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B&S 331800 Smoking - Reliable Engine?

#1

L

LarryJohnson

I picked up a craftsman mower with a smoking 331800 (3318771371, code 100913ZD) B&S engine from my neighbor. Knew it was smoking, mainly just when throttling up hills. Wondering how reliable this B&S engine is. Head gasket blown?


#2

T

Tinkerer200

Probably head gasket but that is a fairly old engine so could be rings. It is basically am oversized 31 series engine, 31 series very common with rating from 16.5 to 20-21 hp and suffers same valve guide and head gasket issues.

Walt Conner


#3

L

LarryJohnson

Tinkerer200 said:
Probably head gasket but that is a fairly old engine so could be rings. It is basically am oversized 31 series engine, 31 series very common with rating from 16.5 to 20-21 hp and suffers same valve guide and head gasket issues.

Walt Conner
Click to expand...

Didn't realize someone replied. Thanks, Walt.
The seller thought it might be the rings. Not sure why he suspected so. The oil looks "weird" to me. Maybe a hint of gas. Can gas get into the oil any other way beside head gasket.
Here's what the plug looked like Does that suggest bad head gasket or bad rings, or both?

Is this thing ready to blow?



#4

L

LarryJohnson

Tinkerer200 said:
Probably head gasket but that is a fairly old engine so could be rings. It is basically am oversized 31 series engine, 31 series very common with rating from 16.5 to 20-21 hp and suffers same valve guide and head gasket issues.

Walt Conner
Click to expand...

Head gasket replacement looks easy enough.
After wiping off the oil and running it this morning, I noticed an oil leak shown below. What's this gasket (behind starter)? Difficult replacement?



#5

T

Tinkerer200

Spark plug looks like excess oil burning and gas generally contaminates oil by the carb float needle leaking gas which goes into the cylinder and from there into the oil. Replace carb float needle AND add a gas line shut off valve and use it when engine is not running.

That oil leak looks like sump gasket leaking requires removing sump, cleaning both services and new gasket using torque wrench for proper tightening. I can send you a Service Manual IF you like. Address below, put in proper format, remind me engine model number and what you want.

Walt Conner
wconner5 at frontier dot com


#6

B

bertsmobile1

What s most likely happening is the float in the carb is not shutting ff the fuel.
Because of EPA regualtions the overflow is inside the carb so the overflowing fuel runsinto the cylinder then drips pas the rings & into the sump thinning the oil
So start with the carb and changing the oil


#7

L

LarryJohnson

Tinkerer200 said:
Spark plug looks like excess oil burning and gas generally contaminates oil by the carb float needle leaking gas which goes into the cylinder and from there into the oil. Replace carb float needle AND add a gas line shut off valve and use it when engine is not running.

That oil leak looks like sump gasket leaking requires removing sump, cleaning both services and new gasket using torque wrench for proper tightening. I can send you a Service Manual IF you like. Address below, put in proper format, remind me engine model number and what you want.

Walt Conner
wconner5 at frontier dot com
Click to expand...

Excess oil buring suggests bad head gasket, no?
When I replace the sump gasket and head gaskets what else should be done while engine is dismantled.
I'll clean or replace carb float needle and add gas shut off too.


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