1986 252TSE nearing TBO

[Bob R.]

My engine is nearing TBO. Currently running great with very little oil consumption. However I'm beginning to explore options for overhaul for when she tells me its time. Anyone with recent experience? Shop recommendations? Overhaul suggestions? Southwest/West Coast would be most convenient. Thanks everybody.

[Mcstealth]

Many will chime in I'm sure

 

@gsxrpilot would be a good direction to look in

 

[carusoam]

Try this on for size...

-a-

 

[A64Pilot]

Depends on how you fly and what are your intentions engine source wise.

‘If you want to overhaul, I’d recommend not overflying TBO, the reason is if you TBO, the odds of your crankshaft and camshaft being in good condition are very good, if you wait until it’s making metal etc the odds are they will need to be replaced. It’s not uncommon at all for a first run motor for the crankshaft to check out to new, not serviceable tolerances. 

So if your the type that believes only fools overhaul at TBO, then budget for an overhaul / exchange motor.

‘The crankshaft as an example has a very hard surface coating, it’s pretty thin though, and as the bearings wear, clearances open up and if the hard surface of the crankshaft is worn through, wear at that point is very rapid.

[N201MKTurbo]

39 minutes ago, A64Pilot said:

Depends on how you fly and what are your intentions engine source wise.

‘If you want to overhaul, I’d recommend not overflying TBO, the reason is if you TBO, the odds of your crankshaft and camshaft being in good condition are very good, if you wait until it’s making metal etc the odds are they will need to be replaced. It’s not uncommon at all for a first run motor for the crankshaft to check out to new, not serviceable tolerances. 

So if your the type that believes only fools overhaul at TBO, then budget for an overhaul / exchange motor.

‘The crankshaft as an example has a very hard surface coating, it’s pretty thin though, and as the bearings wear, clearances open up and if the hard surface of the crankshaft is worn through, wear at that point is very rapid.

Lycoming cranks are routinely ground undersized. If you get a factory reman there is a good chance you are getting a ground crank. They grind them 0.003, 0.006 and 0.010.

I know the cams are case hardened, not sure about the crank journals. 

I just looked it up, they are re-nitrided after grinding undersized. 

Edited April 17, 2021 by N201MKTurbo

[67 m20F chump]

I think someone told me continental cranks only had one turning in them.  I don’t know if that’s true or not.  Any of you know?  IE only one oversized bearing offered.

[A64Pilot]

It’s not all that uncommon for an engine that has been making metal for the crank and cam to be worn beyond the limits that they can be turned down to, unless caught early and not all are

Its similar to brakes on a car, if you change the pads before there is metal to metal, then it’s just changing the pads, but if you don’t, then it’s disks and pads.

‘Now I don’t know this but used to be if you bought a zero time motor from the manufacturer you didn’t get your core charge back until they tore down and inspected and deducted of course for any unusable parts, but it’s my understanding that they don’t do that anymore, if it was running when removed, your getting the full refund.

If that’s true and I don't know that it is, and if your planing on running one until it’s making metal, then maybe that’s for you. It’s not all that hard to get to what Continental charges for a zero time motor or more if you have to replace the cam and crank, and you don’t have a factory zero time motor either.

Maybe I’m just more sensitive to parts prices as I don’t have to pay labor

Edited April 17, 2021 by A64Pilot