After Engine Overhauling

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After Engine Overhauling

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i am just want to know about some of my problems. i have overhaul my engine (just rings and gasket) but the problem is immediate smoke start after overhaul. and the problem was not solved. my mechanic said that the smoke and oil burning will be last for next 1000 KM and then it will be solved itself. so do u think he is telling the truth or it is not right? what u say. he also told me that after 1000 KM the oil should be change and the engine will be ok then, and will not consumed oil and smoke anymore. also tell me that do u experience any smoke after rings and gasket change? or this is just the case with me? also someone told me that the engine should be break in with a mineral oil and one should not use any synthetic oil during the initial break in period because the synthetic stuff is much slippery than the mineral one, because i have refilled with synthetic after ring change therefore after the friend advice i have changed to mineral after 317KM driven so the smoke is still given be the tailpipe and the oil is still consuming. so do u think i should go for valve seal change also with piston and piston rings change or i should wait for 1000 KM drive? please guide me. Thank You.

Gari.pk User 609 asked on 16 Jun 2010 13:54:39 pm

1 Answer

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Samar - on 16 Jun 2010 13:55:04 pm

This is not called an overhaul. You just got the rings replaced - no more, no less. In an overhaul the entire engine is disassembled and each and every worn-out part is replaced, the cylinder lining is honed again and entire cylinder head is also properly machined, valve seats are re-made to perfection etc.

The semi-overhaul that you have got done usually fails (because cylinder lining is not smooth and also because valves are leaking oil). This is only done in case you have worn out your rings very quick e.g. in 60k km. It is assumed in this case that other parts e.g. oil pump etc. have much life remaining and the only purpose is to reduce oil consumption. Take note that in fitness test nobody cares about the condition of your engine (I mean compression etc.) but every fitness test is designed to check for emissions. So if there is lots of soot in your exhaust your car will not pass the fitness test. In places like here where fitness standards are not properly enforced, you would still like to reduce the oil consumption because it is very expensive. I once had a car which required 1 litre of oil per 300 km. I had a running of 3500km per month and needed three 4 litre bottles every month (that means Rs. 3600). So the rings were changed and the consumption came down to 1 litre per 6000km. This was a big (20 times) improvement. The remaining 1 litre consumption was due to leakage from valve jackets. I think this is your problem.

You will soon need a full rebuild (you should have gone for it in the first place). Nowadays are tough times and full rebuilds are not the norm, plus people are also running their cars less because fuel is so unaffordable, so if you run only 20k km this year you'll be able to complete 12 months on this engine. My advice: Go for a total rebuild but not now, only when you start losing so much compression you have acceleration like a hand-cart.

As for your mineral oil question, always break-in using a mineral oil. Then switch to synthetic after 10k km (which would be your third oil change after 1k and 5k). Even for cars which have synthetic recommended as standard you have to use special break-in oils which have less friction modifiers.