Cadillac Tech Tips - How to fix it Discussion, Scotchbrite.....NEVER!! in Item Specific Cadillac Discussion; Someone in another thread mentioned using scotchbrite to clean up gasket surfaces during an engine rebuild.....not a good idea....
Someone in another thread mentioned using scotchbrite to clean up gasket surfaces during an engine rebuild.....not a good idea....
NEVER USE SCOTCHBRITE TO CLEAN UP GASKET SURFACES OF AN ENGINE.
NEVER, EVER, EVER USE SCOTCHBRITE ON AN ENGINE. At least not one you want to run again for a long time.
Scotchbrite seems so benign but it is death to engines. Scotchbrite pads are nylon fibers with 40 micron particles of aluminum oxide in them. Scotchbrite dust leaves behind all those 40 micron particles hidden everywhere. Aluminum oxide is an extremely aggressive abrasive. It imbeds in the bearings and eats the crank....and other things.
Scotchbrite is the bane of the aftermarket re-man engine industry. There are lots of "new" re-mans ruined by cleaning up the old parts with scotchbrite pads and then installing them. Eats up the engine immediately. That is why many engines fail the main and rod bearings after a head job or other work...scotchbrite. People think it is because of coolant getting into the oil ruining the bearings or something when it was really the scotchbrite the mechanic used to clean up the parts... especially a Northstar engine where the block deck surface cleaning funnels the scotchbrite dust down the oil drain back passages.
If you cleaned up parts with scotchbrite you now have a HUGE cleanup job ahead of you cleaning up after the scotchbrite. You must make positively sure that none of the dust remains anywhere on any parts or got into the oil cavity. Hopefully the valley of the engine was covered if you used scotchbrite on the deck surface as if it drifted into the valley or into the pan your engine is toast.
I am very very serious about this. Scotchbrite has a very bad reputation in the industry as it seems like such an ideal cleanup method, seems so benign, yet can cause such extreme damage. Most mechanics in the know stay miles away from scotchbrite as it is harder to clean up after it than any labor it saves.
If you doubt this at all call JASPER or any of the main engine re-man companies and ask them if it is OK to use scotchbrite to clean up the manifold you are going to put on your Jasper re-man....
Excellent post bbob! You might as well use wally world brand sandpaper and let the chunks fall in the internals. I'm dead serious because the chunks are larger and they would be caught by the filter.
The problem lies with professional mechanics. It's industry standard to use a scotch brite pad on a die grinder as a way to clean gasket surfaces. Whether or not they know, the problem is that 99.9% of the professional mechancis simply dont g/a/f. Most of the time get paid the same whether they spend 30 seconds or 30 minutes cleaning gasket surfaces, and if they are paid by the hour, the supervisor/shop foreman/manager perfers the 30 second method to the 30 minute method.
The job is long gone and well out of warrenty by the time the damage shows, so why t/f should they care? They got theirs, so nothing else matters. I'll wrap it up with that because I'm sure that I'm pissing off the 99.9% of the professional mechancis with the truth that goes on behind closed doors. That's okay! I was never popular with my coworkers, and this interacting with 99.9% butcher rate is one of the reasons I bailed out of the industry.
bbob makes a good point, so as a consumer, see if you can do something about it. Good luck because you're going to need it.
I used little pads on the end of a die grinder that were specifically made for cleaning gasket surfaces. They're manufactured by 3M and have a Scotchbrite-type material on them.
Weeeeelllll, I put a new timing chain, valve springs and cam in my Grand National. Got all the mating surfaces on the heads and intake nice and clean with that stuff. Within about 200 miles of putting it back together 2 rods started knocking. I took it to the rebuilder and he called as soon as he got it apart. He asked exactly what I had done to that thing because he had never seen such complete destruction before. In addition to the #3 and #5 connecting rod bearings being hammered out of it, the crank and cam surfaces were all scored as well as the cam, rod and main bearings.
At the time, the engine probably didn't have much life in it anyway, but it was a drag to go through all that work for it to fail so soon. At least I used it as an excuse to punch it out and put stronger internals in it. I just use a razor blade and spray gasket remover now - and take care that none of the dissolver or debris gets where it's not supposed to.
I seem to recall GM endorsing those "biscuits" at one time. Plus, I seem to recall that 3M manufactured those in a way that they were not harmful.
If so...they certainly do NOT endorse any use of scotchbrite now. This has been common knowlege in the engineering/service/reman industry for 20 years at least so it would have to go way back. Any refererence on this to back up your recall or is it just a maybe...????
How, exactly, could 3M or anyone manufacture aluminum oxide particles so that they are not harmful if left in any engine...???....LOL
If you read any of the publications of the re-man industry or subscribe to any of the aftermarket data services scotchbrite warnings are very common.
Whatever....the warning about scotchbrite stands. If you think it is hooey then use it....you have been warned.
Aluminum oxide particles in the oil have an insiduous failure mode. They imbed in the bearing material and just ride along and do nothing until the oil film is forced thinner than the particle is sticking out of the bearing. Since the 40 micron particles will imbed to some extent and the oil film is thicker than 40 microns no harm will be done what-so-ever for many many miles. In fact, many engines can run contaminated with aluminum oxide from scotchbrite pads virtually forever if the stress is low, oil never gets hot, load never goes high, etc. Then, one day, due to higher RPM/greater load/hotter oil/etc. the oil film gets pushed thinner than 40 microns and then the peaks of the aluminum oxide particles start to stick thru the oil film and they start to machine the crank journals down. Catostrophic failure of the bearing follows shortly. This is why, for years, engines were worked on and cleaned up with scotchbrite, the dust was left everywhere and the engines lived. There was an occasional bearing failure later and it was blamed on the previous failure...i.e...coolant in the oil, loss of oil pressure, etc. Guess again...it just took awhile to run the engine in a manner for the aluminum oxide to peek thru the oil film and machine the crank.
Based on all the problems I have seen with aluminum oxide contamination of proto-type parts during engineering development and in the field from casual use of scotch-brite I would ban the stuff from existence.....no LOL. We even had a problem with the parts washers in experimental build becoming so contaminated with scotchbrite residue from cleaning parts that people had used scotchbrite on that the washers were contaminating clean parts with the 40 micron particles of aluminum oxide.
I forgot I had pics (I have pics of everything, in case y'all haven't noticed). Pics of the rod bearings and the fine scratches. It was unbelievable how quickly the engine destroyed itself: http://turbojimmy.4t.com/gn_engine_pull-03.html