3M 120-grit Roloc Bristle "White" Discs for Cleaning Cyl Heads?

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The Critic

The Critic

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I was doing some late-night web surfing and came across this old Subaru TSB on proper surface prep during head gasket jobs:

http://www.bescaredracing.com/sti/tsb/cylinder_head_gasket.pdf

(Link to the 3M Roloc Bristle "White" Disc: https://www.amazon.com/Scotch-Brite-Quick-Change-Attachment-Aluminum-Diameter/dp/B000FW4LDU or https://www.amazon.com/gp/product/B01MSU3PYQ/ref=ox_sc_act_title_2?smid=A1Y3PCPH3CY53X&psc=1)

At least from an OEM, I was a bit surprised to see these discs as an "approved" method of prepping the engine block and/or the cylinder head for re-sealing. I have always used plastic razors and gasket remover.

trav, mattd, clineberger and others -- any thoughts?
 
If you read the other thread, you'll see my thoughts. Those are made for aluminum and I have used them before as wel. The ones I typically use are meant to be used on cast iron and aluminum (green but same exact design different grit rating). As I stated I've always had excellent results with no problems as far as contamination from any "dust".

That being said, without the proper preparation and work habits/technique , there is the possibility of some of the dust getting into the water jackets and oil return ports of the block.

IMO you can cause damage with a razor blade, blocks, and others too if not used properly. The only thing that won't hurt it is the plastic scraper but that has the potential of being very time consuming.
 
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So we have have opposing opinions from manufacturers on the use of them, that is a bit unusual. Personally I have never used them for this job and will err on the side of caution and continue not using them. The way I see it is GM published this after seeing bearing failures directly related to their use, did Subaru publish an addendum to this TSB at a later date?
 
IMO Its a terrible idea to use the wizzer wheel.. but immensely time-saving. In a perfect world they get the job done and fast.

In the real world they do a lesser job and can cause many issues: surface finish,dust, etc.. esp with beating book time .. yada yada.
 
Gasket remover, plastic scraper, and a window razor blade scraper is what I use on my own personal vehicles. Sure I could have used a wheel last time I did a head gasket and timing chain job to speed things along. But I don't think I could keep all the wheel dust going in places it does not belong.

Would like to know the technique that Subaru is using to keep wheel dust out of the engine.
 
Maybe if you could stuff shop rags & towels in every opening in the block, and vacuum out anything that falls on them with a Shop-Vac? Otherwise, there's a lot of fine dust that's going to find it's way into the oil, for sure.
 
The old logic was that Scotchbrite was no good because it shedded abrasives that would skip the oil filter and get in the main bearings.

Way early in my car hobby I got a dodge spirit that needed a head gasket, lifted the head an inch with the manifolds still attached, squeezed my hand and a scotchbrite in there, gave it half-hearted scrub down, put it all back together, and it worked perfectly afterwards.

My thought is if you push down unevenly you might get "microwarps" due to how easy it is to remove metal.
 
I use a razor blades & as many of them as needed. Brake clean takes off a lot of the elastomer left on the surfaces from the head gasket.

These were cleaned with sharp razor blades & brake clean.......

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]
 
People can do what they want, but I will never use anything that can leave behind abrasives. As long as the deck and head are sufficiently flat and have the necessary RA for the HG's in question, I'll use the technique with the least potential for causing damage to the sealing surfaces. Plastic scraper or at most razor blade used with the proper technique so as not to gouge the surfaces.



[Linked Image]


I was going to post a picture of a TF head, but decided that had too much detail, and could pose concerns down the line.
 
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