Fan Housing Refinishing

[dommorton]

Hi,

Sorry if my 993 is too new for this forum, but I figured with all the restorative goings on here that you might be able to help me.

I've had the fan housing for my '98 C4S vapour blasted, along with a bunch of other engine and HVAC components. They have all come up lovely and shiny as new, so I would like to keep them that way if possible without them turning in to a corroded mess.

I've coated the alloy air tube, air diverters, a/c compressor and a/c pedestal, with ACF-50. This should keep them fresh for a while to come and I can top up on visible parts once installed as required to maintain the appearance.

When it comes to the fan housing however I am not so sure on the route to take. I understand the part is a magnesium alloy and with that painting can be difficult as the mag can gas and push the paint off. Also this isn't the factory finish. On all cars I have seen and as was with mine, the part is a flat grey non painted finish. Post vapour blasting, mine is now bright silver as you can see in the pic attached.

Does anyone know if any coating was used by Porsche from new? Or if you have any advice on how best to tackle the refinishing of this part keep it looking fresh please do share.

Many thanks

Dominic

[Mike]

It needs a chromate finish.

[dommorton]

Thanks for the quick reply Mike.

Do you know the process for this? I presume not something I can tackle.

[Mike]

Hi Dominic, Chromating is a chemical process whereby bare metal such as magnesium is dipped to give the raw metal a protective coating, Google it for the technical details.

For your fan housing contact your friendly local Porsche specialist restorer or engine builder, he will probably have a chromate tank or have access to one. The final colour, ranging from a mid grey to black, is dependant on the strength of the chemical mix and the time the housing is left in.

It does need looking after though, WD40 will be your friend. In the picture below that's what's giving it the sheen. Hope that helps.

[dommorton]

Great info thank you.

I’ll hunt out someone who can get it dunked for me ASAP. Love that fresh grey look.

[dean1057]

Try these guys, did my 964 fan surround and fan.
http://www.karas.co.uk/process

[dommorton]

Thanks for all the help and guidance

I’ve found a local place who specialise in Mag Alloy. http://tpcs-magnesium-refurbs.co.uk

Had a chat and will drop off the part tomorrow.

They have warned the modern Chromate process may not produce the same colouration as the old. Yet still they are confident they can achieve something I will be happy with.

They have someone else’s fan housing in at present and for that one are Chromate coating then powder coating in gun grey.

I want to avoid this so hoping the Chromate is close and then may have that clear coated to protect further.

[Nick Moss]

I carry out this service. Up until recently my plater has been using Aluchrome 1200, but due to Heath and Safety concerns now only does 600, which gives a lighter finish and is less protective.

[dommorton]

Seems a similar story here then.

He said he will finish it and send me pics. If happy he suggests I lock it in with satin clear and that will make it lower maintenance.

[dommorton]

So he Chromate coated the part post my having had it Vapour Blasted and it came out too light. He gave it a gentle media blast and tried again and it's come out a lovely darker shade of grey just as it should be.

Told him I am happy, so he is going to lock that in with some satin clear and that's me set.

Thanks for your help in leading me to the correct process.

[hot66]

Love to see a photo if you get a chance


Sent from my iPad using Tapatalk

[dommorton]

This is how manky it was before vapour blasting



Then it was the nice bright silver you see in the OP

Then it went a lovely matte grey with the Chromate, this matching pretty much with factory tone in the end.

I did then have it satin cleared though, which altered the tone a little. Was worthwhile I felt for the sake of durability and once built back up you'd hardly tell the difference.

[Flat 6]

Nice work.

I thought chromating was only the first stage of the finishing process anyway and chromated parts were supposed to be coated with a finish of your choice, I.e. Chromated parts were not expected to be left with just that finish...?