The International Cessna^® 170 Association

This Annual, #3 Cylinder down to 40/80 psi. All other between 68 - 72/80.

Machinist working my #3 cylinder said, Intake valve guide out of alingnment and worn on one side, Valve Seat excessive ware.
The Cylinder itself great shape.

Major Overhal done 15 years ago. All new parts except cylinders, Checked and reconditioned. Parts Magnifluxed where applicable.

Total time since major is 920hrs
Engine runs smooth and strong
I fly about 60hrs a year
Aircraft always hangered.


1. Should I relpace #3 Cylinder re-worked with new parts and keep flying 2 to 3 more years then do a Major Overhaul with New Cylinders

2. Or Just do a top Overhaul with new cylinders and fly 900 more hours ( 12 years) then do a Major Overhaul ??

Need some Advice!!

Pete petetynning@msn.com

I'd replace the valve guide and seat and fly till you had more problems with more cylingers before replacing them.

Send #3 out for inspection. (Typically costs less than $50) and see what the report says. If all you have is a worn valve guide, seat, and valve nees refacing, I'd do that, install new rings, and press on towards overhaul.
If the report comes back, cracks in head, worn out rocker shaft bushings, worn out piston, both valve guides shot, etc., consider a replacement cylinder, and press on towards TBO.
Since the rest of the cyls seem OK, why fix what's not broken?

Buy a used cylinder, replacing the guide, and seat is too much work, for what you will have in the end.

I have to disagree,Tom,who knows how much time on that used cylinder? I'd probably stick with the original if it was me.
I had a couple O-200 cylinders rejected at overhaul/repair time several years ago, due to AD 94-05-05. The cylinders checked out OK for cracks at the rocker shaft bosses,but after the bosses were bored out & bushed due to the shaft holes being too loose, the bosses were JUST below the dimensional limits. Bummer!

Eric

gahorn wrote:Send #3 out for inspection. (Typically costs less than $50) and see what the report says. If all you have is a worn valve guide, seat, and valve nees refacing, I'd do that, install new rings, and press on towards overhaul.
If the report comes back, cracks in head, worn out rocker shaft bushings, worn out piston, both valve guides shot, etc., consider a replacement cylinder, and press on towards TBO.
Since the rest of the cyls seem OK, why fix what's not broken?

Who does the best inspection/overhaul of used cylinders?

I have a client who only this month had less than 700 hours on new cyls, one of which developed an exhaust leak. (Pretty bad leak, 0/80 on the compression test.)
The inspection report (Cost $48 ) came back, burned exhaust valve, worn guide. The piston also had excessive wear at the pin bosses and the rocker bushings were at max. They replaced the guides, refaced the intake valve/seat, refaced the exhaust seat, installed NEW exhaust valve, re-bushed the rockers, installed all new valve springs and valve keepers, supplied new piston/rings and all gaskets/hoses/rubbers for reassembly for total cost per cyl of $330 including inspection-report/shipping. Since that included a new piston and rocker bushings, which Pete doesn't anticipate, I think that was a fair deal. No matter what the "discount" cyl shops advertise, doubling that cost is what an exchange/rebuilt cyl/piston would cost and there'd be no idea how many cycles on the replacement. Tripling that cost would supply a new cyl assy/piston/etc. (I know, I know. There are advertised prices out there that beat my estimates, but when you get through with the whole enchilada including the hidden variables, the bottom line is more like what I've just estimated.)

I like the cylinder shop, who has been in business for 25+ years and has an excellent reputation. http://www.jjairparts.com/
They're just south of San Antonio, and with shipping these days, it makes no difference where the customer is located,...costs/time is about the same. IMHO

""I have to disagree,Tom,who knows how much time on that used cylinder?""

Who knows how much time is on his?

His failed, at least you can inspect the used cylinder before you put it on.

Thanks for responding to my post!

I have descided to have my cylinder rebuilt, about $300 and put it back on my engine. Maybe in a few years I will do a major overhaul if more cylinders go bad.

Thanks again!


Pete

Good Choice