Tell me how to get a little O-ring into a groove around the outside of a 6mm bore.

Having cleaned my oil screen I'm reassembling. The O-ring inside the water pump impeller was damaged so I pulled it out.

I have the luck an assortment of Viton rings here and quickly found a match: 6mm x 2mm:


The trouble is that I cannot get the last quarter of the circumference seated. It's like I have the outline of a packman gobbler thingy with the outside diameter all in the groove and the mouth too stiff to smash out (into the groove) to make a circle.

This is working inside a 6mm diameter bore about half way along the 13 or 14mm length of that bore.

So, tell me the trick. (It's that easy, right?)

Thanks.

FYI. The OEM o-ring I have here measures 1.85mm thick.

Well, trying to fit a big ring in a little space could be more difficult.

You say that the new one is 0.15mm or .006" larger than OEM.

I cannot measure any difference in the thickness. Calipers, etc., show no difference. I've set them side-by-side and compared the edges (and enlarged photos of the edges too) then taken photos straight down to see the diameter. They are the same thickness (the lines show it most precisely at the bottom). The difference should be 7.5% which should show up. It's hard to compare the crushed and cut one to a whole one but the new one does look larger in diameter than the used one (i.e. the one that's been compressed for 50,000 miles).


The new one slips very easily into the groove for 3/4 of the circumference. If it IS too big, that would explain the trouble finishing.

Grinnin,
Have you tried lubricating the 'o'-ring with a bit of Dielectric Silicone grease?
(spark plug boot grease)
And be certain to screw the impeller onto the shaft.
And use your 1/4", INCH pound torque wrench! 87in lb MAX.

I'm saying a new, unused, OEM o-ring from Kawasaki has a caliper measured thickness of 1.85mm. I didn't measure the diameter but if the o-ring is too thick it's not going to seat in the groove. I keep a few spares here just in case and that o-ring is one of them.

What is the measured thickness of your "new" o-ring?? I don't always like to measure old o-rings because of the possibility of swelling from chemical contact or use.

.

pdwestman:
I'm using silicone grease.

klr4evr
I get 1.93mm for the new Viton and 1.87 for the old (measured as 0.076" and 0.074" with micrometer). I had my doubts about measuring a rubber ring, but the micrometer lets the gap adjust until it just drags on the rubber.
It really does start very easily. The cross-section is definitely not too large even if it is 0.06mm (0.002") different.

I may buy an OEM one if I can't get this seated tomorrow. I definitely cannot measure the OD of the torn stocker and the new one looks longer around.

I like to use a pin(small flat ended shaft) just smaller than the bore to gently push downward on the part of the Oring that is sticking up out of the groove. As you push downward it should feed the oring into the groove. Be careful not to shear the ring!
If you measure the shaft diameter plus 2 times the oring thickness that will give you the theoretical groove diameter.
Regards....justjeff
The blunt shank end of a 6mm or a 15/64 drill bit should work. You may have to grind it flat.
jj

Update??

I ordered one after a few more tries. I had a clearish/whitish nylon rod here that I cut at an angle to try to install it. Nope. I'm convinced it's the slight bit of extra circumference.

I've been ordering parts through the local shop (which is well over an hour round trip) but I ordered this and a couple other items from Ron Ayer. Not shipped yet AFAIKT.

That order took over 2 weeks, but I have no idea which part was the holdup.

The "official" 6mm o-ring started in just as easy as the one from the assortment. But the official ones seated fully with just a nudge.

I conclude that 6mm means different things to different manufacturers.

This area had a week of warmer winter. Gives me hope.