How to / DIY > Engines

Paint Removal LPW

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Robert:
I’ve broken down my engine and removed all the grey paint from the aluminium parts of my engine. I thought this was going to be the tricky part. I am now onto the iron head and block but having difficulty getting the red undercoat/primer off underneath the grey. I’m planning to paint with POR15 engine enamel. Does anybody have any suggestions to get it down to bare metal?

cobbadog:
There are many paint strippers available from liquids to gels then hit it with the gurney. I have not used POR15 before but I am aware that it is a very good product. Is it a coloured POR15 you will be using, if so the red oxide may not harm the bond. I once had success using a can of oven cleaner, again dilute with plenty of water after use.
After having a tractor wet sand blasted they put some hydrochloric acid in the rinse water to slow down the surface rust after blasting. This gave me 2 days before surface rust started.

dax021:
Was it not phosphoric acid, which is the active ingredient in most rust converters?  I use hydrochloric (pool acid) to remove surface rust, but unless neutralised with an alkaline or plenty fresh water, it starts rusting almost immediately. Just my 2c, I could be wrong.

When restoring old petrol bowsers, I would completely immerse all the cast iron bits in a strong solution of caustic soda.  Not a trace of paint or primer left behind.  Just make sure there are no non ferrous metals still attached, as it will quickly chow that up.  Again, rinse well before painting, and paint asap, as it starts to surface rust very quickly.

Robert:
I have found somewhere locally that can vapour blast it. What I would like to do is to get it vapour blasted then rebuild at my leisure - I am not the fastest worker and it may take a couple of months! But I don’t want it to be rusty when I finally paint it. Any ideas? Can I coat it with wd40? What to people do?

cobbadog:
Yes dax, you are correct, my mistake and I appologise for misleading the group.

Once the metal has been cleaned you cannot treat it with an oil or anything else as it will not allow your paint or in this case POR15 to bond to clean metal.
Read the instructions on the POR15 to see if they recommend any pretreatment undercoat/primers. Otherwise wait until your ready to do the POR15. You are aware that POR15 has a very short shelf life. Once the can is opened you are all systems go and have a couple of days at most to finish using the product as once the air gets to it the curing starts. They are sealed at the factory using a gas to stop curing.
I have seen but not used a laser blaster used for motor parts. I only last night asked a member from another Forum if he has received his and if it actually worked. Like so many things the videos make you think that this is the answer to cleaning parts up but can come back and bite you. The one in question was less than AU$50.00 plus postage so will be interesting to see how it went if at all.
If there is no information on the can of POR15 send the company an email and ask if they recommend a product but it will not be any oil base products as paint and coating do not stick to oil. If you are hindered in being able to do a full days work due to health or other reasons I would suggest that you get someone to help you complete the POR15 job in one go.

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