After spending a couple weeks in Caterpillar’s failure analysis lab which was incredibly eye opening, I will not say that anything is 100% verity until I’ve completed at least the first few steps of an analysis IN PERSON. It’s unbelievable how many times I’ve been wrong about a diagnosis in the past simply because I was completely unaware of all the types of failures. I’ll use your broken connecting rod picture as an example: It is entirely possible that the connecting rod broke because it already had a failure in the rod and the hydrolocking just sped things up. There could have been an inclusion in the rod in a high stress position that was present the day it was forged. I’m sure the evidence has been bashed off of the face off the crack, but you would have seen beach marks radiating away from a tiny bubble in the corning indicating the progression of a fatigue fracture. In other words, it is possible that the rod was going to break either way! The water just moved things along quicker. That failure analysis class was incredible and highly recommended by the way. One of the instructors was a doctor in chemistry; I don’t think I’ve ever tried to cram so much information into my poor head in two weeks before. :doh:
Is it possible to bend a rod hydrolocking with fuel
- Thread starter musicims
- Start date
After spending a couple weeks in Caterpillar’s failure analysis lab which was incredibly eye opening, I will not say that anything is 100% verity until I’ve completed at least the first few steps of an analysis IN PERSON. It’s unbelievable how many times I’ve been wrong about a diagnosis in the past simply because I was completely unaware of all the types of failures. I’ll use your broken connecting rod picture as an example: It is entirely possible that the connecting rod broke because it already had a failure in the rod and the hydrolocking just sped things up. There could have been an inclusion in the rod in a high stress position that was present the day it was forged. I’m sure the evidence has been bashed off of the face off the crack, but you would have seen beach marks radiating away from a tiny bubble in the corning indicating the progression of a fatigue fracture. In other words, it is possible that the rod was going to break either way! The water just moved things along quicker. That failure analysis class was incredible and highly recommended by the way. One of the instructors was a doctor in chemistry; I don’t think I’ve ever tried to cram so much information into my poor head in two weeks before. :doh:
Big Blue24
Comp Diesel Sponsor
The reason I say the starter is not strong enough to bend a rod because when you run a higher compression 12v with high timing, sometimes a cylinder will fire early enough to completely stall the starter. I've had this happen on the Junker several times and never bent a rod.
I would suspect that, if a cylinder is full of water, and one of the other cylinders fires moments before the hyrdo-locked cylinder approaches TDC, then yes, the engine could have enough power/torque to bend a rod. But the power comes from the other cylinders... engine power... not the starter.
I would suspect that, if a cylinder is full of water, and one of the other cylinders fires moments before the hyrdo-locked cylinder approaches TDC, then yes, the engine could have enough power/torque to bend a rod. But the power comes from the other cylinders... engine power... not the starter.
biggy238
Active member
My co-worker and I were talking about this yesterday. I don't think it's possible for a completely filled/stalled cylinder to be cranked.
I've made partially filled heui engines crank past the lock in the past, but no way to quantify how much was there.
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I've made partially filled heui engines crank past the lock in the past, but no way to quantify how much was there.
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BigPapa
Truckless
When I worked at the truck shop, our experienced Ford tech would put a truck with fuel in the cylinders on the lift, put a breaker bar on the crank, and hang on it till the fuel passed through the ring gaps. It took a while but it was safe.
We had a fresh young tech that decided he'd pull the glow plugs on one and crank it over to get the fuel out. He was under the hood watchin with someone in the cab to crank it over. A "slug" of fuel about a foot long shot out of the cylinder right beside his head and dented the foil-wrapped insulation on the 15' ceiling. It was within an inch or two of his left eye. It would have put his eye out if it had hit it. He never did it again....
We had a fresh young tech that decided he'd pull the glow plugs on one and crank it over to get the fuel out. He was under the hood watchin with someone in the cab to crank it over. A "slug" of fuel about a foot long shot out of the cylinder right beside his head and dented the foil-wrapped insulation on the 15' ceiling. It was within an inch or two of his left eye. It would have put his eye out if it had hit it. He never did it again....
biggy238
Active member
Hahahahaha we have a mark on the insulation 30 ft above one of our bays. All I can say is it wasn't me.
FWIW we are usually good about sucking the cylinders dry, and if we have an issue, rotating the engine backwards by hand is sufficient.
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FWIW we are usually good about sucking the cylinders dry, and if we have an issue, rotating the engine backwards by hand is sufficient.
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