Rust Preventitive on Diff Cover FAILED
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Member
Joined: Mar 2004
Posts: 43
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From: Twin Mosquitos, MN
Rust Preventitive on Diff Cover FAILED
I used an aerosal chromate(?) rust preventitive to spot places all over the underside of my truck when new - I did the 9 3/4 LS rear differential cover using OTC "makes black rust" type.. (not a primer). Big mistake - next time I'll use something else.
When pulling cover for first time at 55k I could not believe how corroded the cover is - it looks like something tossed away at an ocean marina. I took a 4 inch angle grinder to it & some of the rust bumps were 1/4" tall with the corresponding pits in the steel reaching 1/2 the thickness of the stamped steel cover!
I ended up cold-galvanizing w/ 90% zinc primer & hand rubbing the first coat into the pores; no bead blaster to catch the rust I missed & baked it on to hurry getting truck out of driveway.
The cover I pulled looked more like 25 years old then 4 years - I think the aerosal had a plastic clear-coat portion in it & since I spent 3 weekends touching it up for thorough job it kept the surface glossy but wicked ice-melt chemicals next to the steel like a sponge. Leave the stuff off your truck!
Note, I think new tech liquid ice-melt on bridges & interstates are HOT on metal, If you see a tank truck ahead of you you're in for it!
I've had to follow a few of them in Ohio and WV & it'll almost eat the wheel weights off as you watch >: )
When pulling cover for first time at 55k I could not believe how corroded the cover is - it looks like something tossed away at an ocean marina. I took a 4 inch angle grinder to it & some of the rust bumps were 1/4" tall with the corresponding pits in the steel reaching 1/2 the thickness of the stamped steel cover!
I ended up cold-galvanizing w/ 90% zinc primer & hand rubbing the first coat into the pores; no bead blaster to catch the rust I missed & baked it on to hurry getting truck out of driveway.
The cover I pulled looked more like 25 years old then 4 years - I think the aerosal had a plastic clear-coat portion in it & since I spent 3 weekends touching it up for thorough job it kept the surface glossy but wicked ice-melt chemicals next to the steel like a sponge. Leave the stuff off your truck!
Note, I think new tech liquid ice-melt on bridges & interstates are HOT on metal, If you see a tank truck ahead of you you're in for it!
I've had to follow a few of them in Ohio and WV & it'll almost eat the wheel weights off as you watch >: )
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Joined: Feb 2002
Posts: 283
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From: Clarence, NY
Instead of going through all the hassle of refurbishing that rusty cover just go to the Ford dealer and buy a new one for $20-$30. We have that problem all the time at the NY DOT, we just replace them with new ones. We actually found that it was cheaper to do it that way if you calculate man hours etc.
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Joined: Mar 2004
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From: Twin Mosquitos, MN
If money wern't so tight I'd have 2 FMC parts places on speed dial - I will paint the thing at first chance next truck..
The zinc primer is soft so I re-tourqued the bolts a day later; its holding up okay and looks right (hillbilly) with black bolts on flat grey cover.
The zinc primer is soft so I re-tourqued the bolts a day later; its holding up okay and looks right (hillbilly) with black bolts on flat grey cover.
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Joined: Mar 2005
Posts: 14
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From: Massachusetts
I just picked up a '99 Scab, and while going through everything I noticed the rust and corrosion on the diff cover. I'll be getting a new one this week and bringing it to a powder coating shop my friend just opened up and have it coated once and for all!! Anyone happen to know the bolt sizes, so I can pick up some of those and have them coated too? I helped this guy with the plumbing and pnuematic lines while he was setting up shop, so he wants to help me out with a few favors. Yah Hoo!!
Kevin
Kevin