geo metro engine rebuilding DIY

i have a geo metro 93 hatchback 5 speed man 1L 3cyl engine
204000km odometer with a bad oil comsumation of 1 quarts every 150 miles and i dont see much blue exhaust smoke from the tail pipe

i have twice in the pass rebuild farm tractor engine and i would like to do it myself on my car

but after i talked to what i beleive to be a quite good mechanic he told me that the failure on these 3 cyl engines are the exhaust valve witch have a bad habit to burns valve on high milage engines but on my suprized he said if i only change the bad valves and put on new piston rings my engine in no time ( within 10 to 100 miles) it would self destroy on the bottom end most likely pistons failure has he told me

now for my 5 ?

1) is it possible that a lean mixture by any probable cause shorten the engine usefull life of valve first then with new valve cause the piston to fry up ( if no correction has been taken to correct the above condition)

2) is it possible for a car engine to consume a lots of oil without emiting almost any bluesmoke ( this on puzzles me :0( )

3) has anyone here ever done sutch a repaire and had the same resulte as stated above

4) with my present condition my car has this symptome

when my car engine is warmed at part throttle i feel a small stumble at low rpm ( put on a new gas filter and cleaned the injector and the fuel pres regulator) but no change runs good when cold

and at last

5) when these engine are worn out by high milages does the cylinder bore goes out of round

any reply appreciated

Yes. It could be leaking through the rear or front main seals. It's common for oil to leak through the rear seal and into the flywheel area.

If you want to see if the engine pistons or valves are bad, purchase a compression gauge and check each of your piston compressions. The mechanic may be correct in the exhaust valve failure diagnostic, but he might not be. You said he's a good mechanic so I'll go with that.

Might be the pcv is clogged. at 200km I would suspect a bad clogging down there. It's very easy to take off the small 3-way tube that goes between the air filter, valve head cover and intake manifold. It would almost certainly be full of crud. Use a cotton swab or whatever else to reach in there

Try finding the factory service manual, either on ebay or elsewhere.
It gives 10 pages of info for every page in the haynes manual. And the chiltons gives 3x as much info as the haynes manual. Contrary to most cars, the haynes is the bottom of the barrel for metro info.
Haynes basically took apart a sprint, said it was also a metro, copied some schematics from the factory manual and slapped "geo metro" on the cover.

Mine is at '94 at 180k miles. Some are at 230. The biggest job so far was a $250 clutch replacement at 135k. Over the first 100k miles it cost 5 cents per mile to drive, half of which went towards gas.
It still gets lowr 50s-mpg as long as speed is maintained around
55mph. The oil is changed regularly between 2500 and 3000 miles, with very little oil consumption unless pushed very hard for prolonged periods in hot weather with thin oil.

Yahoo metro group: http://autos.groups.yahoo.com/group/geometrosuzuki/ messages/

i've changed the pcv and look at the hose but still use 1 quarts of oil every 130 to 150 miles

i have just received my haynes repair manual looked at the spec and found out that these engine are suppose to have 200psi compression at 9.5:1 com ratio witch i find quite high for a small economy car engine it must be why these cars dont do really high milage without having some kind of problem

The cylinders do not necessarily go out of round. You have to check when you take the engine apart to see what the wear patterns are.