Inspecting the camshaft on a Lycoming without opening up the engine

Peter wrote:

But it seems a dumb design.

They were designed BEFORE borescopes were readily available to A&Ps !

Our current Lycoming engines were designed so long ago, it was before cameras in general were invented :)

So you will have to wait for autonomous nano robots that can swim around in the oil, take some photos, bluetooth them to you, then sacrifice themselves in the combustion chamber.

Seriously though, is there no path to the cams at all? If there is a path, how narrow is it and how much articulation would you need to get there?

In the meantime you could get you a digital clock, make up a handy fixture for it and set it onto the valve spring retainer to check valve lift for each valve. Provided you get the exact numbers of valve lift from the manufacturer you will be able to tell exactly how much wear there is in the valve train. Vic

digi clock

vic wrote:

Provided you get the exact numbers of valve lift from the manufacturer you will be able to tell exactly how much wear there is in the valve train.

In theory, but there are variables that will give you false readings since the valve lifter have hydraulically actuated plungers.

Hmm, do two or three revolutions of the crank, so hopefully the readings should be consistent with the nominal valve lift – provided the hydraulic followers are not junk already ? Speaking of hydraulic followers, that is he base of the problem: With solid followers any mechanic would be able to tell there is wear as he would have to do adjustments at each periodic check – assuming he is keeping records of all previous justments. Vic

vic wrote:

that is he base of the problem: With solid followers any mechanic would be able to tell there is wear as he would have to do adjustments at each periodic check – assuming he is keeping records of all previous justments

Exactly

What about camshaft corrosion or other damage? You can’t necessarily detect that from the valve lift.

You will know very soon by seeing some reduced valve lift in consequence of rust etc . . No need to pull cylinders while full lift is maintained. Vic

I think my choice might be to pull one cylinder and use a bore scope, if the normal valve lift check, achievable static rpm or metal in the filter indicated a problem.