Briggs and stratton vanguard 16hp problem

Flelly

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I have a Briggs and Stratton 305447-0285-G2 engine. It blew a connecting rod, new rods and piston and rings, put together using manual. It will run by itself but when hooked back to the hydraulic pump it runs won't run and pops and backfires thru carb on trying to start. Is there something else wrong with engine that it can't handle a load? Spark at both cylinders, seems to be loading up with fuel or intake valve open during the fire. did a carb rebuild and new fuel pump,new plugs and breather element as well. Any help from someone would be great.
 

ILENGINE

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Is it possible that the flywheel key go sheared or offset because the flywheel wasn't torqued properly or has oil residue on the crankshaft taper. The backfire and popping sounds like a timing issue.
 

Flelly

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I'll put it and check again, timing in inside engine was lined up, i'll check the key and the shaft. Why would it run not hooked to the pump but once it gets a load on it i.e. hooked to pump it doesn't want to run?
 

ILENGINE

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It is probably not running correctly without the pump attached, but the extra load of the pump makes it very noticeable.
 

bertsmobile1

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After verifing the timing key is intact double check the engine timing.
I did get a twin in the workshop where the owner had timed the engine wrong so it was only running one cylinder.
On one cylinder it fired up & ran fine, till you put a load on it when it just petered out & died.
 

(Account Closed)

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After verifing the timing key is intact double check the engine timing.
I did get a twin in the workshop where the owner had timed the engine wrong so it was only running one cylinder.
On one cylinder it fired up & ran fine, till you put a load on it when it just petered out & died.

Twin cam or how did he mess up the timing? Just curious..
 

Tinkerer200

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Yeah, check that it is actually running on both cylinders. Also, not connected to running issue, when an engine throws a rod there is generally damage to the crankshaft throw?

Walt Conner
 

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Yeah, check that it is actually running on both cylinders. Also, not connected to running issue, when an engine throws a rod there is generally damage to the crankshaft throw?

Walt Conner

Not sure what you mean by "crankshaft throw", but the op's replaced the blown parts (apparently no block or crank damage-NOT MENTIONED) and there is only ONE crankpin.

If the rod broke and cleared the crank, the crank could be fine, same re the block...

Why it broke to start with, is what I'd really be interested in...
 

Tinkerer200

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Not sure what you mean by "crankshaft throw", but the op's replaced the blown parts (apparently no block or crank damage-NOT MENTIONED) and there is only ONE crankpin.

If the rod broke and cleared the crank, the crank could be fine, same re the block...

Why it broke to start with, is what I'd really be interested in...

It is extremely unusual for a connecting rod to break and not damage the crank throw, rod journal, or "pin" as you want to call it. I am puzzled why you are concerned about this rather than the OP.

Walt Conner
 

(Account Closed)

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It is extremely unusual for a connecting rod to break and not damage the crank throw, rod journal, or "pin" as you want to call it. I am puzzled why you are concerned about this rather than the OP.

Walt Conner

Most blown rods I have seen have gone thru the crankcase and damaged the crank. High end motorcycles mostly.

These engines, running normally at 3,600 would not be over revved (usually).

Yes, I am interested in WHY / what failed to cause the rod to blow. Anyone can swap parts. Why it failed-lack of oil, clogged oil lines-not cleared/fixed (if the issue) would cause the rod to blow AGAIN.

Whether the Op cares or not, frankly is not my business. In doing my repairs for a failed part, I want to know why so it's repaired and does not come back blown up again-something that I should NOT have missed..



Likely due to over revving (not likely in this case), or a failure elsewhere(IE, had a large Yamaha PW that the pressure release failed and the rod came loose with major knocking / damage)


IE: An Echo CS355T Chain saw, "blown" (locked up) that I went into (out of curiosity) AND was able to repair.

A crankshaft "stuffer" failed (came apart) and locked up the engine. No internal damage to the engine, removed the other one and re-assembled. It's now back into service for my customer with NO NOTICABLE difference in performance. Saved a $350 machine from the scrap pile..


Video of it re-assembled, being tested..

https://www.flickr.com/photos/147134237@N06/45591828684/

 

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