351 w engine,back spin

[CaminoKid]

Was wondering if anybody else has had this or know of this happening,

Upon starting engine it back spun or I guess back fired without the fire and bent a push rod,in turn allowing the piston skirt to hit the crank and broke the bottom of the rist pin girdle off.


Didnt damage anything else.And is the rod length of a 302 the same as the 351?

[fahrenschnell]

Re: 351 w engine,back spin

Holy Hell Woody......KC's truck motor?

Yikes.

Seth

[CaminoKid]

Re: 351 w engine,back spin

yep and he drives it like a little old lady.

[milner351]

Re: 351 w engine,back spin

Did an injector hang open and hydrolock a cylinder?

My '92 F350 351w "kicked" like that on me once - I thought it jumped a tooth on the timing chain -- turned out to be a bad ignition module...

sombiatch, that stinks.

If you need a rod - I probably have a few spares.

[CaminoKid]

Re: 351 w engine,back spin

Not fuel injected,but we will need and rod,maybe a piston also.I will let you know.

Thanks John.

We were thinking that maybe the intake gasket leaked and the cylinder hydrolocked with a small amount of antifreeze.
What you think?

[min301]

Re: 351 w engine,back spin

Not fuel injected,but we will need and rod,maybe a piston also.I will let you know.

Thanks John.

We were thinking that maybe the intake gasket leaked and the cylinder hydrolocked with a small amount of antifreeze.
What you think?

It's likely, considering what you said happened.

[milner351]

Re: 351 w engine,back spin

PM me if you need something - I'm not at the shop much these days - but I can look over there for you - I'm sure I have some stock rods and pistons, just depends on if I have a match for you or not, is it stock bore? maybe shoot me some pictures and we'll go from there.


i think the coolant leak is a plausible idea - they don't kick back for no reason....

[Smack]

Re: 351 w engine,back spin

Did an injector hang open and hydrolock a cylinder?

My '92 F350 351w "kicked" like that on me once - I thought it jumped a tooth on the timing chain -- turned out to be a bad ignition module...

sombiatch, that stinks.

If you need a rod - I probably have a few spares.

Ahhh haaaa. Thanks, You just answered a question i asked myself a couple weeks ago. I had a lawnmower pull the cord back and just about broke my damn arm. Shortly after, oil was coming out of the muffler. I didn't think much of it at the time, (cause my arm was hurting like hell), but now it is all so clear!

[Huskinhano]

Re: 351 w engine,back spin

[quote=CaminoKid ]
Was wondering if anybody else has had this or know of this happening,

Upon starting engine it back spun or I guess back fired without the fire and bent a push rod,in turn allowing the piston skirt to hit the crank and broke the bottom of the rist pin girdle off.


Didnt damage anything else.And is the rod length of a 302 the same as the 351?


???? There's no way the piston would hit the crank normally even if the engined rotated in the opposite direction unless the rod was bent. I'm thinking it's just fatigue or detonation that caused the piston problem. I've seen pieces of piston skirts in oil pans from normally running engines. The skirts take a lot of force on the thrust side.

[CaminoKid]

Re: 351 w engine,back spin

Once the rod bent it shortened the length of travel of the piston and that made it possible for the skirt to hit the4 crank.

The rod bent first then the skirt hit,and we could see this in the rotation of the assembly when we took the pan off.

Also the intake gasket has eaten around the water jacket next to the fuel intake Port and when the truck gets shut off when hot the water seeps into the chamber and down in to the cylinder.IMHO

New engine rebuild with less than ten thousand miles.so I don't think its simple fatigue.

[milner351]

Re: 351 w engine,back spin

Woody
What kind of intake gaskets did you use?

What kind of antifreeze?

I know there are several different kinds of coolant out these days and some coolants don't play well with some materials.

I will look for that con rod for you this weekend.

[Huskinhano]

Re: 351 w engine,back spin

Once the rod bent it shortened the length of travel of the piston and that made it possible for the skirt to hit the4 crank.

The rod bent first then the skirt hit,and we could see this in the rotation of the assembly when we took the pan off.

Also the intake gasket has eaten around the water jacket next to the fuel intake Port and when the truck gets shut off when hot the water seeps into the chamber and down in to the cylinder.IMHO

New engine rebuild with less than ten thousand miles.so I don't think its simple fatigue.

That's different. In the initial post you said "pushrod" was bent not connecting rod.

[CaminoKid]

Re: 351 w engine,back spin

I stand corrected,it was a connecting rod.sorry.