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It seems that the GM problem is far worse than the scotchbright problem. I also would note that if 2 different blocks cut way more on one side of a bank, I might check my machine
It could be how he set it up... He didn't show his clamping technique.. so we don't really know how reliable his methods are. It should still work fine though.
These guys are easy to locate in a shop because they are the same ones that use 1/2 tube of silicon on a timing cover. Just find the ones who request the most silicon, and you have the perp.
Been using scotch brights for years to brush the surface never had a problem. The biggest key to it is your just cleaning it not digging into it. Most newbies need not do it.
As a GM master tech there is multiple red "notes" in our service information engine repair stating NOT to use anything mechanical or abrasive to clean cylinder heads or the block deck. We use CRC gasket remover and a razor blade or scraper to clean aluminum blocks and heads! THAT IS IT! When im done my heads look almost like factory
I mean they must have been sitting there a while to take that amount of material, I use the all the time and haven’t had any issues but I just remove the old gasket pieces I don’t polish the deck surface with it 😂
Don't ever use scotch Brite pads or whizz wheels on anything engine related. The ceramic dust coming off can wreck engine bearings if it gets into the oiling system
Several years ago at the shop I work at, a customer brought in a Subaru with head gasket issues. The customer said they had the head gaskets done at another shop a year or two ago. After removing the head, we discovered the other shop had done this exact same thing, cleaned up the aluminum block surface with a Scotch-Brite wheel. This was supposedly a "Subaru specialist" too. The customer didn't want to pay us to remove and resurface the block so we ended up just resurfacing the heads, spraying the gaskets with copper spray, and slapping it together with a note that we would not be offering a warranty on that repair. The customer ended up getting rid of the car before the gaskets started to leak again. Why somebody would take a Scotch-Brite wheel to an aluminum block surface is beyond me.
I have a Subaru with a leaking camshaft cover. It's going to cost me $1100 just to take the cover off and find out why it's leaking. That's why I'm also going to get rid of the car before I have to deal with it. Never getting another Subaru again!
Nice to see that GM still hasn’t changed the mill cutting head that they decked that block with since the 70’s ! Seen that wave ( minus the scotch bright bandit) on many of small blocks chevys .
Sometimes I am glad I have a healthy dose of fear of messing something costly up so thread very lightly when I work on my projects because something like this can happen. Great video Gerald👍👍👍👍
Was the second cylinder bank perpendicular to the cutter? It seems that the cutter did not even touch the deck at all towards the outside of the block for several passes of the cutter. (Maybe GM cut the deck at an angle!)
The swirl marks are too symmetrical and uniform to be done with a Scotch Brite wheel and like you say the block is either cut wrong and with the cutting marks from the factory or the block is not set up plumb and level in the surfacing machine.
You may say that but my personal experiences have been different. A mechanic with 30 years of experience who retired from the GM technical center told me the fins on your radiator had to be able to move some to cool the water inside. Another told me that a drum of solvent was bulging because of the “combustion inside”. I believe he was referring to Vapor Pressure.
well I'm not a keyboard Warrior I'm an experienced 40+ year machinist boring Mills Machining centers, Lathe's Blanchard Grinders centerless Grinders vtl's you name it I've run it and I know he's doing it wrong.
Another great video. That explains the disparity in performance between identical vehicles. I had no idea scotch-brite could do that kind of damage. OEM lack of quality is unbelievable.
OEM quality has zero to do with it, a moron with tools and lack of skills did the damage. They mass produce engines with tolerance stack in mind, their goal is never maximum power. Fact is for any serious performance build you'd mock up a piston at all four corners and deck to the spec you want, and the ra number finish the gaskets you are using call for. Guaranteed none of them call for a scotch Brite pad. The owner should have dropped it off and has it checked/decked. Not went crazy with scotch Brite pads on the end of a power tool.
I don't waste my time with aluminum blocks , they are to finicky and for the few pounds you save it isn't worth the hassle . Most street builds you will never have to worry about the extra weight .
the liners are hard to cut with scotchbite wheel, but they're inline with block surface. that makes me believe the block surface is out-of-flat due to massive overheating, not the scotchbritig (altough partial damage may take place on peripheral areas).
Those scotch brites are no joke. I used to use them at the bike shop for removing stubborn gasket leftovers but I'd turn the air down to the right angle grinder and go way slow and easy. Sometimes you can just pass it back and forth by hand/no grinder and get the job done.
About 2004, at a Chrysler dealer, one of the techs cleaned up the decks on a 3.3 with Scotch Brite wheels and the customer sued us when it started knocking. He took it somewhere else and they found the bearings wiped out. In court, the CUSTOMER shows US a Technical Service Bulletin that says "Never use Scotch Brite wheels on internal engine parts"! Turns out, Chrysler sent the TSB out but, the service manager never gave ANY bulletins to the techs! Nice. The previous manager made sure we saw every bit of info possible and we made 5Star. Lost it with the new manager. One question; can you measure a BBC 454 to see if it's ever been decked? I've got an LS6 that was cast in '72 and, is stamped as a '70 Chevelle but, looks like the correct broach milling.
I’m sure many of you know already but mentioning for general consumption for those that don’t know. There are different rolocs/scotchbrights for different materials. 3m (parent company for many of these) has a 40+ page catalog for 100’s of applications. Everything from heavy rust removal to bristle brush try cleaners.
I used to work in machine shops for 40+ years.Some of the blocks and heads back in the 80s looked like they were threaded . 3.8 ford v-6,2.3and 2.5 Taurus were the worst
Gerald. Good job mate. Your channel is always top shelf. Do you have someone editing? I personally used to watch the techs at the dealership use scotch brite on the surfaces to speed up the cleaning process. Know wonder people go elsewhere once the warranty runs out. Too much pressure because of book time. Independents crush the ever-growing maintenance/rebuilt demand in the automotive market place.
I use to have a machine shop and did work for multiple dealers, I've had to take a cut on a head, then take them back to the dealers to show them what they were doing to the heads with those pads, great tool but they will fuck up both aluminum and iron heads and blocks fast !!
I just found your channel, I love watching machine work! When you see a block this much off on the 1 side of the block, do you ever question your setup being off a little? or is this just from many years experience and knowing that factory machine work is subpar?
Yep I used to hate that lazy mechanics would used. But then they would smear form a gasket on it with the gasket and the gasket would turn the mush 6 months later.
I just slowly shake my head and roll my eyes when I walk into a "professional" shop and see workers cleaning off gasket surfaces with a 20k die grinder with a scotchbrite pad zinging away and knowing they are not going to be resurfacing that area. I see diesel shops doing that all the time.
Yeah I'm sure few a spot was caused by scotch bright but a big majority of it was a factory surface angle cut versus your surface angle cut, as yours's could have been more square versus the factory cut, something you forget to factor in was they may have gotten the engine a little too hot so the aluminum did not shrink back into its original position.
Great Video. You don't know how much these videos help this rookie machinist. How much are you cutting per pass? I just got my BHJ Blok-Tru all set up and ready to use. Hopefully deck my first block today.
Thank you for posting every interesting videos. Although it may be ok for daily use, but now I know the quality of the block isn't good enough for high performance vehicle.
I had to take .007-.008 off a set of 706s that someone went over with a cookie on a wizz wheel just to get them flat again... -_- (fyi, those low spots were between cylinders) I cant believe people still do that and expect it to work well.
I once had an older mechanic bring in a pair of heads that he used a body grinder on to clean every surface. It had the edges so rounded the heads were scrap.
Chisel gasket removal spray . Razor blade scraper , brake clean ,or a buddy with a wash or dunk tank is all you need and yea ls blocks are that bad straight from GM , cash iron or aluminum, anything mass produced can always use refinement, excellent work gentlemen.
Yep, I still have an old wood chisel from 1970's that's about half the length it was new as it's been sharpened so often with oilstone (never been on a grinder) That's a lot of engines. 😎
Yes, I'm fond of the sprays as well, can do a LOT of the grunt work for you with no risk of surface damage. Have had a chisel in my toolbox for 45 years for those tough spots and a proper razor scraper for almost as long.
Some people are pretty stupid when it comes to abrasives and soft metal. People are applying techniques that used to use on cast iron blocks to aluminum and that's a big no-no
Wow man they really like scotch brite pads lol. Are you going to have a hard time now getting the correct length rods and will it require custom size pistons now or it is not that far gone. Thanks man. And yea ruby was saying I need my toy Dad.
I use a 2 inch wood chisel to remove the stuff off the surface then put em in the washer cabinet before I throw em on the surfacer, I had an old boy bring me a iron duke head to surface, I put a straight edge on it and you could of thrown a cat under it, Had to cut .021 to fix it, he must of worn out out a whole box of wheels
All blocks be they iron or aluminum should be decked on the mill, same with heads, intakes and exaust manifolds, this way everything can be matched tolerance by the machinist to fit perfectly instead of " eyeballing it" . I weigh every internal component to make sure all parts weigh the same, in my eyes this is the most critical measurement and the crank balancing, polishing and chamfering, rifle drilling the blocks oil passages, installing restictors and stands where needed etc. Working in the aerospace industry made me a bastard for details, lives are at stake
That’s a great example of people not knowing what they are doing, and what tool is correct for the job. Over the years I’ve seen many a precision parts ruined by these. I think the worst was a rare flywheel that someone “scotchbrited” completely ruining the part!
John doc has actually done a video awhile back where he took a wiz wheel or scotch bright wheel to a block and then had tkm see how bad it Jack's them up its crazy how fast u can blow thousands of dollars with a 40 dollar tool and not even realize your doin it till its too late lol
I've seen so many techs and mechanics do this scotchbrite shit and comebacks with headgasket failure and they're super butthurt they have to do it again.
Too many think "oh I know what I'm doing" those are dangerous. I had a Mazda head on a B2200 back in the 90's. He had taken it to all the pro's and they kept tossing headgaskets at it. When I got it the block looked ok but the head looked funny. Took it to my machine shop guy who I learned my tiny bit if machining and his old ass spotted it right away. He told me to use it as a door prop. They had gouged the head then took it to a bad machine shop who ground the head at an angle. Since the headbolts didn't make full contact (yes it was that bad. Full run-out on one side hardly ground on the opposite) they loosened up which I caught and said they didn't torque it fully then saw the wonky head deck job. Lucky he was the parts counter guy so he ordered another head and sent that junk in for core. My machinist had to deck the one he ordered but nobody had to do another headgasket on that pickup lol.
I have a brilliant idea. Let's make a video and I'll whisper as a large, loud machine is running. I had to have the volume so loud.Everybody in the house was asking me what the hell's going on.
How off that block was reminded me of an episode of Roadkill Garage. Steve Dulcich had a shop zero deck a 360 - well, it wasn't making the power he expected on the dyno. Pulled it apart and found (If I remember correctly) #2 piston was like .020 downhole - and #8 was .010 down. You can bet he never took another engine to that shop.
I just always used a wire wheel on my grinder for years ..like 30 to clean blocks. I even know machine shops do the same for a cheap reseal. I never had a issue. Its beyond me why people use roloc discs to clean alu. Especially when they make plastic bristle roloc discs
In the seventies and eighties, in our Japanese motorcycle shops (we had all four brands spread over eight stores) we used high-quality wood chisels, kept razor sharp. They will remove just about anything cleanly.
On an LS engine you literally pretty much only ever need brand new razor blades and brake cleaner it’s that easy brake cleaner will lift up the black parts of the gasket and the razor blade was scrape it smooth without digging gouges into the surface, if somebody uses a buffing wheel on any machined surfaces in my shop they get a big talking to!
The problem is the scotch brite. Any serious gear head knows this. The trick is to use a FLAP WHEEL because its more rigid is stays flatter and gives you a perfect deck job. Nobody needs to pay a machine shop psshh what a rip off😂😂 in all seriousness though ive been honing heads and blocks on a marble block for 2 decades and have yet to have any issue. Thats REALLY pushing the motors as well. 30+ psi at a minimum. Done right with a trued marble table.. not just some tile from home depot lmao. Now anything that remotely shows or any deck height modification- straight to the machine shop for a deck job. (Plus having them hot tank a block or a head is ultra nice for reassembly)
Having learned machining in the ariospace industry I'm always amazed at how badly automotive factory parts are made. Their tolerance are just all over the place, amazing that some of the factory stuff will even hold a gasket at all. In aerospace when you start seeing you are a thousands out you start looking for why, you'd never see deck angles anywhere near that far off.
As an engine builder, I hate seeing either scotch brite or wire wheels used on ANY gasket surface of any material. I have seen several cast iron diesel and gas blocks ruined by either process, usually because the holes in the block are "shadowed" Most people do not realize that many types of head gaskets rely on those machine marks to hold properly. Belt sander surfacing machines can destroy heads also even if properly maintained (usually not the case) because the surface scratches run across the cylinders, not between them like a milling machine does. If you have to use anything on non critical areas (oil pan rails etc) use a soft wire wheel going with the grain of the original marks being sure not to remove them.
Could the scotch brute damage be pre-existing, from a dealer warranty head gasket replacement, butchered, for warranty flat rate? Thinking I’d want to take a close look at the head bolt threads, in case the fix was to overtorque the heads.
In this case of this video, he was square decking a block that wasn't square. And that's completely normal when doing a factory block. All the ''look at what the scotch-brite did'' stuff was just garbage. There was even a couple instances where he pointed out ''scotch-brite'' gouges on clean spots. And clean spots are high spots that got machined down. Gouges make low spots that stay red.
Interesting to see what scotch brite does to a deck of a block. Just wondering how much did you end cutting off the deck?? Love the content and the information Gerald.
learned a long time ago, never ever use scotch brite anything on an engine block. the green pads contain 40 micron aluminum oxide in the fibers, and the lighter pads have even smaller aluminum oxide particles. gets every where if you don't like washing and cleaning a block after/before machine work is done, better to avoid the stuff like a plague. scotchbrite is a curse you will remember.
2 questions. One what is the depth of cut? Two did you run an indicator down the bores to make sure you are square? Those passes all looked heavy to the back of the machine.
Deff have to be careful. Have used red pads by hand to clean up blocks when a composite gasket is being used after without issue. Also have seen people royally screw up deck surface, Same deal people buy metal layer gaskets and not have the surface finish to correct RA then wonder why they keep having issues.
