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View Full Version : Vanguard Seizes at 1600 Hours


RVTECH
04-26-2011, 10:12 PM
2005 Bad Boy AOS with a Briggs & Stratton Vanguard 31. Engine smoked for about 10 seconds. They stopped, shut it down to check the oil. Everything looked fine. We noticed an idler pulley with a bearing out. Tried to start it to move it in the building and found out the engine seized. I couldn't believe it. Pulled the engine and disassembled. I had to get it all the way down to find the seizure. It was the bushing/bearing on the crankshaft magneto side. The crankshaft and crankcase look fine. The brass bushing is torn up a little and extremely tight on the crankshaft. It was dry and blue. The plastic teeth from the oil pump were missing and laying in the crankcase. Everything else in the engine still had oil and look good. I contemplated a new engine, but decided to fix it. About $350 in parts for all the gaskets, seals, oil pump, and the bushing/bearing. It is a brass bushing and is the most expensive part of the whole deal ($120) I'm waiting on parts. I'll post when it's running again.

tacoma200
04-26-2011, 10:47 PM
Keep us informed. 2,500 hrs is the average I expect from a air cooled engine. Sometimes things just happen. Hopefully it will not cost that much to fix. If I get close to 2,000 hrs out of my Vanguards I'll be more than happy for the price I paid.

all ferris
04-26-2011, 10:47 PM
So the oil pump broke and the engine had a lack of oil. You are doing the right thing. I would hone the cylinders and put new rings on the pistons too. Maybe new valves also. Then the engine would be like new.

The only reason I say put valves in it is because I had a valve break before and that will destroy an engine.

RVTECH
04-27-2011, 07:04 AM
I'm going to leave everything else as is. If I were going to replace the pistons, rings, valves, and hone the cylinders, I would just throw in the towel on this engine and buy a new one. This engine has never used any oil. Typically, I would not fix an engine that lost oil pressure. The damage is usually devastating. I think this one got shut down quickly enough to avoid much damage. That's a judgement call based on my 31 years of engine repair experience. Doing all those extra things would put the cost close enough to a new engine that I wouldn't even consider it. All that said, I don't like to hear about a valve breaking. I'm also not quite certain what caused the oil pump teeth to go. They are plastic, but it made it to 1600 hours proving to me that plastic is ok. There was no debris in the engine. I took the pump apart and there's nothing in it either.

topsites
04-27-2011, 08:08 AM
31 years of experience doesn't mean much if you're wrong, what I mean is if
you are wrong then where do you stand in terms of cost?

There are always those unknown factors, such as what caused it or what kind of collateral damage
there is that you can not see, these unknown factors which can make the rebuild fail as well...

Either way it is a tough call but that's what I would figure on, if you are wrong how much are you out of,
and now is it still worth it because you'll have to consider what to do at this point, which I think you might
be better off short blocking it, but that's just me.

RVTECH
04-27-2011, 08:28 AM
I agree. I thought the same thing. A short block puts me at about $1700. A complete engine new is about $2200. I decided to risk the $350. I don't want to put the extra $$ in this unit that currently has 1600 hours on it. Considering all the other worn components such as mower deck and blah blah blah....As always, the problem with it not running is that it has basically no value. Everything has some risk. On the bright side; at least we can do the labor here and save that cost.