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MOT failure on emissions

My X reg Mondeo failed the emissions test of its MOT and had a diagnosis done, which came back as a faulty cat and failed lambda sensor, which were replaced.

When I bring the revs up to 3100 for the test it smokes. They said it was drawing oil they said it's probably had a blocked breather as when you blow down the rocker breather oil comes up the dip stick.

The car runs normally any other time, no loss of power on normal running. Should I get a compression test done? Could it be head gasket or valves?

Asked on 18 July 2011 by koicarp123

Answered by Alan Ross
Well if you are saying the car runs ok(no misfire etc) then it should be ok.Not sure how many miles the car has done,but if over 100k then you may want to carry out a compression check, this may show worn piston rings, but it may be that your valve guide seals are leaking.(are you using much oil?)
If it is blue smoke then it is oil being burnt,( ie valve stem seals)if its black smoke it may be the valves are clogged up due to a faulty EGR valve(exhaust gas recycling unit)
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