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[Tezray]

Well after all the work i've put in it would appear my MV6 has died I had been driving it all day, then this afternoon when pulling away from my friends house it felt very down on power, there was a loud hiss like a burst pipe and the engine died. I thought at first it was a burst lpg pipe so I tried to restart on petrol. When I turned the engine over though it just span making a whirring noise like there was zero compression 

The AA man came out and agreed there seems to be no compression but refused to do a compression test on a V6! I've checked the timing belt and its on and tensioned and no sign of stripped teeth. When the engine turns though it appears there is zero compression  :-? it just whirrs round. I've checked the plugs and they're all in. I'm really confused to be honest but I do think its terminal... I still dont understand what the loud hissing noise/burst was and the brake pedal also went instantly hard and unresponsive.

Any ideas anyone?? As the compression isn't there I can only imagine the belt has slipped. It's not due for its 40k renewal for another 4k miles. It's looking like I may be breaking it if it is terminal...

[Matchless]

Undo the top cambelt cover screws and prise the cover open slightly, then get someone to turn the key to see if the belt is moving.
If no...there is your problem..stripped teeth on the belt.
If yes then check the timing marks all line up, but you need to remove the cambelt cover to do this properly.

[Brikhead]

As the compression isn't there I can only imagine the belt has slipped. It's not due for its 40k renewal for another 4k miles.

It's easy enough to check if the timing marks are all still lined up and the timing belt renewal schedule is dependent on time as well as distance...

[Bionic]

Hope you have not persisted in trying to turn it over if the belt is out of sync cos you will probably have damaged the valves......but if you have you have nothing left to lose.
As with all problems, start at the begining and work to the end. Maybe silly but have you looked to see if the crankshaft turns when you operate the starter?
If not it could be the starter motor/flywheel that is the problem cos they have been known to strip flywheel teeth.
If the starter does turn the engine over then the most likely problem is as already said - stripped teeth on the timing belt...
Unless you turn the engine over by hand, there is no shortcuts either, using the crankshaft you will not be able to fully examine the teeth and it only takes a few missing to stop it turning.
 

[activamad]

If the timing is out any damage will have been done when it cut out any amount of cranking won't make any difference valves only need to hit the piston once to bend and that will have happened when it stopped.

Wonder if with the hissing noise whether the exhaust is blocked?

[old git]

Maybe wrong but hissing noise and hard brake peddal sounds like the vacum pipe for the servo has fractured .i think the pipe connects on the plenum chamber rear right as you look at engine.
A maybe???

[old git]

just digging into mine and there are also 2 small vac pipes  on the servo pipe to the left of the plenum just before the inline filter /valve probably feeding the(crap)stuff on the back of engine.so if there is a leek on that part if will take a few things down.
I've got to change plug leads ,one defo burnt through ,probably do dis pack as well while i'm at it

Dave

[Tezray]

Sorry for the late reply guys. I've been out getting the timing belt cover off tonight and it's not good news, as expected 

The timing has come out and cranking it over by hand it's obvious that there is piston/valve contact. The belt, rollers and tensioner are all intact, however I can only assume that the tensioner is not applying enough force anymore. The timing belt kit was replaced in May 2008 at 81k miles and it has now failed in July 2011 at 117k miles, how pants is that  I can see the marks on the belt teeth where it has slipped over the cam sprockets, but otherwise the belt and teeth look in excellent condition;









Looks like Wots will be breaking for parts 

I could repair it I did a top end rebuild on my ex-plod mv6 when the drivers bank headgasket blew, but I don't have the time and i've already thrown enough money at it so I think it's the end of the road...

[TheBoy]

Is that with crank set to tdc?

[Tezray]

No TB, I just looked at the alignment of the cam sprockets. If the cams are clearly out though, what difference will it make? Valve/piston contact has definately taken place.

[Matchless]

You have to turn the crank to TDC before you can see if the cam timing is out, the marks on the belt only line up once in a blue moon.
There is a notch on the crank sprocket which should point downwards and line up with a mark on the alloy. #1 mark on the left hand cam wheel should now line up with the backplate notch, #2 mark on the 2nd from left camwheel etc etc.
If #1 is miles out, turn the crank through one complete rev and try again.

[Bionic]

Is there any vacuum at all in the main line to the Brake servo? Maybe the internal diaphragm has burst which would explain the hissing.
Can I be the only one who looks at the pictures and sees that the belt appears to be not as tight as it should be? There seems to be a lot bend where it should be straight as a die between the pulleys. Maybe the belt tensioner had slipped or was not adjusted correctly in the first place.  If that was the case then a rapid pedal to the metal and huge increase in torque would make the belt jump the teeth.
Never forget that not all spanner wielders are as good as they would like us to think they are. I have been down that road myself and now have no more worries because I use only one guy to do mine (mentioning no names but he loves pink and R.A.)
Hope you get it back on the road with your pockets relatively intact and few tears.......