Briggs and Stratton Endurance 20hp blowing blue smoke

[FordnMassey]

Hi,

I have a Briggs and Stratton Endurance 20hp motor in a Husqvarna ride on mower. This is a single cylinder OHV motor. Recently it started blowing blue smoke suddenly while working hard cutting long grass and has continued since. It has 109h on it. The oil was changed at 50 and 100 hours and Husqvarna 10/30 oil was used. After the smoking started, the oil was changed for Penrite 30w mineral oil (a reputable Australian brand for those elsewhere). The smoking continues.

Spark plug removed and found oily. Dry compression test, throttle open, starter cranking, 100 psi. There is significant blow by - oil sprays out the oil filler pipe when running and fumes swirl in the oil filler pipe after stopping.

Numbers to identify the engine are:

Engine Serial Number on sticker:130920 ZD 86480
Number stamped on exhaust manifold tube: 581880901

I was wondering if anyone could help with the following:

1). Does anyone know the compression ratio on this motor?
2). Does anyone have the expected compression test results?
3). can I perform a wet compression test on a horizontal cylinder?
4). Does anyone know if the rings and or head gasket are susceptible to failing at 100 hours?

Thanks in advance.

FordnMassey

 

[Caveman 192]

Hi,

I have a Briggs and Stratton Endurance 20hp motor in a Husqvarna ride on mower. This is a single cylinder OHV motor. Recently it started blowing blue smoke suddenly while working hard cutting long grass and has continued since. It has 109h on it. The oil was changed at 50 and 100 hours and Husqvarna 10/30 oil was used. After the smoking started, the oil was changed for Penrite 30w mineral oil (a reputable Australian brand for those elsewhere). The smoking continues.

Spark plug removed and found oily. Dry compression test, throttle open, starter cranking, 100 psi. There is significant blow by - oil sprays out the oil filler pipe when running and fumes swirl in the oil filler pipe after stopping.

Numbers to identify the engine are:

Engine Serial Number on sticker:130920 ZD 86480
Number stamped on exhaust manifold tube: 581880901

I was wondering if anyone could help with the following:

1). Does anyone know the compression ratio on this motor?
2). Does anyone have the expected compression test results?
3). can I perform a wet compression test on a horizontal cylinder?
4). Does anyone know if the rings and or head gasket are susceptible to failing at 100 hours?

Thanks in advance.

FordnMassey

Sounds to me like a blown head gasket.

 

[FordnMassey]

Hi Caveman 192,

Thanks for the speedy reply.
Does that mean it blows thru to the valve stem passage?
So is 100psi compression ok? Can I wet compression test a horizontal cylinder?

FordnMassey

 

[skipmarcy]

Sounds like a stuck or broken ring.

 

[Tinhack]

100psi is probably a little reduced. For a low hour engine, I'd expect it to be around 110-130. And if it's sucking oil out of the valve pushrod cavity, you already have a wet compression test.

I agree with Caveman. It's most likely a blown head gasket in the area between the cylinder and the pushrod cavity. (Overhead valves)

 

[ruffdog]

A blown head gasket can pressurize the crankcase, overwhelm the vent, and ingest the oil in the intake. Being that the spark plug was found "oily", then you are already wet testing the compression.

 

[RandyT]

The head gasket on the Briggs OHV singles will burn through between the cylinder wall and the push rod cavity. Which created the issue of pressurizing the crankcase pushing oil vapor through the intake system on the compression stroke and power strokes of the piston but will also pull oil through the push rod cavity into the cylinder on the intake stroke as well through the normal air/fuel intake

 

[kenmbz]

I replaced my head gasket and adjusted valves after the same thing happened to mine.
Not a hard job. Kits are available on line pretty cheap.

 

[FordnMassey]

Hi,
Sounds like the head gasket, thanks for the help.
Can someone help me find/understand the engine number? B+S website advice on the numbers doesn't match what I found on the motor which are:

Engine Serial Number on sticker:130920 ZD 86480
Number stamped on exhaust manifold tube: 581880901

Thanks

 

[Caveman 192]

Hi, I think usually the model, type & code is stamped on the valve cover. Hope that helps. I agree, it is not too bad replacing the head gasket . If it is bad you will see it between the push rod galley & cyl. It doesn't take much of a bad place for oil to get in the cyl. or pressure to get in the crankcase. I agree with Kenmbz & several others on here. I have done several of these. They are not bad to replace.