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B&S 18 HP Opposed Twin Binding

#1

G

George K

I was having issues with the governor so I opened the engine. Since I had it open, I decided to change out the piston rings. When reattaching the connecting rods as per the repair manual instructions, I found that they are binding on the Crankshaft. I applied oiil and it still takes a wrench to turn the crank. I didn’t change the rods or the crankshaft. Why should they be binding?


#2

Scrubcadet10

Scrubcadet10

Are you turning it with the crankcase cover on?


#3

G

George K

Crank case cover is off. Sump cover is on.


#4

Scrubcadet10

Scrubcadet10

George K said:
Crank case cover is off. Sump cover is on.
Click to expand...
crankcase cover/sump are one in the same.

If the sump is on, you may not have the proper end play for the crank and it's binding, the opposed twins used different gasket thickness to set crank end play. Does it turn free with the cover off?
What's the engines model #?


#5

Hammermechanicman

Hammermechanicman

Are the rods binding on the crank or is the crank being pinched by lack of clearance between crankcase and sump cover?


#6

Scrubcadet10

Scrubcadet10

From my opposed twin manual:
Crankshaft endplay is .002"-.026" (.05mm to .66 mm) on vertical crankshaft engines, On horizontal shaft engines it is .004" to .012" with one .015" gasket in place, if end play is less than .002" which can be the case if a new crankcase cover is used, additional gaskets, 005",.009" or .015" thick may be required to obtain correct end play.


#7

G

George K

Hammermechanicman said:
Are the rods binding on the crank or is the crank being pinched by lack of clearance between crankcase and sump cover?
Click to expand...
With rods disconnected, the crank turns easily.
Scrubcadet10 said:
crankcase cover/sump are one in the same.

If the sump is on, you may not have the proper end play for the crank and it's binding, the opposed twins used different gasket thickness to set crank end play. Does it turn free with the cover off?
What's the engines model #?
Click to expand...
Scrubcadet10 said:
crankcase cover/sump are one in the same.

If the sump is on, you may not have the proper end play for the crank and it's binding, the opposed twins used different gasket thickness to set crank end play. Does it turn free with the cover off?
What's the engines model #?
Click to expand...
Briggs and Stratton Model 422707-1214-01
I also put in some off brand oil seals. That may be causing the improper end play. I just got 2 new B&S seals. Let me take off sump cover and I will let you know if it turns freely.


#8

Scrubcadet10

Scrubcadet10

You did get standard rings didn't you?


#9

G

George K

Scrubcadet10 said:
You did get standard rings didn't you?
Click to expand...
I’m learning slowly. No, I got off brand rings. But just to see if it was the rings, I took them off and put back the old ones. Still binding. So I don’t think the rings are the issue.


#10

Scrubcadet10

Scrubcadet10

I doubt this is the issue, but what are you torquing the rod bolts too?
in my manual it says,
"Torque connecting rod screws to 190 inch pounds, rotate crank 2 revolutions to check for binding, connecting rods should be free to move SIDEWAYS on the crank pin. (what the rods bolt too)
*Note: failure to use a torque wrench can result in loose connecting rod causing engine damage or tight connecting rods causing scoring.


#11

G

George K

Scrubcadet10 said:
I doubt this is the issue, but what are you torquing the rod bolts too?
in my manual it says,
"Torque connecting rod screws to 190 inch pounds, rotate crank 2 revolutions to check for binding, connecting rods should be free to move SIDEWAYS on the crank pin. (what the rods bolt too)
*Note: failure to use a torque wrench can result in loose connecting rod causing engine damage or tight connecting rods causing scoring.
Click to expand...
I had them torqued to 190. But even when I give them just a firm tightening, they bind. At 190, it took a lot of force to turn them


#12

G

George K

I’m going to go pull the sump cover. Do you know what gasket should go on this. There are 3 to choose from. What thickness should I get.


#13

Scrubcadet10

Scrubcadet10

George K said:
I’m going to go pull the sump cover. Do you know what gasket should go on this. There are 3 to choose from. What thickness should I get.
Click to expand...
I don't think its binding due the cover since its only with rods on.. I'm a bit on the confused side.


#14

Hammermechanicman

Hammermechanicman

If the rods ar binding on the crank you have a real problem. Take the rods off and check the crank journal for scoring and aluminum transfer. The rod bearing surfaces should be smooth. If they are binding something definately wrong.


#15

G

George K

I appreciate the help. Give me a couple days to break it all down. It’s cold and raining for the next couple days. I will let y’all know when I get back to it.


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