Could I use roll on truck bedliner to do this or should I use the POR15. I know the bedliner is $40/gallon and the POR is $150/gallon.

I am wanting to stop the rust and protect the gas tank, fenders, floorpans, ect.. Would the bedliner help stop/prevent rust or could I put rustoleum rust prevention before the bedliner is applied or would you use the POR??

Hoping someone has some good advice they could give me with past experiences or knowledge.

Thanks!

 

The bedliner is awesome and thicker than POR so I'd use it. If it's good enough for a truck bed then it should work great on the underside.

 

id por 15 it then spray bed liner on top of it :P

 

Bedliner will not stop the rust nor will it protect the undercarriage from any future rust. Any current rust will continue to grow and will eventually rust through. Bedliner will still allow moisture to get through as its not air or water proof. Its also fairly easy to scratch off and is not that chemical resistant as I've seen on a few cars now.

POR-15 on the other hand is water/air proof. It'll encapsulate the metal keeping air and moisture away from it. Without moisture and air, existing rust will stop and it will not continue. New rust will not start as it requires moisture and air. POR-15 is VERY chemical resistant! I've actually tested this a bit over the last few months and have been very happy with it. Once its dried and fully hardened its very scratch resistant and durable.

I'd suggest going with 2 to 3 coats of POR-15 and then hitting it with the bedliner if you'd like with 2 more coats.

I've got 3 coats of POR-15 on the chassis of our 67 coupe front to back. We sprayed all 3 coats and it took about 1 1/2 quarts. POR says 2 coats is enough however by spraying your not applying as much as you would with a brush hence the 3rd coat. If your gonna do it with a brush then 2 coats would be fine. If spraying I used an HVLP gun and put it on straight without their Solvent (thinner). Went on fine and used regular Lacquer Thinner for cleanup.

I have 2 full gallon kits of 2-part bedliner which has the separate hardener and a bag of "speckles" I was given. I might follow up with 2 coats over the POR on the undercarriage at sometime.

 

A quart should be enough if I am brushing it on then?

 

Couldn't say for sure as I didn't brush it on. What I did brush on was mostly on small items so couldn't say for sure regarding the undercarriage. Remember that you'll need to apply the 2nd and/or 3rd coats before the first coat dries. If you run out and need to order more then you'll have to wet sand the PORed areas before applying the additional coats. As with most jobs, you're better off with extra materials just in case as running out before its done is a PITA.

The stuff is about water thin and spreads nicely. That said, where will the car be.. on the ground, up on jacks or a rotisserie? Have you cleaned the bottom of the car completely down to the bare metal, everywhere, in very nook and crack? POR-15 does need to be applied directly to clean metal. The metal also needs to be cleaned with Marine Clean and treated with Metal Ready before the POR-15 as well. Its a huge job but worth it in the end. We had our 67 on a rotisserie which made it easier but still took a few weeks since we, at that time, had to do it all by hand.

While POR-15 on bare metal is great, applying it to currently painted surfaces is a complete waste of time, effort and money.

If your not willing or unable to take it down to bare metal then I'd suggest the following:

• Start by cleaning and degreasing the entire bottom of the car as best as you can. Remember that POR, paint or bedliner will not stick if its greasy or dirty so really spend time on this.
• Next sand the entire undercarriage to roughen the paint or primer there currently.
• Find and locate any rust areas and repair (either cut out and replace or POR-15 just those areas).
• If you used POR-15 allow 2 days then lightly wet sand the POR with 400 to 600 grit paper to basically dull it a bit as it dries really smooth.
• At this point you could just use bedliner or better yet give it a good coat of Epoxy Primer first and then allow 2 or more good coats of bedliner.

 

can you spray in on with out a rotisserie? or brush it on?

 

I'm curious to this as well. I have epoxy and urethane on the bottom, and was thinking about bedliner.. Or a rubberized spray undercoating.. You guys don't like that stuff?

 

racin66: Whats "it"? POR or bedliner? No to POR as you'd have to use an HVLP paint gun and there isn't enough room IMO. Bedliner you could use the spray cans yes.

JohnnyK: If you want to go over whats there now without taking it down to bare metal then go with the bedliner. I've used the rubberized undercoating a couple times and do not like it.

 

Would I have to use a new brush each time I put a coat on? How long should I wait to put on a 2nd coat? I bought a qt today.. $45 geez

I'll also be on my back...