Painting DP-G out-drives - back to bare metal - NOT ANTIFOULING

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Hi all,
Another winter job this year is to strip the engines back to bare metal and re-paint.

I am on fresh water - so no antifoul! Every year we just scour pad the out-drives and they come up clean. However, out-drives were previously anti-fouled and they just look terrible now.

So.....
Sand back to bare metal
Prime - Etch primer I presume? Or is there a better primer for under-water? (2 costs should be fine)
Light hand-sand to smooth things off

Main question.... FINAL COAT. I love the OE Volvo grey. Can anyone offer advise here? Single back? 2 pack? Gloss? Brand? etc. etc.....

I have a 200l compressor and equipment so will be spraying, not painting.

Thanks all
 
I would ring sms paint coatings who deal with jotun paints.. they are very helpfull and know their stuff..
 
I can give advice. Unless you are back to bare metal over most of the drive dont do it. Put a barrier / tie coat on and repaint. Dont ask me what it is about the alloy of the Volvo outdrives or what etch primer and paint they used but I have spent 5 years redoing mine and I even had them professionally blasted, filled and repainted for quite a considerable sum and that job only lasted 3 months before you could wipe it off with your hands. I have this year given up on painting them and have put on polyurethane epoxy resin enamel (gelcoat basically) to 5 mm if not to adhere to it to at least seal it and the results of that are by no means certain either. I've never seen the like of it and I have painted aluminium successfully many times alongside Mercruiser legs and outboards. I'm sure some one will be along soon to say they did it just fine. There's always one or two. But it's not my experience on either of my outdrives and one is a replacement to boot
 
We understand that, but which one? I have done many motorcycle engines in my restoration hobby, as well as my previous mercruiser legs but this one defies me. It's almost as if the alloy becomes saturated with oil or something. Paint dries and without corrosion simply looses adhesion after a couple months once fully cured even if the etch primer is still on and stained the alloy yellow. The only other thing that's changed is the Volvo's have always been done in winter in sub optimal temps. This year I had 3 heaters running in the garage to try and keep temps above 10C
 
Hi,
I think that its Chromate Etch Primer (green) is what you need, but that is not for sale to mere mortals in the UK because of its toxicity?
The 2 part Etch Primer you hand paint is much better. I have used that followed by 2 part epoxy primer like Interprotect; (even used some left over Gel-Shield!) Followed by a tie coat (primocon or antifouling) before the epoxy primer has cured. That can usually last for (up to) 2 to 3 Bellows Change with only minor touching up.
I have not had a lot of success with the rattle can etch primers...
I am no expert though ... maybe someone will suggest a better resolution!!
 
N
I have used Cromadex 700 series paint previously. It's a 2 pack epoxy chemical resistant paint (used in acid resistant tanks)
I found that it was the only paint that would stick to duoprop propellors.... if it'll stick to them it'll stick to the outdrive casing.
used with abraded and well cleaned ally and etch primer. it ends up being similar to a plastic coating. Can be sprayed but make sure that there is a generous film thickness.
It's a bugga to try to sand off afterwards.
 
Thanks for all the info.

The original paint is still there, it's just been antifouled over. There is 1 or 2 very small bare bits on the skeg, but that's it.

For prep, is the general consensus to NOT sand back to bare metal? Or to sand back to bare metal and use a chrome primer (green - i've seen this on Youtube).

Regarding topcoat, i'm still none the wiser!
 
I would not sand back to bare metal, unless most of the original paint is missing - it's really hard to get a good bond to the aluminium.
 
Hi Bruce .Its a can of worms ....literally if see what happens doing it wrong .
“Chromate “ Is the process and paint .Its to do with gas coming out of the magnesium castings .
They will have Mg in them in alloy form of course .Patchy results ...which is where you are I believe?

Alodine works better see here .

Aluminum / Magnesium Wheel Restoration


710B17FF-0E36-4AE8-B675-944777F93481.jpeg
conventionally refurbed ....see what I mean by a can of “worms “

182BE007-C832-42DA-95A1-72DB0151B7A5.jpeg
Alodined ^^^
 
As Porto says "its a can of worms" and you need the type of material you are priming to get the correct etch primer and usually this is in the manufacturers technical sections; once armed with this data you the correct etch primer by looking at manufacturers data sheets and finding what they do in their range.

Many people assume that any aluminium etch primer will do when it won't.
 
So what is the Volvo leg alloy and what is the correct primer. I looked up Alodine and it's a brand of chromate by Henkel from what I can tell. I know these drives get repainted by the refurbers CR, IVSS etc but I've gone the chromate route and where as that seemed to stick the paint certainly didn't
 
When I rub down the paint and get the odd bare metal patch come through, I just paint with hempel underwater primer, it hasn't come off when I come to repaint antifouling again 12months later.
 
Truthfully the odd bit was fine for me too. I have terrible barnacle issues and they seen to start off a sort of crevice erosion so I took mine back to bare metal, filled and painted. And have had issues ever since with adhesion that has left me having to repaint them each year as a maintenance task. As above this year I effectively gelcoated them over a soft ali primer in the hope it's the last time. We shall see.

after 1 season after having them done professionally in exasperation for £1300 for the paint job. To say I was disappointed is an understatement

btcO77s.jpg


enamel epoxy resined this year

AKsGDog.jpg
 
They did look good so can understand your frustration, I would feel the same after all that effort and cost. I was thinking after many years of paint layers, stripping back mine but after reading this thread, think I stick to rub down and repaint.
 
An interesting thread! I'm now in limbo as whether to go back to bare metal or just rub down.... decisions!!
 
Probably a very stupid question but here goes. Would Hammerite smooth take on the legs then prime and AF on top? Also on the ali props as I've yet to see a lasting prop AF.
 
They sell the paint but I've never seen the primer. Care to point that one out?

edit. If you are referring to Primer 1141562 I dont believe that is an etch primer. Rather a tie coat
 
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