Radiator exploded during MOT!

[BigglesPiP]

Would a car engine be expected to sit idling for ~40 mins or so during an MOT?

Ive never waited whilst one's been done so I'm not sure if thats something thats fairly typical, or whether its just laziness on the testers part on not turning off the engine when its unnecessary.

The MOT lasts one hour (or the computer gets angry), a lot of that time is spend with the engine on. If your emissions suck then you'll spend a couple of minutes at 2000 to 3000 RPM.

 

[Confused]

My dad leaves engines idling whilst doing the MOT, to ensure that the catalytic converter is warm enough to give it a good shot at passing the emissions test (or, at the least, to minimise the time required revving at 3k RPM to warm it up)

 

[realscot]

I try to minimise the amount of time the engine is running when i'm testing. Too many older cars don't like it. You really only need it on for a few minutes on the ramp, then to do the brakes and emissions at the end.
You take a whole hour to do a test Biggles? what do you do on new small cars? stand under them daydreaming?
Our local Vosa examiner said 40mins was fine on 3-4 year old smaller stuff, audi's vw's etc, and 50mins for everything else. You can log off at any time, its just a problem if someone looks into your testing.
One time I accidentally logged onto a car as a full test instead of just a retest, and stupidly you then loose the ability to run the previous fail through even though you abort/abandon. So what I did was just check the car over, then log it off and print out the pass ticket, so I was around 10 minutes. As far as the computer is concerned I did a 10 minute complete test, but I knew I didn't. I was prepared for the phone call from VOSA but it never came.

 

[Clarkey]

Garage I use leave the engines running for the whole test, always been like that. Frankly if a car overheats due to this then its a heap of junk that deserves to fail. A working thermostat and rad fan isn't that much to ask really.

 

[BigglesPiP]

I try to minimise the amount of time the engine is running when i'm testing. Too many older cars don't like it. You really only need it on for a few minutes on the ramp, then to do the brakes and emissions at the end.
You take a whole hour to do a test Biggles? what do you do on new small cars? stand under them daydreaming?
Our local Vosa examiner said 40mins was fine on 3-4 year old smaller stuff, audi's vw's etc, and 50mins for everything else. You can log off at any time, its just a problem if someone looks into your testing.
One time I accidentally logged onto a car as a full test instead of just a retest, and stupidly you then loose the ability to run the previous fail through even though you abort/abandon. So what I did was just check the car over, then log it off and print out the pass ticket, so I was around 10 minutes. As far as the computer is concerned I did a 10 minute complete test, but I knew I didn't. I was prepared for the phone call from VOSA but it never came.

Maybe whomever would be calling could see the vehicle's record and realised what had occurred? Not to leave you with the wrong impression; I'm not an MOT tester, father is.

 

[matt_fsr]

Garage I use leave the engines running for the whole test, always been like that. Frankly if a car overheats due to this then its a heap of junk that deserves to fail. A working thermostat and rad fan isn't that much to ask really.

Thats a fair point but how would a driver ever know that theirs has failed, until the car is put under completely unusual 'non-driving' conditions such as sitting idle for 1hr without moving during MOT?

£425 bill. New radiator, new fan, new thermostat, new fan bracket, labour to fit and cost of MOT. Didnt fail the MOT on anything.

Now got 3 little dents in the bonnet to remind me of the event

As I said, I'm really more glad that its just a bill and some dents, not a young lad with half his face scalded off.

 

[Fido McNasty]

Wow. Funny you should mention this. Two weeks ago I saw a c180 'elegance' of the same era, just an 1.8 but the exact same issue during MOT. Blew the expansion cylinder off the rad. Luckily again the bonnet was down for the tester and it was clearly a big bang lol.

Not entirely sure even now exactly how it came to be other than to say the temp had obviously risen enough to turn the coolant to steam, and boom, up it went. Bizarre.

 

[matt_fsr]

Wow. Funny you should mention this. Two weeks ago I saw a c180 'elegance' of the same era, just an 1.8 but the exact same issue during MOT. Blew the expansion cylinder off the rad. Luckily again the bonnet was down for the tester and it was clearly a big bang lol.

Not entirely sure even now exactly how it came to be other than to say the temp had obviously risen enough to turn the coolant to steam, and boom, up it went. Bizarre.

Wonder if its' a common fault. Mine's the same 1.8 engine.

Might ring Merc, see what they have to say.

 

[robnut]

Same thing happened to my 328 while sat outside a garage, tank blew off the side of the rad as my viscous was broke.

 

[Dogbreath]

Thats a fair point but how would a driver ever know that theirs has failed, until the car is put under completely unusual 'non-driving' conditions such as sitting idle for 1hr without moving during MOT?

You mean just like being a a very slow moving or stop/start traffic jam then?

 

[Fido McNasty]

Wonder if its' a common fault. Mine's the same 1.8 engine.

Might ring Merc, see what they have to say.

Well I guess the trouble there may be that you just get the cold shoulder a bit because they don't really count for much support as far as dealers are concerned now, however yes, it may be worth a go. And by that I mean there is a common theme here... 1.8 unit, expansion tank atop the rad, MOT with engine running for a long time etc.

I don't know much about Mercs but still, it is a compelling issue given the hazard potential.

 

[matt_fsr]

You mean just like being a a very slow moving or stop/start traffic jam then?

Perhaps, but even in a traffic jam there'd be a bit of movement, and some wind blowing some air. Or you'd turn off the engine so save petrol if the jam was very bad.

Granted, the engine SHOULD be able to handle this situation properly, just unfortunate that it didnt. Age / wear and tear on parts seems to play a large part in it.

If nothing else, Merc may be able to advise garages that this could potentially happen on W202 C-Class 180's, and to check parts before an MOT.