Polished My Pullies
12-28-2009, 02:56 PM
#1
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Polished My Pullies
After my 94 Cab dumped me on the interstate with a failed alternator one night in November, I decided to use the oppertunity to spruce up the engine compartment a bit. I had the fan and shroud blasted and powder coated by Vehicle Craft in NJ and I polished all the belt pullies by hand with a Dremel (VERY TIME CONSUMING). Pics below are prior to installation.
JF
JF
Last edited by 993PET; 12-28-2009 at 06:08 PM.
12-28-2009, 10:17 PM
#3
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Aren't the pulleys just steel? They really look terrific, but will they oxidize/rust? I guess there is no coating available which would stand up to belt wear in the groove of the pulleys. But I hate to see the exterior degrade after you spent so much time making them look beautiful. Could you also powder coat (clear) the pulleys? Just my 2 cents. Kudos for your effort 
, especially since everything turned out so nice.
, especially since everything turned out so nice.
12-29-2009, 12:30 AM
#4
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Steve:
Good point, I only polished the areas that are visable, not the inside surfaces that come into contact with the belts. I will clear coat the polished surfaces prior to installation. The polishing transpired after I attempted without success to clean up the pullies since they looked so shabby next to the newly powder coated fan and shroud.
JF
Good point, I only polished the areas that are visable, not the inside surfaces that come into contact with the belts. I will clear coat the polished surfaces prior to installation. The polishing transpired after I attempted without success to clean up the pullies since they looked so shabby next to the newly powder coated fan and shroud.
JF
12-29-2009, 08:25 AM
#6
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Clear coat may not stick, and then you risk sucking sheets of the paint film through the fan where it could lodge in the cooling passages.
I am no expert by any means, but there is a science on how to get paint to stick to metals. Polishing steel chemically activates it - the strain energy in the smeared surface wants to be released, and that drives the corrosion reaction. Even behind a paint film, activated steel will react with water and oxygen that diffuses through the film. Coatings slow down, but do not stop rust (witness the rust blisters that appear after cheap paint jobs).
If the polishing rubbed the original zinc chromate coating into the grains, then "do nothing" may be the correct option. Try this simple test: mist the polished surfaces with tap water, and leave them to dry. If you see any trace of red rust, you have an active surface and will need to coat it. If only the hard water stain is left, you can probably wipe it clean and run like it is. How long it will last depends on how often the car is out in the rain. It could last many more years if you garage the car and minimize wet-weather driving.
If you need to paint, strongly consider treating the pulleys with a "metal prep" or "metal treat" product. They contain phosphoric acid, which will passivate the steel and leave a micro-etch for the paint to grab onto. Even better, use an industrial corrosion-proofing paint system and apply in accordance to the application guide. Rustoleum is one brand that sells in hardware stores.
Final option to consider is simply purchase replacement pulley halves from the dealer. They will look like new!
I am no expert by any means, but there is a science on how to get paint to stick to metals. Polishing steel chemically activates it - the strain energy in the smeared surface wants to be released, and that drives the corrosion reaction. Even behind a paint film, activated steel will react with water and oxygen that diffuses through the film. Coatings slow down, but do not stop rust (witness the rust blisters that appear after cheap paint jobs).
If the polishing rubbed the original zinc chromate coating into the grains, then "do nothing" may be the correct option. Try this simple test: mist the polished surfaces with tap water, and leave them to dry. If you see any trace of red rust, you have an active surface and will need to coat it. If only the hard water stain is left, you can probably wipe it clean and run like it is. How long it will last depends on how often the car is out in the rain. It could last many more years if you garage the car and minimize wet-weather driving.
If you need to paint, strongly consider treating the pulleys with a "metal prep" or "metal treat" product. They contain phosphoric acid, which will passivate the steel and leave a micro-etch for the paint to grab onto. Even better, use an industrial corrosion-proofing paint system and apply in accordance to the application guide. Rustoleum is one brand that sells in hardware stores.
Final option to consider is simply purchase replacement pulley halves from the dealer. They will look like new!
12-30-2009, 11:39 PM
#7
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Springer 3:
Thanks for the info, very interesting, I will try the water mist test. As you say if it doesn't work out I can always purchase new pulley halfs.
JF
Thanks for the info, very interesting, I will try the water mist test. As you say if it doesn't work out I can always purchase new pulley halfs.
JF
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12-31-2009, 01:05 AM
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Looks good and I think you will be ok. I once took all of the removable components off my engine including steel pulleys (on another car) and polished them. I was bored over a long winter and polish crazy.
The steel pulleys fared the best. Al parts needed a 6 month rebuffing.
I am not a metallurgist, but it seems like the steel on rotors rust instantly. Pulleys do not IME.
The steel pulleys fared the best. Al parts needed a 6 month rebuffing.
I am not a metallurgist, but it seems like the steel on rotors rust instantly. Pulleys do not IME.