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The truck is a 1990 F-350 4WD Dually crew cab with only 50K miles. It has a 460 with a ZF5. I recently moved to central Missouri, and we have gotten loads of rain recently which has led to flooding. I misjudged a low water crossing on a road I wasn’t familiar with and splashed water over the hood got a gulp of water down her throat. She locked up, died, and left me sitting in 2ft of water. In a panic, I tried cranking her over, she didn’t wanna for a minute, but eventually she fired off and we got out of the water. Since then, there has been a knock that seems to come from down low, near the rear of the motor/bell housing/starter. Not so much the top end. I’ve changed my oil multiple times til there was no signs of water. I haven’t taken anything apart yet because I wanted some ideas on where to start. Any thoughts?

Save your dips**t comments, please. I’m already kicking my own behind for this.
 

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You likely bent a connecting rod.








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HI, water would not effect the starter or bell housing.. If it did ingest water rods are the usual damaged parts.. If it would NOT turn over (move with the stater) it was hydrolic locked.. if it just would not fire or start you may have wet the electronics and it had to dry out.. You can use a short piece of hose hold one end to your ear and move the other end around the motor to tell exactly where the knock is coming from.. Down low is usually rods or crank..
maybe do a compression test ..
good luck
tim
 

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Yes. Same thing happened to me. Wife drove through some deep water and the motor locked but eventually started...she never told me about it. Noticed a subtle knock but drove it for quite with no issues. The truck was still under warranty so the dealer tried a bunch of things with no improvement until they called and said it was done.Showed me a rod that was literally "C" shaped. My wife finally came clean after I traded the truck a couple years later.
You likely bent a connecting rod.








Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
Customized crate engines
ParklandAutoMachine.com
R-H-P.biz
"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
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Bent connecting rod. Happened to me when the mechanic fitting my headers thought all those 5/8 hoses must carry the same working fluid and connected the idle air solenoid to the heater system. Then complained that the starter was broken, and were stumped until I pointed out the green liquid dripping from the new headers. If I'd been a lawyer, then another shop would have fitted a new engine, but as it was I got my RV out of there ASAP.

I had no knock for 11,000 miles hauling about 16,000lbs around till there was a big bang (as loud as a front tire blowout), and then a loud tapping noise. Rod had become twisted, and had eventually fatigued, broken just under the little end, left the piston up in the bore, and on the next up stroke, the new top of the rod met the block, and folded over just above the big end, snapped off and broke in two pieces which fell into the sump. If the part of the rod still attached to the crank had been a quarter of an inch shorter, then it wouldn't even have been tapping on the side of the block and the oil pan. Not that I knew all that at the time.

My rod was bent when cranking, at a much slower speed than yours, so I can't see you getting 11,00 miles. After crack testing and straightness checking, and anew set of rods, it's rebuilt, and doing fine. They seem to be quite tough :)

I'd suggest rebuilding now before more damage happens.
 

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I was timing my olds 455 once upon a time with the air cleaner off. My sisters kid threw a water balloon at me and it busted on the air cleaner post and almost killed the engine. ( I might have been at 2500 rpm when it happened). Had a weird knock after that at midrange rpm. Long story short, cracked piston.
 
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