Connecting rod bearing?

TomB985

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Good evening, everyone.

Trying to help a friend with a blown B&S 14 HP single cylinder lawn tractor engine. Connecting rod broke last year, and he's trying to replace it and get this thing working as cheaply as possible. Took things apart and the majority looks pretty good, but the crank was scored up pretty good. Ordered gaskets, connecting rod, and a new crankshaft, and something just isn't right. Here's what we're working on:

Model: 311707
Type: 0125-E1

Connecting rod: 692420
Crankshaft: 690136

And here's the issue:
2017-05-29 13.23.22.jpg

The rod journal is much smaller than the rod. Is there supposed to be a bearing in here? Can't find one on any part schematic, and this is very clearly not right.

Thanks in advance for the help!
 

Tinkerer200

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Sounds to me like you have a crankshaft for a 28 series engine instead of for a 31 series. They will interchange except the connecting rod. 31 series has a larger connecting rod journal on the crankshaft. Your mistake or theirs. NO insert bearing. .

Walt Conner
 

TomB985

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Sounds to me like you have a crankshaft for a 28 series engine instead of for a 31 series. They will interchange except the connecting rod. 31 series has a larger connecting rod journal on the crankshaft. Your mistake or theirs. NO insert bearing. .

Walt Conner

I don't know about that...I don't have a micrometer, but the journal on the old and new crankshaft appears to be the same size. There isn't enough of the old rod left to compare, though.
 

Tinkerer200

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The difference should be evident so I don't know what your problem is.

Walt Conner
 

bertsmobile1

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Crankshaft 690136 codes out to a type 28 engine https://www.partstree.com/parts/briggs-and-stratton/parts/690136/
According to the B & S parts books 311707-0125-E1 could have more than one rank depending upon the date codes.

So at a guess ( & it is only a guess ) looks like B & S did a batch of (cheaper) 31's for Snapper using obsolete 28 cranks.
But don't you go believing a B & S Master Technician, what would Walt know ?

try reading it on the web ( because it must be true )
http://www4.briggsandstratton.com/miscpdfs/RNT/Engine%20Specifications%20Chart_ms3992.pdf
Note the crank journal sizes.
Funny enough they are just what Walt already told you.
31's are bigger than 28's by .300" and that can be measured with a rule, no need for a micrometer.
 

TomB985

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Thanks, guys!
Crankshaft 690136 codes out to a type 28 engine https://www.partstree.com/parts/briggs-and-stratton/parts/690136/
According to the B & S parts books 311707-0125-E1 could have more than one rank depending upon the date codes.

So at a guess ( & it is only a guess ) looks like B & S did a batch of (cheaper) 31's for Snapper using obsolete 28 cranks.
But don't you go believing a B & S Master Technician, what would Walt know ?

Sorry for that, wasn't trying to imply anything of the sort. Guess I should have worded that a bit differently. My point was simply that the factory crankshaft appears to have the same journal diameter as the replacement, and both are too small for the connecting rod. That's all.

Your explanation makes sense. How would I go about finding an appropriate connecting rod that would fit with the 28-series crank? Just pick a model number in this series?
 

Tinkerer200

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No problem here, while I appreciate bertsmobile1 comment he is giving me much more credit than I deserve. I have worked on 31 series engines since the very firsrt ones and dozens since and have never ran across that. IF it were mine I would be looking at returning the crankshaft for one with the larger connecting rod throw. Realizing that may be a hassle, a connecting rod for any OHV 28 series engine will fit. Note that there are 28 series engines in both flat head and OHV.

Walt Conner
 

bertsmobile1

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If you bought them on line from a real mower shop, ring them up or drop them an email with the photos.
If there is no signs of them being used most will swap them over.
The B &S parts books are not as accurate as one would hope and then there is the chance that the wrong part was put in the right parts bin.
Dip your old crank in hydrochloric acid ( from a swimming pool shop ) sitting in the sun, keep pets & people away, beware of splashes etc.
When all of the alloy has been eaten away, add chlorine to bring the pH back to 7 and dispose of the solution.
Measure the old crank, dirty they are quite deceptive.
This is where the extra few $ you pay at a dealer are justified.
They have the experience to order you the right parts in the first place and that experience comes at a price.
If a briggs part was used on a JD I get them from a JD shop 25 miles away, bypassing 2 others and I order them from the salesman who is missing 1/2 thumb & 2 fingers, he came from the workshop & he knows
 

TomB985

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Oookay. Called Jack's Small Engines and they didn't know, just that the B&S schematics showed the parts I had were compatible. They suggested I call the B&S technical line, which was my next call. They came up with the same info, that the crank and rod I had were correct for the application.

So I played around with some parts diagrams and model numbers and came up with the next likely candidate. Gonna try 794122 as a replacement connecting rod, it's on the way. Thanks for all the help, will post up when it comes in and we get this figured out.
 

Tinkerer200

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Oookay. Called Jack's Small Engines and they didn't know, just that the B&S schematics showed the parts I had were compatible. They suggested I call the B&S technical line, which was my next call. They came up with the same info, that the crank and rod I had were correct for the application.

So I played around with some parts diagrams and model numbers and came up with the next likely candidate. Gonna try 794122 as a replacement connecting rod, it's on the way. Thanks for all the help, will post up when it comes in and we get this figured out.

Isn't that absolutely incredible.

Walt Conner
 
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