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Huntley · Feb 26, 2007, 08:51 AM

I have a 14.5 B&S engine on a Yard Machine tractor. It appears the head gasket went on me this am. Blew smoke, and oil under gasket. Will start back up and run but then dies in a cloud of smoke. Can you give me a rough idea of what I can expect to pay to replace? Is it something a do it yourselfer can do?

newaukumdon · Feb 26, 2007, 06:11 PM

Check the oil level, it may be fuel in the oil causing the level to rise and push into the air filter through the crankcase breather. This is a common problem in the briggs line.

If an head gasket blew, unlike an automobile it will have very little sign. Generally you suffer a loss of power and you may hear a chirping. Extended periods of operation will result in terminal (fatal) damage either on the cylinder head or engine block.

Bad gaskets can cause crankcase vacum leaks and push oil out the breather as well, but with the amount of smoke and the suddenes I believe the culprit is fuel in the oil or just overfilled.

PS remove air filter and run after checking, it may be oil soaked.

Regards,
Don

thebriggsdude · Feb 28, 2007, 07:22 PM

Been gone a while...

Briggs head gaskets fail easy sometimes (thin spot in the design) and just simply blow out..
This will overpressurize the crankcase and make it puff like a train...
BUT DO check the oil... over filled and smells of gas... can cause oil burning...
A loose filler neck/dipstick can do this... torn/worn out seal.

If you take the head off... look at the thin spot for a burn spot (black)

I saw a guy running his briggs with the head gasket blown a few weeks ago... I thought he was burning leaves... do not run it low on oil!

Huntley · Mar 1, 2007, 07:44 AM

Thank you for the answers. When it happened I checked the oil level and it was fine. Changed about 15 hours ago. Oil looked clean and not over the top mark. I will check its smell for gas tonight. I will also check the airfilter.

I am not a mechanic, but where it appears I see oil discharge is around what I think is the head gasket. It's the flanged part of the engine where the spark plug goes in, which on my mower is above the muffle. As such I surmized that a leak dropped oil on the muffle as well as a momentary loss of compression.

Engine started just fine a few minutes later, but under load (plow some snow) it happened again. Fearing doing damage to the engine I shut it down.

Any other advice would be great!

newaukumdon · Mar 1, 2007, 09:34 AM

If it is marked "ohv" it will be the valve cover gasket. Good luck

If it is above the spark plug and is tin, it is more likley the valve cover and very easy to replace. The loss of power could have been the burned oil vapor being drawn into the carburetor through the air filter

Huntley · Mar 2, 2007, 09:21 AM

newaukumdon - Thanks. It is an OHV engine. After digging around and looking at it quickly last night I think it is indeed the valve cover gasket. I will take a closer look this weekend and give a shot fixing it. Any suggestions on the process? I fgure I will just go to a local B&S dealer and pick up a gasket. Anythng else I will need?

Again thanks for the help !

thebriggsdude · Mar 4, 2007, 02:27 AM

AH yes ohv gasket leaking.. if its got a muffler under the cylinder it'd burn it. Local small engine shop should have it... don't try to use "make-a-gasket" stuff... do it right and get a new one and make sure the old ones scraped off, its 4 little bolts to pop the cover off, and make sure nothing gets inside...

While your there, you could adjust the rocker arms.

Huntley · Mar 8, 2007, 07:07 AM

Thanks... The saga deepens. I replaced the gasket with OEM part. I also figured I would check the oil once again. This time it was well above the top mark. Had a smell of gas. I drained it out. Checked the air cleaner. It two has some gas in it. I cleaned it. Then with the air cleaner off I tried to start the engine. A stream of gas shot out of the air cleaner.

Figured it was beyond my capabilities. Took engine off the tractor and took it to this 70 year old guy who fixes engines, has for years. He cracked open the engine. The head gasket was fine. And the oil appeared to have gas in it again, not much but enough to smell and weaken the viscosity.

He then asked me, does the engine backfire, and I said it does and I was told that was normal. He then asked if the battery was OK, and I said well come to think of it it does go dead after a week of sitting. It's a brand new battery.

We checked the electric solenoid on the carb. It appeared to be OK. Now looking at my key ignition and the float. Thought is that the key never turned the solendoid off, and since the tank is above the carb the gas slowly filled the carb, crankcase etc... Also holding the solenoid open drained the battery.

Hope to have it resolved by the weekend!

Huntley · Mar 8, 2007, 10:55 AM

The saga deepens. Pulled the key ignition off. It does not match with the part number in the tractor/engine parts lists. Looks like originally the "Demo" tractor I bought from Tractor Supply had a V Twin engine that was replaced with a single cylinder engine of the same horsepower.

newaukumdon · Mar 8, 2007, 11:01 AM

That would be unlikley, the manufacturer could have a vendor change in mid production but not many would change engines with any other than original. Swapping like that would be a real pain in the butt and not worth it for most dealers or distributors.

I have experienced no scenario with a failed ignition switch causing the solenoid issue. I would certainly look at debris holding float open as well as a bad float.

Huntley · Mar 8, 2007, 01:55 PM

Newaukumdon, thanks. I just figured if the original owner blew the engine returned the mower, maybe they went with a cheaper (single cylinder) motor when they replaced it. We are going to check the float as well. I am going to take the serial number and contact MTD to see what there records show was on the mower when it left the factory.

Huntley · Mar 12, 2007, 05:37 AM

OK, turns out there was a misprint, well bad writing in the parts book from MTD. The ignition in the manual was incorrect, only to be determined by the elcticial diagram which showed a different ignition for the OHV engine.

Everything else checked out. The result is that the float was stuck with some small debris. Cleaned that out, added a shut off valve and ran the engine just fine on the bench.

Now looking to find out why my new battery can not hold a charge on the tractor. Any suggestions on how to find where the problem is?

newaukumdon · Mar 12, 2007, 06:40 AM

The battery's supplied by parts houses are poor quality, have it checked. Not likley a drain. Just in time for spring!
Don

Huntley · Mar 13, 2007, 11:39 AM

Had the same battery for three years of use. Decided to get a new one. Bought it at Wal Mart. It lasted one year and could not hold a charge. Last year picked one up at Sears. It lasted 6 months. I can not think of what else could be causing the power drain. My light bulbs did stop working a few years ago.

I think once I get it back together I will just not plug them back in and see. Also I now know the purpose and color of the wires and will see is anything is staying hot after I take out the key.

Any other suggestions?

newaukumdon · Mar 13, 2007, 07:09 PM

You can disconnect the battery, let it sit to see if it drains with nothing else connected.
A battery tender will extend life of the battery. Do you have a electric blade engage? Or is it a lever? If it is electric that could drain the battery if the switch were left on.. . Other than that I think you will have a bad battery.
Don

Huntley · Mar 16, 2007, 05:13 AM

It has a manual blade engage. I will fully charge the battery and see if it hold being unconnected. Might have to buy a new battery as I think the one I have has been charged and run down so much its useless.

Thanks for the help!

Oh one last question - The manual that came with my engine say to use Synthetic 10W-30 which covers all temp ranges. The B&S repair manual says to use traditional 30 weight. What would you suggest.