TSIO-520P top end or complete overhaul

[JOHN SEMERC]

Coming up at end end of a wonderful life with my millinium cylinders, unfortunately they can't go past TBO. Contemplating doing just the top end instead of a complete overhaul any opinions from those with the experience on either end?
Much appriciated, happy flying!

 

[weilke]

If you just do the top and 500hrs from now you have to do the bottom, you either have to re-do the top or continue counting from 0.

When where you planning to overhaul if it wasn't for the milleniums ?

 

[Checkout_my_Six]

all depends on how much $$$$ you want to spend. I just did a top on my TSIO-520. It has 1,200 hrs on the crank and 400 hrs on the cam and tappets. I figured it'll go another 700-800 hrs with what it's got.

 

[Stewartb]

I'd major it.

What cylinders do you plan to replace with? Just curious. I also have one run Millenniums.

 

[JOHN SEMERC]

my compression's are stellar, always all within 3-5lbs from one another ranging in the lower 70's. I have 4 millenniums left that cant go past tbo, the other two were replaced with the previous owner and are continentals. I thought to replace all with new millenniums, port, polish and balance and leave the bottom alone take it as far as it'll go with the new top end.

 

[Dr. O]

Yes, put on all new cylinders and sell the two with legal hours left on them. Don't waste money on port/polish/balance nonsense on a 2800 rpm engine. Balance may make it feel smoother - but it will all be in your head at that rpm. The most I would do is pair the cylinders into 3 sets of two, matching opposing pistons as close in weight as possible. You haven't given us any hours/condition on the bottom. Talk to your mechanic. It may be the bottom can be expected to outlast another set of cylinders. Don't spend money up front just for bragging rights. As my old dad always said, 'if it ain't broke, don't broke it'. (he was the factory field mechanic on the Packard Merlin engines)

 

[JOHN SEMERC]

the bottom was done 1500 hrs ago during a complete overhaul prior to my ownership. I'll inspect the cam and see what that looks like it'll hopefully give me some insight on the health of the bottom.

 

[Checkout_my_Six]

It's gonna be a crap shoot. If you decide to sell you'll get the tire kickers who will bemoan the TBO engine....me, I don't care bout TBO. I did my TO in my Rec room last winter....and redid the firewall and engine bay.