How do you Inspect chain rails

[JFP in PA]

Originally Posted by Homeoboxter

True, but the large ones last much longer, I don`t think those should be worn off at this mileage. You can`t see the lower small pad, I agree. This test is good to tell you if the upper is shot, and then you don`t have to hesitate to pull the cover off. I think you can have a vague idea about the condition of the large ones after removing the pump and the tensioners and looking down toward the crankcase with a camera or small mirror. The crank-to-IMS chain pad is partially visible after the RMS is removed, that also can give you a vague idea. In my engine at 100k the four long rails were in perfect condition, the crank-to-IMS pad was shot, and the four little pads were disintegrated and the chain was running on the tensioner, metal on metal.

We have seen all of the rail pads go south at one time or another; the little ones between the cam fail most often due to their small surface area, but the larger ones are not immune. We have also seen the longer units break near their pivot points, which is why updated parts are now available.