Using Oil Fast

[steve24]

i have an 03 plate IS200 (owned since new).78,000 miles; it has suddenly started to burn oil, emmitting a white cloud intermittently on acceleration. just prior to emmission, you hear a ticking noise, from under the vehicle which seems to be coming from the CAT.

Have completed a full top end service, flushed and replaced oil, changed plugs, changed coolant but the problem is still there.

compression was low on one cylinder but this returned after service to close to optimum

on a process of elimination and before any "open heart surgery" I wonder if there could be anything else that i should look at that i have missed

any help or advice would be greatly appreciated

[steve2006]

Seems strange that the low compression problem disappeared after the service but has it been rechecked since, any mixing of the oil and water? Has the engine overheated at any time?

If the oil level is dropping and there are no leaks it is being burnt by the engine, the cat ticking could indicate unburnt oil is being put through it increasing its operating temperature, won't do it much good long term.

I would carry out a cylinder leakage test and suspect the cylinder head gasket as the cause.

There are other possible causes for example sticking valves, worn valve stem oil seals or worn valve seats but these can be checked as the head needs to come off anyway.

[steve24]

thanks Steve; appreciated. it hasnt overheated and there was no trace of oil in water. hoping for an inexpensive resolution but it looks like surgery as you say.

[steve24]

Steve; been suggested that we could be re circulating exhaust gases due to a faulty exhaust regulator valve. the recirculating gases are therefore burning the oil. when the exhaust gases are finally emitted after pressure build up, dirty oil could then have contaminated the cat. oil level hasnt dropped since we last posted

does this sound feasible?