B & S Md# 33r777-0005-g1 replaced by a B & S 33S877-0043

[HusqvarnaRider]

Greetings Ya'll,

Our Husqvarana riding mower Md# YTH18542 motor began smoking while under load, as well as blowing oil out of the fill tube. This happened two weeks after the Warranty went out on the Mower!

There are two B & S Motors listed as replacements for the original motor being a Md# 33S877-0019-G1 and a Md# 33S877-0043.

The Md# 33S877-0043 appears to be a newer, "revised version" of the Md# 33S877-0019-G1, & I can buy it for far less $$$ than the "0019-G1".

Has anybody run in to any problems with the Md# 33S877-0043?

 

[Rivets]

First, if it is only two weeks out of warranty I would be going a GOOD authorized Briggs repair dealer and see if Briggs will authorize repair. To me it sounds like a blown head gasket, which will definitely rule out replacing the engine, but repairing the problem. Even if you have to repair the engine, far cheaper than replacing. Just my opinion for what it is worth.

 

[HusqvarnaRider]

Greetings Rivets,

I tried two local "Repair Shops", that weren't "GOOD" apparently, & they shut me down over the warranty, & that was back in May 2025. Since that time, I fanatically kept the oil level up to where it is supposed to be, & would give the Mower a rest for about a 1/2 hour, & then finish the Mowing. The weird part about this was that it would not always belch smoke, & there was never any "Rattle" that suggested problems with the valves, etc.

I made several calls to other Repair Shops, over in the next County, & they were all to busy to take a quick look at it, & they basically told me that they would not be able to work on it for 3-4 weeks, and that just looking at it would cost at least $150.00, & The repair could go in to several hundred dollars more, with all labor & parts having only a 90 day warranty.

That's why I decided to keep our lawn mowed, until I could find a replacement motor.

That all "came to head", last thursday, for the motor just stopped running, & after about 5 minutes, I was able to restart it, & drive it back to the house. The weird part about that, was it appeared to have full power, but it did smoke somewhat.

But I Believe that the motor is now "In Hospice".

 

[Auto Doc's]

The 2 basic engines are the same but assembled with different carburetors and intake systems.

Yours likely just need the head pulled, then leveled/ resurfaced properly and the head gasket replaced. These were bad about the head gasket failing on the pushrod side and blowing compression pressure back into the crankcase and sucking oil into the combustion chamber.

If you remove the top air shroud on yours, it has likely had excess grass and dirt blocking the cooling fins, or a huge mouse nest is hiding under there. Air cooled engines need good airflow from the flywheel fan.

I recently pulled a top air shroud off of a similar engine and it was stuffed full hay bale string and cotton batting. It took hours to clean all that debris out and remove all the heat shields for a thorough cleaning.

There are lots of good videos about repairing this engine design.

 

[Rivets]

I would contact Briggs customer service and explain the problem. Only costs you a little time no matter what they say. Being a service tech for more than 35 years I’m pleasantly surprised at the answers I get more than once. Try this number, stay calm and explain everything you’ve done to resolve the problem. 1-800-356-632