Valve guide wear O320 A2B -- thoughts please

[QDMQDMQDM]

I am doing some preliminary opinion-seeking here.

The valve guides on three out of my four cylinders are excessively worn at the 400hr SB inspection and the fourth is marginal. I am being quoted £276 per cylinder to replace the valve guides, but who knows what else is lurking in the cylinder heads or the cylinders themselves (last overhaul was 10 yrs ago, did only 100hrs in the first 6 yrs and 300hrs in the last 4yrs since I have had it).

New RAM cylinders bought in the US are £610, new ECI Titans are £457. Don't know the price yet of Millenium (about £700, I think) or Lycoming.

I am tempted to bite the bullet and go for new cylinders of some variety. What do people with some experience in this area think? Also, are these FAA-PMAed cylinders legal in the UK? I know Millenium are, aren't they, but the others?

Thanks,

QDM

[spernkey]

and boy have i paid over the years!! Best go for new cylinders - millenium are good but FIRST with an old engine try to asses if the cams are spalling on the followers as low utilisation often leads to corrosion which prevents engine seeing out its life. Once bought a plane with just 60 hours on engine - it struggled to make a 1000 before been total scrap from crankshaft and engine corrosion and we threw 400 hours p.a. at it. Turns out it had sat outside for 2 years prior to sale.
Whatever you do a product called Microlon is a massive help and can be got at EGBD. Costs b***** all either.
Hope that helps.

[camlobe]

QDM,
I would suggest before you cough up for cylinder replacement/repairs, have your camshaft and followers inspected by a good engineer. Spernkey's comments on corrosion affecting low utilisation engines is most relevant. These parts suffer more on Lycomings that on Continentals if left idle over long periods of time. The other part that suffers corrosion badly if inactive are the cylinder walls. You may well find that the engineer will consider the cylinders U/S when he removes them. In that case, don't waste your money on new guides and valves.

If your camshaft and followers are OK, you can consider the pro's and con's of replacement new cylinders.

All new cylinders from Lycoming should have 'Hi-Chrome' exhaust guides fitted. This can be verified by a circle with a 'C' inside it on the boss of the oil drain back tube outlet on the cylinder head. These are not so prone to guide wear and this is reflected in both Lycoming Service Bulletin 388 latest issue and also in EASA AD 2005-0023.

There is an FAA AD out referring to ECi cylinders. You would need to verify you don't receive affected ones.

Superior's Millenium cylinders are good (no, I am not an agent) and don't seem to suffer lycoming cracking problems either.

All the above non-Lycoming cylinders are FAA-PMA approved.

Hope this is of help.

camlobe

[QDMQDMQDM]

Thanks very much. That is very helpful. Will get the camshaft and followers assessed. Sounds like the Millenium are probably the best bet if I go down that route. Any thoughts on the others, such as the ECi? They are a lot chepaer.

QDM