Worn cambelt - symptoms

[blugnu]

Had my car in for a service and a look over as it's new to me but old in miles.

All is good except the trusted mechanic says the timing belt is really badly worn - he could see bits of belt so he took the covers off and has advised I don't drive it - it's getting done on Monday.

Just wanted to check (as he sounded too busy on the phone and didn't want to take up time) my suspicions that a worn/slipped belt could explain a few other things about the car (the engine is a 2 litre HDI in a Picasso)

1) makes a weird noise when it's cold (suspect water pump - also suspect this wasn't changed when the belt was last time. Belt isn't 'officially' due for 50k miles)

2) it's fine to start during the day but in the morning it's odd. It really struggles to turn - very slow - but then after a few seconds is picks up speed and then starts - momentarily releasing a pall of white smoke and then settling down and emitting no smoke. I had thought this was the battery, but it's fine starting during the day, and the fact that it turns over more quickly the longer you leave the key held doesn't fit with the battery being depleted.

3) it doesn't do the mpg I was expecting - it's 'missing' about 10-15 mpg. Obviously oil and filters will help here too.

Hopefully I'm going to get back a car with all these issues resolved too - mech says that otherwise it's in good order. How do you rate my chances?

(very odd to be without a car for the weekend though - can't remember when last that happened!)

[Steve_D]

I doubt a 'Worn Belt' would contribute to any of those symptoms.

Steve

[Krikkit]

A worn belt and tensioners might give the first, but the others I doubt (unless the timing is slightly out for consumption).

[Mr2Mike]

blugnu said:

2) it's fine to start during the day but in the morning it's odd. It really struggles to turn - very slow - but then after a few seconds is picks up speed and then starts - momentarily releasing a pall of white smoke and then settling down and emitting no smoke. I had thought this was the battery, but it's fine starting during the day, and the fact that it turns over more quickly the longer you leave the key held doesn't fit with the battery being depleted.

This is a possible symptom of a failing head gasket. A slight leak between the cylinder and a coolant passage which allows pressurised coolant to seep into a cylinder when the engine is stopped. The greatly increased compression ratio from the incompressible coolant causes the sluggish turning over, and the whist smoke can come from anti-freeze burning off. If you engine uses a water cooled EGR valve (and I think the HDi does) then these can also fail and cause white smoke from coolant. Dropping coolant levels will point to this kind of problem.

White smoke is also caused by unburnt diesel, which could be down to duff injector(s), low compression or bad injector timing (very unlikely on a common rail engine). A very sluggish starter could fail to get enough compression to ignite the fuel which would cause white smoke - so a check of battery cables, terminations and ground points might be a good idea.

[blugnu]

Thanks all - it came back from it's service and check over in much better fettle. The mechanic has noted that one of the battery cables was loose, so he's tightened it up. It starts much better now (and he showed me the pictures of the old timing belt - caught just in time, there were bits falling off all over it!)

[blugnu]

Mr2Mike said:

White smoke is also caused by unburnt diesel, which could be down to duff injector(s), low compression or bad injector timing (very unlikely on a common rail engine). A very sluggish starter could fail to get enough compression to ignite the fuel which would cause white smoke - so a check of battery cables, terminations and ground points might be a good idea.

It's much better now the connection has been tightened up - my theory is that in the very cold nights, the terminal post was contracting more than the clamp, so it was an even worse connection until the current warmed it up a bit. No idea if that is plausible, but I like it

[davepoth]

blugnu said:

Thanks all - it came back from it's service and check over in much better fettle. The mechanic has noted that one of the battery cables was loose, so he's tightened it up. It starts much better now (and he showed me the pictures of the old timing belt - caught just in time, there were bits falling off all over it!)

Loose battery cable would possibly cause some of the problems you mentioned-the fuel injection gubbins take a lot of amps, and if the battery cable was loose there would have been a bad connection. I guess there wasn't enough current until the starter had cranked the engine all the way up to full speed and the load was reduced a bit.