- Joined
- Aug 9, 2022
- Messages
- 144
One of the new cams I purchased had a couple spots of flash rust on the heel of one lobe, so I soaked it in PB blaster penetrating oil and tried to rub it off with a towel. This was not aggressive enough to remove the rust spot, so I used the least aggressive white scotch brite pad #7445 (equivalent to 0000 steel wool per brochure) soaked in some PB blaster which mostly removed the spots other than a barely visible stain that remained after a fair bit of rubbing. I then sprayed off the entire cam well with some contact cleaner spray, then scrubbed it down with a toothbrush soaked in mineral spirits, and wiped it dry with a clean towel.
I came across some information after I had done this indicating that some OEM's put out a technical bulletin stating that scotch brite should never be used on any internal engine parts. It states that the micro abrasives which are too small to see can embed into bearing material and tear up journals in as little as a few thousand miles. I was aware of the caution not to use scotch brite pads on a grinder to clean head/block surfaces because it can generate a large amount of debris to enter the engine, but is there any risk using a scotch brite hand pad on a camshaft outside of the engine like I did considering the porous surface of the cast iron? I looked up the technical information on the white scotch brite pad, and it uses nepheline syenite as the primary abrasive which has a hardness of about 6 Mohs or 65 HRC. From a quick search it appears that cam/crank journals have hardness around 55-60 HRC on average, but could be a bit higher.
The scotch brite pad was soaked with penetrating oil so it didn't generate dust, however, it did start to shed some fibers after rubbing with it for a while. I was also reading that the proper way to clean parts after using any abrasives was submersion in hot soapy water, so should I consider removing this camshaft before installing the valve cover to clean it further since I didn't submerge it?
I came across some information after I had done this indicating that some OEM's put out a technical bulletin stating that scotch brite should never be used on any internal engine parts. It states that the micro abrasives which are too small to see can embed into bearing material and tear up journals in as little as a few thousand miles. I was aware of the caution not to use scotch brite pads on a grinder to clean head/block surfaces because it can generate a large amount of debris to enter the engine, but is there any risk using a scotch brite hand pad on a camshaft outside of the engine like I did considering the porous surface of the cast iron? I looked up the technical information on the white scotch brite pad, and it uses nepheline syenite as the primary abrasive which has a hardness of about 6 Mohs or 65 HRC. From a quick search it appears that cam/crank journals have hardness around 55-60 HRC on average, but could be a bit higher.
The scotch brite pad was soaked with penetrating oil so it didn't generate dust, however, it did start to shed some fibers after rubbing with it for a while. I was also reading that the proper way to clean parts after using any abrasives was submersion in hot soapy water, so should I consider removing this camshaft before installing the valve cover to clean it further since I didn't submerge it?
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