Flange corrosion prevention.

[ambermarine]

On my Mark 1 Ls400 the flange connection at the cat to exhaust slowly over the years corroded away until there was little metal left and the exhaust started to blow.

It needed repair and that was either new flanges on cat and exhaust pipe or a welding job that turned out to be inadequate.

When I purchased the Mark 4 this area was something I have monitored very closely and over the five years and 20k miles there as been some regular flaking of the metal on the flanges relative to the use of the car. I realize that over time this will lead to a similar scenario I had with the mark1.

So I did some online research into protective coatings for this area and got some interesting results,these first of all entailed the temperatures this flange area gets to.The catalyst core can reach over 1500 degrees and the manifold at exhaust port 2000 but these are extremes and normal running temperatures are lower by 20% so looking at the flanges I reckoned they would get to a thousand maximum bearing in mind air flow cooling etc.

The fahrenheit scale I have used (old school) LED me in the direction of Rust-oleum product "hard hat"which gives heat resistance to a maximum of 750 degrees Centigrade this equals around 1380 F  peak, plenty of cover for my 1000 F  estimate at the flange area.

I ordered a 500ml  spray can and applied it liberally after removing all the flaking rust with wire brush and paint scraper.

I went for a ten mile drive this morning and could smell it cooking during the trip, on my return I checked it and after it had cooled down tried to scrape off the paint it was as hard as enamel and impossible to scrape off I took these pics and it as not scorched or broken down so hopefully it will arrest the oxidation process that occurs on these flanges.

Should it require a regular reapplication of the paint that is not a problem there is enough in the can to do 3 sq metres so I suggest that this is a very economical prevention method of replacing these flanges.

 

[runsgrateasanut]

Very interesting Phil. The "y" pipe joint also gets weak I believe.  Can it be used to spray Calipers, I wonder? Sold in various colours.

[plexus914]

Please, keep us updated on that matter.

[ambermarine]

I expect to report back after the winter on how well the application  as withstood the conditions,the question on brake calipers is something that needs research but why not on a temperature basis you would have to give the brakes some continuous  wellie to achieve those parameters.

Having done further research I believe this is a ceramic aluminum compound that creates a durable coating when heated up and is probably the same compound they coat mild steel exhaust systems with when in manufacture.

[NothernDan]

This one wins the prize for the thread title most likely to appear in next months "The Viz". I can hear Finbar Saunders and his double entendre's now!