Rust treatment and protection

MarcusMaximus

I have a 2017 Nissan Leaf and I noticed the other day that there is some corrosion on the front chassis cross-member, as viewed from under the bonnet. There is probably more elsewhere but I would have to remove the underbody panels to inspect it properly. I would like to treat any existing rust as well as protect those areas against further corrosion. Someone in the States recommended getting a lanolin-based product but I have also been looking at Hammerite underbody treatment, which contains waxoil, as well as some other products like Bilt Hamber and Liqui Moly etc. I’m just wondering what people here would recommend, both in terms of how best to deal with the issue as well as actual products?

MarkN

Lanogard. There’s an Irish distribution company for it called FK something or other. It stops and protects but doesn’t treat though.

BrianD3

Spraying Waxoyl or similar or some underbody seal on top of the rust won't do much. You'll need to physically remove the rust (as much as possible) treat and paint and then you might slow it down for a few years. I've used POR-15 for this and it turned out to be rubbish. I've also used Bilt Hamber products (Deox treatment + Electrox primer) and that job seems to be holding up well but it's only been a couple of years.

When you say front chassis crossmember what exactly is that, is it welded to the longitudinal members. Or is it a bumper reinforcing bar which are often bolt on. Or a subframe. If it is a bolt on part, it may not be worth the hassle of trying to treat the rust.

MarcusMaximus

Thanks. Yeah I've come across that but was a bit put off by the lack of treatment, as well as the cost though that was from the UK. I suppose I could treat it with a rust inhibitor first, as long as they wouldn't react with each other.

MarcusMaximus

I can only get a limited view from the motor compartment but it's directly under the radiator. The underbody panels make it hard to access for further inspection. I'll attach a couple of photos from the top.

I heard that the only way to change the cross member is to take the whole motor out first! However that might be incorrect. As regards what to put on it, yes I agree that taking off the rust and then treating would probably be the best approach.

RINO87

I'd say +1 for Lanoguard for underbody anyway....piece of piss to put on, apply it every spring to a 92 T4 here and she is still clean as a whistle underneath, and those transporters like to rust too. It dries clear, so you can still see if there's trouble brewing.

Now that said, I'm not sure how it would hold up on the area in your pics there. That close to the rad/engine might just cause a lano coating to melt and drip off.

MarcusMaximus

That's a good point about a lanolin product possibly melting off. Given it's an ev it could get pretty hot around the motor I'd imagine. I might do as you say for the rest of the underbody, however I would have thought the panels would provide some general protection? I was intending to just treat the areas that are already affected, like this beam.

Here are a couple more pics showing a bit more where it is located and also that it is in fact bolted on. Would it be possible to replace it from underneath without too much disassembly?

BrianD3

5:10 in this video shows the bottom radiator support being removed. The rusty part in your case may be the actual subframe which is also bolt on but likely a much bigger job to replace.

Either way I wouldn't get too excited about it. The metal in those parts is thick so should be good for a while, clean it up as best you can in situ and spray something on it. Treating it properly will involve removing it and in that case you'd probably be replacing it.

https://www.youtube.com/watch?v=Z7fZh1dmNGg

MarcusMaximus

https://www.boards.ie/discussion/comment/123218852#Comment_123218852

Thanks for posting that. At around 5:23 it shows both the rad support and the subframe behind it. Yeah, that looks like a much bigger job alright but I think the support would be hard enough for me to remove as well. Judging by the location of my part compared to the video I think it probably is the support.

However it doesn't sound like it needs replacing, at the moment anyway. By doing it in situ I presume you mean from underneath the car with the panel removed? I wouldn't be able to do much from above I think.

BrianD3

https://www.boards.ie/discussion/comment/123219320#Comment_123219320

When I said in situ I was thinking of from the top with no dismantling, scraping off flaking paint and then spraying it with the lanolin stuff. But that might not be feasible given the access.

If you are going at it from the bottom it seems from the video that you'll have a lot of plastic to remove and that it willl be PITA if you don't have a lift as in the video. But once you've removed the plastic, removing the support itself seems trivial and it may be a cheap enough part.

MarcusMaximus

Ah right. The lanolin mightn't work because of the heat around there as @RINO87 pointed out but I could probably find a product that was designed for higher temperatures. Certainly doing it from above sounds a lot easier despite the access, maybe with some tool for reaching lower areas. I'll have a think about it.

For sure removing the plastic underbody panels would be a right PITA plus I'd have to hire a couple of ramps to raise the car. I was considering doing this in order to inspect the rest of the underbody to see if there are any other trouble spots that need treating, as well as attending to that support/frame. Does that sound like overkill?

MarcusMaximus

Finally got round to getting under the car and removing the front cover today. The part in question seems to be some sort of support as it forms a hollow square right under the motor compartment. All four sides have rust like that front section, some of it going up the sides on the inside. So I cleaned it off as best I could and applied some wax-oil based treatment that I got in Halfords, which is designed to go straight on rust and to stop it. I chose it as it's also heat resistant, because of the location.

While I was at it I inspected the area behind the front wheels and found a bit of a mess in terms of corrosion. I'm just wondering if it's likely to be superficial and relatively normal or if it needs attention. Here are some pics if anyone would care to comment. Thanks.

MarcusMaximus

Here's a clearer version of the first photo above.

Never mind. It didn’t actually look any clearer so I deleted it, seeing as it seems I can’t delete the whole post.

BrianD3

I don't see anything in those later photos which would be abnormal or concerning. Driveshafts, brackets, anti roll bars, struts etc. will rust but the metal is thick, it would take many years for it to become an issue and anyway they are replaceable parts.

It looks like the "chassis" of the car in that area is rust free.

Fabio

Lanoguard works but it needs to be applied annually and it doesn't remove rust (although it does slow its progress by depriving it of oxygen if covered properly). However, it's easy to apply once the area is cleaned up and loose rust removed, and it's safe on electrical items, rubber, and plastic bits.

They do a grease (Moto Grease I think) which you can melt and brush on. Might be worth trying that and seeing how it holds up. Maybe it'll stand the heat because you'll have air flow down there too.

MarcusMaximus

https://www.boards.ie/discussion/comment/123313074#Comment_123313074

That's great to hear. Yes the chassis in general looks very clean and sound. Many thanks.

https://www.boards.ie/discussion/comment/123316028#Comment_123316028

Yes I'm sure the Lanoguard is great however I ended up getting Tetroseal Wax/Oil Rustproofing from Halfords as it is both a rust treatment and a preventative plus it is heat-resistant. Also you can apply it directly to rust without using an inhibitor/converter first. I put that on all the rusty areas I could access, apart from behind the wheels as it is not safe for rubber or plastic. Though I might coat the metal parts carefully. I brushed it on as the trigger spray you can get for it didn't work, probably too viscous.

Here are some photos of the subframe that started it all! As you can see some of it was pretty bad:

However it looked worse than I think it was. Once I scraped, wire-brushed and sanded it, the rust appeared to be more on the surface. The metal is pretty thick and strong there so hopefully what I have done will arrest any further corrosion at least to some degree and help prevent re-occurrence. I gave everything two coats for extra protection.

Here are a couple of photos of it after cleaning it up and before treatment. It was a bit awkward under there so a little hard to get good pics but hopefully they will give some idea. I'm curious about the big 'EV' written on it. Looks like it may already have been replaced at some point from a breakers or wherever. I doubt Nissan labeled their original parts like that!

Fabio

https://www.boards.ie/discussion/comment/123317494#Comment_123317494

That Tetroseal stuff looks decent. I'd seen it before but didn't give it much thought…maybe I should have!

MarcusMaximus

https://www.boards.ie/discussion/comment/123323816#Comment_123323816

Yeah it seems pretty good and feels/looks like a decent 'skin' over the rust. It also seems to have darkened the colour which might be down to the inhibitors it contains. I think they tried to take a multi-pronged approach with this product. Time will tell how effective it actually turns out to be!