Reddit reviews 222 Viton O-Ring, 75A Durometer, Black, 1-1/2" ID, 1-3/4" OD, 1/8" Width (Pack of 5)
We found 2 Reddit comments about 222 Viton O-Ring, 75A Durometer, Black, 1-1/2" ID, 1-3/4" OD, 1/8" Width (Pack of 5). Here are the top ones, ranked by their Reddit score.
Made of Viton (fluorocarbon elastomer) for use with a variety of chemicals and fuelsRound cross-section to provide a seal between cylindrical overlapping surfacesCan be used across a wide temperature range from -15 degrees F (-26 degrees C) to 400 degrees F (205 degrees C)Durometer (hardness) of 75A for resistance to penetrationMeets standards defined by Aerospace Standard AS568A
could be a bit low on oil. you can isloate the sound by using a stethescope it doesnt always work brilliant but it will at least tell you in the general area to elliminate a crank or rod bearing but i think a crank or rod knock would be much much louder.
Also replace the CAS o ring. http://rallyways.com/specialty/cas-o-ring-miata-oil-leak/
I bought these but if you are willing to drive around places to find a viton 222 o ring you might save a bit of money. I had some other gaskets and junk I was waiting on so figured might as well order at the same time.
http://www.amazon.com/dp/B000FN0YG2/ref=biss_dp_t_asn
if you dont get viton make sure you get buna n or some other rubber which is oil resistant and withstand the heat of the motor.
Have you replaced your CAS O-ring recently/ever? If not, this may be the root cause -- a slow oil leak from the CAS (at rear of exhaust cam) onto the heater hose, which over time degrades the hose. Feel around back there and see if the hose is covered in dirty oil.
If you do need to do that job, you can get a 5-pack of Viton O-rings in the correct size from Amazon. It's an extremely simple job as long as you don't try to do it without taking off the valve cover.