Piston Ring Lubrication At Assembly

soaking a piston in oil before installation is nice.... if you were assembling a compressor.

In an engine the lowest piston ring (oil scraper)is intended to keep the oil away from the top ones (the compression rings).
You want to top ones ( which indeed wil become very hot) as dry as possible.

Using wd40 is not a bad idea i think but when you instal the pistons from the top you could simply apply some oil on the cilinderwalls. That will do the job too. Soaking won't

good luck!

 

Install the rings on the pistons then just dip the piston with rings installed upside down in a container of engine oil. You don't need to dip any deeper than the wrist pin. After inserting the pistons in the bores, wipe the excess oil off the piston top. Many people advocate breaking in engines with conventional oil; use that if you are concerned. We broke in/ran all engines on Mobil 1 synthetic.

 

My $0.02; There is nothing wrong with oiling all of the rings before assembly. I oil the walls and the rings with motor oil before compressing them. I would NEVER use WD-40 on rings unless I was trying to break them free before taking the piston out. I've seen that stuff leave too much of a deposit behind when it "evaporates" to want to use it in a new assembly.

 

Motor oil on all three rings is the way to go. Yes, the bottom ring is an oil control ring but that ring still let's a fair amount of oil past (there is, after all, a gap where the ends of the ring meet and you should measure this clearance) so the top two most certainly do not run in a dry environment.

Couple of tips that may be helpful:

1. I assume you've had the cylinder bores honed? If not, big mistake to install new rings as the shoulder on the new rings will impact the lip on the bores related to the uppermost travel of the prior rings. If severe enough of a lip on the cylinders, the rings will break quite quickly.
2. Offset the clearance gaps of the rings so they're not all in a row. In other words, with three rings, place the clearance gaps at 120 degrees to eachother.

Good luck!

 

If you oil the pistons and the rings, you'll have a while before the rings seat. When we were building motors, we'd oil the skirt of the piston, not the rings, and we'd get the rings seated within 10 miles or so. Of course that was for a racing engine, but the idea was the same.

Art

 

Dipping the piston in oil used to be accepted but its not anymore, at least on high end builds. There is a claim you get too much oil behind the ring which effects how it seals as well as once running the oil can cake up from the heat and carbon up in behind the ring. I pour a light stream across the rings and let it run around the outside and off before inserting the pistons. Also if you could get a proper tapered piston installing sleeve to install the assembly rather than a band you would be even better off because they dont put verticle scratches on the ring faces.

 

I have always just oiled the cylinder wall with a rag, as well as the band. Tapered sleeves are nice if they are made well, but I have also seen people break new rings in them. I never had the luxury of the sleeve, but the band has worked well.

 

Regardless of what method you choose of the various opinions about lubing the piston, BE SURE you individually check the piston rings for proper fit in each piston/cylinder and file them for the proper ring gap. Do NOT mix the rings for different cylinders. Measure/adjust them for each cylinder and keep them in the proper order for installation.

 

If the ring manufacturer recommended a specific method for his piston rings, use that method, NOT what any of us recommended. You did good, put the last one in the same way. In the shop we mostly assembled them dry because that's what the ring manufacturer we commonly used recommended. But dipping the assembled piston in engine oil will always work ok in the absence of specific guidelines from the maker. I guess I assumed that when you asked, there were no recommendations from the ring maker.