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Collection, Preservation and Display of Old Lawn Mowers

Sloper Engine Petrol Tank

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Hi Everyone.  I've been renovating a Ransomes Marquis MK4 for some time (Wristpin you'll know this as you helped me with how to dismantle it 18 months ago!) and I am closing in on reassembling it having done a bare metal respray and cleaned every nut and bolt by hand!  However, I have just realised that the inside of the petrol tank is very rusty and I certainly wouldn't want to be contaminating my sparkling carburettor with petrol from the inside of it...!  Has anyone found a good way to remove rust and debris?  Thanks.  Mowermad.

 

 

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robint Tue, 07/08/2018

Chris G has commented recently on professional internal coatings - expensive

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wristpin Wed, 08/08/2018

I use electrolysis. Other than washing soda to make up the electrolyte, no expensive chemicals and a little electricity via a battery charger. 

Mowermad Wed, 08/08/2018

OK.  Sounds good but let me clarify:

Block up where tap and pipeline attach.  Fill with solution of washing soda (normal strength?). Put a metal pipe into top of tank (I assume insulated from the tank?).  Attach battery charger positive to metal pipe and negative to edge of tank.  Switch on and leave for - an hour - more?  

Many thanks.

 

Chris G Wed, 08/08/2018

Via this process its a bit more than an hour :-)

There are some complete idiot video instructions on you tube for the electrolysis route, beware...

Hopefully WP will revert

wristpin Wed, 08/08/2018

You need to make sure that the positive electrode cannot touch the tank either at the lower end or where it passes through the neck of the tank. It will need rather longer than an hour. I will leave a bad tank “ cooking” for a week taking the electrode out daily and cleaning it back to bright metal . The field of vision of the electrodes is more or less “ line of sight” so as well as the straight electrodes I use L shaped ones to reach the “ roof” of the tanks.

NM Thu, 09/08/2018

I’ve experimented with a couple of lengths of box section and a bucket of crystals but have question. Are crystals supposed to completely dissolve because about three hours after stirring crystals seem to have settled at bottom of bucket. Is this not enough currant or amps or something else. 

After treatment what’s the best coating for the tank interior.

Thanks Nick

Mowermad Thu, 09/08/2018

I'll leave that one to the experts!  I'll check mine out tomorrow to see if all has dissolved and that I'm making progress.  Will report back.

Mowermad

wristpin Thu, 09/08/2018

Never had an issue with non - dissolving crystals. If you are only making up enough for doing the tank, a couple of big spoonfuls in hot water and they should all dissolve. I've got a 205-litre drum that I made up three years ago and I just dunk the small tanks to fill them and then set them up in a similar manner to yours.

I don't bother with any subsequent protective coating. I either keep them full to the brim or bone dry. In both cases with the tank cap vent hole sealed.

Chris G Thu, 09/08/2018

Would not get too worried about a coating after this process either, it is fairly gentle compared to aggressive chemical stripping which will flash rust and need sealing - horses for courses... its a mower tank and should be fine if you keep an eye on it now and again.