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Hot-tanking/heated parts washer

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So hopefully this is a good spot for this since I suppose it is for all other motors, not just Subarus...





Whats the difference between hottanking a block and putting a block in a heated parts washer?


Can you hottank/HPW a shortblock assembled or is it better to tear it down? Can you damage seals/bearings/races/pistons etc this way?


Why do I ask? Ned is slowly dying, and I need to get the other engine built, however I noticed some pine-needles in the engine on the bottom (the oil pan was removed and block was upside down, not fully covered. I have been thinking I should hottank it to get rid of the debris that COULD be in the engine further than what I see/could blow out with compressed air. However I have no intention of disassembling a short block right now.


Now part two... a reputable shop around here quoted me back with "$80 to hottank the shortblock provided it has been pre-prepped, $180 if we prep it for you" type of answer... Seems a bit steep. Then a coworker asked why I didnt have a company mechanic hottank it for free on the weekend and pointed to a big silver machine in the corner... Alladin "heated parts washer" but I dont know if those are one in the same... his best answer was it would do the same thing...


What are my options? I just want the block to be cleaner so I can start assembly and get this show on the road :D but Im a little weary of spending a bunch of money if it wont actually help.


By bunch of money I mean Im $500 into this... I realize now I should have just bought an EJ, resealed it and thrown it in there and gotten USMB assistance on wiring it all.

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I have never seen any sort of washer that was effective in cleaning an engine without dis-assembly.  Anything with a water based washing you aren't going to want to put anything with a steel part of casting into.  Cases, once torn down are ok as you can dry them immediately with compressed air but anything like a bearing or crankshaft is a huge no no.  As soon as it rusts you are in deep trouble.

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  • 1 month later...

I agree with them. Everything should be tore down before washing/hot-tanking them. Heads can be done with the valves and springs still in them, but only if you're putting them back on right away and running the engine because some moisture can still be trapped in the valve guides. I run a machine shop for 19yrs now. The caustic solution will also "blacken" the aluminum if left in too long. I usually charge $50 to "cook" a bare block, so $80 is probably right depending on your area. Besides pine needles, I'd be concerned about moisture getting into the steel areas of the engine and rusting up.

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I would recommend blowing out the block with compressed air before and after either treatment,you never know where dirt/grease might decide to sit afterwards.I had a cylinder head done for a 82 datsun and a piece of debris fell into the rearmost camshaft lubrication hole.It wasn't long before the camshaft seized and and destroyed the head.

Edited by Uberoo
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