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MG Midget and Sprite Technical - Preventing corrosion on aluminium?

My new water pump has been on for about 8 months. When I took the radiator out the other day I was disappointed to see that the pump's aluminium casting has already started to corrode. I had already wiped some of the corrosion off when I took the photo.

I don't want to paint the pump as I rather like the bare metal look but I would like to preserve it.

Does anyone have any suggestions as to what I should do?

One option would be to clean off the corrosion that's there and spray with WD40 but this would probably only work as a temporary measure and would also attract muck. Would laquer work or is there something else out there that would do the job?

I know that the whole engine could really do with a coat of paint but that's not going to happen until I have to take it out some time in the future.

Any suggestions or comments gratefully received.

Colin


Colin Mee

In my opinion WD40 is very over-rated and doesn't do a very good job of corrosion protection. I have read good reports of LPS products but haven't used them my self. Personally I find Duckoil very good and use it on my own kit for corrosion protection and it seems to stand up well and give good protection. I buy it in the 5 Litre fluid containers and it lasts for years but also available in aerosols. I mentioned it to a guy I know recently and he is a convert from WD40.
David Billington

If you can get it really clean you can preserve the bare metal look with several coats of RS circuit board spray lacquer. It is a good heat-tolerant coating.
Greybeard

I find this is very good - use it for lots of applications.

I find their cavity wax and de-rusters good as well.

http://www.bilthamber.com/lubrication/ferrosol
richard boobier

I have acquired a jar of Poorboy's wheel sealer to prevent the alloy wheels on my other car from corroding. It is an American product, if it is as good as it is claimed to be it should protect under bonnet aluminium. Anybody had long term experience with it?
L Langley

Hi Colin,

I've just (almost) finished overhauling my wiper motor and after cleaning, then soda blasting the housings I've applied a couple of light coats of Halfords heavy duty lacquer, supposedly for alloy wheels. No idea about longevity at this point but wanted to give the finish some protection.
I'm working on the premise that alloys can get hellovahot in certain circumstances. Like Graybeards idea of the circuit board lacquer though.
a reid

Hi I have used Halford's HD lacquer on the master cylinder when I fitted a new one to stop it looking grotty. Even the odd spill of brake fluid has not affected it
Bob Beaumont

Excellent Bob thats my next port of call - the master cylinder is just out the electrolysis bucket and looking pitted but shiny - lacquer next!
a reid

Colin

The corrosion on the aluminium may be due to electrolytic action (different metals together causing one of the metals to oxidise quicker, also with oxigenated water in contact) - the thermostat housing can go dusty then crumbly too with aluminium oxides.

Lacquer can help, but there is a certain inevitability about this.

I think of the water pump and thermostat housing as sacrificial aluminium parts to protect the steel and iron parts of the engine, which you have to replace/remove eventually for other service reasons too (u/s water pump or thermostat).

Thanks
Mike

PS how did the hillclimb season go and what mods for 2016?
M Wood

Thanks for all the suggestions. I'm trying the PCB lacquer route first. Three coats and it still looks the way I want it, like bare metal and not glazed and shiny.

Mike - interesting comment about the electrolytic action, although this lot is all external. I wonder if there's any significance in the corrosion being on the out-flow side of things. I had to replace the previous pump because the outlet had all but disappeared due to corrosion.

As an aside, when I re-filled the system following its flushing and cleaning out in the spring I used distilled water with the last of my Bluecol (living in a damp cottage and needing to run a de-humidifier has some benefits!). When I drained the system this time the water was perfectly clear with only a few particles and just a bit of brown sludgy stuff at the bottom of the (new)radiator. Is distilled water less inclined to promote corrosion?

As for the hill-climbing, the target for the year was 75 seconds at Loton Park. My son managed 76.23 with me 3/10 behind at the first event and I spent the rest of the season trying to match him! Fortunately he didn't improve on his time and I finally got to just 3/100 behind him on my last run of the year (with a loose, rattling fan, hence the current work in progress). If I hadn't knocked it out of gear at the third corner I might have managed a 75!: http://youtu.be/OPT0jUpQEe0

Not much on the list for the winter, just sort the fan and get rid of a bad dent in the exhaust down-pipe (not my fault - there when I bought it!) I hope that will improve the breathing - along with the K&N filters that I'm hoping Santa might bring! With a bit of luck we might get into the 75s next year and finally manage to break the national speed limit through the speed trap - 59mph on the last outing was the best so far.
Colin Mee

That's a good comment Mike, with the proviso that it isn't electrolytic corrosion. That requires a current to be present from an external supply. Technically what you're describing is a galvanic cell, i.e. galvanic corrosion, which generates current like a battery.

Sorry to be pedantic.

Part of the trouble is that the antifreeze additives needed to protect alloy are different to those to protect the iron components. So the further apart on te galvanic scale the metal parts are the more one or the other suffers.

Externally it shouldn't make too much difference to Colin's pump. But the lacquer should help to preserve the appearance.

I use Caterpillar's proprietary coolant CAT ELC which is formulated to provide long term corrosion protection to CAT diesels, built mainly of CI, but with lots of cast alloy ancilliaries. Partly because it seems to work well - my coolant always looks clean - but also because I get it for free :-)
Greybeard

>>Is distilled water less inclined to promote corrosion<<

In a word Yes.

Hoard it jealously!!
Greybeard

THREAD DRIFT ALERT! (Living in a damp cottage and needing to run a de-humidifier has some advantages!) Colin, I also live in a damp old house and have been thinking about a de-humidifier for a while. Are they expensive to run, seeing as how it would need to be on all the time, and how effective are they?

Apologies for the drift.
Bernie Higginson

Dehumidifiers are pretty cheap to run, I use one to dry the washing and had it in a damp old cottage at one point.
While the thread is drifting a bit, I use the distilled water produced for various parts of the aluminium anodising process. I use anodising for all sorts of parts, unfortunately you can't anodise a water pump without disassembly which as far as I'm aware isn't possible.

My Minispares type window winders on the Mk IV are next on the anodise list as they've corroded. Electricity, acid, chemicals, it's great fun...
P Simpson

This thread was discussed between 01/11/2015 and 06/11/2015

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