My son's Corolla reg 53 developed an odd smell from under the bonnet, almost like burning plastic (no sign of smoke). He checked it out and there were no visible signs of anything unusual, although he had heard a 'pop' sound earlier as if he had ran over something. The smell went away after a few hours and the next day he drove home to Scotland (250 miles) with no problems. The car is running well but yesterday the smell returned, again for just a few hours.

Any ideas???

Sometimes people run over plastic bags and they stick to the Cat or exhaust causing the smell. Check that out

i picked one of them up sometime ago same year, had a burning smell comeing from it.. it turned out to be the cat, it was glowing red..

Please excuse my ignorance guys, but what is the cat? (no smart alec answers are required)

The Catalytic Converter in the exhaust system, which boosts the temperature of the exhaust gases to burn off unwanted emissions to meet regulations.

Thanks dd. This sounds like a possible culprit but also pricey to repair. I will pass on the info' to my son and he can get things checked out.

Its unlikely to be the Cat itself if its overheating, for it to overheat it needs fuel and so something must be wrong that's making the mixture rich. The engine management warning light would normally come on if this is the case - check the bulb is working when you switch on.

Its much more likely its just a bit of plastic on the exhaust somewhere or a possibly a shortage of coolant in the cooling system.

Also some oils can be very smelly and even a small amount dripped/dripping onto some hot bits can take days to burn off. Worst culprit are Castrol Oils which seem to wronk much more than most others.

Hope you're right, dd. Thanks for your advice. Will keep you posted on the outcome.

if you like you can pop down to my garage and ill look at it for nowt

Oil leaking onto exhaust?

Thanks for the offer, chris but the car is now with my son in Scotland.