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Top overhaul minimum parts list?

Top overhaul minimum parts list?
With a mishmosh of different castings and field repairs and now cracked cylinder at exhaust stud and multiple exhaust leaks, high oil consumption and high levels of chrome in the recent oil analysis it’s time for a complete top overhaul. (1000smoh Mattituck1990) about 600 on the most recent overhauled cylinder. My question is as follows:
We’re replacing all cylinders with factory new kits… what else should be replaced while we’re this deep into it? Piston wrist pins regardless of wear? Rod bearings, bolts? Pushrods? Etc… Thanks!!

Model: Bonanza G35
Posted 10/30/2023 - 4 months ago
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It’s assumed but just in case it matters…
E-225-8 with hydraulic prop

Posted 10/30/2023 - 4 months ago
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Daniel, it has been 33 years since the bottom end of your engine has been apart. Not a lot of time in service, but a lot of time. If you have had a spin on oil filter for your 1000 SMOH and oil pressure is good, you might be OK. There is really no way to tell for sure. That is why the factories recommend TBO limits in both calendar years and hours. Look very closely at the E225 oil pump in the picture below.

IMG_2814.jpeg - 1.8 MB

Posted 10/30/2023 - 3 months ago
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We do have the spin in oil filter… From what we can see inside the case after removing cylinders it’s spotless with no visible wear or corrosion. Oil pressure is only at the bottom of the scale at idle on a hot day otherwise it’s around 50psi during cruise and close to 60 when cold.
I’ll look at an exploded view of the engine diagram, but are you suggesting we inspect the oil pump gear or are you suggesting a complete overhaul?

Posted 10/30/2023 - 3 months ago
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Daniel, E-series engine bottom ends are solidly built, but 33 years is a very long time. Even if all the bearings are in great shape and there is no corrosion, the seals and gaskets will become dry and brittle. My last E-225 (which I built) was still running great at 20 years and 2000 hours, but I am personally not going to run an engine longer than that.

There is another, more practical consideration. Parts for these engines are getting harder to find and more expensive. I’d do it now while you know you can still get parts. I wrote about my last E-225 “field overhaul” in the ABS magazine in 2019. In reality, this was a tear down, inspect and repair as necessary (IRAN). I think I had less than $15K in parts for the whole job.

Posted 10/30/2023 - 3 months ago
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Top overhaul minimum parts list?