I fear the worse. My daughters 500 MJD broke down last night. The AA towed it back to her house as it was late, but in his opinion its the timing belt snapped.

However, is this the end of the car. Its done 100k, its 11years old, but it has many new parts over the last couple of years. Will pistons have met with valves etc, or, can i put a new belt on and re-time everything? Or, do i look for a write-off with a good engine?

Easy to scrap it and look for another but 50 years ago men walked on the moon (allegedly), not because it was easy...

These engines have a chain, but its not impossible that the chain has snapped.

These have sacrificial rockers between the valves and the cam shafts, if the cam chain snaps, then the rockers break, hopefully saving the valves from damage. its a belt and braces approach for such a little engine but does mean its likely redeemable.

Thanks for the quick reply. She loves the car and if it can be fixed then that would her preferred option. Obviously if its £700+ its not economical to repair, but I feel better already. It has been an emotional roller coaster with this little car.

Ah.. fix it. £700.. what will you get for that?


Ralf S.

It's very rare they just snap
They are normally very rattly for a while when they get worn so give plenty of indication

What were the symptoms?
Did it turn over at all?
Any indication of it firing up?

HI, she wouldn't know if it was rattly or not, but I heard her drive off a couple of weeks ago and it didnt sound like it was about to break.

She was driving up the M1 last night when the car juddered a bit.she started to lose power so she pulled in to the left hand lane but it wouldnt accelerate. So she pulled off on to the hard shoulder and engine warning light came on so she turned it off for a couple of minutes then tried to restart it, but it wouldnt start and she didnt like the noise. AA guy cmae and ran a diagnostic and said it was the fuel pump. They took her home and left it on her drive and came back today to tow it to a garage, he had another look and tried starting it and concluded the timing chain must have snapped. She mentioned something about using some sort of spray to check whether it was electrical or mechanical fault, I've never heard of this before.

I'm going to look at it now, does any of this sound familiar?

Definitely didn't sound like a chain snapping
That would likely just stop dead no losing power it would just stop running
A fuel pump Definitely sounds more likely or some other fault with the fuel system


And I assume it was using something like easystart spray to see if it would run on that

Work I would say

chris3234 said:

Definitely didn't sound like a chain snapping
That would likely just stop dead no losing power it would just stop running
A fuel pump Definitely sounds more likely or some other fault with the fuel system


And I assume it was using something like easystart spray to see if it would run on that

Click to expand...

It was easy spray. I'm going to take the oil cap off and turn it over and see if anything up top is moving. If nothing moves it must be the chain. If the cams turn then I'll look at where the fuel is present. There is no oil or fuel under the car and I'll have a good look and feel around for leaks. Can the fuel pump fail and not leak?

chris3234 said:

Definitely didn't sound like a chain snapping
That would likely just stop dead no losing power it would just stop running
A fuel pump Definitely sounds more likely or some other fault with the fuel system


And I assume it was using something like easystart spray to see if it would run on that

Click to expand...

kinda perfectly sounds like what happens if a chain or belt snaps, going along on a motorway, you'll just find the car no longer works the engine will still clatter away if in gear and you'll eventually roll to a stop.

greg pdu said:

I'm going to take the oil cap off and turn it over and see if anything up top is moving.

Click to expand...

you won't be able to see anything there are baffles in the rocker cover that stop the cams throwing oil out the filling port.

Realistically if you suspect a cam belt or chain has snapped the one absolute thing you should 100% never do is try and start it any more, once its stopped, (as in when it broke down) leave it till you can get a cam cover off and look.


Worth noting that the fuel pump is run off the far end of the cam, so the error messages on diagnostic may have included a warning about the fuel pump.

It doesn't sound terminal to me.

If the beast just ground to a halt on the motorway, then that *could* be a "belt" (or chain) failure but it could also be a fuel pump failure.

Normally I would suppose that "The most likley thing to go wrong is the most likely thing to go wrong" so that means it's more likely that "something else" packed up, rather than the belt/chain broke.

I would start from first principles. Turn the engine over by hand (socket on the crank pulley nut) through 720 degrees, to see whether there is any hard resistance to the engine turning over, or any noise to suggest that there are loose bits of metal in there that even duct tape is not going to be able to fix.

If it all feels/sounds good ("too easy" to turn over by hand might not be a good thing) then give it a couple of cranks with the starter to listen to what it sounds like. No clonking or grinding or rattling is the correct answer.

If it turns over normally then check the fuel flow at the fuel rail. You could have a failed high pressure pump or you could have a failed fuel pump (the one in the tank).

If there's no fuel at all it's more likely to be the one in the tank.. (or a fuse or a relay or the fuel shut-off valve etc.) If there's some fuel but no pressure then it's more likely to be the high pressure pump.

Meanwhile, as you go, look for the obvious. If the HP pump pulley turns but the spindle into the HP pump doesn't... then that's the HP pump.. etc.


Ralf S.

Would MES not give any clues to this with the ignition on?

It might, so it's worth a read... but the MES only looks for abnormal or missing sensor readings. If the fuel pump in the tank is knackered then the brains won't know, since there's no sensor to tell it that the fuel pump isn't working.

On the other hand, if something is supposed to give a signal (it sounds from the above thread that the high pressure pump is supposed to register every time it goes round?) then a failure of the pump to go round would be noted.



Ralf S.

Hi, well its a broken timing chain. She has the radio on so loud she wouldnt notice a rattle!

So pricing up a replacement kit, oil and filter change and new water pump whilst you are at it, £300, and thats not taking in to account any damage to other bits.

there is a whole engine available thats done 64k for £600 delivered, with 3 months guarantee. Thats tempting....

Sorry to hear that, seems all the signs where there.

Also you'll want to change the oil pump and various seals while doing it. Chances are that a few of the rockers will have broken hopefully saving valves, you can get whole kits of all the rockers for about £90 or the tappets and gaskets as well for about £130.

The Cam shaft will need close inspection to make sure it hasnt got a rocker imbedded in it, The £600 engine may seem tempting, but its also an unknown commodity, you may want to change the chain on that new engine as well just to be on the safe side.

We are hoping to have it all back together tomorrow, then the moment of truth, turn it over and hope it fires up. Then hope we don't get any warning lights.

We bought a complete timing chain kit, including new rockers. Injectors cleaned and new seals. Camshafts cleaned and inspected. All valves moved nicely, proving the sacrificial rockers work! Didn't change the oil pump.... Yet. I'll price one up

It's back on the road

We had a bit of a scare, after tightening the crank bolt (left handed thread) we took out the locating pins and tried to turn it over by hand..... It wouldn't budge!!! Had to slowly strip it back to find the problem. The two years at the top didn't quite mesh and so locked against each other. Bit of jiggling and carefully rebuild.

Sounds and runs as good as ever. Thanks for everyone's advice and comments. Hopefully we get through the next 6 months without more drama, this will mean time and money well spent