undercoating under the tub...yes or no?

What is the best way to treat (paint/undercoat) the bottom of a jeep tub?

  • completely cover with bedliner undercoating

    Votes: 12 52.2%
  • prime and paint with regular paint

    Votes: 6 26.1%
  • other (please post a description)

    Votes: 5 21.7%

  • Total voters
    23

WildTurkeycj8

Legacy Registered User
CJ-8.com Member
City
richmond
State
va
#1
Well, should have just about all the rust removed from underneath the tub bed after a couple more work sessions on it.

I am leery of putting a thick undercoating on it because I think, once it cracks somewhere, water will get up in there and be held under the coating, actually promoting rust. I think it might be better just to prime it real good and paint it.

Let me know what you think...Vote above and post your real-world experience tales to help me figure this out!

Thanks!

-Mike W
 

baldwin

Basic User
City
Lavon
State
TX
#2
I'm planning on spraying Herculiner on the bottom of my tub. Haven't done it yet, so I'm curious to hear what people have to say about this.
 

scott anderson

Old age Mutant Ninjaneer
City
Paragould
State
ar
#3
i never worried about rust when i had a jeep engine...the light coating of oil that was constantly present prevented that...but now i think that if i ever have the tub off i will probably use herculiner or something to seal it..i also heard that it reduces noise
 

jpdeuce

Basic User
City
Houston
State
TX
#4
At the very least I would think a good coat of paint would help. A step up from that which is probably what I would do is laying down a coat of OSPHO or POR15..or something similar. I would think bedlining the whole undercarriage to be a bit of overkill and damn heavy once you spray both sides. But who knows.

I'd go with the rust treatment type approach and slap on some OSPHO in generous amounts.
 

txsbill

Legacy Registered User
City
Houston
State
TX
#5
Bed Liner....

I used the cheap duplicolor roll on bedliner underneath my tub. i figure it's at least as good painting it....
 

Stouttrout

Registered Jeep Nut
City
Sour Lake
State
Tx
#6
I used a chemical stripper on mine and then a rustreatment, OSPHO. After it was all treated I primered it with epoxy primer. You can do that yourself if you have a sprayer and a compressor. Epoxy primer is extremely durable. It will not chip like most. After that I had it Linexed. You could stop at the epoxy primer and then top coat with a good paint but that epoxy prime is some heavy duty stuff. they use it on refinery and farm equiment i this are and it holds up well. Any auto paint supply house should have it.
 

Lugnuts001

Legacy Registered User
City
NJ
State
NJ
#7
Mike,

I put POR-15, POR self-etching primer, and smooth Durabak underneath my tub. I've only had it back on the road for less than a week so I don't have any long term experience, but it looks pretty damn good and durable. My biggest concern is that I didn't get perfect coverage in all the little crevices. I think someday I'll just get an aluminum tub.

Phil
 

twmattox

Legacy Registered User
City
Arcadia
State
IN
#8
Everything I have read indicates that truck bedliner is thick and gets brittle with age. This will allow hairline cracks to form, allowing water (and in my case also salt) in. Since it has reduced airflow, it lingers longer. This gets compounded by the fact that the bedliner material can hide rust underneath (so you don't see it to repair it).

That being said, I had an '84 CJ-7 that was Ziebarted. Held up relatively well, till the last 5 years or so. It was never re-coated (Ziebart offers an annual inspection/recoat for free). Problem with Ziebart is that it is a wax based material. This means it can get brittle with age (read above problems). Other problem is that when you work on anything that has been coated, it is very messy.

I have looked into a product called RustCheck. It is thinner and can "creep" into a lot more places. It doesn't build up as thick a film (not as messy to work around), but does need reapplied annually. My local shop will charge $200 for the first year and $45 for re-application annually.
 

Marine-OpLaw

'ANTIQUATED' PackRat
City
Fredericksburg
State
VA
#9
Hammerite

If I put more than regular old Tractor Supply implement paint under there - w/ a good coat of Rustoleum primer first, it'll be Hammerite (available at True Valuye Hdwe stores).

And just found an interesting site on body prep/rust control: Eastwood Products.
 

Randyzzz

Blown Budget
LIFETIME
CJ-8.com Member
SOA Member
City
Redmond
State
OR
#10
I've always used basic undercoating, either spray off the shelf or by the quart. The stuff is nasty sticky, and stays that way until it gets a good coat of dust on it. But I've never had a problem with cracking, and no rust issues. It is a pain to work around though...seems you always get a smear of it on you somewhere whenever you work on it!
 

CBRogers

Perpetual Parts Collector
LIFETIME
CJ-8.com Member
City
Yorktown
State
Va
#11
I would go with:

1) Strip all the way, ospho, POR15, chassis coat in some color.

2) Strip all the way, Cold Galvanizing, primer, Farm implement paint.

3) Strip all the way, Epoxy primer, Hammerite or Farm Implement paint.

Guess that those would be my choices based on money and time.

Carl
 

Stouttrout

Registered Jeep Nut
City
Sour Lake
State
Tx
#12
twmattox said:
Everything I have read indicates that truck bedliner is thick and gets brittle with age. This will allow hairline cracks to form, allowing water (and in my case also salt) in. Since it has reduced airflow, it lingers longer. This gets compounded by the fact that the bedliner material can hide rust underneath (so you don't see it to repair it).

That being said, I had an '84 CJ-7 that was Ziebarted. Held up relatively well, till the last 5 years or so. It was never re-coated (Ziebart offers an annual inspection/recoat for free). Problem with Ziebart is that it is a wax based material. This means it can get brittle with age (read above problems). Other problem is that when you work on anything that has been coated, it is very messy.

I have looked into a product called RustCheck. It is thinner and can "creep" into a lot more places. It doesn't build up as thick a film (not as messy to work around), but does need reapplied annually. My local shop will charge $200 for the first year and $45 for re-application annually.
Everything said here is so true. In my area Salt water is a big concern. it travels in with our fall and winter storms. the Gulf Coast areas in this state are as bad as the rust belt. I praticly live at the Beach and have tried just about everything. The Ziebart has worked real well. i have it on a Ramcharger. It does require treatment now and again but it is also somewhat gooey. Mine has never dried up and cracked but I have heard of others that have. I have had it on there for 10 years. No rust yet. I went with Linex for looks and it is nice and clean. not like a tar type substance.

I think the main thing is to seal it up good. Use a good quality primer and make sure you spray it in every little crack. i think if you do this you are way ahead of the game. That is why I when with Epoxy primer and sprayed it intstead of brush it. I think the main goal was to find something that would hold up over time and seal very well.
 

WildTurkeycj8

Legacy Registered User
CJ-8.com Member
City
richmond
State
va
#13
Thanks for all the replies!

For the record, I was reading the label of some Hammerite paint the other day, and IIRC, it said DO NOT APPLY PRIMER. I could be wrong about that, but I don't think so.

I have been using a grinder with a cup brush to get off a lot of the rust, but am also using a paint stripper and naval jelly to get down to bare metal. That naval jelly is working GREAT!

Thanks again

-Mike W
 

Stouttrout

Registered Jeep Nut
City
Sour Lake
State
Tx
#14
Mike, if you haven't tried OSPHO yet it is really good stuff. It is easy to get here because the plants all usee it but not sure in other area. ACE usually has it. It has the consistency of water. It gets in every little crack. Also leaves a coating that can be painted easily.,
 

WildTurkeycj8

Legacy Registered User
CJ-8.com Member
City
richmond
State
va
#15
Ospho

Yep we have it here. Was looking at a gallon if it at the Duron paint store today for about $18. I'll probably pick some up before it's all said and done!

-Mike W
 

FELNTPSY

Booty Fab Master
City
Morehead City
State
NC
#16
Mike,

I would use the Por-15 metal ready (does the same thing as Ospho..turns the rust to neutralize it.) then if the tub is off already...try to flip it on it's side or upside down and paint the POR-15 on.....this is pure liquid and will get into all the nooks and crannys. With the new spray can self-etching primer that they have you can then apply that and topcoat with rattle can stuff or bedliner.

The plus of POR-15 is that it wil bend with the metal and not split open. The only drawback is that anywhere that isn't topcoated will fade with exposure to UV light....not that big of a problem under the tub...but I would still top coat.

Just my opinion.

Later,
 

gp'n Jake

can you repeat that?
City
morris county
State
NJ
#17
i'm glad i read this b/c i just got a quote on rhino lining the the bed, the cab and the underside of the entire tub and it was PRICEY. i don't know enough about using that stuff (rhino lining) underneath, but wouldn't it provide a "buffer" against rocks and other road debris from knicking the bottom of the tub and giving rust a place to grow?
 

Stouttrout

Registered Jeep Nut
City
Sour Lake
State
Tx
#18
Well, I paid $450 for the inside of the tub from front to back, The underside of the tub and the wells on both front fenders. I had done most of the prep work myself and he siad he really should have charged me $500. He used Linex. I like it because it is flexible and seals good. Problem is, it goes on thick so it will not "Run" into the little hard to get areas. This is why a good primer and sealer would be good first. My whole tub was Epoxy primered. We had a long nozzled sprayer we used to get into the hard to reach areas. That epoxy primer won;t crack or chip. One thing it did do was quite it way down.
 

canzo

equal opportunity annoyer
City
Alexandria
State
VA
#19
I really liked this thread. I was just wondering what to use on my new acquisition's underside to stop the surface rust from becoming rust rot.

I have a question on the liner: Is rhino lining the inside a bad idea because it will crack and give rust a place to start eating away? Or does it protect it from rusting?

I live 6 blocks from the Atlantic Ocean and am worried my Scrambler will become so much red dust in a few years.
 
City
Aurora
State
IL
#20
Mike,
I used POR 15 on the underside of the tub, the firewall, and the inner front fenders. Its now 2 years old and still looks yesterday new. It cleans up very well. It also flowed very well during application and sealed all the seams tight.
The inside of the tub got Rhinolined. I like it and would use it again, however it is hard to get clean. The dimples in the texture of the product hold dirt and water and give it an overall dirty appearance, this is especially true with the black color I have. Not really a big deal.
Mike

What kind of progress have you made lately?
 
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