Vehicle Testing (Hansard, 16 February 1993)

§ Ms. Walley
To ask the Secretary of State for Transport (1) what advice he has issued to vehicle testing stations; and if he will place the full details in the Library;
(2) what information he has on how many diesel cars have suffered engine damage as a result of the new smoke emission tests in the MOT test;
(3) what steps he has taken to inform the public of the diesel engine new smoke emission tests; what evaluation of alternative test methods which are less liable to cause engine damage has been made; and if he will make a statement.

§ Mr. Kenneth Carlisle
MOT testing stations have been advised how to test diesel-engined vehicles, and with what equipment. They have been specifically instructed not to test vehicles where the engine is not in a satisfactory condition, and they have also been given guidance on how to establish this. I have placed in the Library a copy of the advice to MOT testing stations about the MOT diesel smoke check, together with the relevant extract from the MOT tester's manual about the test procedure.
The test involves measuring smoke density while the enigine is run to its maximum governed speed so as to impose a similar sort of load on the engine as it experiences in normal driving conditions. The only alternative to measuring smoke density during a free acceleration test would require the use of a dynamometer. This would be a very much more expensive investment than the smoke meters which have been in use since 1 January.
The purpose of the test and.the procedure are described in an advisory note which MOT testing stations have been providing to applicants with diesel-engined vehicles before tests have been carried out. As the note explains, the test procedure is not harmful to properly maintained engines, but an engine may well need prior attention where it has not been maintained in accordance with the manufacturer's recommendations.
Unfortunately I have received reports that there have been some cases where light-duty diesel engines have suffered damage during the metered test of smoke levels while the engine is under load, and I have therefore decided to suspend that part of the test temporarily as from today pending an investigation into these matters.
In the meantime motorists should continue to take diesel-engined vehicles only to MOT testing stations which have been authorised to test diesels, since they will still be continuing to check by eye that vehicles are not emitting excessive smoke or vapour at normal idling speed. Taken by itself, this visual check is not such an effective test because it does not indicate how an engine performs when 149W a vehicle is out on the road. However, it will at least identify those vehicles with serious in-service performance deficiencies.
I hope that it will be possible to reinstate the metered test a little later in the year. Emissions testing during roadworthiness tests is an important feature of our policy on improving the environment, and if a diesel engine is putting out too much smoke we have a responsibility to ensure that the problem is rectified.

§ Ms. Walley
To ask the Secretary of State for Transport whether he will require all vehicle testing stations to undertake MOT tests of diesel engines.

§ Mr. Kenneth Carlisle
No, the decision on whether to invest in smoke-measuring equipment must be a matter for individual MOT testing stations to make. If we were to introduce a requirement that all stations should be able to test diesel-engined vehicles there would be substantial over-capacity, and a lot of equipment would be left standing idle for long periods of time.

§ Mr. Gareth Wardell
To ask the Secretary of State for Transport what steps he is taking to inform the owners of diesel cars and diesel light commercial vehicles of the need to ensure that their vehicles are serviced before being submitted for the Ministry of Transport test diesel smoke emission levels test.

§ Mr. Kenneth Carlisle
Diesel-engined vehicles do not necessarily need to be serviced before the MOT test, although an engine may well need prior attention where it has not been maintained in accordance with the manufacturer's recommendations. MOT stations have been providing an advisory note about this to all test applicants with diesel-engined vehicles before a test takes place. The note explains the purpose of the smoke check; the procedure involved; and it also advises against proceeding with a test in any case where an engine may not be in a fit state to be tested. In addition, testing stations have been instructed to review the service history of a vehicle with the applicant before starting the test, and to carry out a number of preliminary safety checks on the engine. I have placed a copy of the note and our instructions in the Library.
Unfortunately, notwithstanding the various precautions which have been taken, I have nevertheless received reports that there have been some cases where light-duty diesel engines have suffered damage during the metered test, and I have therefore decided to suspend that part of the test temporarily as from today pending an investigation into these matters.