21B707 On the Troybilt

[PTmowerMech]

Briggs 21B707 0453 E3 on a Troybilt Pony 13WM77KS011

When I give it full throttle too quick, it starts running like it's being choked. LOTS of white smoke and some black smoke in there too.
Engage the blades, and the engine starts shaking, deck starts shaking. And it smokes like the devil.

Disengage the blades, throttle it down, and it goes back to normal.

What I've done...
Took the carb bowl off and turn the needle around. Yup, it came in that way. The guy says his son was tinkering with it.
Without taking the carb completely apart, (and making sure the needle valve didn't have a ring around the tip. I cleaned out what I could get to without taking it all apart.
Adjusted the valves, which were way out. Push rods were still straight.
Replaced the spindles and bearings. Check the idlers and they were fine. Before putting the deck back on, I made sure everything was spinning freely.

Compression is at 90lbs.

 

[PTmowerMech]

Found 1 crack in the frame when the engine bolts on. The left read engine corner.

I suspected the engine wouldn't last long. So the customer and I agreed to remove the deck and I was to keep it, for a discount on just returning it at a rider. But told the customer to not give it over 1/4 to maybe 1/2 throttle.

 

[bertsmobile1]

Briggs 21B707 0453 E3 on a Troybilt Pony 13WM77KS011

When I give it full throttle too quick, it starts running like it's being choked. LOTS of white smoke and some black smoke in there too.
Engage the blades, and the engine starts shaking, deck starts shaking. And it smokes like the devil.

Disengage the blades, throttle it down, and it goes back to normal.

What I've done...
Took the carb bowl off and turn the needle around. Yup, it came in that way. The guy says his son was tinkering with it.
Without taking the carb completely apart, (and making sure the needle valve didn't have a ring around the tip. I cleaned out what I could get to without taking it all apart.
Adjusted the valves, which were way out. Push rods were still straight.
Replaced the spindles and bearings. Check the idlers and they were fine. Before putting the deck back on, I made sure everything was spinning freely.

Compression is at 90lbs.

HAve you checked for a blown head gasket ?
Is the engine bolted down tight ?

 

[PTmowerMech]

HAve you checked for a blown head gasket ?
Is the engine bolted down tight ?

Yes, it was bolted down tight. No, didn't check for a head gasket leak. The customer was already on the edge of just leaving it with me. Said he didn't wanna get over $200 on repairs when I picked it up. It was old. I wanted to check it. And probably should have. But I wouldn't have gotten paid for it.
I need more exp. with the leak down tester.

 

[Scrubcadet10]

aren't these the ones that tend to blow out between the cylinder and push rod pocket?

PartsTree - Home of OEM Parts for Outdoor Power Equipment

Parts lookup and repair parts diagrams for outdoor equipment like Toro mowers, Cub Cadet tractors, Husqvarna chainsaws, Echo trimmers, Briggs engines, etc.

www.partstree.com

 

[PTmowerMech]

aren't these the ones that tend to blow out between the cylinder and push rod pocket?

PartsTree - Home of OEM Parts for Outdoor Power Equipment

Parts lookup and repair parts diagrams for outdoor equipment like Toro mowers, Cub Cadet tractors, Husqvarna chainsaws, Echo trimmers, Briggs engines, etc.

www.partstree.com

View attachment 54731

He said when he gets another one, he's gonna let me have this mower. Maybe it'll be soon. It's only got 90lbs of compression. But if the head gaskets bad, I can use it around the shop to pull other mowers to the front.

 

[StarTech]

You don't mean you are too lazy to do a leak down to check for a blown head gasket?

This is easy to do with only the valve cover off during the dang leak down test. 90 psi is well with good specs; although, a leaking head gasket don't always cause a loss of compression when an ACR is involved. The major sign this is usually excessive oil usage only.

 

[bertsmobile1]

You don't need the full kit for gaskets
Just a 14mm bolt drilled through with a nipple on the head end with a couple of inches of fuel line ( pressure line would be better ) on the end of it.
Plug the air duster into it , set the engine to TDC and puff come air in
Unless you listen the heavy metal rock or the workshop is between two side of an interstate, you will hear the air rushing out.

These silly little tools only take a few minutes to make but save hundreds of hours over the year
The same "tool" with a grease nipple in place of an air nipple gets used for pumping grease into a siezed cylinder to break it free from the bore .

 

[PTmowerMech]

You don't mean you are too lazy to do a leak down to check for a blown head gasket?

This is easy to do with only the valve cover off during the dang leak down test. 90 psi is well with good specs; although, a leaking head gasket don't always cause a loss of compression when an ACR is involved. The major sign this is usually excessive oil usage only.

No, I'm NOT too lazy to do anything I'm getting paid to do.