Broke a connecting rod today, still unsure what caused it - JeepForum.com
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post #1 of 16 Old 09-15-2017, 08:37 PM Thread Starter
foxrox0617
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Broke a connecting rod today, still unsure what caused it

So while randomly driving on the highway today I hear a boom and first thought my driveshaft let go, to describe the magnitude of the feeling. I limped it home for 10mins(killing any wildlife up to 20yrds behind me) instead of shutting it down, unsure if the engine would have even been saveable had I stopped. Only thing I did was change the oil using 5 qts rotella t4 15w-40 and half a qt castrol synthetic 5w-30. Prior to that I drove couple hundred miles with marvel mystery oil since the engine had alot of sludge in it. I noticed the oil pressure seemed abnormal, idling around 60psi but did not think much of it. Also noticed one of the bolts holding in the main bearing cap on the broken rod was finger loose, not sure if that was caused after the fact. The oddities in the oil pan are a broken dipstick, unsure if that was after the fact as well, and a weird looking metal washer that I'll get better pics of in the morning if it helps solve the mystery. I think some piece of the rod also hit and dented the sides of the oil pan

I'll get better pics of everything in the oil pan tmrw. Pics of the carnage

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20170915_164023.jpg   20170915_164114.jpg   20170915_164142.jpg   20170915_164049.jpg  

Past: 1996 ZJ, 1995 YJ, 1996 ZJ, 1995 XJ, 2001 XJ
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post #2 of 16 Old 09-16-2017, 05:51 AM
rogerv
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I know the feeling- had a piston separate from the wrist pin. Made some wild noises when it happened.

If it's not broke- modify it, so it won't break
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post #3 of 16 Old 09-16-2017, 07:34 AM
Jeepsr4me
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No reason to run anything in the oil but regular oil... trying to flush out crud causes more harm than good.

I would blame that as you state nothing else was changed..
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post #4 of 16 Old 09-16-2017, 08:43 AM
mrit
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Only thing I could imagine is some buildup got loose and clogged an oil passage. Is the rod bearing seized to the crank?
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post #5 of 16 Old 09-16-2017, 02:22 PM
Chrisnvegas
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Originally Posted by Jeepsr4me View Post
No reason to run anything in the oil but regular oil... trying to flush out crud causes more harm than good.

I would blame that as you state nothing else was changed..
Agreed.
Leave the sludge alone unless the engine is being disassembled.
15w40 is going to flow less than 10w30.
Marvel "mystery" oil is kerosene, naphthalene, xylene, acetone. YUK!
Zyklon B is safer to use in an engine!

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post #6 of 16 Old 09-16-2017, 05:21 PM
bpounds
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While I agree that just oil is all you need, I don't believe the snake-oil caused that failure. And that engine is actually quite clean, so I don't think floaters did it either.

Most rod failures will be caused by hydrolock. Either water, coolant, or excess gasoline from a stuck injector. The thing is, it might have happened years ago before you even owned it. A part partially breaks, but the engine keeps running with no symptom. Of course the break will eventually come apart, and here we are.
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Bill
Dodge did not build my Jeep.
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post #7 of 16 Old 09-16-2017, 09:09 PM
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Quote:
Originally Posted by bpounds View Post
While I agree that just oil is all you need, I don't believe the snake-oil caused that failure. And that engine is actually quite clean, so I don't think floaters did it either.

Most rod failures will be caused by hydrolock. Either water, coolant, or excess gasoline from a stuck injector. The thing is, it might have happened years ago before you even owned it. A part partially breaks, but the engine keeps running with no symptom. Of course the break will eventually come apart, and here we are.
I don't think it was the direct cause.
Probably was a problem to begin with. Probably why the super-thin lubricant washing solution ended up in the oil pan to begin with.
It surely didn't help matters.

"Auto racing began 5 minutes after the second car was built."
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post #8 of 16 Old 09-16-2017, 10:27 PM Thread Starter
foxrox0617
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Quote:
Originally Posted by bpounds View Post
While I agree that just oil is all you need, I don't believe the snake-oil caused that failure. And that engine is actually quite clean, so I don't think floaters did it either.

Most rod failures will be caused by hydrolock. Either water, coolant, or excess gasoline from a stuck injector. The thing is, it might have happened years ago before you even owned it. A part partially breaks, but the engine keeps running with no symptom. Of course the break will eventually come apart, and here we are.
I think you hit the nail on the head bpounds. The day I got it a couple months ago the guy filled up at a gas station in bfe that had water in it so it knocked some of the ways on the trip over and I stupidly bought it. I added HEET to the tank and never experienced a problem after that thinking I was in the clear Sucks as it ran fine the whole time until yesterday. Just seemed suspicious it would happen the second time driving after an oil change. Next used engine will be getting nothing but regular oil, thanks everyone.

Past: 1996 ZJ, 1995 YJ, 1996 ZJ, 1995 XJ, 2001 XJ
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post #9 of 16 Old 09-17-2017, 08:04 AM
Nailgun
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First, thanks for sharing your engine damage story with the forum. Picture #3 best describes what really happened. I had to resize and crop it to show you the cylinder wall damage that seized the piston in the bore. Note the wall damage is at a right angle to the wrist pin on the wall. This wall damage did not occur after the rod broke and not long before. You have to remember, A Jeep inline engine is in my mind, 1950's technology. It is pressure lubricated for bearings and splash lubed for cylinder walls etc. Running a heavy weight oil starves these surfaces of lubrication resulting in your stuck piston. Sorry about your luck. Stick to what the manufacturer recommends.


https://1drv.ms/i/s!AnTe-irbvYO0hEzs9JpWcpwFKTbm


Edit...I wanted to post that picture....but somehow it failed. If somebody else could...I'd appreciate it.




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post #10 of 16 Old 09-17-2017, 09:30 AM
bpounds
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Quote:
Originally Posted by foxrox0617 View Post
I think you hit the nail on the head bpounds. The day I got it a couple months ago the guy filled up at a gas station in bfe that had water in it so it knocked some of the ways on the trip over and I stupidly bought it. I added HEET to the tank and never experienced a problem after that thinking I was in the clear Sucks as it ran fine the whole time until yesterday. Just seemed suspicious it would happen the second time driving after an oil change. Next used engine will be getting nothing but regular oil, thanks everyone.
Just to be clear, I was referring to ingesting water through the intake, typically from deep water crossing. Water, coolant, or liquid gasoline, which will not compress, cause hydrolock. Water in the gas tank would still be atomized through the injectors, and won't hydrolock the engine.

Nailgun, your pics are not showing, but I took a good look at the one you mentioned. All I see is cylinder damage from the rod flopping around. Maybe I'm just not seeing the piston galling that you see.

Bill
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post #11 of 16 Old 09-17-2017, 10:02 AM
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I'm sorry about your motor.

I've never trusted those additives or anything fancy. Oil has worked for a long time, and it will continue to work for a long time. Unless you're racing, good old whatever it says in the manual, is going to last (in my opinion) just as long or longer than somebody that uses every snake oil they see an ad for.

My brother in law is a mechanic, and he says the only safe way to clean an engine is to take it apart, and the only reason to do that is when something fails. He says if he has a really crappy looking oil coming out, like it was really contaminated or sat too long, he just cleans it with (you guessed it) oil by running it 200 miles and changing it again. I'm sure there are mechanics with other opinions, and I respect those too, but I'm sticking to what jeep says goes in there.

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post #12 of 16 Old 09-17-2017, 08:02 PM
azzkicker
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Quote:
Originally Posted by Nailgun View Post


First, thanks for sharing your engine damage story with the forum. Picture #3 best describes what really happened. I had to resize and crop it to show you the cylinder wall damage that seized the piston in the bore. Note the wall damage is at a right angle to the wrist pin on the wall. This wall damage did not occur after the rod broke and not long before. You have to remember, A Jeep inline engine is in my mind, 1950's technology. It is pressure lubricated for bearings and splash lubed for cylinder walls etc. Running a heavy weight oil starves these surfaces of lubrication resulting in your stuck piston. Sorry about your luck. Stick to what the manufacturer recommends.


https://1drv.ms/i/s!AnTe-irbvYO0hEzs9JpWcpwFKTbm


Edit...I wanted to post that picture....but somehow it failed. If somebody else could...I'd appreciate it.




I don't want to say I disagree with you, but can you help me understand how you know the damage didn't occur after the rod broke?

07 WK 5.7 QD2, 4" lift, 33X10" tires, M8000s
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post #13 of 16 Old 09-18-2017, 12:24 PM
Drednot
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Yeah, all I see is damage from the remains of the rod flopping around. I doubt water in the gas had anything to do with it either. That's an odd place for a rod to break from something external. My thought is that it may have just been a flaw in the rod that finally propagated to a failure.

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post #14 of 16 Old 09-18-2017, 01:21 PM
mike134
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I'm usually skeptical when people say that their maintenance flushes caused problems.

You are probably performing a maintenance flush BECAUSE you have a notion in the back of your head that somethings going on.

Just like when people say "don't change the fluid in your automatic transmission" . It's myth. If it was going to break, then it was going to break. Having issues is why people suddenly changed their automatic fluid after 300,000 miles before the catastrophic failure.
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post #15 of 16 Old 09-19-2017, 02:02 PM Thread Starter
foxrox0617
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Quote:
Originally Posted by mike134 View Post
I'm usually skeptical when people say that their maintenance flushes caused problems.

You are probably performing a maintenance flush BECAUSE you have a notion in the back of your head that somethings going on.

Just like when people say "don't change the fluid in your automatic transmission" . It's myth. If it was going to break, then it was going to break. Having issues is why people suddenly changed their automatic fluid after 300,000 miles before the catastrophic failure.
Aside from a little valve train noise at startup I had no issues. My notion was that I had sludge when I changed the valve cover gasket. So I ran a qt of MMO for 200 miles until it was time to change my oil and upon reading about the high zinc content/cleaning detergents of rotella, changed my engine oil with T4. If I had an idea what would have caused the engine failure I wouldn't have made a thead asking everyone.

Past: 1996 ZJ, 1995 YJ, 1996 ZJ, 1995 XJ, 2001 XJ
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