Broken piston... top end rebuild (turbo motor)

This is a continuation of the compression check thread I started here.

I know there are plenty of pictures floating around of people's rebuilds but I thought I'd add a few more. I'll ask most of my questions here instead of in private conversations so more people can benefit and learn. I've never done anything like this so please bear with my ignorance.

The cause of my low compression in cylinder #1 and resulting excessive blow by, which causes tons of oil to spew out the crankcase vent, is clearly seen in the following pics... broken 2nd and 3rd piston lands. All 7 pieces were still perfectly attached to the piston when I pulled it out and there appears to be no damage to the liner. There are burn marks on the liner but they are smooth and no worse than the ones I’m seeing on cylinders 2 and 3 which don’t have any problems. I was surprised to see the compression ring gap on all 3 pistons still well within tolerance.






Cylinder #1 liner




Cylinder #2 & 3 liners




Now I need to decide do I just replace this one piston with a replacement OEM or do I spend the money on a set of new JE pistons with stronger lands? After pulling the first piston I was hoping I’d see something similar on one of the others to help justify going aftermarket on all three.

When doing the valve check I found more than half were out of spec. I couldn't get my .04mm feeler under a couple of the intakes and one of the exhaust valves was at .31mm. Any tips on getting the shims off for measurement and replacement? I'm asking before I've even tried. Hopefully it's rather simple.




The head bolts seemed extremely tight. I will most likely buy the Carpenter ones that don't stretch even though they're kind of spendy. They seemed so tight I started wondering if they were reverse threads. I was just waiting for one to snap but I got them all eventually following the release pattern in the manual. I just want to confirm that I do have the OEM's now. Can someone comment on that based on this head bolt pic? The head did come off once before I bought the bike.




All three connecting rods have the word "distorted" written on them. All I can say to this is WTF? Any ideas on this one guys?




Exhaust valves in the #1 cylinder with the bad piston reveals a rich mixture. So did the plugs. I'm guessing less air is getting pulled in due to the lower compression but since it's a turbo the air is actually getting pushed in. In any regard I'm guessing it didn't look like this before the piston broke and is a result of the lower compression. Any thoughts on that?




My head gasket has a copper film all over it. I'm guessing this is copper anti seize compound? Is this common practice on a head gasket? I was going to buy some nickel anti seize for the exhaust bolts. Don't have any copper anti seize.




The manual mentions using molybdenum disulphide grease in a few places when putting things back together. Would any high temp high pressure grease be just as good or must it say molybdenum disulphide? What are people using for this?

Thanks for any answers or comments.

Also, much thanks to Scott (Warp9.9) for the tip on disconnecting the connecting rod from the crank and pushing the piston out from the top. Why anyone would remove the pistons by the method shown in the service manual is beyond me.

More random pics and a short video:

Quick question. You said you might switch to Pistons with stronger lands, do the stock Pistons have weak rings that commonly fail or is it just a boost issue? Or just a random fluke in your case

Those in the know say the stockers are good to 300hp. I think mine was an over boost or detonation issue. All the evidence I have points to this happening before I bought the bike. A previous owner replaced the head gasket but for whatever reason didn't fix this.

Well that's good to know. Also good to see major engine work can be done without tearing the bike completely apart.

Also weird that your rods say distorted on them

A quick tip: go and get some aluminium baking trays from your local supermarket and use them to hold the parts from each section. This will keep them together, and will really help when re-assembling everything. You can also use them when cleaning the bits.

Torque addict said:

All three connecting rods have the word "distorted" written on them. All I can say to this is WTF? Any ideas on this one guys?

Click to expand...

Lay them on something flat like a shirt of glass and see if the two ends are in same plane. It's possible the previous owner abused motor and damaged them than was too cheap to fix correctly

Hey these are worth it for the rods alone. Not to mention the pistons are still good they have 14000 miles on them out of a 2011 touring. I bought the transmission Slick Rick bought the crankshaft and is running it in his 2006 Carpenter Beast..

http://rover.ebay.com/rover/1/711-5...0001&campid=5335943355&icep_item=200833325512

Now you have found the reason for your issues. You NEED a good tuner. Boost sensitive ign and fuel mapping. Detonation will shatter the ring land/crack rings on ANY piston. BTW take the cams out to change shims, I would recommend checking all guides, seat sealing etc. Also your plug colour is no accurate guide, especially when the motor is tired. Good luck.

Just purchased the pistons and rods. Thanks Scott. That probably settles the aftermarket piston question too. Been thinking about it all day and at this point I just don't see a reason to do that.

Nev, agreed about the good tune as we've already discussed. Just for the record... this piston was damaged when I bought the bike. It was damaged while running Turbo Connection's proprietary controller, not the PCV it's got now, on who knows what kind of tune.They guy blew the head gasket too. He fixed that but not this and now I'm dealing with it which is OK. I've actually had a blast doing this and have gotten to know this bike very well. Just glad the liners OK. I put a little over 2,000 miles on this piston in this condition.