Piston Install: WD40 not Oil on Rings

Engine, Transmission & Driveline

  1. 1970FuryConv

    1970FuryConv Senior Member FCBO Gold Member

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    Instruction video on 440 assembly:



    · He sprayed WD-40 on pistons and rings. He does not recommend using engine oil on the rings, because the rings need to seat against the honing pattern in the cylinder bore. Oil can cause glazing.

    I have always used oil on the rings during install. Has anyone else heard of using WD40 not oil?

    · He says that rings rotate as the engine moves, so it doesn’t matter where the gap is when you initially install them in cylinder bore. However, in relation to each other, compression ring gaps should be 180° apart. The gaps should also be 90° apart from the oil ring and gaps. Thus, the gaps will form an X pattern.

    Do rings really rotate as the engine moves, but keep the same position relative to each other?

    What do you think on these 2 questions? thanks, Ben
     
  2. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    Rings are installed 180 degrees apart to minimize compression leaks, rings do not move around the piston when the engine is running otherwise they would eventually cut the top of the piston off or reduce the diameter of the ring to the point it would break. Rings create a wear pattern on the cylinder wall which will be maintained for the life of the engine.

    WD is a solvent, it is a piss poor lubricant. In any case it would be washed off by circulating engine oil almost immediately, so as a break in aid it probably would not help much. Properly fitted, modern rings will seat them selves without any help.

    Dave
     
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  3. max1196

    max1196 Member

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    At the 7 1/2 minute mark he makes a reference to a miss packaged set of rings for a small ford. NO if there was a ring in the kit for a oversized bore there would have been an end-gap overlap issue, not a extra .030 extra end gap like he said.
    As for his block deck surface prep it sucks! dowels were not removed and turds remain around them.
    Rings do not rotate. they may move slightly from the as installed location but they do not rotate.
    He uses the term don't use thick oil on the piston, He's right there, not assembly grease, but also I wouldn't ever use WD-40.
    Anyway that was a waste of 41 minutes for me.
     
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  4. 70bigblockdodge

    70bigblockdodge Old Man with a Hat FCBO Gold Member

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    Use regular oil.

    Wd 40 is a can of stuff you buy to leave on the shelf so your wife can lube some hinges on a cabinet door, or some such thing.
     
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  5. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    From everything I've read on the subject tells me that rings do rotate in the pistons and as I understand it, they rotate slower under load.

    That makes sense to me.

    I do stagger the ring gaps on assembly though. I don't make a big deal about it when I do.

    I use engine oil, old school method of dunking the piston to make sure it's lubricated. Every engine builder I know uses engine oil for this, although maybe not dipping the piston.

    IMHO, using WD40 is about the same as installing the rings dry.
     
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  6. 3C's & a D?

    3C's & a D? Senior Member

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    I'm no pro, but in theory, most, if not all, but a film, would have leaked down by the time the engine was assembled and installed. I know of some who do use a "heavy" stp style oil for piston rings, and bearing surfaces.
     
  7. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    Some ring migration is built into the design by way of the rocking of the piston and the interface of the cross hatch pattern put on to the cylinder bores. Different cross hatch patterns engage the rings at different angles and speed up or slow down the migration process. Some migration is desirable to spread the wear pattern. That having been said, this process needs to be carefully controlled or fast excessive wear of the ring grooves and the rings themselves will result. When I think of ring rotation, I think of rings that are rotating too freely, either because of a mismatched cross hatch pattern or rings with excessive end play. That never ends well.

    Dave
     
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  8. Gerald Morris

    Gerald Morris Well-Known Member

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    WD40 is a bottom end solvent and moisture displacer, NOT a lubricant! I really wouldn't recommend it for installing a piston, or any other part of an engine being rebuilt, save as a light duty solvent and water chaser.
     
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  9. max1196

    max1196 Member

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    Here's an example. This was built somewhere else, now is at my shop, It has 6 hours of running time on it and has a cam failure. What the picture shows is the blow-by past the top ring leaving the sooted stain, if the ring was "rotating" the width of this soot pattern would not have been just a narrow streak like it is. The blow by is caused by other factors of the build not being correct.
    100_2582.JPG
     
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  10. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    I think we have to define "rotation". The rings do move around a bit, different materials expanding at different rates and allowing for cylinder taper and out of round.

    Cross hatch has to make a difference, I'm sure.

    From what I've read, we are talking about a very very slow rotation of the rings. It probably can be better described, as you said, " migration".

    But you know, we've all seen engines put together with crescent wrenches in a sand box that still run.
     
    Last edited: Feb 4, 2020
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  11. 68 4spd Fury

    68 4spd Fury Well-Known Member

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    I don't why you'd want to try and improve on a method that's been used forever and something that doesn't need improving anyway.
     
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  12. commando1

    commando1 Old Man Wearing a Hat on the Porch FCBO Gold Member

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    Who dafug came up that brilliant claim. And from where? And it spreads on the internet. [​IMG]
     
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  13. MEV

    MEV Active Member

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    I always use ATF. Never had a problem.
     
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  14. stubs300

    stubs300 Senior Member

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    This I would like to see happen which it never would! The ring groove is cut deeper then the ring, the ring is shaped different and has a spring loaded action within and against the cylinder wall which would further restrict the ring from spinning within the cylinder. Why do you think you need a ring compressor upon installation? Where do you people dream up some of these ideas? Y'all need to lay of the cheeba.
     
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  15. 70bigblockdodge

    70bigblockdodge Old Man with a Hat FCBO Gold Member

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    Well, let's see.
    Oil causes a film. Yes that is it's job, viscosity is resistance to flow, meaning it doesn't just drop off the parts like water. Wd40 has about the same viscosity as water so putting the pistons in dry would be about the same, unless you hurried assembly and got it on a run stand or Dyno before the WD40 evaporated. Who thinks any of that is a good idea?
    The crosshatch hone or glaze breaking for us reringers is to have a "rough surface for the new rings to wear against and seat with together as a matched set. The oil also helps to seal by sticking to the walls and in the ring lands. We have all beared witness to trying to pull a wet, full, garbage bag out of a can, same idea of the oil on piston rings and cylinder walls.
    ZDDP also comes into play here. It forms a protective wearing surface across microscopic irregularities in the metals. Old engines with their gaint 5/64 rings have a lot of this surface and still wear out.
    If he is talking glazed from burning or overheated oil. Well, come on everyone should be able to see the problem that should not occur if done properly with good oil.
    Rings move! If not that soot will build up in the lands and stick the ring completely losing the seal or seizing it. Oh wait, looks like it did.
     
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  16. Demonic

    Demonic New Member

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    But it was on the internet. It must be true. :rolleyes: Have to sift through the b.s. and wannabe's some days.
     
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  17. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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  18. 440sportfury

    440sportfury Active Member

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    Funny thing a neighbor of mine who was an old German machinist specifically told me do not use WD40 on your rings and pistons. He said you do not want to use motor oil use tranny fluid or marvel mystery oil. He said he has heard of people using WD40 and it is the biggest mistake you can make and is the equivalent of using nothing. I followed his advice and have always used tranny fluid. I am not a professional but have assembled six engines without incident. It was 40 years ago and I never imagined using WD40 but he was adamant and the thought of someone using wd40 drove him crazy. This man was in his 80's and as a 18 year old he was my go to guy. He would think nothing of coming over laying under your car for hours showing you how to do something. He loved Chryslers and sharing his knowledge with anyone who was interested. I always scattered the ring gaps but never in any specific way . Just my 2 cents for whatever its worth.
     
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  19. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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  20. 413

    413 Active Member

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    Do not dunk the pistons and Rings in oil. They do not need all that liquid in there. They are not designed for it and never have it while under running conditions. The oil rings remove the liquid and leave a film on the cylinder.
     
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