The car is a 1996 Daewoo Nexia with 140k on the clock and every now & then (always when cold after it's been sat for several hours) I start up and the engine runs really rough & spluttery like its not running on all
4 cylinders and you can smell unburnt fuel from the exhaust. While it's in this state, if I stop the engine and re-start it will spin over very fast as though there's very little compression or resistance. After a few moments it clears itself and runs perfect again. Does this sound like a sticky valve problem?
While it's in this state, if I stop the engine and re-start it will spin over very
Certainly does. Don't know the particular engine, but think they are all based on GM units (Cavalier etc). Hydraulic tappets sticking. Maybe a case for service with flushing oil first, followed by decent semi synthetic and a good blast down the motorway. DaveK.
Just a quick question Dave what is the correct procedure for using flushing oil? I really should know I sold the stuff for a good while but never used it myself I preferred using detergent diesel engine oil just before oil changes Derek
Just a quick question Dave what is the correct procedure for using flushing
One of the high street service places is advertising a service with a drain and fill with flushing oil before refilling with proper engine oil. Many years ago guys in the know (they said) used a gallon of paraffin and let the engine tickover for ten minutes on that, before draining and refilling with proper stuff. The 'proper' stuff was like treacle, dark green and was delivered out of a hand cranked bin pump, or big heavy glass bottles. As years went by the general view was that flushing oil could disturb the semi solid crap at the bottom of the sump and what was glued to the oil pump strainer so it went out of fashion. I've stripped and rebuilt engines years ago, and despite the use of flushing oil you still needed a paint scraper and caustic soda to shift the carbonised residue in the sump and crankcase. I don't know why they have reinvented it because modern detergent oils and synthetics don't leave the sticky mess behind anymore. If you feel the need, it's just a matter of draining the old oil,-leave the filter in place. Fill with flushing oil and let it tick over to circulate around the galleries and oilways. Then drain, change the filter and refill with good stuff. Maybe a run up the motorway for half an hour with a sumpful of supermarket cheap oil would have the same effect. Personally I wouldn't bother. Modern engines should last well over 150,000 miles without excessive wear if they get the oil and filter replaced according to the book. Trouble is after they have about 80,000 miles up, they tend to be driven by people who don't know. DaveK.
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