Jump to content

Radiator Paint flaking off


Newoldbiker

Recommended Posts

Newoldbiker

Just cleaned my bike prior to a ride tomorrow and noticed that on the left side of the bike, just above the rubber hose exit, the paint has flaked off the metal on the radiator.  It also seems it's made of aluminium as a magnet didn't want stick to it.  How to repair or do I just leave it?

 

Thanks

Link to post
trisaki

Heat resistant paint will be the answer 

  • Like 2
Link to post
embee

Trisaki is correct of course, however in practice I find most decent make aerosols will cope OK with the 100C that a radiator gets to. The usual problem with aluminium parts is the ineffective priming of the bare metal.

 

If you rub the paint back to bare aluminium you really need to use an etch primer to get it to take. Aluminium forms a thin oxide layer very quickly in air, and it needs a paint which will attach successfully to this layer, which most regular top-coat paints won't, and will flake off again. I usually get automotive aerosols (satin black, silver etc for general use) from Eurocarparts (they always have a discount offer going, check what it is on the home page), for example this https://www.eurocarparts.com/ecp/p/car-accessories/paints-and-primers/car-maintenance-accessories/primers/?553998640&0&cc5_143 which with the discount code at the moment works out at £8-70 a tin. Halfords also do similar products.

A regular satin black over the top of a grey primer will work in my experience. If you do want a heat resistant paint, try an engine enamel like https://www.eurocarparts.com/ecp/p/car-accessories/car-maintenance-accessories/paints-and-primers/engine-paint/?553998710&0&cc5_162

  • Like 2
Link to post
sullspots
18 hours ago, embee said:

Trisaki is correct of course, however in practice I find most decent make aerosols will cope OK with the 100C that a radiator gets to. The usual problem with aluminium parts is the ineffective priming of the bare metal.

 

If you rub the paint back to bare aluminium you really need to use an etch primer to get it to take. Aluminium forms a thin oxide layer very quickly in air, and it needs a paint which will attach successfully to this layer, which most regular top-coat paints won't, and will flake off again. I usually get automotive aerosols (satin black, silver etc for general use) from Eurocarparts (they always have a discount offer going, check what it is on the home page), for example this https://www.eurocarparts.com/ecp/p/car-accessories/paints-and-primers/car-maintenance-accessories/primers/?553998640&0&cc5_143 which with the discount code at the moment works out at £8-70 a tin. Halfords also do similar products.

A regular satin black over the top of a grey primer will work in my experience. If you do want a heat resistant paint, try an engine enamel like https://www.eurocarparts.com/ecp/p/car-accessories/car-maintenance-accessories/paints-and-primers/engine-paint/?553998710&0&cc5_162

 

The Simonez is less expensive here...https://www.carparts4less.co.uk/cp4l/c/Volkswagen_Golf_2.0_2006/p/-/-/-/-/?553998640&0&cc5_143

 

The paint on my radiator has gone too so I’ll be looking at some of this next time the radiator is off,let’s know how you get on.

 

 

Edited by sullspots
Correction
  • Like 2
Link to post

did my'n last november-- 3 coats upol primer and some high temp gloss black

 

  • Like 2
Link to post
Trumpet

Ahh. Honda Radiators. My 1994 CB500 lost its radiator paint. My 2010 CBF500 lost its Radiator paint in a similar postion .. My 1000 mile old 2016 VFR1200F had lost a bit of paint along the bottom, Expecting my 2017 NC750x to do the same !

Edited by Trumpet
Link to post
listener

I recently replaced my NC750X DCT (2015) with ... another NC750X DCT (2018). Prior to that I had a manual NC700X.

 

Both the 700 and 750 suffered from radiator 'skin flake'.

In both cases, the right 'cheek' (as you sit on the bike) was a wee bit scabby, while the left 'cheek' was missing a big chunk of paint.

 

 

I can't remember suffering the same issue with previous bikes, so it must be due to the NC's 'built down to a price' nature. :(

  • Like 2
Link to post
Guest shammy411

Hi there, I have the 2012 DCT Version 700 and mine is exactly the same on the left hand side just above the hose. I too have some etched primer which i will be using through a spray gun, and the will be trying a standard black gloss. Suppose while i have the radiator off, i may as well check the valve clearances and change the coolant.:ahappy:

Link to post
  • 2 weeks later...

I noticed the same on my 2012 NC700X. First there were what looked like a few bubbles under the paint and at some point later the paint just would flake off. I was offered to have the radiator power flushed and cleaned,  tanks and sides shot blast and repaint for between £75 and £95 plus VAT from "www.radiator-repair.co.uk" with a 2 day turn-around in their workshop plus shipping to/from. They advised not to use any primer on any radiator as it impacts the heat exchange!

 

Unfortunately decided to go for a cheaper option from a guy around the corner and paid £40 plus VAT for a valuable lesson in "what not to do / never to do again" (The finished radiator looked like a 5 year old had painted it as part of a pre-school project and the paint started to flake off again about 2 weeks after the job was done).

 

Anyway, in the build up servicing the bike myself (and whilst waiting for the radiator to be returned) I manufactured my own radiator guard to prevent any further damage. I'll service the bike again in September this year and look forward to what the radiator looks like when I take the guard off.

 

 

Link to post
embee

I wouldn't worry so much about heat rejection as long as you don't pile a thick layer on it. You only need a light covering of etch primer on bare metal, it's just to provide something which attaches successfully to the aluminium and which the paint can then attach to. As you find out, if you don't use a suitable etch primer for alum then a normal top coat will simply flake off, it doesn't attach to the oxide layer. A thin layer of paint isn't a particularly good insulator, particularly in a forced convection situation like an auto radiator (the word "radiator" is misleading in reality, it's principally a convector not a radiator)

You won't get aerosol down into the fins anyway.

It seems to usually be the end tanks which suffer most, and these are the cosmetically obvious parts. Heat rejection from the tanks themselves is minimal.

  • Like 2
  • Thanks 1
Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...