Briggs vanguard 18hp 350777 broken rod

[junkman108]

hey i got an engine with a broken rod. it had oil in it why did the connecting rod break??? The piston and cylinder look good. the rod is broken about 1.5" below piston the rest of rod is in pieces. the camshaft is broken in half but i dont see any damage to heads or tappets... crank journal has material on it but im hoping it just aluminum that will come off???


are the aluminum rod the weak link??? should i replace the connecting rods when rebuilding this engine??? seems with these small engines its always the connecting rod that goes.


TIA

 

[ILENGINE]

Rod breakage close to the piston is normally a sign of overspeed. So governor may of been the initial failure. Rods break 99.9% of the time due to two reasons. overspeed which breaks close to the piston and rod seized to the crankshaft due to lack of oil. Is the aluminum stuck to the crank shaft look like just impact transfer, or is do it appeared smeared around the bearing journal.

 

[junkman108]

can i use the sump pan?? take a look at the crank thrust surface. I bought engine for $60. Dude said it still ran on one cylinder but no way because camshaft is broken in half So far im looking at rod and camshaft. Hopefully crank will clean up. There was oil in it but it definitely looks like it was run low or hot.

 

[junkman108]

 

[bertsmobile1]

If you are going to take macrographs, please use a camera, not a phone and even then sit it on some sort of a platform.
You can not a phone or camera still enough when you are looking at the screen on the back at arms length.

From what I can see , which was not much was a lot of wear on the end of the semp plate.
Can not tell if your "crack" is a crack or just a casting flash.
The crank looks bad, degrease it then dump it in a bucket of Muratic acid for a few hours, not overnight then check the journals for roughness & / or ovality.

And yes been run short of oil.

 

[junkman108]

Ok Muriatic acid. I heard some people say Lye is better??

 

[bertsmobile1]

Muriatic acid will over time attack the steel
Lye will not
With acid it is basically dip or brush on the wash off
Lye will passivate so you will need to take it out wash it off, runb the surface then back into the lye again.
Acid will work fine cold
Lye needs to be hot

 

[ILENGINE]

With the condition of the sump bearing, and the crank journal for the broken rod, I am curious what the other rod journal and magneto bearing looks like. Also the condition of the camshaft bearing surfaces in the engine. I suspect that they are also damaged.

 

[Tinkerer200]

I don't think that crankshaft will clean up without turning under size.

"Also the condition of the camshaft bearing surfaces in the engine. I suspect that they are also damaged."

I suspect the camshaft bearing bosses are cracked.

Walt Conner

 

[junkman108]

no camshaft journals are good surprisingly perfect..
crankshaft has hot spots but no scratches i can catch fingernail.
same for bearing cap discoloration but no scratches/
I ordered a puller from amazon so i can remove flywheel and crankshaft.

Can i use the sump pan or is it no good???? i know ill have to use the muriatic and measure the crankshaft rod journals. hopefully the upper crank journal isnt scored. Maybe it has a bushing in there???