner up (he lives in another province so he couldn't come for a test drive). as i am driving i am holding the phone so he can hear the scream suddenly i hear a new sound, a rattle. i tell him to keep listening but i think we have a bigger problem and just as i take the phone from my ear a BANG and the engine quits. now i know it wasn't my fault but i can't prove it so while we wait for a tow truck itell him that i will split the cost with him, he pays the labour and i pay the parts.

what am i getting at? you don't know how the mech drove the truck on his test drive, chances are he drove it nice BUT at the same time maybe he was reving it up to try and clear the system. i would appraoch him and see what he has to say... maybe he will split the cost on another engine or maybe supply labour or he might tell you to stuff it. it costs nothing to ask.

that is my take on the situation.

cheers and best of luck...

 

[Jan-78FJ40]

No, it was running fine before it was filled with gas. Running rough on the gas/diesel mixture. It wasn't actually me that blew up the engine; it was the mechanic who I took the truck to to find out why it wasn't running (who shall remain nameless). Should the mechanic have done something different? I'm wondering if I have cause to bitch at him.

who filled it with gas?

personally I do not completely subscribe to the theory that the gas fumes blew the engine apart. If you had it running on diesel before, it will still be a diesel gas mixture. also, the gas will not really atomize through a diesel injector, and gas will not explode from pressurizing it, like diesel. what are your thoughts about this, wayne, please?

j

 

[lshobie]

Gas in a diesel engine doesn't blow it up, doesnt make sense in my opinion. The truck is old, the engine is old, do you know the complete history of the truck and engine? Maybe it's time just came and the mechanic had the bad luck of turning the key at the time. If I lend my truck to someone and the engine blows or give it to a mechanic and the engine blows then it is my responsibility - especially if it is a 20 plus year old vehicle. NOw if it is a new vehicle and my nephew rights it off then that is a different matter.

A case of bad timing and bad events I think. Although I do think the gas station is responsible for the cost of the fuel and the cost for the mechanic to change and flush the system.

 

[crushers]

who filled it with gas?

personally I do not completely subscribe to the theory that the gas fumes blew the engine apart. If you had it running on diesel before, it will still be a diesel gas mixture. also, the gas will not really atomize through a diesel injector, and gas will not explode from pressurizing it, like diesel. what are your thoughts about this, wayne, please?

j

i really don't think gas contamination blew up the engine as i have seen guys drive a gas diesel mixture for 1 1/2 hrs with no ill side effects except piss poor power...

it probably is just real bad timing or abuse by the mech...

 

[mac]

who filled it with gas?

personally I do not completely subscribe to the theory that the gas fumes blew the engine apart. If you had it running on diesel before, it will still be a diesel gas mixture. also, the gas will not really atomize through a diesel injector, and gas will not explode from pressurizing it, like diesel. what are your thoughts about this, wayne, please?

j

Gas will not explode from compression alone? Oh yes it will. Diesel combusts at a controlled rate, it burns, it doesn't explode when introduced to the compressed air in the combustion chamber. Gasoline will not burn in the same way, it produces a more volatile and less controlled, explosive reaction. This is true especially if the Gas/air mix is on the lean side. ( I had a 2 stroke run away on me that was too lean. It didn't need spark plugs to run until it blew itself apart. The plug wires were pulled off. Compression alone.) This can be very damaging to a diesel's internals.

 

[lshobie]

The only thing I could think of would be a hydrolock type of situation - where a cylinder was full of fuel with no where to go - now could that of happened - i doubt it.

 

[Jan-78FJ40]

Gas will not explode from compression alone? Oh yes it will. Diesel combusts at a controlled rate, it burns, it doesn't explode when introduced to the compressed air in the combustion chamber. Gasoline will not burn in the same way, it produces a more volatile and less controlled, explosive reaction. This is true especially if the Gas/air mix is on the lean side. ( I had a 2 stroke run away on me that was too lean. It didn't need spark plugs to run until it blew itself apart. The plug wires were pulled off. Compression alone.) This can be very damaging to a diesel's internals.

Again, I doubt this, but you might as well be right

Gassers shut down by turning off the electrics. sometimes they keep running (dieseling) after that due to ignition of the fuel. This is mostly due to carbon deposits that glow and ignite, not due to the compression.

still doubting that a cold diesel engine would ignite gas by compression...

j

 

[jcolvin]

Gas will not explode from compression alone? Oh yes it will. Diesel combusts at a controlled rate, it burns, it doesn't explode when introduced to the compressed air in the combustion chamber. Gasoline will not burn in the same way, it produces a more volatile and less controlled, explosive reaction. This is true especially if the Gas/air mix is on the lean side. ( I had a 2 stroke run away on me that was too lean. It didn't need spark plugs to run until it blew itself apart. The plug wires were pulled off. Compression alone.) This can be very damaging to a diesel's internals.

Those are my thoughts exactly. The cylinder is full of unburned gas fumes from previous strokes and/or you are adding in a diesel/gas mixture from the injectors, and the mixture is igniting before the cylider reaches TDC. Enough of that and something's going to go. Another diesel mechanic told me that gas in a diesel engine = potential bomb. You need to drain the system completely, remove the injectors so there is no compression, and turn the engine by hand until all traces of gas are out of the system. Only then is it safe to try to start.

 

[crushers]

if it did we would run gas injection instead of propane injection.
gas in the system makes it run worse

 

[jcolvin]

Again, I doubt this, but you might as well be right

Gassers shut down by turning off the electrics. sometimes they keep running (dieseling) after that due to ignition of the fuel. This is mostly due to carbon deposits that glow and ignite, not due to the compression.

still doubting that a cold diesel engine would ignite gas by compression...

j

The diesel has glow plugs. It is well known that you can blow up a diesel by using ether (starting fluid) in the intake. It can ignite as soon as it hits the glowplugs. Why would gas be any different?

 

[Jan-78FJ40]

The diesel has glow plugs. It is well known that you can blow up a diesel by using ether (starting fluid) in the intake. It can ignite as soon as it hits the glowplugs. Why would gas be any different?

xcuse me? why would the glow plugs ignite that stuff? ether burns a LOT easier and at lower ignition temps than gas/diesel...
Also, it would have blown then when the glow plugs were energized before cranking over, not long after that. afaik no juice tho the glowies while running...

anyway, not looking for a fight...I am just passing through.

J

 

[crushers]

The diesel has glow plugs. It is well known that you can blow up a diesel by using ether (starting fluid) in the intake. It can ignite as soon as it hits the glowplugs. Why would gas be any different?

flash point and on the 2B it is a manual glow right? so if what youare are saying is correct then the damage would have been done as soon as you tried to start it... but it wasn't, it was after you tried and failed and move the truck to teh mechs...

 

[jcolvin]

xcuse me? why would the glow plugs ignite that stuff? ether burns a LOT easier and at lower ignition temps than gas/diesel...
Also, it would have blown then when the glow plugs were energized before cranking over, not long after that. afaik no juice tho the glowies while running...

anyway, not looking for a fight...I am just passing through.

J

It didnt blow up when running. It blew when trying to start it. The ignition temp of a gas/air mixture is around 230 C. The temperature of the tip of a glow plug is around 700 C. It looks to me like there an ignition source in that cylinder.

 

[jcolvin]

flash point and on the 2B it is a manual glow right? so if what youare are saying is correct then the damage would have been done as soon as you tried to start it... but it wasn't, it was after you tried and failed and move the truck to teh mechs...

No, it also had a dead battery. We tried to bump start it and it wouldn't go. The mechanic put in new batteries, and a new alternator, and a new starter before he figured out it had gas in the tank. Then it blew when trying to start it.

 

[Jan-78FJ40]

It didnt blow up when running. It blew when trying to start it. The ignition temp of a gas/air mixture is around 230 C. The temperature of the tip of a glow plug is around 700 C. It looks to me like there an ignition source in that cylinder.

I see, my mistake, thanks.