General Underseal or not to underseal?

[markdarbypearson]

My punto had an advisory for underbody rust last mot. Any recommendations?

 

[Pugglt Auld Jock]

Is it just a general statement that rust is visible or is it more specific? For example, inner sills? How old is the car?

 

[markdarbypearson]

Is it just a general statement that rust is visible or is it more specific? For example, inner sills? How old is the car?

Mot says sills and sump. Planning to wire brush and treat obvious stuff then paint with hammerite??
Car is 2004 with 68000 on the clock

 

[Pugglt Auld Jock]

Thanks for that. Of course I don't know your level of ability so I hope you won't be offended by any of this? As you may know rusty sumps are very common on the FIRE engines. My boy's 2012 Punto 1.4 8 valve is looking very crusty and I think we'll probably fit a new one this summer if all this virus stuff lets up a bit (he's grown up with his own family so doesn't live with us). Our own Panda 2010 1.2 dynamic eco had a new one fitted by it's last owner about 3 years ago. At the age of your car it's probably not the original sump so it just depends on it's present condition as to whether it's worth rubbing down, applying a rust neutralizer and repainting. The metal is quite thick and they get quite "pimply" with rust before they get porous and start seeping oil. If it's looking "pimply" then personally I'd be fitting a new sump. If so I'd also give it a coat or two of something like Frost's Chassis Black to reinforce the manufacturer's coating which is often a powder coat and can be a bit brittle whereas the chassis black is an enamel and a bit less prone to chipping I find. I used to be a great believer in Hammerite and still love it's swirly finish for some applications, but I've noticed when painted on axles etc it does tend to chip rather readily so I personally don't use it in places where it's liable to be attacked by stones and road chips.

Before spending time on the sills you need to get underneath - with the car safely supported on stands etc, not just a jack - and take a small hammer or screwdriver handle or similar and give those sills a good tapping to see if they are sound. If nothing disintegrates and no holes appear then rubbing down, anti corrosion treatment and painting would be good but, sills are often subject to the "iceberg principle" in that often they look not too bad from the outside but hide a multitude of sins inside. If you end up with rotten holes appearing - and don't be too timid with the hammer, you want to find any rotten bits if they are there - welded repairs will be needed. If you feel they are good enough to just derust and paint you might want to consider an injection product like Dinitrol or similar to apply internally, which you can buy in a spray can if you don't have a compressor and gun. If obvious rust is present I wouldn't just wire brush and paint over the top, you need to use a rust converter (Jenolite, Curust, etc) otherwise the rust will just come back later.

Hope that's helpful
Let us know what you end up doing won't you?
regards, Jock

PS. If you want to go "belt and braces" you could spray a stone chip product over it all after you've painted.

 

[markdarbypearson]

Thanks for that. Of course I don't know your level of ability so I hope you won't be offended by any of this? As you may know rusty sumps are very common on the FIRE engines. My boy's 2012 Punto 1.4 8 valve is looking very crusty and I think we'll probably fit a new one this summer if all this virus stuff lets up a bit (he's grown up with his own family so doesn't live with us). Our own Panda 2010 1.2 dynamic eco had a new one fitted by it's last owner about 3 years ago. At the age of your car it's probably not the original sump so it just depends on it's present condition as to whether it's worth rubbing down, applying a rust neutralizer and repainting. The metal is quite thick and they get quite "pimply" with rust before they get porous and start seeping oil. If it's looking "pimply" then personally I'd be fitting a new sump. If so I'd also give it a coat or two of something like Frost's Chassis Black to reinforce the manufacturer's coating which is often a powder coat and can be a bit brittle whereas the chassis black is an enamel and a bit less prone to chipping I find. I used to be a great believer in Hammerite and still love it's swirly finish for some applications, but I've noticed when painted on axles etc it does tend to chip rather readily so I personally don't use it in places where it's liable to be attacked by stones and road chips.

Before spending time on the sills you need to get underneath - with the car safely supported on stands etc, not just a jack - and take a small hammer or screwdriver handle or similar and give those sills a good tapping to see if they are sound. If nothing disintegrates and no holes appear then rubbing down, anti corrosion treatment and painting would be good but, sills are often subject to the "iceberg principle" in that often they look not too bad from the outside but hide a multitude of sins inside. If you end up with rotten holes appearing - and don't be too timid with the hammer, you want to find any rotten bits if they are there - welded repairs will be needed. If you feel they are good enough to just derust and paint you might want to consider an injection product like Dinitrol or similar to apply internally, which you can buy in a spray can if you don't have a compressor and gun. If obvious rust is present I wouldn't just wire brush and paint over the top, you need to use a rust converter (Jenolite, Curust, etc) otherwise the rust will just come back later.

Hope that's helpful
Let us know what you end up doing won't you?
regards, Jock

PS. If you want to go "belt and braces" you could spray a stone chip product over it all after you've painted.

Thank you so much Jock for that valuable advice. I've not had a proper look under the car yet. I'll be borrowing a friend's van axle stands and the hammer/screwdriver advice will be first job.
When I said rust treatment in my previous post I should've said that it's a rust remover gel which is supposed to dissolve the rust back to bare steel and not a kurust type product.
I'm hoping this will give me a better idea of the condition of the metal.
I'm liking your idea about the dinitrol and thinking maybe following this by going straight for the stone chip. Do you agree?
Thanks in advance for your valuable advice!
There is no substitute for experience!!

 

[nitramtpr]

The Sumpis very common for attracting rust as are the sills.
I had a similar advisory on my last MOT, specifically the rear section of the sills by the arches. I put the car on ramps (didn't have axle stands), got a wire brush and gave the sill a good brushing all the way from the front to back then sprayed with hammerite underbody protection. Not had a look recently but hopefully it's done the job.
A new sump is quite cheap but a massive pain to take off as you really need to take the exhaust manifold off

 

[Pugglt Auld Jock]

Going back over this I realized you've headed it "Underseal or not to underseal" and none of us have actually mentioned underseal!

I'm not at all a fan of traditional, old style, bituminous underseals because they tend to crack as they age which then lets water and salt get in between them and the metal and due to the impervious nature of underseal it then doesn't dry out and you just end up, long term, with an even worse problem than it you'd left it alone! There is a quite common practice where new metal is welded in - for an MOT repair for example - of then just slapping a nice thick coat of underseal on top without any other preparation (ie no undercoat or chassis black etc) This is likely to see you through a couple of MOTs but is no long term solution. If you have to go with underseal, Waxoyl do one which has a percentage of their wax product mixed in I used it once - still got half a tin sitting in the garage and it seemed to work quite well. I mention it because I took the lid off a few part used tins recently and the Waxoyl product was still nice and soft and could definitely have been used.

Rusty metal must be passivated in some way and good metal (and your passivated rust) undercoated and top coated before then applying something like your underseal - if you must - or wax based compound, or stone chip, or whatever. Stone chip has historically had a rather "shady" reputation as it's often applied over rusty metal or "dodgy" repair work to disguise it for reasons of sale etc. If I'm looking at a car someone is thinking of buying - something I tend to try to avoid - if I see stone chip on the sills it tends to ring alarm bells and makes me wary. However if the under lying metal and it's paintwork is in good condition stonechip can work quite well at, well, preventing stone chips! Tends to crack when it gets old though.

Lots of people on this forum are interested in how to stop - or, more realistically, slow down - the rust problem on our back axles. Whilst some have gone for quite sophisticated solutions which sound wonderful but involve a lot of work (but will probably last for many years) I think many go for a good pressure wash down, a bit of wire brushing/chipping to remove the worst of the rust, maybe some Jenolite/Curust or similar rust passivator and then applying either a wax or oil based substance which has the ability to creep back if "attacked" by foreign bodies. Do a bit of searching, there's lots about it on the forum.

Kind regards and stay safe
Jock

 

[AndyRKett]

I agree with everything jock says.

Many years ago I used to have classic range rover. This had sills made mainly of paint.

If I learned anything from this, that is that never put any sort of rust protection over loose rust, or over bad paint, you need to get rid of all the loose rust and paint to get down to the metal. Otherwise you can spend houses meticulously covering the car with rust preventives only to have some rust flake off and leaving a big hole in your newly added rust preventing barrier.

I spent a very long time welding new complete sills into that range rover, which involves about half the floor on both sides of the car.... then realised every other part of the car that wasn't Birmabright, was replaced with rust.

 

[markdarbypearson]

Going back over this I realized you've headed it "Underseal or not to underseal" and none of us have actually mentioned underseal!

I'm not at all a fan of traditional, old style, bituminous underseals because they tend to crack as they age which then lets water and salt get in between them and the metal and due to the impervious nature of underseal it then doesn't dry out and you just end up, long term, with an even worse problem than it you'd left it alone! There is a quite common practice where new metal is welded in - for an MOT repair for example - of then just slapping a nice thick coat of underseal on top without any other preparation (ie no undercoat or chassis black etc) This is likely to see you through a couple of MOTs but is no long term solution. If you have to go with underseal, Waxoyl do one which has a percentage of their wax product mixed in I used it once - still got half a tin sitting in the garage and it seemed to work quite well. I mention it because I took the lid off a few part used tins recently and the Waxoyl product was still nice and soft and could definitely have been used.

Rusty metal must be passivated in some way and good metal (and your passivated rust) undercoated and top coated before then applying something like your underseal - if you must - or wax based compound, or stone chip, or whatever. Stone chip has historically had a rather "shady" reputation as it's often applied over rusty metal or "dodgy" repair work to disguise it for reasons of sale etc. If I'm looking at a car someone is thinking of buying - something I tend to try to avoid - if I see stone chip on the sills it tends to ring alarm bells and makes me wary. However if the under lying metal and it's paintwork is in good condition stonechip can work quite well at, well, preventing stone chips! Tends to crack when it gets old though.

Lots of people on this forum are interested in how to stop - or, more realistically, slow down - the rust problem on our back axles. Whilst some have gone for quite sophisticated solutions which sound wonderful but involve a lot of work (but will probably last for many years) I think many go for a good pressure wash down, a bit of wire brushing/chipping to remove the worst of the rust, maybe some Jenolite/Curust or similar rust passivator and then applying either a wax or oil based substance which has the ability to creep back if "attacked" by foreign bodies. Do a bit of searching, there's lots about it on the forum.

Kind regards and stay safe
Jock

Many thanks Jock I'm on it while the weather is good and in between replacing the steering column with a NOS one before it fails completely. I'm a bit of a novice so a little daunting!!

 

[Pugglt Auld Jock]

Many thanks Jock I'm on it while the weather is good and in between replacing the steering column with a NOS one before it fails completely. I'm a bit of a novice so a little daunting!!

Good luck. Do let us know how it all turns out.
Jock

 

[nitramtpr]

Many thanks Jock I'm on it while the weather is good and in between replacing the steering column with a NOS one before it fails completely. I'm a bit of a novice so a little daunting!!

Don't forget, there is a really good guide (in 2 parts):

https://www.fiatforum.com/punto-mk2...eplace-pas-column-punto-mk2-hgt-part-1-a.html

https://www.fiatforum.com/punto-mk2...eplace-pas-column-punto-mk2-hgt-part-2-a.html

I followed the guide and found it fairly straightforward.

Here are my notes from using that guide:

https://www.fiatforum.com/punto-mk2...-column-punto-mk2-hgt-part-2-a.html?p=3432376

Good luck

 

[judderbar]

You must underseal if you want to keep the car.


I have two weak spots on my car. The bottom of the front wings was exposed metal for a year or more. Potentially I caused that because the guard was inside the wing at the bottom rather than over the wing (inside the wing around the side is correct)

I then might have blocked up the gap between the wing and the body where the wing joins the body with a bolt when I treated that rust and this might have caused the wing to fill with wet rubbish. Subsequently I added a washer on the bottom two wing bolts to create a bigger space and it seems to remain clear of rubbish that can now fall out thru the gaps. I got front mudguards because the wing was being sandblasted but I am not sure they are necessary if the guard is correctly fitted. Potentially the factory guard was longer when the car was new and hung down a bit more. The mudguards create their own dirt trap and cleaning problem.


Next problem area was under the very small plastic guard at the bottom rear of the sill where the sill meets the rear arch. There was some very thick filling material under that guard from new which was hiding a strip of rust and enabling water to accumulate. I think i have stopped that completely from rusting.

I gave the inner and outer sill a good dosing of a penetrating antirust wax.


Twice a year I crawl under the car and spray a penetrating wax on any chips and then go over with it a harder spray wax.


I am currently still imagining I might never need to buy another car again.