Classic cars forum & vehicle restoration.

[steely dan]

I realise that this subject has been touched on many times before but I seek some info.
I'm comming to the end of a fairly extensive restoration of my early E24 BMW . I've replaced the inner and outer sills plus the central strenghening membrane . These three sections sandwich together at the bottom of the sills and are spot/plug welded together. The external edges are seamed sealed with a quality PU sealer , painted and then stonechipped so will remain watertight and well protected . I want to apply a creeping proofer into the internals of the sills that will be fluid enough to creep down into the triple layer and penetrate between the welds thus giving total protection. I ( unlike others it seems ) have used Waxoyl for decades and it has been a great product but to get it to do what I want would have to be thinned down to a very " watery" consistency probably diluting it's effectiveness .
So I ask , has anyone USED a preventative fluid that would do what I want.
Trawling the net I even read of chainsaw bar chain oil being used for this very purpose as it has excellent anti rust qualities and if gently heated , will flow easily .
I add that after I treat the triple seam I will be applying further treatment over the rest of the cavity internal surfaces .

[colwyn500]

Chainsaw oil has sticky qualities...it's normally got anti-fling additives, so I guess it would sit in place for a while. It's not actually a particularly viscous oil, I have heard of people using cooking oil in place of it.
Unless the section has no drainage holes and is pretty well sealed at the bottom seam it's likely to let oil drain away to a dirt attracting mess.
I keep seeing Dinitrol products recommended but I have yet to reach the stage you're at so haven't researched.
I will be interested to see what people come up with.

[kevin2306]

i recently did my mazda eunos
1990, totally rust free and never welded so i am keen to preserve it just like it is.
i did loads of research and in the end went for dinitrol 1000 for the cavities which can be really hard to treat and generally corrode from the inside out.

out of the can its like water, i warmed it up tho just to make sure. i then lifted the front end of the car so it would creep into the rear corners (left overnight elevated) and then elevated the rear so the front end got the same treatment.
i checked the cavities with an endoscope and they had been thoroughly coated (i did buy a decent application gun with a long thin probe that had a 90 degree spray attachment on the end). i did this process twice and then gave everything (inc the cavities) a couple of thorough coats of standard dinitrol. after the initial cavity treatment i did see dinitrol seeping out from any unsealed seam and this continued for several days.
id advise you give the dinitrol tech dept a ring and ask them for their advice..i found them really helpful and informative.

[steely dan]

Many thanks for the replies .
I've fired off some questions to Bilt Hamber , Dinitrol & Auson ( Noxudol ) but the Dinitrol 100 sounds very interesting in as much as it has a low viscosity.
Like yourself Kevin , I will use conventional cavity waxes once the seams have been sealed .
I curse Karmann , who built the early E24's for spraying thick wax into the sills through the designed application holes horizontally which left a neat line of set wax three inches above the sill seams. I also have great difficulty understanding why BMW designed the sunroof drain pipes to vent directly into the sills at the front allowing salted water in winter to flow right into the unprotected seams .
I'll post back after I hear from them.

[Bitumen Boy]

[Ellis]

[baconsdozen]

I have heard of ATF being used as a rust resistant coating either on its own or mixed with a thin oil. I know some people use it as a releasing agent because of its creeping properties.
_________________
Thirty years selling imperial hand tools for old machinery(Now happily retired).

[ukdave2002]

Early Minis had expanding foam injected into the sill box sections, this apparently did a good job in preventing corrosion from the inside. Although I have never heard of anyone doing it, I'd have thought that as long as the stuff would not absorb moisture it could be effective in protecting box sections ?

Dave

[baconsdozen]

I've worked on a few car sills filled with this foam and found them rusted. I think if water gets in the foam holds it and stops it evaporating.
_________________
Thirty years selling imperial hand tools for old machinery(Now happily retired).

[Bitumen Boy]

If memory serves the Minis that had foam in the sills were the ones that had a seam lapped the wrong way, and the foam was an effort to stop water leaking into the car. Given that, it's quite possible there was greater attention to detail with seam sealing and painting than most which could have given rise to this reputation for lasting well - though it's not as if Minis only rot in the sills

[Nick57]

I read recently on another forum somewhere that Shell Ensis V or PW 265 is very good, but not cheap.

nick

[AussieGeoff]

Penetrol, by the Flood Company, converts Rust, I spray it on with Air brush.!! Drill or find a hole, or holes in hollow sections, inject with a suringe, from the chemist, They look at you like you are a Druggie. Apply this after wire brushing loose rust scale, it's magic stuff but it needs you to help a little………If this product is not available in the UK, a 15% solution of Phosphoric Acid will provide similar protection, it's just NOT as SAFE to use an same application methods can't be used. The Phos. solution needs to be rinsed off with water, when dry apply a light primer coating.

[AussieGeoff]

Mollasses + Water, 1part M to 5 or 9 parts Water, in a container, no lid, will eat all rust, no effect on paint, does not remove metal. Takes a week or more, when derusted, rinse with water, dip into a 15% solution of Phosphoric acid, the part is derusted, and protected by a Phosphate, when dry apply a Primer.!!!

[AussieGeoff]

I have removed all rust i can see, and a lot i can't see chemically and i use an Electronic Rust Device to hopefully eliminate future Rust Formation, i think is available in UK, google Cat 111

[AussieGeoff]

When the Restoration is finished, Registered and you enjoying drives in the country, FISH OIL in door & all other enclosed cavities you can find, will stop any rust formation. This doesn't mean you don't add a bit more in a year or so, or neglect clearing the drain holes in the bottom of your doors.!!……………Happy Motoring