Surface corrosion on tappet

[N360DF]

Folks,

My engine parts was stored in oily paper to avoid corrosion.
But unfortunately the paper was bleached and properly had a chlorine content. The loss is big and parts need to be bought again.

The tappets is pretty good, but some have some surface pitting.
Very shallow. I am not afraid they breaks down, they will not.
But I have not knowledge how the tappets works ?

Maybe someone may help me?

Do they seal or is the oil film leaking between case and tappet?
Could some pitting reduce pressure some way?
I was told they actually rotate to spread the wear ?
Anyone who know more in detail ?

Look at picture! This is the worst one! The rust easy goes off and
I just slightly used 1200 wet paper. I will check OD with micrometer.
And polish to get smooth surface.

The tappet surface against cam is perfect.

Thanks for all help!






https://www.dropbox.com/s/u8iiu9hjq7...appet.jpg?dl=0

[Boyd Birchler]

The OD is not likely to cause any problems from minor pitting. provided you polish it off. As long as the face that goes against the camshaft is clean and smooth they should be OK to install and function properly.

[mahlon_r]

Not a part I would put in my engine! That is gross pitting not minor.
To answer your question the oil bleeds out around the tappet body in the crankcase bore. Some of that oil is supplied to the lifter inside the Tappet body and the lifter acts just like any other hydraulic lifter. Oil flow out of the lifter is controlled by the fit of the lifter piston to the lifter body. If you have too much wear of the tappet stem or the crankcase tappet bore the result is lower oil pressure in the engine. Not really noticeable at power but very noticeable at Idle RPM's due to the increased clearance between the tappet body and it's bore.. The tappet body does rotate in the crankcase bore. this is accomplished because the face of the tappet isn't flat. It is radiused and the apex of the cam lobe is tapered to match the tappet radius. As the tapered cam lobe interacts with the tappet face, it causes the tappet to rotate in it's bore. So, if you are planning to polish the tappet faces and or the apex of the cam lobes be very, very careful as they are NOT flat surfaces and to change the radius of the tappet or the taper on the lobe will greatly effect their interaction and cause destruction of both, from rapid wear, is very low operating hours. The match of the tappet face radius to the cam lobe taper is critical and something that is controlled by the final grinding process of each part on manufacture or overhaul. It is not something that can be done in the field.
Hope this helps.
Good Luck,
Mahlon

[9GT]

I would most definitely listen to Mahlon on this one and replace those lifters.

[JDeanda]

Long time A&P here. I would not install those parts. No sir, no way.

[titanhank]

Throw them in the trash and get a set of dlc coated lifters.

[Gash]

Thank you for that reply Mahlon. I love it when I can get valuable education here for the price of my annual VAF donation. That was excellent!