Preparation for undercarriage sand blasting? (2 Viewers)

[RND1]

Being a New England LC, my '03 has typical undercarriage rust consistent with the region. I've been using fluid film since I bought it a few years ago, but have noticed that it doesn't hold up if you use the high pressure undercarriage wash at the car wash (which I do in the Winter).

So, I'm thinking of having the undercarriage sandblasted and then painted and I'm wondering what I should do in preparation to protect vulnerable areas such as brake lines, gas tank, exhaust, etc? Will duct tape work or will the sand just blast right through it?

Thanks for any suggestions.

 

[abuck99]

I'd put some thought into doing this: blast medium will get everywhere you don't want it- (linkages, connectors, fasteners, etc). I'd consider a different strategy. At a minimum use a soda blaster as the medium will dissolve in water.

I like rust converter. Slower process but mitigate scale & loose rust best you can with wire brush, die grinder, 3" angle sander, then use a good rust converter, then zinc chromate, and a top coat. Then spray with favorite winterizer fluid if compelled.

 

[DirtDawg]

IMO the only proper way to blast a frame is full removal. Everything off, just the frame. If you don't, all those areas you could not reach are going to rear their ugly head, especially in your region. Plus you risk damage/unwanted blast material after the fact. If you wanna do it right, remove the frame, get it blasted, then you can get it coated and hopefully never see the rust again.

 

[Patineto]

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[RND1]

Thanks guys for the feedback. While I certainly agree that removing the frame would be the best solution, that's not a realistic solution at least as far as my budget is concerned! There's another recent thread on NH Oil Undercoating and that would be my 2nd option, but it seems like it's the same as applying fluid film over the rust. At $189, it's cheap but it's a temporary solution that has to be repeated at least yearly.

I'd like to remove as much of the surface rust as possible, then treat it for long term rust protection. I don't have the time, tools, or inclination to spend a weekend under my rig to remove rust. So, my options are as follows:

1. Spray Amsoil HD over the undercarriage myself and see if it holds up better than Fluid Film? Cheapest short term solution @$10/can.
2. Take it to Krown in VT (2 hour drive) - $140
3. Take it to NH Oil undercoating (1 hr drive) - $189.
3. Have undercarriage sand blasted, epoxy primed and painted (2 hr drive) - $600.

I'm willing to spend the money on the sand blasting, but I am concerned about the issues @abuck99 and @DirtDawg brought up. However, I was given the sand blasting referral from a fellow MUD member who had his 80 done and he said it came out great and would do it again. He did say that he had a lot of rust so one of the brake lines was nicked and gas tank seam was a problem. In spite of these issues, he highly recommended it.

 

[spaber05]

I'll be interested to see how this turns out as well. Being in the area this is always a concern of mine and the only thing I've been doing is regular thorough underbody washes (which in fairness, seem to be doing fine).

If you do the sandblasting, be sure to take some before/after pics for those of us thinking about it. If it turns out alright and all of those concerns you mentioned are alleviated, I'd be tempted to do something similar as it seems to be a MUCH longer term solution to the annual (perhaps bi-annual) application of Fluid Film or similar.

Out of curiosity, where would you have this sandblasting and painting done? Was there a specific place that was recommended by the 80 guy?

 

[Patineto]

I have been doing it the opposite way, bucket with water and household detergents to remove the mud cakes, then mechanically wire brushing (seven inch grinder for the most part) removing the bolt sout one by one to mask them (to drill them for safety wire, sometimes and/or others for cinc rust coating), also moving/masking brackets, hoses, etc finally POR15..

For sure it looks patch up, but the part I get done, is done (Hopefully the POR is as good as they say it is..)

Maybe some day one of my fancy friends get one of those trick "Laser rust removers" but for now is big headphones and face shield, not fun..

 

[RND1]

@spaber05 - it's a guy that works for a media blasting company and moonlights doing this sort of work. He's in CT. If I go with him, I'll try to document the whole process before / after.

Coming back to my original question, anyone know if duct tape will work to protect brake lines, gas tank seams, exhaust seams, etc?

 

[abuck99]

If you are determined to go the blasting route, look into soda blasting. Like I said earlier, it dissolves in water and the bicarb medium actually creates a (temporary) corrosion barrier.

You might also post up in the Paint & Body section for more opinions: Paint and Body

 

[RND1]

Soda is pretty soft on the blast media hardness scale - do you know if it's hard enough to remove the rust? Thanks - I'll spend some time in the P&B forum.

 

[spaber05]

Thanks @RND1, definitely interested. $600 seems totally justifiable if it removes and protects against the rust up here, that's the only thing that can kill these rigs.

To answer your question, I would think that duct tape would work depending on the rust in the area that needs to come off. If there is some heavier oxidation next to a seam/line etc that you don't want touched, I'd be wary of how long it would last because of the amount of blasting required for that particular spot. However for the lighter surface rust that requires just a quick pass with the blaster to be taken off, I believe duct tape would be effective.

However, I'm no expert so take that with a grain of salt.