How do you know if your cambelt has snapped?

My car just conked out about 40 yards from home, just got a slight hesitation then a clunk....

I've never had a timing belt go before and wouldn't know what to expect, but this is a diesel engine and once it's started it normally just chugs on with no probs - so wondered if something fatal had happened. I vaguely remember hearing/reading that if the timing belt has snapped, the worst thing you can do is to try turning over the engine...hence I haven't tried to start it again.

Any help much appreciated.

 

I am no expert here so ignore this but I assume you have checked to make sure there are no visible signs of a snapped belt? There should be a few pulleys at side of the engine block if there is no belt there you have your answer. A lot of cars have a seperate alternator belt though so you need to be sure which is which.

I think you have done the right thing by not tryng to start it. I know at least on my dads car you can clearly see the cam and alternator belts and its obvious which is which.

 

What's the make and model of car? Many cars have timing chains instead of belts and these are harder to inspect visually as they're usually inside the engine casing.

 

Do modern cars still use chains? I thought most modern ones use belts now because they are cheaper and less noisy. I know my mates car is chain driven and yep that is inside the engine, you can't see it.

 

My BMW M3 engine uses a timing chain, as does the current M3 and many other high performance engines:

When my M3 engine was having some work done, the timing chain very visible:





Michael.

 

What type of car is it ?

I'd take the side covers off to inspect the belt, most modern cars have belts these days , rather than chains. Some cars have inspection ports so that you can inspect the belt without taking all of the covers off. If so you might be able to carefully revolve the engine crank (bottom end of the engine) and see if the cam shaft pulleys rotate ( top of engine) this will tell you whether the belt is working or not.

Not all cars get the engine trashed if the belt goes. My wifes 8v Punto has a 'safe' engine ( I've physically checked this when i replaced the cylinder head gasket last summer), however the 16v engine will get trashed if the belt goes.

I've been in a Diesel 1.7 Astra when a timing belt went about 5 years ago. We were just accelerating ' reasonably' out of a motorway service station when the car just lost power and stopped, nothing dramatic at all, no loud bangs , etc. There was a small clunk under the car as the tensioner pulley bounced under the floor of the car and rolled down the road .

I'd advise you to phone your local garage to see whether your particular model of engine is a safe one or not. Don't trust the Haynes manual, they say all cars are unsafe - they're not. I've proved this to myself by measurement.

Good luck and hope everyhting is ok, especially if the vehicle is out of warranty.

There are many Car Maintenance discussion groups on the web. Get googling here is one to get you going:
http://www.kelsey-forums.co.uk/cgi-bin/cmm/YaBB.pl

 

so do merc sprinter vans and the ford cosworth v6 engines. better to get a non interference engine where the piston and valves don;t overlap - that way you can snap a cam belt and just not worry about it as nothing bad will happen. the original lexus had this type of engine.

 

Yep the FIAT Fire 8V engines are like that too, if the belt snaps its just a £100 repair job.

My mums freinds belt snapped on her 1.6 Zetec, it cost £700 to repair.

Side and Coke how much of a job of a big job is the head gasket replacement on the 8v Punto 1.1? It is one of the cars I am considering buying but it seems if you keep them engines long enough the head gasket will fail . They seem to be has bad as the K series engines for that.

 

AT, just buy yourself a very cheap car with reasonable bodywork. If you pay pennies if it goes wrong it won't matter. If it doesn't break it will be a bonus. Pay £500 for a car and it will be free after half a year when you think about the cost of finance. You worry far too much about things you don't need to worry about. If the head gasket goes and you can't fix it, get another one.

 

I could have done it within a day quite easily, including getting the Head skimmed, however i was doing mine outside on the back drive last summer and it decided to rain most of the week ! Luckily we only needed one car that week so i took my time and did the job totally unrushed, with lots of rain and tea breaks . As it was my own car and i had a vested interest in it i probably minced about a little more than usual making sure that everything was done absolutely perfectly, rather than just adequately...
Financially it cost me about £100, that's including fitting a new Timing belt and tensioner pulley.

I'll also add that the car started at the first turn of the key, with no leaks either ! :banana:

Funny you should mention the Rover K series engine. It is the only car that i've actually owned that had a timing belt snap on it. The really annoying thing is it only takes about an hour to change the timing belt. I found this out as i fitted one after mine had snapped ( it only cost me £7.50 ) to see if the engine was trashed - it was ! so I scrapped the car as i couldn't be arsed fixing it.

I'm not that familair with Diesel cars, however your problem might not be as bad as you think. The Clunk could just have been the engine/transmittion reaction to a sudeden loss of power , especially if at low speed. Other things that instantly spring to mind with a diesel include a blocked Fuel Filter, or debris in the fuel tank blocking the tank outlet to the filter. There are also some Vacuum pipes on the engine that can often perish, causing the engine to suddenly die , or more normally not start. This happened to my work buddies car ( Vectra 2.0 DTi ) a few months ago. Simply fitting new vacuum pipes solved his problem.

If you are in the AA, RAC, Green Flag , etc, call them out and let them get cold and wet finding your fault, it's what you pay for...

 

AT
According to the AA the cheapest way to own a car is to buy a recently seviced one with a year's MOT for about £500. Run it for a year. THROW it away and repeat.

 

Sound advice, as long as you have the facilities, tools and knowledge to fix it yourself when it goes wrong. I hate paying garage bills...
I don't even bother carrying a tool kit around with me , just my Green Flag rescue card at about £10 per month. I usually have one 'dog car' which gets gradually trashed and smelly due to my mutt and one nicer car that the dog never goes in. so far my Dog car has cost me:

Original Auction Purchase price = £230.00 09 September 2004

Faded paint, no Tax but 11 months MOT. an afternoon with my pressure washer, T-Cut and Polishing machne soon sorted the paint out

Plus the following extra's :- not all of them essential
new wheel trims - £15.99 10 September 2004
Haynes maintenance manual-£14.99 10 September 2004
new oil filter - £3.49 10 September 2004
Blind spot mirror - £2.99 10 September 2004
New Battery - £25.00 12 September 2004
Tesco 10w40 motor oil - 5 ltr - £5.97
New Spark plugs - £7.05 19 September 2004
Alternator Bracket (Scrappy ) - £2.00 20 September 2004
New Alternator Bracket & rubber bushes -£2.87 20 September 2004
New Fan belt - £1.88 23 September 2004
new Timing belt - £7.80 23 September 2004
replacement Alternator (scrappy ) - £15.00 23 September 2004
New Rocker cover gasket - £6.00 24 September 2004
Waterpump tool - £7.99 27 September 2004 - Never used !
new Waterpump gasket, Oil sump gasket & 2 Ltr Anti-Freeze fluid - £5.47 28 September 2004
new Air filter element - £5.00 30 September 2004
Redex fuel Injector cleaner fluid & Molyslip engine oil additive - £5.00 30 September 2004
Window wash pump & Rubber door trim mould - £6.00 30 November 2004
Clutch cable - £7.48 09 May 2005
MOT & Re-test Fee - £35.02 11 August 2005
Exhaust bits, track rod end ( for MOT) - £46.47 11 August 2005
Track Rod Ball joint splitter - £16.49 12 August 2005
1 x New front tyres ( for MOT) - £41.00 16 August 2005
Instrument bulbs ( Clock, thermo, ) - £1.18 18 August 2005
New Petrol Tank - £49.00 27 November 2005

Total So Far £567.13

Not too bad for an older car, I only do about 8 - 9,000 miles per year in this car, and most of them are short journeys, either 9.5 miles to work and back or 3.5 miles down to the beach with the dog .
I'll put it in for another MOT in August, if there's anything major ( or expensive) wrong with it I'll scrap it and get another one for peanuts from the Auctions...

 

The problem with that is you do need to know what you are doing. Stuff like spark plugs, battery, instrunment bulbs, is DIYable but other stuff such as fuel tank is not.

My dads car is going to cost between £150-£170 to get through the MOT it needs:

a new boot lock and catch
track rod end
seat welding

There is still an ECU issue with it but they seem to think it pass the emessions. They said the engine is as good as new even though it has 90k the clock and its well worth getting through the MOT.

Funnily enough my dad only does 9k a year but its all city driving up speed ramps etc.

 

It's a Renault Espace, TD, L reg 94.

I had a quick look after I posted this morning and there were no obvious signs of anything wrong in particular. Didn't manage to get the belt cover off because it looks like a pain in the arse - Haynes manual recommends draining of the cooling system and removal of the radiator before rewmoval of belt cover

I did eventually turn over the engine because I was in a bad mood and thought f**k it, give a try. It sounds a bit strange, not painful or owt, just like it's turning over with little resistance or something. Ho hum. I'm a member of the AA but only 'roadside assistance' cover so may get someone to tow me 1/4 of a mile away, as I've broken down too close to home to qualify for a callout...*sigh*....

Failing that, I may just do my damndest to get the belt cover off without removing the radiator, as I need to know whether I'm barking up the wrong tree....if the belt has snapped and shagged the engine then I'm not spending out on getting it fixed, it'll be a 'spare or repairs' sale!
Fortunately I still have my 318i that I haven't managed to sell yet, so I'm not entirely without wheels, and like all post-93 bmw's it has a timing chain . To be honest it's great driving the beamer after wallowing about in that bl**dy bus.

 

Even without getting the belt cover off isn't there any way you can get a finger behind it just to be able to feel if the belt it still all there?

btw timing chains can go aswell - but they usually last a lot longer before needing to be replaced.

Michael.

 

If getting the cambelt cover off is too much hassle, you might be able to remove the valve cover and watch to see if the cam moves when you turn the engine over via a wrench on the alternator pulley.

It might even be possible to do this via the oil filler cap with a bright torch and no unbolting!

 

There's so little space in the engine compartment that the belt cover is impossible to remove without taking the radiator out first, but after much messing about I managed to poke a biro in a small gap where I could see the cambelt, and it was very slack so I guess it's bust. Ho hum. Local mechanic quoted £90 labour + belt + VAT to replace the belt just to see if it's shafted the engine, and about another £500 (guesstimate) to fix the engine if it's busted. Bugger.

 

It doesn't look very promising, the fact that you've said it was very slack is the givaway, the belt should be uniformly taught throughout its length. It might not be that the belt has actually snapped, they are pretty tough things, it could be that one of your pulleys has crapped out, most likely the tensioner pulley, or tensioning device that the pulley will be mounted on.

Do make sure that it is the timing belt that you found slack though, just in case there is another belt inside the timing cover, some cars have auxiliary drive belts, counter balance belts , etc in there too....

Bad luck, its always the weakest link that wrecks the whole strong chain....

 

Thanks for the extra thoughts.

Well it'll be in the hands of a good mechanic next week so fingers crossed the damage done is fixable within a reasonable price limit - I'll get the belt done if it has gone, it's worth the money to see if the engine is OK or not. If anything else has failed then it'll be a balance of cost vs value + how much I want to keep the car; it's a useful size to use both as a family car and for transporting my work stuff around so I'm hopeful it'll be cost effective to fix it!

 

Cars eh! Who'd 'ave 'em

Mine had to go to the vet today for a new clutch and a new thermostat. As if that wasn't eye-watering enough, they presented me with a portion of one of my coil springs which fell out on the floor during dismantling. Fortunately enough spring remains for it to be driveable but it's booked in to be done next week (along with more eye-watering). Oh well. It's still cheaper than replacing it.

Hope yours isn't too badly damaged.