Av8ferg

L28 full rebuild assembly

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    The Purple Power is bad a$$ stuff. Finally all the pistons are totally clean, and all look immaculate. Got my scale and started weighing each whole assembly minus the rings and bearings. The lowest is 1273.6g and the heaviest is 1279.3g (off of memory). All the others are between those. I’ll post the weights when I get back to the garage later tonight. I also weighed the rod ends alone (without bolts). It appears Nissan has already tried to match the lighter rods with heavier ends. Average rod end is around 173.3g. One is 179.2 grams and it’s already on the lightest assembly. The bottom line is I have a 5g delta between my heaviest and lightest assembly. That is equivalent to 2 pennies. Not sure is the worth trying to match them up. It’s a stock motor and it was good enough for Nissan.


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    It might be minimally smoother if you do, but if you are not pushing the boundaries, I suspect you wont be able to tell the difference

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    I just looked up the SDS for Purple Power, and the main cleaning agent is sodium hydroxide (lye) which can be an issue for damaging aluminum. Looks like a quick ten minute spray and rinse is OK, but I wouldn't dunk the pistons in it and leave them overnight.

    1. Sodium Hydroxide 25%
    Concentration 3 - 4 % (weight)
    CAS no. 1310-73-2

    2. Chelating Agent
    Concentration 1 - 2 % (weight)
    CAS no. 67401-50-7

    3. Diethylene Glycol Monobutyl ether
    Concentration 1 - 2 % (weight)
    CAS no. 112-34-5

    Notes - I looked up the chelating agent and it's Ethylenediaminetetraacetic acid (EDTA) and the last item is an organic solvent (2-(2-Butoxyethoxy)ethanol.

    Reference - https://f405ae25-bd48-4e9f-92a9-0f03256f19bb.filesusr.com/ugd/14ad0e_342940d078d94505b11d1358c997718c.pdf

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    Interesting. Thanks for looking that up. I blasted the assemblies with carb cleaner after to remove all the purple power so hopefully that’s sufficient to purge it all.


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    I use Super Clean (formerly Castrol Super Clean), which I believe is similar to Purple Power, but with sodium metasilicate and sodium hydroxide.  I get it by the gallon at Walmart on a regular basis.  I do know from experience it is quite alkaline, and will eat your skin at full concentration.  I've used it to clean aluminum without ill effect, even when soaked for a day or more.  But it usually doesn't take that long to be effective, especially if it's warm.  If I'm remembering my college chemistry correctly, the key is to fully immerse the part.  If you dip it and leave it exposed to atmospheric oxygen, it can oxidize the aluminum if not rinsed off.

    Incidentally, it is fantastic for stripping paint from plastic parts without damaging the plastic.  Don't try that with regular paint stripper (methylene chloride)!

    Edited by the_tool_man
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    7 hours ago, Captain Obvious said:

    I just looked up the SDS for Purple Power, and the main cleaning agent is sodium hydroxide (lye)

    I stopped buying Purple Power and just buy this for $8.00, can probably make 4 gals with it. Should be at most hardware stores or pool supplies places.

     

    Screenshot_2019-12-11 Home 500g Pure Lye Crystals Cleaner Home Hardware.png

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    10 minutes ago, grannyknot said:

    I stopped buying Purple Power and just buy this for $8.00, can probably make 4 gals with it. Should be at most hardware stores or pool supplies places.

     

     

    You lye you lyer!

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    So, I measured my ring gaps yesterday and they are a little bigger than the FSM published. Book recommends .0098 to .0157 with a wear limit of .0394. The How to Rebuild books recommends .012 to .017. These are for the compression ring. See pics of pages in pubs.
    My ring gap at the top, 3/4” down the bore was .019 on two rings and .018 on the rest. I the grabbed my old rings to see where they were. .021 to .022.
    So my ring gap is bigger than the FSM and rebuild book. Is this a concern? I think no, but I thought I get a consensus.
    Questions:
    1. Is my Ring gap okay?
    2. the rebuild book says to look for a “pip” or dot marking on the ring and make sure it’s facing up. I don’t have a dot but have and “S” on mine. I’m assuming this is a “pip” Mark. Even the instruction that came with the stock Nissan standard rings mention a dot mark but it’s not on the rings. See pics.
    3. Back to crankshaft bearings. When reading the FSM last night about ring install I saw this paragraph about crank bearings. It says bearing #4 is different (plainly obvious, it’s flanged) and all the rest are the same and then the next sentence says 1 and 7 are the same. Are they same as 2,3,5,6 too? I did notice that when I installed my bearings #1 seemed a more little narrow compared to the flange it lays in. I’m wondering if I mixed up #1 with another 2,3,5 or 6 bearing.
    e51ecbe6136b9a10d8c5e5e7a23bbc99.jpg1e32fbffdeb63ffe799e28a6c7d140aa.jpg70417b4e1e735eb31d6696bc870d3b10.jpgb323ee16c428cfc580cdd15052d175cc.jpgea3f3490b189167899a691e562624616.jpg


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    I took a look at the FSM to refresh my memory, and the ring gap should be measured at the bottom of the bore where the wear is the least (77 manual EM-15 bottom left). Makes sense since what you really don't want to have happen is for that gap to close up to zero when things heat up.

    You're a couple thousandths smaller gap at the bottom of the bores, right?  I'm no engine rebuild expert, but I think you're fine.

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    Whose rings are you running? What is their recommendation for the ring gaps? The FSM and rebuild book are based on older materials. Some of the newer ring alloys might require a different standard?

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    Did you hone the block or bore it? I don't remember. CO's recommendation on measuring at the bottom of the bore might help. Are the bores with in spec? You really need a bore mic to check this. If the bores are with in spec then I would probably move forward.

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    My perfect circle rings came out with bigger gaps also - maybe because the cylinders were honed . I think your gaps would be okay . No where near wear limits . I would think ANY markings would identify top. Usually packages also identify rings by any type bevel or taper cut into the ring .

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