Radiator sides aluminium corrosion

[A44rider]

My 1300 is 2004 vintage, low miles, and with the plastic off for coolant change etc seems in good nic for its age. However the radiator sides black paint is long gone. I am tempted to leave it as it is, white powdery covering included, rather than clean, rub down and paint , as I have always understood that aluminium cools best without being polished or painted, and if cleaned up will simply corrode again in time.
I do not intend to ride on salt covered roads, so does the team think that leave well alone is reasonable?
Many thanks in advance for your thoughts.

 

[paulcb]

If it were mine, I'd leave it alone. My radiator has some missing paint spots as well, I suspect they all do. Even if it leaks, it's not a catastrophic failure.

 

[CYYJ]

I am tempted to leave it as it is, white powdery covering [coating?] included...

Although I don't think that "missing paint" is a problem, if you have a white powder on aluminum, that's corrosion. I suggest you clean it off and repaint the sides, because the white powder will retain moisture and that will encourage more corrosion.

So far as paint interfering with heat dissipation, I think whatever effect there might be is negligible. There's a heck of a lot of airflow over all parts of the radiator when you are using the motorcycle.

To successfully paint aluminum, you need to really clean the surface well. If you have corrosion (white powder) on the surface, you will need to sand the surface to get rid of that corrosion. You don't need to be overly aggressive and dig into the bare metal, but you do need to get rid of the corrosion or it will continue to corrode underneath the paint. Once you have sanded to bare (bright) metal, wash the surface thoroughly with detergent, rinse well, and allow to air dry overnight. Then wipe the surface down with alcohol prior to applying the paint.

Michael

 

[A44rider]

Thanks for your thoughts. Powder corrosion holding moisture is a good point, so wire wool and a thin protective coat of paint it is!

 

[Oldbikefixr]

Rust never sleeps. It's always best to remove it and refinish the part.

 

[jfheath]

My first 1100 had this issue. Cleaned off (as Michael described) and having nothing better, I painted it with some heat reistant metal paint - a Hammerite product designed for 600 degrees C outdoor stoves. It worked very well and stayed put for all the time I had the bike riding.

 

[CYYJ]

Powder corrosion holding moisture is a good point, so wire wool and a thin protective coat of paint it is!

Uh, do some research first before using steel wool on an aluminum part. Although I don't know "for sure", I believe you might be setting yourself up for a different kind of problem (electrolytic corrosion) that will arise from tiny particles of the steel wool left behind in the aluminum.

Aluminum is a less noble metal than steel. If any moisture gets below the paint - perhaps from a paint chip - you now have a 'battery', and particles of the least noble metal (aluminum) will be drawn to the more noble metal (steel). The aluminum will then pit and you are right back to where you are today with the exfoliation corrosion. This kind of electrolytic corrosion is of great concern in a saline environment (e.g. the UK) - it might be less of a problem in the Sahara desert.

I suggest you only use non-metallic abrasives such as a 3M ScotchBrite Pad to remove the existing exfoliation corrosion from the sides of the aluminum radiator.

Michael

 

[rwthomas1]

I'd coat it with CorrosionX, Fluid Film, NH Oil Undercoating, Boeshield, etc. or some similar product that stops corrosion and be done with it. Can't see it, it's behind tupperware, stop the problem and go ride. RT

 

[SMSW]

If you use a fine sandpaper you should be ok. The most common sandpaper is aluminum oxide - very hard grains and you can get it in a number of grades. I'd try a 180 or 220 grit to start with. The higher the number the finer the grit. Many years ago, a high school shop teacher taught us to take the sandpaper and with the grit side up, run it over the edge of a table/workbench, bending it sharply as you pull it across the edge. This breaks up the glue and makes the paper more flexible to get into nooks and crannies. Spin the paper 90 deg and do it again. If I'm working on my lathe, and want maximum flex, I will also do this on the diagonal.

 

[A44rider]

Thank for all comments. Suitable abrasive and paint will be suitably applied.