Uh Oh, removed the head for suspected head gasket issue, discovered bore scoring...

Yep, my wife called yesterday to let me know it "just stopped".... Ended up pulling the head and sure enough, there's a buggered head gasket but then I noticed....BORE SCORING!!! Got a new gasket on order from amazon though, just going to slap it back together and see how we go. Hopefully it lives on.. Cheers, Julian PS. never took much notice but John Deere green is a lot like viper green...might slap on some RS decals

Oh boy....sorry to hear it!

That's a lawn mower, right? At least it doesn't look like a flat 6.

Thats right a flat single, can't be called a boxer so maybe its a jabber? Anyhow, yes it's my (till yesterday) trusty John Deere mower. When I saw the bore scoring I couldn't resist the temptation to post some photos here... Cheers, Julian

Apexhunter, In your opinion, what is the cause of your bore scoring? You seemed surprised by the text of your message, so no real action that lead to the piston skits causing metal to metal contact with the cylinder bores?

I suspect it's just down to the engine design by Briggs and Stratton. Unlike the M97's in our 987s, some excess oil use or miniscule drop in power over the life time of the mower will probably go unnoticed. Cheers, Julian

LOL per JD pics. Just goes to show you when I'm not focusing. I think for a quick second - I was like - that's not a Boxster motor - but didn't really pause. BTW, check your JD's IMS bearing while you're at it. If your mower generally sits during the winter, there's a high rate of failure with those.

My first thought was when is the cease and desist letter for repairing your Johnny Deere engine showing up?

I've been thinking of opening Flat1s mowersport and offering a bespoke resleeving service.

OK it was a joke on us, too bad about the John Deer tractor though. We have seen enough bore score in real caymans, as another one just happened.

My guess you ran it out of oil… funny story, My neighbor bought a new toro and fired it up and half way mowing the yard, it locked up (bad sound)… I go over and he’s scratching his head “this is brand new!!” I walked over to the box and held up a new quart or pint of oil it came with that didn’t get added 🤣 Btw, most modern engines that fail all have scoring… it’s really common, it just seems to be more Porsche common because a motor doesn’t cost 5k for a new short block

It's shocking how robust and tolerant to abuse modern small 4 stroke motors are. I've re-pinned valve seats down with reckless abandon on B&S engines and they fire right back up and take abuse for another 2 years. I think the worse you maintain them, the longer they last LOL!

If it’s a Honda… 🤣

I tell you what tho, the confidence boost I have in my mechanical ability after being able to do a “top end rebuild” (head gasket change) and get it running again! 😊 I’m thinking about dropping the engine in my Boxster and doing a rebuild just for the hell of it! Probably rebuild the gearbox while I’m at it, how hard can it be? Cheers, Julian

I’ve also wanted to pull apart a flat 6. The builders make it sound so involved, and maybe it is… I’ve rebuilt a 3S turbo MR2 motor, bridgeported rotary and part of a 2GR V6… I love those motors.. stuck one in the MR2. Anyway, I’d like to try

That sounds about right. Later on a real Porsche engine rebuilder sent him parts, then told him to send the mess to them to rebuild the right way all on camara. They actually got some cash to finish the job from some of their subscribers. Its sort of what not to do after all those sessions. I think they ended up with a 3.8 motor and a lot of free advertising to that rebuilder.

In all seriousness, should a flat 6 not have any marks on the cylinder walls? My 987.2 engine was clearly bore scored and using oil so I looked for a used engine. I found one from reputable people but just prior to purchase they disclosed that the engine had been previously sold and returned due to bore scoring. The seller disagreed and had no compunction about selling it again. They did their own scope and the photos clearly showed marks on the walls. They evidently feel that it is just normal wear on a 39,000 mile engine.

Knock on wood, but my M97 engine uses no oil between 4000 mile oil changes. That should be what you are looking for. Hard to know though as a used engine from a wrecked car, has no owner telling the oil use story. A leak down test is the only test except for a bore scope though the spark plugs. The 9A1 engine should be more robust than the M97 engine though. Different pistons/skirt coating and different matrix cylinder wallls. This means your search should turn a good one up sooner than later.

In the seller's opinion this one IS a good one. What I'm wondering is if some scoring is normal or should cylinder walls remain pristine? FWIW this engine wa built by TPC and supposedly has Nickasil coated cylinders. I cut bait and sold the car. The buyer has found another engine. .

Cylinder walls need to be clean of bore scoring if the engine is to survive. In the bidn10 case, a turbo engine that was never intended to be turbocharged no matter what TPC did to it (started as a (9A1 3.4). TPC simply cannot predict how users can mistreat there build. On the other hand, Porsche does a great job with their Turbo engines. You never hear of one of these motors with bore scoring. You can ask Jake Raby of flatsixinnovations.com. He has many videos and a help desk to answer questions about bore scoring like this. He also as a service that rebuilds a lot of these bore scored motors. You send him the car and he takes it off the truck and rebuilds it with his proven methods. Not sure he will touch a modified turbo though.