The best solution to remove rust on the underside of the car

[w4o73]

Hello, this is my first post on the forums but I can't think of a better place to ask this question.

 

My 52 Plate Fiesta Finesse is a bit rusty underneath, the previous owner didn't take particularly good care of the underside - since it's mine now and only 70k on the clock I've replaced a few parts

• Brake pads
• Brake disks
• Water pump
• Expansion Coolant Tank
• battery
• Thermostat
• Full Engine service (Sump plug, sparks, oil, filters, etc)
• Ignition Coil
• Second hand filler neck (Rusty not corroded)

However, the underside is rusty - not corroded. So I was wondering if there's an ideal solution to fix it up myself, and what tools I would need? I will be getting a jack to crawl under it.

Whilst at the garage the mechanic showed me a leaky corroded filler neck and I noticed some of the rust, the garage and 2 other garages have confirmed it's in good condition for it's age and these are just age related issues. 

I want to get it cleaned up before it's MOT in July now winter is done with. 

 

Thanks,

Dean

 

[isetta]

I have always used wire brushes and waxoyl undersealer (not the waxoyl fluid , but the blank undersealer).  I expect others have their own favourites

"However, the underside is rusty - not corroded."  rust is corrosion.  

"now winter is done with. " not sure it is, we are still in January

 

[w4o73]

Thanks Isetta, I understand rust is corrosion, I meant there are no holes there... Yet! 

I will look into waxoyl undersealer. 

When using the wirebrush, is there any certain technique to follow or is it simply scrub off the rust, clean and apply underseal?

Thank you for your recommendation!

[Micro]

12 hours ago, w4o73 said:

I will be getting a jack to crawl under it.

Get some stands with that jack. Do not go under a vehicle raised only on a jack - If the jack hydraulics fail or the car is shifted the car falls - if there are no stands, then it falls onto you. I bought a jack, and a pair of 3 ton stands for £30~, it is just not worth the risk.

[jbell]

4 minutes ago, Micro said:

Get some stands with that jack. Do not go under a vehicle raised only on a jack - If the jack hydraulics fail or the car is shifted the car falls - if there are no stands, then it falls onto you. I bought a jack, and a pair of 3 ton stands for £30~, it is just not worth the risk.

Just out of curiosity (I haven't used my stands yet) - where's best to stick them? 

I figure the pinch weld I put the jack isn't a good place for the stands. 

[isetta]

i can't remember exactly what the construction looks like underneath your model of car for placing axle stands. On occasions I have put a block wood in the v part at top of axle stand so the car is on the wood so the axle stand does not damage the car.   Of course you need to make sure it can't slip off due to uneven / sloping ground etc.

Yes, wire brushes, you just need to make sure you keep scrubbing as much as you can bear to do. wire brushes will wear out and the spikes will break off and litter the ground and then get stuck in your clothes. Some people may use a rotary wire brush on an electric drill. I guess the quality of the rotary wire brushes may vary but when I tried this years ago it did not seem so effective and it ended up polishing the rust instead of removing it. in some areas I have used a file .  also check carefully along the edges of the rubbery undersealer stuff that the manufacturers put on the car. sometimes damp creaps under the edge and then rust starts forming, once it's there the presence of the rubbery undersealer potentially makes it worse as it holds the damp in and does not allow airflow etc to dry it out so if there is any dodgy bits of that rubbery stuff make sure you scrape enough of so the border is clean metal with the rubber stuff still adhered well

[TomsFocus]

Axle stands should ideally be placed under the arrowed jacking points on the sill where it is strengthened for exactly that purpose.  Obviously it's difficult with the jack there as well though so I tend to look for a solid part of the subframe that won't slip, usually where it is bolted to the chassis.

On the subject of jacks though...I've been using an old car jack to save lifting the trolley jack recently (I don't go under without stands though)...but then this happened yesterday lol...they aren't as strong as you'd think!

[dansallis]

19 minutes ago, TomsFocus said:

Axle stands should ideally be placed under the arrowed jacking points on the sill where it is strengthened for exactly that purpose.  Obviously it's difficult with the jack there as well though so I tend to look for a solid part of the subframe that won't slip, usually where it is bolted to the chassis.

On the subject of jacks though...I've been using an old car jack to save lifting the trolley jack recently (I don't go under without stands though)...but then this happened yesterday lol...they aren't as strong as you'd think!

Jeez, I do hope you weren't under it matey! 

In terms of jacking points OP, I usually put the trolley as close to the arrow on the sill as possible whilst leaving just about enough room for an axle stand to go next to it. After a couple of lifts, you soon work out how much space you need to leave.

[TomsFocus]

Nah I wasn't.  Unscrewed the brake fluid cap to check the level and immediately dropped it straight down onto the undertray...    So just had to lift one corner and get a stick through the wheel arch to retrieve it lol.

[Jethro_Tull]

http://www.fordownersclub.com/forums/topic/93025-home-rust-treatment-guide/?tab=comments#comment-664458

[Nikstryker]

Give it a wire brush & then Jenolite the rust - it is basically phosporic acid like most of the solutions you can buy and it converts the rust to iron phosphate.

Then undercoat with quality underseal!

Or apply a "Shaken like buggery" Jethro_Tull home made if you are of the impecunious type.

>;o)

 

[auldreekie]

Consider putting on some eye protection when scrubbing it with the wire brush, nothing worse than some crap getting in your eye resulting in a trip to the eye hospital to get it removed. Happened to me several years ago.

[isetta]

yes i have also been to eye hospital to get rust out of my eye from laying under a car. they had a good old moan at me about it.but I did not have to wait in a queue. wonder what the wait would be like these days.

[Nikstryker]

Yep rust in the eye had it too but managed to wash it out.

Not as bad as jenolite on the eye I hazard to add - now that was nasty!

Then we have petrol in the mouth and brake fluid in the grazed knuckles!!!

[isetta]

petrol on my gonads. I was sanding down a motorcycle petrol tank removed from bike  still had small amount of petrol in it. had it on my lap whilst I was sitting on a stool . my leg accidentally turned the petrol tap on. petrol slowly soaked through my clothing and I suddenly realised. rushing around stripping off and pouring water over me. Lucky I wasn't smoking. it did sting

[biff55]

i'd wait until the end of march when you can be sure of no further road salt gritting then you can give the underside a good hose down and remove all the winter road grime prior to applying your chosen protective products.

Jan / Feb is still too damp / cold / dirty for this sort of work tbh.