Lorenzo Zaga said:
My puma have about 260.000 km i have to replace pistons and rings? The pistons are available now in todays market?
Hi, answer #1: Most probbly the rings would do with replacement.
Answer #2: This is the part I HATE about Ford the most. There are NO piston rings for 1.7 engine, neither from Ford (NLA), nor in aftermarket. However, you can patch up a set combining rings from NPR for Honda accord A18 engine (only the second rings) and the set for Nissan engine with also 80 mm bore. However, if your engine is drinking oil excessively, it could just be a matter of baked in oil rings which do not spring out anymore because of carbon build up (usually a result of neglecting oil changes in time). If the compression is good, then it is just this, the piston rings need cleaning properly and after reassemble it will OK.
I am talking about this (this is a honda piston, but the problem is clearly shown here)
The rings should spread out like the two top compression ones. The 3rd set of rings is the oil control one and it is seized solid in: it wipes no more oil from the cylinder wall and that is why the engine uses oil.
And this is how it should be after clean (and new rings installed since for Honda they ARE obtaineable).
Unfortunatelly, the oil ring(s) are not very good visible here, but they are spread out as well, only at the back of the image. So, if you try a compression test, and it turns out fine, that means the oil is sealing the compression rings. Also, if you can use a small camera to look inside cylinder (Lidl one is completely OK for peanuts money!) the piston should be full of burned oil. Something like this:
So just cleaning up everything and reassembling should bring the oin consumption to normal levels. Having said that, Honda engines are notorious oil drinkers if you engage VTEC mode often (it kicks in at 5600 rpm, roughly) and if you are exploring the engine revving often, given the age, it is normal for it to use oil....