Lawnmower has no compression - Craftsman Briggs and Stratton 7.5 intake valve seat

This is the second time it's happened, my lawnmower has no compression when I pull the starter cord. I'll take the engine apart down to the cylinder head and find what I unfortunately expected, correct it, and then put it back together.
The automatic punch I used can be found here: amzn.to/442wKxm
The wonderful thing about lawnmower engines is that they are actually easy to fix, just pay attention to what came from where so that you can put it back where it belongs.
00:00 intro
00:28 start tear down
06:19 remove cylinder head
07:58 the problem, and the fix
10:26 putting the lawnmower engine back together

[@workbenchz]

11:40 the short screw goes in the lower hole, the longer screw bottoms out before seating... 12:15 yes I know I trapped the governor spring, I freed it later.

[@AbdicateDotNet]

Great video!! My dad was a great mechanic and taught me a bit, but as I got older, I never messed with engines of any kind. Thanks for the tip and the walk down memory lane! 👍👏😁

[@workbenchz]

Growing up, my dad was my teacher on "learn to fix it yourself when you can". Thanks to youtube that's even easier today than back in the day.

[@EdWeibe]

I'm in the middle od ressurecting an old leaf vacuum engine and man thanks for this educational video. My issues arent like this just yet, but any valve workings, I love.

[@workbenchz]

Small engines are intimidating until you get into them, and lots of help on youtube. @Chickanic is really good for lots of small engine repairs.

[@petelugo2681]

Outstanding video. This is exactly the problem I have with my mower, and now I suspect it is the cause by watching your video. Thank you so much for taking the time and making the video.

[@workbenchz]

I was a bit intimidated at first, and had resigned myself to probably replacing the mower, which gave me the freedom to give myself permission to tear it apart and not worry about making it worse, LOL

[@carlodonnell146]

I have just been enlightened about the air-vane; I did not know that it keeps the choke opened, though I have seen numerous lawnmower videos. Thanks for mentioning that, so clearly.

[@workbenchz]

I'm happy you found this useful.

[@garybuffington6021]

GREEN Loctite works great as used for "bearing races". It then takes HEAT from a torch to remove the item after using GREEN Loctite. RED Loctite would be better than nothing. GREEN Loctite works better than "staking" like you did to retain it. Automotive Machine Shops use Green or Red Loctite on Valve Seats to retain them in the head.

[@workbenchz]

I'll have to look into that, thanks.

[@carlodonnell146]

yes I never heard about green loctite until now, sounds good!!@@workbenchz

[@chrisssmallengines7163]

Great video , I used a hammer and punch which gives a little more of a divot to keep the seat in place . So far so good it has not come out again .

[@workbenchz]

thanks, 8 months and this is still holding up. If it goes again I'll try that.

[@lzh3131]

I really liked your video. Very thorough explanations, the spacer for the gas tank assembly, spot on, I had an extra piece left over.🤭 Scotty C. has a video very similar, with the exception, he removed the exhaust cover, and adjusted the valves, before reseating the valve seat. His video wasn’t quite as detailed as yours. Because you did this last year, do you think this extra step might be part of the solution, to not having to repeat this again? I checked out your channel, some neat projects, I’m subscribing! Good job!👍👍👍

[@workbenchz]

I didn't see any indication on mine that would lead me to adjust the valves, hmmm...

[@chicocash9668]

nice idea with the pin punch

[@workbenchz]

I can't take credit, I watched a LOT of other videos about fallen valve seats do that, so that's what I tried.

[@cantwinifyadontscratch7679]

Good vid but he really didn’t have to tear down the engine to fix that problem. I’ve done this job many times over

[@workbenchz]

My previous Tecumseh engine mower allowed you to remove the head by itself. This Briggs & Stratton uses the upper left head bolt for the carb mount. I'd love to find a way to remove the head without unmounting the carb.

[@luisegallegos8120]

Bien chingon trabajo gracias por el video amigo ayuda mucho estos videos mil gracias

[@workbenchz]

thank you.

[@87GP400]

Thanks for this nice video !

[@workbenchz]

A permanent fix would require a machine shop mill the intake and a new seat, or replace the block. This is how I saw so many other youtubers deal with the problem and it worked.

[@outboardfixer]

It would have been nice to see what the compression was when finished.

[@workbenchz]

I'll need to buy another tool for that...but it was good enough to keep going and cut the lawn many times.

[@gfriedman99]

You haven’t addressed the reason the valve seat is coming loose. This is caused by overheating of the aluminum head. A number of issues can contribute to this. Improper lubrication, blocked exhaust, and improper timing are some of them.

[@workbenchz]

Interesting idea, would overheating also loosen the exhaust seat?

[@barackobama5304]

@@workbenchz It could, especially if its due to carbon buildup in the exhaust port. Therefore I think its one of the other causes. Do you ever get kickback when pulling the starter cord? If so then the timing is off.

[@paulettacox6893]

I work on lawn equipment Dan the man from Ohio

[@workbenchz]

Is this something you run into, valve seats that won't stay put?

[@paulettacox6893]

@@workbenchz not very often

[@robertknight4672]

I've seen a few KZbin videos on KZbin fixing this problem. However I don't think it happens that all often especially on these Briggs Quantum engine. I've actually never had to take the head off a Briggs Quantum engine.

[@workbenchz]

My first craftsman lawnmower had a tecumseh engine and it lasted nearly 17 years. Their design make disassembly easy and you didn't have to unmount the carb to remove the cylinder head. I've had this Briggs & Stratton for almost 10 years, and had this apart more times already. On both the metal/fiber head gasket made reusing the gasket easy.

[@robertknight4672]

@@workbenchz the other thing I like about the Briggs Quantum is if it appears to have a carburetor problem you can sometimes do a quick-and-dirty cleaning of just the carburetor bowl nut and it will run.

[@carlodonnell146]

the large valve on my briggs/stratton has little indentations around it similar to what you just showed there, but it was done that way from new. Why would it be so?

[@workbenchz]

"From New"?! I couldn't say. This pattern of dimples around the valve are one technique to get a loose valve seat to stay in place; there shouldn't be any on a block that is new.

[@carlodonnell146]

@@workbenchz that is what I think too, the dimples are not in the exact same spot as yours are but they are there more on the block a little bit away from the valve. thanks for responding

[@dannylinc6247]

Lean condition makes a hot condition. Airflow blocked partially makes a hot condition. I would get air to it any way I could. A muffler full of soot can partial block exhaust. A rich condition can account for a lot of black soot and carbon fouling of the sp plug. I wonder if TARYL has a quantum valve seat video. He seems to repair almost every valve seat that drifts or comes loose. Change the oil and air filter and clean it up would be sensible for cooler run. Or just do sections of mowing at a time if this persists till more ideas are found for this failure, I would have to say. Good luck. Other people's mowers they gave up on can be a good part source.

[@workbenchz]

thanks for the feedback. I'd love to see a video of valve seat replacement on this B&S engine.

[@tomt9543]

Pretty sure I’ve seen it! Donyboy also has a vid on it.

[@jamesbrannon9594]

Did you reuse the same head gasket?

[@workbenchz]

Yes, these seem to be quite sturdy and I've had the head off twice without having to replace the head gasket.

[@TheSwampDaddy]

Can you reliably refuse the original head gasket?

[@workbenchz]

If I'm careful to not damage it, I have reused the head gasket on several lawnmower tear-downs with great success.

[@adddad9779]

Briggs best motors...

[@workbenchz]

I really liked the Tecumseh motors, I got 13 years out of my last one, but they aren't made anymore. B&S are almost as easy to repair.

[@mgomez5606]

What is the approved B&S method? I don’t have a manual?

[@workbenchz]

I haven't found an "Approved B&S" method yet.

[@mgomez5606]

@@workbenchz I did the peening method. I was just wondering. Probably dry ice the area and install a new oversized one. I'm just guessing.

[@workbenchz]

Browsing other videos of machine shops doing valve seats, it looks like you would heat the block and freeze the seat blank that has a 0.001+ interference fit.

[@tinalau7696]

There is no need to remove the carb to remove the head

[@workbenchz]

I recently ran across another video where they just loosened the bracket and "slipped" the head out from under it, I'll try that next time.

[@EdWeibe]

no rehone huh?

[@workbenchz]

Yeah, it looked ok so I gambled that the seat was still good enough. I don't have the tools or experience for a machine shop level repair. Maybe if I win the lottery ...

[@mgomez5606]

Why don’t you take the starter off if you don’t use it.

[@workbenchz]

The battery was drained and B&S doesn't recharge the battery while running like Tecumseh did.

[@frankie7508]

By his own admission it is a temporary repair. And he didn't even take the time to clean the lawn mower. All around a completely sloppy job. I won't watch any more of his videos.

[@TCBOT]

lol id bet it outlives the mower deck its on still done this alot with the 80,/90s ride on mowers as a kid (was common issue for few years in the 80s -erly 90s i know this mower is newer but still the same issue only other fix involves a new engine defo not worth it

[@frankie7508]

@@TCBOT You are an illiterate.

[@workbenchz]

@TCBOT Pretty much, $350 for a new block with valve seats installed. At that price point a new mower is a better answer.

[@chuckstewart7331]

What’s wrong??? It’s a CHINESE Briggs & Stratton …. Duh

[@workbenchz]

LOL

[@stevesmith6058]

No it’s not a Chinese engine it’s A Briggs & Stratton quantum Duh

[@219enri1]

Uh oh, maybe it's just time to ditch that ancient stinky gasoline thing and make way for something new. There are quiet electric battery mowers available today that are certainly better. Or why not switch to a handheld, cheap efficient and promotes fitness.

[@workbenchz]

I did get a quiet electric battery mower, you can see it here: kzbin.info/www/bejne/aqfcZ2ymoZp6ntE

[@stevesmith6058]

Battery lawnmowers are junk

[@BH-ro4ly]

@@stevesmith6058 They're not bad but they're definitely not as good as a petrol mower. If you live in town and only have a small section to cut its probably better to just get an electric mower. But if you have a bit of grass to cut then petrol's better. Reliability wise petrol will probably last longer since the electric battery's dont last very long. I've had a petrol mower for 10 years and its still going strong but I've just needed to do this repair in the video as the valve has popped out. Hopefully it'll get another 3 years from it before something else goes wrong. 10 years service its done well im satisfied.

[@Talachachannel]

Goofy jobs

[@workbenchz]

Yup