Rebuilding engine - what is this?
 

Hi fellow cubbys,

I am fairly new here. Bought a 1641 a few weeks ago that needed an overhaul.

On idle, the engine didn't appear to smoke, but full throttle - it smoked bad. Plus, it didn't have enough power to pull the mower deck.

So I bit the bullet and started tearing it down. Engine is cleaned up and on the work bench - the valves are carbon up bad from all the oil burning - so I took the heads to a shop to have a valve job done.
I opened the crankcase and found this::::
http://i1195.photobucket.com/albums/...oks/spring.jpg

Lying loose in the bottom of the crankcase.

Where could it have come from?
Actual size - about 1 inch long X 1/8 inch thick.

The cylinder walls look new - perfect condition. The only possible damage I can find likely caused by this spring being in the crankcase is one rod end has a score on it where it bolted to the crank. The crank has very minor discoloration from this rod, but can't feel anything rough... It appears to be okay.
I ordered a new rod with pistons, rings, and gaskets.

Back to the foreign object.
Does anyone recognize this spring as being part of a 1641's Briggs Vanguard engine?

Is it supposed to be connected to something in the crankcase? I can't find where it would have been...
How could it have gotten in there?

Thanks for your help.

Fred

Only spring inside the engine that I see in the service manual is the spring # 5for the compression release on the camshaft flyweight.

It's amazing what you find inside engines sometimes. Nuts, bolts, sockets, wrenches..... That looks like an external governor spring, but your pic is really small. If the motor has never been apart, it's possible it fell in at the factory. Seen stranger things happen. I agree with Sam, I don't see anywhere it could have come from. I wouldn't worry. It's just a mystery! :bigthink:

Jon

Look at the spring for the ACR on the cam.

Yep, it could be that! I couldn't find it separate (as in a pic) in the parts book. I didn't look in the service manual. Bet that's what it is. :beerchug:

Yeppers... You guys are genius!!
Pulled the Cam and there is no spring - but easy to see where this one used to be!!!

Now - I have to either find one or bend a curved end back on this one. Obviously one of the curved ends is partially broken...
Which likely was the culprit that scored the rod end...

BTW... What purpose is the 'compression release' ???
What would that spring being gone cause the engine to do?

The engine idle so quiet and smooth - but throttle it up - and it seemed to 'labor' to get there. Like it would take 5 seconds for it to reach full throttle just sitting in the driveway.
Of course it smoked when throttled up - but I assumed the slow response was from burning oil instead of gas.

Could this little spring cause this, OR, loss of power????

Thanks,
Fred

The compression release is for starting. Just helps the starter not to have to work so hard. It's not the cause of your problem. If anything, it would have made it hard to crank/start.

Sounds like the motor had some "problems". The revving issue sounds more to me like a bad valve/ lack of vacuum issue. I'd go clear through the motor. BTW, have you looked at parts availability yet? Might check into that. I'm not sure what is available for internals on the Vangaurds.

Yes...
Before tear down I did a quick check for parts and/or new engines. It looked as though parts are available, at least somewhat. Meaning, this is a 94 model engine, and anything pre-2007 you can't just buy rings for it - you have to buy piston and rings for 90 bucks each. gasket set was not a problem at 62 bucks.
I got the part numbers from the briggs partstore website - but ordered everything from Repair Clinic as they said it was all in stock. Paid 19.95 extra for 2day shipping.

So - I should have all the parts here on Wednesday.

We'll see.... Hopefully they are right.

I've used these guys for Vanguard parts.

http://www.jackssmallengines.com/hel...10EZJ10E1502BA

If you have questions they are very good to talk to.