Naval jelly to remove slight rust on cylinder walls?

Discussion in 'General Tech' started by IdahoDoug, Jun 13, 2018.

  1. IdahoDoug


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    Aug 9, 2003
    Restoring a 1988 Supra Targa 5 speed with my son. Has not run for 18 years. Beautiful car, terrific big straight 6. Two cylinders have condensation-caused rust spots on the cylinder walls. They must have been the unlucky ones with open valves. At the rings, there is also a slight line of rust.

    I would like to remove the rust best I can, then we will hone the cylinder walls with a ball hone and re-ring this low mile engine. If I don't remove the rust first, I don't think the ball hone I bought will work like the traditional actual hone stones, which would knock down a high spot better. The ball hone is more "flexy" and I'd be afraid it would not place higher pressure on a high spot, thus leaving possible remains of a high spot.

    I've got a piece of right diameter PVC I was going to gently work these problem areas with before honing, using some mild abrasive. However I got to wondering if Naval Jelly would dissolve it and physically remove the substance that is mildly proud on the cylinder walls (the rust).

    Anyone have experience - does it truly chemically dissolve the red rust deposits and based on your experience with it, would this be a good move? It will be a bare block, so no pistons and I can easily clean any residue.

    Thanks in advance.
  2. badlander


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    Sep 2, 2010
    Sarasota, Florida
    I've used naval jelly many times and although it has its place, for your purpose I think I would just go ahead and clean it up with 400 or 600 wet/dry paper depending on the condition. Use kerosene or any light oil as a lubricant to help keep the paper from clogging. Hone after cleaning up. Naval jelly is pretty weak stuff as far as rust disolvers go. If it is just a dusting of light surface rust it is pretty effective but any crusty stuff and you would be wasting your time.
  3. thabruiser


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    Feb 7, 2017
    Cookeville, TN
    I've used PB blaster, and Seafoam's Deep Creep (sp?) for that purpose (mini cooper with blown headgasket that sat for a year with coolant in cylinders). Or any rust penetrant you have on your shelf. It'll dissolve the rust pretty good, plus it's got your lubricant in it too. just spray liberally, use a brillo pad (what I did) to break it up, spray some more. More than likely you'll have a little etching or impression left because the rust has actually eaten away a piece of the cylinder wall. At least in my experience this was the case. But I found that compression and oil consumption did not suffer. Just hone the best you can, and let 'er ride.
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