Broken lifter and worn cam lobe

[Steven D]

I've been chasing a high RPM backfire into the carb issue for about 3 months now and finally believe I have a smoking gun. The attached photo shows the lifter from the #4 exhaust. The cam lobe is worn almost completely round, it was just cracking the valve open. Any thoughts on what might cause this? I'm guessing the lifter chipped and the rough surface wore the cam down?

I've got another cam and lifter set out of the original motor in this boat (1969 Sea Ray 185) that I'd like to put in, any issues i should be aware of? The 69 cam is from a 160 going into a 79 165... Other than changing the oil any other special precautions I should take with the metal that must be in the pan?

Thanks,

 

[Silvertip]

Re: Broken lifter and worn cam lobe

The rusty color on the bottom of the lifter tends to indicate water was in this engine at one time. That said, it is not uncommon for a cam to be heat treated incorrectly during manufacture so one or more them rounds off over time. However, a chipped lifter says it may have been the culprit. A new cam and set of lifters is the minimum repair but ensure water is not getting into the oil.

 

[Steven D]

Re: Broken lifter and worn cam lobe

The color on the bottom is from a lamp behind the lifter, bottom is bright and shiny. No evidence of water that I've come across.

Thanks,

Steven

 

[hblair]

Re: Broken lifter and worn cam lobe

I just had to replace a brand new cam that had a lobe BROKEN off, two other lobes chipped and a few chipped lifters. I'm thinking the cam was bad and caused all the problems. All parts were brand new.