21HP V-Twin Head Gasket Repair

StarTech

Lawn Royalty
Top Poster Of Month
Joined
Feb 19, 2020
Threads
93
Messages
11,603
Hey, that would make some good content... "Driving my racing mower until it throws a rod" Iol 😉
Well I had a go cart in the shop a few years ago that they putting it up on blocks to start it and rocking it off the blocks to ride it. They took a piece of field fence wire and had crippled the governor. It was the complaint that it in with the kid's father that it could be started without it taking off across the lawn.

The darn kid did it again but this time the governor part was not available. I have no idea has happen to it now.
 

GasGuzler

Member
Joined
Nov 18, 2024
Threads
2
Messages
19
Torque specs for this engine can be found online. Always look up correct specs for important parts such as head gaskets, and use a torque wrench. Gradually tightening head bolts in a pattern to correct torque is the right way. Reusing bolts will be no problem. Did you do a leak down test to determine bad head gaskets?
It had no oil in it and I believe it has a sticky valve, so heads will need to come off regardless. And once that happens, I’ll have to do head gaskets anyway.
 

Craftsman Garage

Well-Known Member
Joined
May 2, 2021
Threads
34
Messages
480
Was it ran without oil or just leaked out over time? You might wanna crack the sump open and check for damage.
 

slomo

Lawn Pro
Joined
Jul 14, 2019
Threads
78
Messages
5,129
No oil in a Briggs, she will be fine if you can get her to spin over. Little polish on the crank and such. Good to go.
 

GasGuzler

Member
Joined
Nov 18, 2024
Threads
2
Messages
19
Was it ran without oil or just leaked out over time? You might wanna crack the sump open and check for damage.
I’m not sure, the guy who I bought it from said it was in a storage unit he purchased. While spinning it over with the battery, one cylinder makes a loud popping sound through the intake and it feels like it’s pushing air back out through it. I don’t know if the oil was drained for while it was in the unit or if it was going to scrap.
 

Craftsman Garage

Well-Known Member
Joined
May 2, 2021
Threads
34
Messages
480
Hmm, are you going to take both heads off and adjust the valves?
 

Craftsman Garage

Well-Known Member
Joined
May 2, 2021
Threads
34
Messages
480
You shouldn't have to rebuild it unless you have low compression on one side. It sounds like it could be a bent pushrod or valves need adjusted. A top end refresh is smart tho. Could only be a carb.
 
Top