Buttercup

Yep totally different, the only things that are the same between LTx and SBC are crankshafts, cams, valvetrains, rods, pistons, the heads are WAY different with a change in coolant passages, likewise with the block, oh, wait a minute

You shouldn't do it with any engine. I'm sure there's plenty of people that have gotten away with using abrasives. It's not that it WILL completely destroy an engine but that it CAN

Where's that "bang your head against a wall" smiley???

That's fine if a few of you like doing and want to keep doing it. You can lead a horse to water......

MACGI 98 Z28

Roulette.

Scotch Brite pads will kill an engine. They are great on the workbench, and have their uses. Unfortunately engines isn't one of them. Keep doing it and you will have an engine fail from it.

nitropatch

this is like the 5 time i have done it on my motor and other peoples motors and they have no problems at all so i will keep doing it.

CGrant

Are we talking about the red/grey scuff pads that you can putchase at any autoparts store, or the actual scotchbrite pads that have metal in them, I have used the red scuff pads on lots of parts with no problems, Now the scotchbrite pads with little metal particles in them i could see maybe having a problem, I must say that I for one dont want to try or test the scotchbrite theory!
JMO!
Chris...

RCF925

As I posted earlier I used Pads with no metal in them and seafoam, I ended up taking the motor completely apart anyways to stroke it so I can't say if there was any harm done. I am still not convinced you couldn't use a non-metallic pad and seafoam to clean the tops if you are careful, It seems to me if any particles did get between the piston and cylinder wall they would stay above the top ring and either melt or get blown out the exhaust. If they were non-metallic they wouldn't be scraping anything.

Vader

Being non-metallic has nothing to do with it. Many abrasives are non-metallic and cut all kinds of metals easily. If that is your only criteria, then why not just bring the bead blaster over and shoot all the piston tops? Get some carborundum paper, or emery cloth, or garnet paper, and scrape away. All of those things will score the cylinder walls very effectively.

NOMAD

Honestly, what the hell does it matter if there is a little carbon deposit on the top of the piston ? It's not like it won't accumulate again after a few thousand miles of driving.
Bring each one to TDC. Wipe with a dry cloth. Spray with carb cleaner. Let dry. Wipe again. Spray again. Let dry. Oil cylinder. No abrasives and your cleaning all the loose deposits out. If any more particles are left they will be scorched and exited out the exhaust on the first fire up.

It's nice to clean pistons, but when it comes to engines, you need to be surgically clean. If not it's a waste of time and effort. It might not fail your engine, but is it worth the risk to just have pretty piston tops for a few thousand miles ?

-Shannon

RCF925

The reason I didn't want carbon on the tops of the pistons is on a blown motor it contributes to detonation. If I have tear down this new motor which I don't plan on any time soon I will probably use the carb cleaner method as I also agree the internals should be surgically clean.

dave1w41

Next time you do it, send the oil out for an analyisis at the first oil change. The aluminum oxide, aluminum, lead, and iron will be through the roof. Let me offer this suggestion based on having seen about 5000 engines get rebuilt in my career, you can do it on your own but don't ever do it on anyone elses. And if you do, hopefully they will find a way to even it up with you.

I guess you would have to see an actual destroyed engine and the bits of aluminum oxide embedded into the bearings under a microscope to change your mind?


What we are talking about here are red/green scotchbrite pads, disks, or Roloc bristle disks - or copycat products like them. They aren't metallic, they have metallic oxides that are molded into a plastic substrate of mesh or a solid plastic disc with molded bristles. They look pretty harmless to the average joe but under a microscope they are full of little abrasive rocks.


http://products3.3m.com/catalog/us/e...er/output_html

You might take note as to what these products are used for in industry. Metal finshing, grinding, metal conditioning, deburring, etc. And in each and every application, a flushing process is used so that the part does not carry its abrasives into the finshed product to destroy it. Unfortunately, you can't clean parts that are assembled to other parts, it just isn't possible. Hence the reason that you don't use them on assembled engines.

Keep in mind, I am not bashing 3M products here. They make excellent products but any product can be misused. And using these to clean engines where the particles can get in between parts or into the oil is a misuse of a perfectly good product. If you asked them directly, I would think that their answers would be the same as mine. Their product brochures state "User is responsible for determining whether the product is fit for a particular purpose and suitable for user's application." These products just simply aren't fit for cleaning assembled engine parts during repairs. Some of them are fine for cleaning parts where the part can be thoroughly washed to remove the abrasive. I use them all the time but never on engines that are together.

Metal or not, you can buy a scotchbrite sponge at a grocery store with enough green scotchbrite (about 3x4") attached to it to completely destroy a couple of engines. Have you ever noticed how nicely those sponges clean a stainless steel sink? Try this sometime, when you are scrubbing the sink or a stainless steel pot, keep rubbing one spot for about 30-45 seconds. When you lift up the sponge the bottom of it will be gray with stainless steel that has been machined off of the surface of the item. Stainless steel, even the cheap stuff is much harder than aluminum or the tin/lead coating on a bearing. If you get enough in the engine to embed in the bearings, the bearings just become little polishers that machine the crank down until the clearances open up and then you have no oil pressure and the engine fails. It isn't rocket science, just plain old common sense. People wonder why these engines fail so often after cam installs and head installs.... It is because people out in the field are set in their ways and won't take good advice and stop doing obviously stupid stuff.

Pasky

Good info on this post . Was just looking on how to clean pistons and stumbled on this. Good thing I read this, a friend told me to soak my pistons in wd40 over night and take a green pad to it to get the carbon off, I think im just gonna spray some wd40 and wipe it with a rag now.