MOT grumblings


Took the tonk (1997 4trak) in for its MOT and passed with a couple of advices.

Now, to tell a little more of the story, the old boy who does my MOTs is a one-man band out in the countryside. We spend more time yarning about shooting than doing MOTs, so the test took 2 1/2 hours (God knows how the guy makes any money !) No great probs so far as I'm concerned, especially as he lets me in the workshop and I work the lights an do other odds and sods as the test progresses.

Now, the weird thing is that the emission test two years ago was 2.2 units, the previous year an amazing 1.1 units and this year 2.7 units (just passed). In that time the vehicle has done 8000 miles (now has 140000 on the clock). My routine for prep for the test is the same with a half bottle of injector cleaner in about the last 2 gallons in the tank and a 20 mile run before the test, so why such a huge difference in the numbers Unknw I suspect that the test is rather more unrepeatable than our Lords and Masters in Government would have us believe.

Next thing .... headlamp alignment. I'm forever getting grief on it being too low, even though I'm illuminating the rear view mirrors of cars in front of me when following in town. Out of courtesy I drop the load leveller a notch permanently, except when I forget for the MOT.

My MOT man sometimes has some strange ideas about science and these creep across into his opinions on the test. The enigma variation this time was that the scuffing on the inside edge of the rear tyres was due to the rear shocks not damping sufficiently and allowing the back axle to bounce which caused the scuffing, despite the shocks not leaking, or the back end of the vehicle not behaving like an American lurch and wallow limousine when the towbar is stood on.

And finally, despite the rear wheels locking up progressively on the handbrake test, he reckons that the service brake only just passes the MOT at 73% efficient. The prognostication here is that the rear drums are full of dust .... WRONG .... I had them apart a week ago. There's 3.5mm left on the shoes, there's no grease on them, the drums are perfect if a little worn, the brake slave cylinder is free and full movement as are the handbrake and cables and the auto adjusters are working freely. Yes, and I stomped on the brakes a few times to get them adjusted up too.

OK, have I missed something, or am I slowly going bonkers?


Remenber the MOT test is the the testers opinion,or how he interprets the test, following his tuition on how to conduct the test. (look after a fair tester)

I actualy heard a tester fail a truck (Land Rover) before the test, and I have had my truck passed when I was sure there may be a problem, and requested they fix if required. (front wheel bearing, the play is required to allow the 4WD to work) my view was it was to much trouble to dismantle the the Auto Hub , needless to say I ask for a retest, and this was okay, but within days asked for a second opinion from my present garage, who imediatly replaced the front wheel bearing.(they were shocked as they and I had never heard such crap).

Many years ago I had a Mk1 Land Rover fail on the point that it had no hand brake cable, this was in a service center, that did all, tyres,exhaust,clutches that probabley not seen any Land Rovers, the tester did not know that the handbrake lever worked directly on the drum to the rear of the gearbox, that was a suprise for him, as he did not even get to the point of testing the hand brake.

I have used my present testing station for 4 years and the guy is an person of mature years, and I think a fair minded person who I now trust as I have the only Fourtrak they test, and I also am suprised as my truck gets older the immission test levels fall. I also use a fuel addative/injector cleaner and do a hi speed run twice around the bypass before the test, though I do run a 50/50 veg oil mix, and the test machine is of the same brand. He also gives me a verbal report on the rest of my truck which is not applicable to the test.

Talking about brakes, I said I used engine braking as much as possible, and he told me to stomp on the brakes a few times to take up the slack or else I would find them lacking when I needed them.

Edward (ews) '92 Fourtrak 2.8 TDX

Emissions tests are funny

Emissions tests are funny things at the best of times as there are so many variables, particularly on how the test equipment operates.

I always put a tin of cleaner through at least a month prior to a test, this removes everything and gives it time to work. Putting it in just prior to a test can dislodge and clean everything, but this crap is still being burned by the engine, increasing emissions. Put the cleaner in a full tank of diesel, not just a small amount, this gives it time to work, adding a large quantity in a small quantity if fuel will remove deposits too quickly and not allow them to burn off properly.
Engine temperature is another issue, along with the air filter; always run the vehicle for at least 20 miles, when it is FULLY WARM give it full throttle several times. Measuring equipment uses a light and receiver, this measures everything including soot accumulating in the exhaust. At full revs during the test it is often dislodged, this then reads as emissions when in actual fact it is accumulated soot. One tip if it is marginal is to remove the exhaust at the manifold and clean it out with water, block the end and fill it. Battery acid from an old battery mixed with the water helps tremendously, then flush it all out, preferably with a jet wash to pressurise the system. This removes most of the crap and reduces the accumulated soot, and lowers readings.

Ambient air temperature plays a part, cold air ensures a reduced emissions level, always test in cold months if possible, more efficiency. Wet weather is the best when the air is full of damp.

With drum brakes, these have a propensity to glaze, take some emery paper to the drums and the surface of the shoe and scuff them up. This gives added bite to the brakes when being tested.

Testing equipment is crucial, it varies from garage to garage, as does its operation, so is a subjective issue. Interpretation of the legislation is also another subjective issue, many garages interpret it in many ways.