mgb281
|
| posted on 15/9/24 at 02:34 PM |
|
|
How to prep and paint an alloy (aluminium) engine block
I have googled but with no real result, I want to prep and paint a Jaguar AJV6 engine and just want to know the best way. The engine is low mileage
with no oil leaks so I don't want to dismantle it, so what it the best way to clean off the oxidation to get ready to paint? I have no desire to
blast clean it.
|
|
|
|
|
cliftyhanger
|
| posted on 15/9/24 at 05:32 PM |
|
|
Soft wire brush in a drill? Strip-it discs?
I was discusiing painting a rocker cover with a chap who has worked on high end car repairs all his life (you should see the panels he hand made o=for
his car, not to mention his paintwork)
He is going to blast the cover for me, I suggested I would spray with epoxy primer and then 2k paint. He was horrified! Suggested a wash coat of etch
primer followed by a heat resistant paint.
However, I have previously used 2k paint on iron engine blocks/heads and it seems OK after a few years, maybe ally is more difficult?
|
|
|
Ugg10
|
| posted on 15/9/24 at 06:42 PM |
|
|
Just to jump on the thread as I am in a similar position, once wire brushed and cleaned can you use hammerite?
---------------------------------------------------------------
1968 Ford Anglia 105e, 1.7 Zetec SE, Mk2 Escort Workd Cup front end, 5 link rear
Build Blog - http://Anglia1968.weebly.com
|
|
|
40inches
|
| posted on 15/9/24 at 06:52 PM |
|
|
quote:
Originally posted by Ugg10
Just to jump on the thread as I am in a similar position, once wire brushed and cleaned can you use hammerite?
Wire rotary brush and Halfords engine paint
 
Description
 
Description
 
Description
|
|
|
mgb281
|
| posted on 15/9/24 at 07:18 PM |
|
|
I have actually decided to use the VHT primer and the VHT engine enamelw, about £14 each but they are both rated upto 220c (500f)! However plenty of
people claim to have no problem with ordinary etch primer and ordinary car paint. I just don’t want to have it fail so £28 seems okay to me. Although
I said that I wouldn’t blast it clean ground walnut shell wouldn’t pose a great threat if a trace found its way into the intakes. I have just finished
blasting a MGB GT body shell to a white metal finish and that’s how you find out how the media dust penetrates everything and everywhere. Same thing
will apply to RX8 gearbox.
|
|
|
cliftyhanger
|
| posted on 15/9/24 at 07:25 PM |
|
|
Re blasting mechanicals.
A supplier was selling Triumphs diffs. Their supplier(usual stuff) was blasting the diff cases.
About 100 were done (what I heard on the grapevine)
What they had not realised is that teh mdeia was embedding itself inside the cases. And eventually releasing with the oil/heat cycles.
And yes, all those diffs destroyed themselves.
If you are going to blast mechanical stuff, use vapour blasting or walnut shell. Eveything else can destroy the component.
|
|
|
Mr Whippy
|
| posted on 16/9/24 at 07:01 AM |
|
|
As above I use to paint all my engines and simply used the wire brush on the drill and engine lacquer, seems to last a while. Doesn't serve any
purpose other than cosmetic as a rusty or oily engine is perfectly fine. I actually spray my cars whole engine bays (including the EV) with loads of
GT85 so corrosion isn't an issue anyway.
Fame is when your old car is plastered all over the internet
|
|
|
coyoteboy
|
| posted on 16/9/24 at 12:31 PM |
|
|
My experience with Alu is that no matter what you do to it, it'll corrode through or flake off and become a mess. I painted up a nice Audi V8,
prepped it with media blasting and multiple degreasings. Sprayed it with high temp matt black and it furred up and came off. Did it again, different
paint, furred up. Did the cam covers with VHT - left it in a damp garage, all gone to pot now.
|
|
|
Mr Whippy
|
| posted on 16/9/24 at 01:17 PM |
|
|
quote:
Originally posted by coyoteboy
My experience with Alu is that no matter what you do to it, it'll corrode through or flake off and become a mess. I painted up a nice Audi V8,
prepped it with media blasting and multiple degreasings. Sprayed it with high temp matt black and it furred up and came off. Did it again, different
paint, furred up. Did the cam covers with VHT - left it in a damp garage, all gone to pot now.
Yeah that's why I just use GT85 oil, it soaks in and the white fur completely vanishes. My Leafs motor bay looks like new despite being 8 years
old and their notorious for the motor & transfer box's alloy casing to go a horrid white mess as they were never coated from the factory.
Also costs about £3.50 for a big can 
My experience with VHT paint was that it is just total garbage and does not stop corrosion forming. Fine for rocket nozzles but rubbish for car
exhausts...
[Edited on 16/9/24 by Mr Whippy]
Fame is when your old car is plastered all over the internet
|
|
|
mgb281
|
| posted on 18/9/24 at 06:51 PM |
|
|
The Problem with VHT paint for exhausts is that it isn’t VHT paint at all, if you look on the can it says 500F which is only about 260C! Now for most
drivers that pootle along that 500F would be rarely if ever reached but if you drive hard with lots of revs then you can nearly reach 1000F.
Painting an aluminium engine isn’t easy because you need a high temperature etch primer, without the prime the paint won’t last. Cast iron is far more
forgiving when it comes to painting engines, back in the day every one was painted. At the moment Lidl’s have a Matt black paint capable of taking a
claimed 572F, still not high enough for an exhaust manifold.
|
|
|
40inches
|
| posted on 19/9/24 at 08:34 AM |
|
|
quote:
Originally posted by mgb281
The Problem with VHT paint for exhausts is that it isn’t VHT paint at all, if you look on the can it says 500F which is only about 260C! Now for most
drivers that pootle along that 500F would be rarely if ever reached but if you drive hard with lots of revs then you can nearly reach 1000F.
Painting an aluminium engine isn’t easy because you need a high temperature etch primer, without the prime the paint won’t last. Cast iron is far more
forgiving when it comes to painting engines, back in the day every one was painted. At the moment Lidl’s have a Matt black paint capable of taking a
claimed 572F, still not high enough for an exhaust manifold.
The Halfords Engine Paint I used 10 years ago is still there and like new. No primer, straight onto bare ally. The Satin Black is brilliant, brushes
on with no brush marks
|
|
|
