foxy_s2k

If it's a failed ring, what am I looking at in order to repair it?

I've been offered a second hand engine (07 F20C with very few km), for a reasonable price, should I be going for that quickly before he changes his mind (he's not that keen on selling it anyway).

Moddiction

No I would not go buying an engine. It could be something less serious.
First thing is just to do a compression test and see where your at.
There are always good deals on engines it seems these days.
Couple people part out s2k's all the time and have good prices on used engines if need be later on.

foxy_s2k

Not in Greece they don't and an 07 engine from the US would be the wrong displacement (illegal in Greece).

Yeh, but how much will it be to replace all the rings? I imagine it would be no more expensive to replace 4 than 1 in terms of labour?

Also, if a ring has gone, I may never completely trust this engine again.

Someone please tell me what a leakdown test is!

fltsfshr

A leak down or "cylinder leakage" test is similar to a compression test in that it tells you how well your engine's cylinders are sealing. But instead of measuring pressure, it measures pressure loss.

A leak down test requires the removal of all the spark plugs. The crankshaft is then turned so that each piston is at top dead center (both valves closed) when each cylinder is tested. Most people start with cylinder number one and follow the engine's firing order.

A threaded coupling attached to a leakage gauge is screwed into a spark plug hole. Compressed air (80 to 90 psi) is then fed into the cylinder.

An engine in great condition should generally show only 5 to 10% leakage. An engine that's still in pretty good condition may show up to 20% leakage. But more than 30% leakage indicates trouble.

The neat thing about a leakage test (as opposed to a compression test) is that it's faster and easier to figure out where the pressure is going. If you hear air coming out of the tailpipe, it indicates a leaky exhaust valve. Air coming out of the throttle body or carburetor would point to a leaky intake valve. Air coming out of the breather vent or PCV valve fitting would tell you the rings and/or cylinders are worn.

A leakage test can also be used in conjunction with a compression test to diagnose other kinds of problems.

Copied this for you

fltsfshr

Moddiction

A leakdown test is similar to a compression test. But it shows you how much pressure you are losing not how much compression there is. \
Helps identify blown seals and all.

Ah didn't realize you were from Greece. makes it different but get on your mechanic's case. He can do a lot more to start testing for things.
First thing is always to do a compression, wet compression(oil in cylinders) and a leakdown test at least. Will help eliminate things.

foxy_s2k

Thanks guys, I guess the leakdown is the way to go then, thanks for the detailed info flt.

So, how much is a ring replacement? Lots of labour huh, as the pistons will have to come off the crank...

drewmob

Foxy - Take a couple of deep breaths, it'll be okay! My entire top end is in pieces in my garage right now, so I feel your pain.

http://lmgtfy.com/?q=leak-down+test

foxy_s2k

By the way, you guys rock. I really feel I've learned a lot from this. Thanks.

foxy_s2k

Thanks man, but I still need to know if the ring is going to be an expensive fix, I need to know how much money I need to possibly prepare to withdraw.

Moddiction

Yeah a ring replacement would be expensive. Might have to hone the cylinders out a bit too and all. Sucks it's so hard to get a used engine there as they are real cheap here especially just for a block.