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6v92 TA Detroit

cowboycowgirl

New member
Hi,

We blew our engine and after taking the engine down found 1 con rod broke and another bent, the back 2 stabilizers were compromised also. The crank shaft seemed ok. we wend ahead and replace both back con rods and rebuilt the engine. Start up was fine but when we went on the test run white smoke was coming out of the breather and black smoke out of the exhaust and engine was running rough. the oil pressure started out at 50 and then started going down. Any ideas out there would be greatly appreciated. Even our mechanic is stumped or is saying it dont sound good.
 
"We blew our engine" isn't much in the way of a back story as to WHY this happened. These engines are not known for breaking or bending connecting rods and the only scenario I can think of would be hydrolocking. Hydrolocking could occur due to water intrusion or maybe an extreme case of fuel entering the cylinder which might happen but likely in only ONE cylinder at any given occurrence.

If it was water, are you sure that you correctly identified the source? A little more of what you saw and heard during the failure and to what extent your "overhaul" entailed could help someone here come up with some better theories.

The "white smoke" from the crankcase draft tube is more than likely steam. So, if water intrusion was the initial cause for failure, it could still be happening.
 
On a broken engine, I mic everything, magnaflux the crank, and with any broken rods, replace them all. Usually I junk the engine but if not I would do a total rebuild and send the heads to a qualified rebuilder. You could have head damage, additional bent rods, damaged valves, all could cause rough running. If you didn't change the sleeves, they could be misshaped. Loss of oil pressure could be bearing failure, oil pump damage or debris holding the pressure relief valve open. You also could have timing gear problems.
If it was my engine I would strip it down to a bare block, inspect, and buy a complete engine kit. Send the heads and crank out. If valve damage is found, the cams could also be damaged. It would be cheaper to buy a good used engine.
 
I know a guy who bent 2 rods from hydrolock.
One you could not tell by looking at the rod that it was bent.
But it was enough to make the engine run rough and smoke a lot.
Scrap it and get a John Deere . :)
 
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