Engine issues........BIG TIME.

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dodgetkboy78

dodgetkboy78

EDELBROCK HEADS SUCK!
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Long story short.

My Boat has a Chrysler 360 in it, that replaced the 318 it came with. ((Some of you see a red flag) Anyway, I found the PPwork, and it is a solid cam, balalnced, blueprinted, dyno'd marine engine, real nice job. Motor purred like a kitten. Anyway, they took the 318 out, and put the 360 in..... (flag anyone?) Well, yesterday morning, in a 7' swell, the crank came clean off at the rear main. All bolts are tight. Bellhousing is tight. I had a gut feeling about this since I bought the boat, but just figured I was being paranoid. No vibrations, no funny noises...........

Someone used the 318 flywheel on the 360 huh?

Damn them.




Here's the next questions. Besides the obvious cam, dist, ect, what are the internal differences in the standard and counter rotating small block?
And what do you think happened to the rest of the motor in the three seconds it ran without a flywheel at 1/2 throttle?

It still turns over from the front, but thats it..............

Any input would be great, I am pretty upset about this.
 
So you think the wrong balance flywheel was used and it vibrated off?

When you say the crank came off the main, what do you mean exactly?

I'm no boating buff.


If it's just the flywheel, I would say nothing bad happened to the rest of the motor.
 
The crank sheared off at the rear main journal, flush with the seal, the snub is still attached to the flywheel. Just like the cars, the LM318 and M340 use one flywheel, and the M360 uses another. Internal/external balance thing. We all know that, except for the guy who put the motor in...... Yay.

I wonder what happens to a motor at 1/2 throttle when the crank breaks there. Would is hit a gazillion RPM's? Or would it be to lopsided and out of balance it wouldn't know what to do?
Was a real nice motor, god I should have gone with my gut instinct.
 
Besides the crank, I think you're good, I mean there was no load after that flange broke off.lol

I seen a broken 318 cast crank in 74 d100, guy was trying to haul many 50 gal drums full of motor oil, but never seen one break the flange off, especially over an out of balance flywheel?

WEIRD

I wonder if it had issues that weren't caught before assembly, I mean you see guys all the time slamming cranks down on to the ground on there flange.
 
1wild&crazyguy said:
Besides the crank, I think you're good, I mean there was no load after that flange broke off.lol

I seen a broken 318 cast crank in 74 d100, guy was trying to haul many 50 gal drums full of motor oil, but never seen one break the flange off, especially over an out of balance flywheel?

WEIRD

I wonder if it had issues that weren't caught before assembly, I mean you see guys all the time slamming cranks down on to the ground on there flange.
Click to expand...

when i worked at a shop decades ago the owner would fire you for slamming a crank on the flange like that. we did have a motor come back with the flange snapped off, from what i remember just put a different crank and bearings in it....
 
Possible, oops, dropped it, I guess I'll put it in anyway..............People, why do I work on my own **** again?
God I hope the rest of the motors OK........ A marine engine is not cheap to build.
 
You guys don't think the thing hit 12+K when it came off huh? I was too busy to look at the tack, but it sure sounded like hell down there.
 
inkjunkie said:
when i worked at a shop decades ago the owner would fire you for slamming a crank on the flange like that. we did have a motor come back with the flange snapped off, from what i remember just put a different crank and bearings in it....
Click to expand...

wow, so I'm not the only one to watch that kind of crap happen.:cheers:

It's amazing what people do when they don't think.
 
I hang my cranks.................

Doesn't make sense to bang a cast piece of iron with sharp cuts in it on the concrete, no one told me not to, it's just common sense...
 
The cranks are different from what I understand.. the knurling on the seal area is opposite on RR. (I'm no boay guy, but I recall a close friend who is a marine mechanic told me that) I'm sure it spun right up to the valve spring limits. If the piston to valve clearance was good and nothing broke I would just inspect everything closely when it's apart. It's probably fine.
 
Just what Moper sez, the valve springs will loose their ability to control things at any serious rpm, so the engine quits revving. Look everything over good and you'll find that, more than likely, the engines Ok, other than the crank, of course.
 
1/2 throttle and instant no load=lots of rpm. I would seriously check all valve springs keepers and retainers or just replace them for cheap insurance. I doubt the vibration caused the failure. I agree with the droped or faulty crank.
 
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