Undersealing recomendations

[^woody^]

I'm after recommendations for undersealing and rust proofing/treating the underside of a car. Chassis, cills, maybe the floor pan although that seems in good nick, and main components such as wishbone arms and roll bars and such like.

There is some flaky metal, but not a great deal, and the rest is basically surface rust and cracked/chipped coatings where rust has got behind.

It will be done off off a drive, no ramps or pit.

Product type, name and whether spray or brush is better would be great.
Ideally a one-coat product that just requires me to give things a quick brush or sand and the product will stabilise rust and give a good protective coat for several years. Also if the product is safe if it gets on rubber or plastic would help, but not essential.

Also the exhaust and boxes. Can I coat with a heat resistant cold galvanizing paint or should it be just a heat resistant paint? One of the boxes is quite flaky at one edge, but still sound - it looks like the whole system was nice and thick to start with.

Thanks

 

[Swwils]

Neutrarust 661 ​

 

[Mottie]

Does anybody do that nowdays? in the old days you would coat the underneath with old engine oil! I haven’t seen a blowing exhaust for years now - when I first started driving you would cut up a coke can and use a couple of jubilee clips. Failing that you'd use gun gun or an exhaust bandage.

OP. What car/age are you talking about?

 

[Burnerman]

Use a neutraliser such as 661 - there are others, some cheaper but they all work the same.
Isopon 182 is a zinc rich paint which has some effect.
Anti roll bars are often plastic coated which splits, letting water in - waxoyl is as good as anything, which isn’t much!
I’ve used the super duper products from Bilt Hamber - at great expense - but they are only successful if you can get down to raw metal.
Ignore the exhaust - you won’t stop corrosion here but it may look better for a while.
A spray on body shutz will do for chassis and floor parts etc.
A really good underbody clean is essential too, allow a couple of days for drying, and traffic film remover is good for removing any oily substances.
John

 

[RandomGrinch]

OP. What car/age are you talking about

Given @^woody^ 's avatar, I'm thinking:

 

[Nige F]

Underseal used to be a trademark name ( like Hoover ) from 3M = Minnesota Mining and Manufacturing. L learned that while messing with "classic" cars when they were just old bangers,

 

[norseman]

I have my old Range Rover (a typical LR rust generating model) treated with Dinatrol every five years with a check 'n top-up annually.
The thicker stuff goes on the outside of the chassis/underside with a lighter variant sprayed into the cavities/sills etc.

Seems to work for me as the 35 year old car is unrestored with just two small welded patches where the rear seat belts mount to the inner wings.
I've had Waxoyl applied in the past, but it doesn't seem to stand the test of time.

 

[Harry Bloomfield]

I'm after recommendations for undersealing and rust proofing/treating the underside of a car. Chassis, cills, maybe the floor pan although that seems in good nick, and main components such as wishbone arms and roll bars and such like.

There is some flaky metal, but not a great deal, and the rest is basically surface rust and cracked/chipped coatings where rust has got behind.

It will be done off off a drive, no ramps or pit.

Good luck with that. I would suggest you will need much better access to do it properly. Mine came from the factory extremely well protected, except for the pressed steel, box section rear arms. MOT guy last time, suggested it was time I got something done to protect them, so I found a local who claimed to specialise in protection coatings. They made the underside of the arms look great, but ignored the fact that boxes have four sides, two outside surfaces and two inside - they just tackled the one surface and left the other three to continue to deteriorate.

 

[norseman]

Good luck with that. I would suggest you will need much better access to do it properly. Mine came from the factory extremely well protected, except for the pressed steel, box section rear arms. MOT guy last time, suggested it was time I got something done to protect them, so I found a local who claimed to specialise in protection coatings. They made the underside of the arms look great, but ignored the fact that boxes have four sides, two outside surfaces and two inside - they just tackled the one surface and left the other three to continue to deteriorate.

I've owned Land Rover's potential rust buckets for decades & in my experience the 'corrosion protection specialists' industry has more cowboys than a John Wayne movie.

 

[Belle427]

Dinitrol make some very good products but if it’s a car that’s not daily driven in all conditions I’d probably not bother as I’d rather see the areas clearly.
For it to work effectively it needs reapplying every few years.

 

[norseman]

Dinitrol make some very good products but if it’s a car that’s not daily driven in all conditions I’d probably not bother as I’d rather see the areas clearly.
For it to work effectively it needs reapplying every few years.

That's my situation; second car, parked in the open & driven 1 to 2K miles per annum.
Having it's annual check next week, full treatment again in 4 years time.

 

[Diver Fred]

I've never had a problem with Waxoyl on my old moggie van. inside the chassie rails and the underside. Bitchmastic in the wheel arches and front wings oversprayed with Waxoyl. just don't get it on brake disc's.

 

[^woody^]

Is Jenolite any good? I have some for rust removal and rust conversion.

I also have some Jenolite Original a Wax Oil spray, which I was going to use in some of the nook and crannies and hollow sections that are not exposed wont get impacted.

 

[^woody^]

Is there any real difference between traditional bitumen type underseal, and "stone chip protector"? Apart from the stone chip being over paintable.

I understand that bitumen affects rubber materials, so would I be better off spraying or brushing or looking for a particular product that does not affect rubber -or just be careful

 

[^woody^]

Good luck with that. I would suggest you will need much better access to do it properly. Mine came from the factory extremely well protected, except for the pressed steel, box section rear arms. MOT guy last time, suggested it was time I got something done to protect them, so I found a local who claimed to specialise in protection coatings. They made the underside of the arms look great, but ignored the fact that boxes have four sides, two outside surfaces and two inside - they just tackled the one surface and left the other three to continue to deteriorate.

To be honest, the underside is not that bad.

There is small hole starting to form on a joint on the chassis - its not clear if it started on the inside or on the outside, but the drainage holes are clear. I can deal with that and once resealed I don't think it will get any worse. Also on the cills where the garage monkeys have misplaced the jacks in two places over time and bent the lip and flaked the stone ship coating, and there is some rust bubbling there. And a couple of places on the bottom of the back wheel arch lips, about 4" are starting to bubble but the metal is still sound.

The rest of it is OK.

I've had a quick go underneath, and what looked like flaking rust on the main components is mainly just flaky paint and dirt, once wire brushed the surface is very smooth not rust pitted. The floor pan is great, the original underseal is in good condition, just dirty and grimy.

Once those few rust places are dealt with that could be it, and It will be good for several years. But I feel that while I am under there I may as well treat the rest off the underside as best I can and give it a lot more potential life.

The exhaust on two boxes, is quite bad, but there are no holes. I think a quick once over should get a couple of MOTs out of it yet.