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Omega 2.0 ecotec smoky confusion

OK then, here's the story. I've had this Omega some time now, but when I bought it the engine was in bits - all the inlet valves were bent or broken, so looks like it broke a cambelt. Anyway I sourced a second-hand-engine, from a local engine specialist, who promised they had run it and checked it was OK. Unfortunately, what with installing it in my spare time and being supplied the wrong crank sensor, it was more than 30 days (the warranty period) before I got the engine running. When it did, it smoked - badly. Blue oil smoke, a constant stream while idling, and clouds when it was revved. The engine supplier said it was probably due to oil having found its way into the wrong places when the engine was tipped over and should clear with running. It didn't, and as I have no tax or MOT I can't take it on a road run. I have run it in the back yard for up to half an hour at a time though, no improvement.

So, a discussion with my friend, an ex-AA man and time-served mechanic, who suggested crankcase breathers (no, not pressurising crankcase), valve stem oil seals, or rings. So I stripped the engine, replaced the rings, big ends at the same time, valve stem oil seals and of course cleaned & lapped the valves while I was at it. To my dismay, it was just as bad when I put it all back together.

At this point I discovered my cousin does engine machining for a living and asked him, as by now my friend was suspecting a cracked head (as somebody here had suggested earlier. My cousin thought that unlikely as these heads don't usually cause oil problems if they crack. His suggestion was that it could be oil remaining in the exhaust, even though I've run it quite a bit, could be residual in the cat. Thinking about this, the broken cambelt could have caused a significant cough of oil into the exhaust, so it sounds plausible. His other suggestions were that the rings may need bedding in - I didn't hone the bores as I don't have the tool - or a scored valve guide.

What does the panel think? I'm about to take the head off again for another look, and at least I know where I can get it checked out, but how likely is this exhaust issue to still be the problem, all things considered?

Reply to
Chris Bolus
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Firstly, if the oil is pasing through the bores from some source into the exhaust- i.e. the engine is actually burning oil, then it should be very obvious from the bore / head / spark plugs which cylinder(s) are guilty. You say there are clouds of smoke so its loosing a fair bit of oil.- the sump level is dropping yes?

When you stripped the engine the second time, did you replace or inspect the oil control rings?

Some more info on the replacement engine would be good too, how many miles its done and what was the general condition of it when you opened it up??

Tim..

Reply to
Tim (remove obvious)

I once repaired a seat which had run out of water and blown the head gasket, after repair it smoked like a bastard, so I replaced the rings, it was ok till I drove it, when it produced copious quantities of smoke, no amount of fast driving would clear it, although you had to drive it faster to get the smoke, I eventually realised that the exhaust system was full of oil !! To clear it I ran the engine with the car on a lift (no smoke because not enough heat getting far enough down the exhaust system) I then heated the exhaust, starting near the front using a large oxy acetylene flame, I moved back till I could see smoke from the tailpipe, when that cleared I moved further back and so on, eventually all was clear and on driving it I was extremely relieved to see there was no smoke. I returned it to the customer (an ex friend who then took about two years before paying me, after I threatened court action)

So, yes you might well have an exhaust full of oil. Have you tried removing the o2 sensor to see if the exhaust smoke is there immediately at the engine (as opposed to further back)

mrcheerful

Reply to
mrcheerful

With this amount of smoke I'd have thought the reason obvious at strip down - severe bore/piston wear or even a holed piston or deeply scratched bore. Don't think valve guide problems would give this much smoke.

To check on if it's crankcase pressure, remove the oil filler cap. The engine may not idle properly, but it should show if there is heavy blow by.

Reply to
Dave Plowman (News)

Not been able to run it for long enough to measure a drop in oil level TBH. There was no obviously oily piston or plug.

Full set of new rings fitted.

I think about 170K. I was originally told less :-( It was full of sh*t, I had to scrape the inside of the sump, and I put the cam cover from the original engine on it for the same reason. However the valves & pistons were in good condition.

Reply to
Chris Bolus

That's a good idea, I'll try that. One thing I forgot to mention is that it does not smoke from cold, but starts after a couple of minutes - quite possibly when the cat gets warm.

Reply to
Chris Bolus

No, it wasn't obvious. Which is why is puzzles me so much.

No, I've already been down that road. Just a bit of splashing from the camshaft.

Reply to
Chris Bolus

I'm erring towards oil in the exhaust too now...

Tim.

Reply to
Tim..

If I hadn't come across almost the exact same thing before, then the natural assumption is a fault, another bizarre one I saw was when the owner had put some fuel from a can in, he then saw smoke, the reason? the can contained two stroke mix!!

My nephew once bought a car that had been rolled and left upside down for a while, the engine and exhaust were full of oil in unusual places and being a diesel it took ages to burn out.

mrcheerful

Reply to
mrcheerful

It's looking increasingly likely. From Mr Cheerful's idea I heated the disconnected exhaust with a blowtorch and oilly-smelling smoke emerged from the end. So once I reassemble the rest I'll try a couple more tests and burn it off or replace the exhaust. To think of the time & money I've spent on the engine! At least I'll know I have a good engine. I'll report back when I know more... thanks guys!

Reply to
Chris Bolus

Well that's clarified things. Not cleared it up, but I know now why I was confused. Having heated the exhaust and run the car for about an hour, I've pretty well get rid of all the oil in the exhaust. But not the emissions - they've just changed to white, ie steam. The water level definitely did go down. So it's looking like a cracked head after all - the oil in the exhaust had given a smell and blue tinge to the clouds emerging from the exhaust which had misled me. At least I know what I'm up against now. Unfortunately it's off with its head yet again, and over to my cousin for testing. I have a spare head which with luck may be serviceable.

Reply to
Chris Bolus

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