The Importance of Cam Belt Changes

[Tonka777]

Took the head off of an old(ish) Iveco Daily van at work today, to investigate a suspected engine seizure. The only info from the customer was that he was driving along, when the van ground to a halt with a big noise.

The mess i was confronted with the head removed was the worst i had ever seen, and illustrates the point of making sure your cambelts AND tensioners/pulleys are changed at the correct time.

Pics;

The head. No.1 Cylinder is on the right, one valve is completely missing, the other has lost its stem and the head has turned upside-down;



Close up of No 1 cylinder valves (or lack of) The roundish lump just beneath the centre is the injector. More than half of the valve seat of the left valve has been smashed out and deposited in the top of the piston and in the head. The square/sharp looking lumps are the bits of valve seat.



The Block, No 1 at the front with what is left of the piston, with bits of valve and valve seat hammered in for good measure. No 4 at the back, which has sucked in a lot of the debris from No 1, indicating a fairly high engine speed when this happened.





No 2, which has also made contact with at least one valve. The circular indent on the right is where the valve hit, the indent was 3 or 4 mm deep. The hole in the middle is the combustion chamber, the injectors sit above this. No 3 was similar.



It would not be economical for for this engine to be repaired, not only are most of the pistons damaged, but it is possible that the crank shaft might have been bent, and it is quite probable that the block would need to be skimmed too once the pistons have been hammered out of the bores.

Anyway, I found the sight interesting, and I thought some of the Hexus.PetrolHeads might be interested to see what could happen if a cam belt breaks.

*The cam belt hadn't actually broken on this engine, but it had definitely jumped a few teeth, possibly due to bottom end seizure, or possibly due to a valve failing and dropping in to the engine. The damage shown could be worst case scenario of a cam belt breaking at high engine speed on an interference engine, either way, its new engine time for this vehicle.

[abaxas]

Great post on the dangers of lack of car maintenance or what can happen when things go wrong.

[GoNz0]

glad my straight 6 has a timing chain!

[finlay666]

Glad mine is in for service next week, first proper service since I bought it and know I need to get other stuff sorted like the water pump

[1stRaven]

yeah mine too.

I have replaced an engine with a cam belt failure before. Housemate replaced his power steering pump, spilled atf fluid over the aux belt. Left it overnight, then he drove into work the next day. Aux belt snapped, got caught into the cam belt at the bottom pulley and made the cam belt slip around 8-10 teeth.

Took us the weekend to replace the engine (luckily, had a spare one in the garage).

I'll try and find a picture but one of the valves punched its way through the number 1 piston.

[abaxas]

glad my straight 6 has a timing chain!

Just as many stories of timing chains which have jumped a tooth.

[GoNz0]

Just as many stories of timing chains which have jumped a tooth.

would love to see you prove that m8.

[abaxas]

would love to see you prove that m8.

Maybe ask the OP! He'll tell you.

[peterb]

glad my straight 6 has a timing chain!

QFT! (Unlike the newer BMWs that I think have belts

Years ago when I had an Ford Escort XR3i, I was travelling up the motorway when the waterpump seized - stripping the cam belt. I was lucky in that I 'only' needed seven new valves...

Just as many stories of timing chains which have jumped a tooth.

Not if the chain tensioner is maintained and the correct tension applied.

[Konan555]

Just as many stories of timing chains which have jumped a tooth.

I've seen a tooth jump.

I've seen them snap and I've seen them completetely abandon the pully after a tensioner failure or a worn tooth. The chain alone can make quite a mess!

The main problem with chains is that people assume they'll last forever and ignore the warning signs.

[jon bda]

Had a Transit van dragged into work the other week with the dual mass flywheel failed. Towed it onto the ramp and replaced it all...job done...or so i thought.

Fired it up to test drive and it was running like it was gonna shake itself to bits and missing like a pig...stripped it down a few days later to find out what was going on...



Should all that be in there?



Whoops!!!



Thats the bit that got my hopes up...saw that after stripping the rocker cover off, rocker shafts were loose and sitting so far off the valves they weren't opening #1 and barely opening #2.

And to think the poor guy was moaning about having to pay for a new clutch and flywheel!!!

[Agent]

Great pics guys.

I would add my own from a recent engine rebuild (purely a side project, did it over 6 months) from where the engine ran dry on oil and seized the engine, but I didn't take any

It's a bit of a long story of why it happened, but it ended up destroying the bearings between the crankshaft and the connecting rod, which in turn damaged the crankshaft itself.
If the crank had been ok, it would have cost next to nothing (apart from time) but sadly the cranks for this model of engine were not cheap or easy to get.

The engine was extremely low mileage, so it was worth a punt...and after 6 months it fired up like nothing had happened first time. Have to say it took longer than I wanted, but I learnt so much about engines and there isn't much I wouldn't be happy doing on a vehicle these days.

I still have the crank and broken parts though so I'll dig them out and add it to this thread when I get a sec

[peterb]

<---snip the bearings between the crankshaft and the connecting rod, snip--->

AKA the big end bearings.

[Agent]

That's the ones - You know when you have it on the tip of your tongue but just can't remember?

[Lucio]

So if your engine is making a flappy noise that goes away if you put a little light oil on the cam belt, it's time to get it changed

[Tonka777]

Jon, that's a really messy sump, any indications as to why the webbing failed? I'm sure you now already, but you can revert the Transit back to a solid flywheel to keep the costs down, but the they judder really badly afterwards. They do seem to last though, unlike the Vauxhall's which seem to eat clutches every 10k after being converted back to solid.

I've had little experience with timing chains, but yes, they are just as likely to break and cause damage if the engine is not maintained. I can't imagine a chain skipping a few teeth though, unless it has lost tension or the sprockets have damaged teeth.

Finlay, yes it is very much worth getting the water pump changed at the same time as the belt and tensioners. Very good point. A lot of belts break due to the water pump breaking up or seizing.

I would not recommend putting oil on your cam belt Lucio. Most cam belts are covered up an a fairly well sealed area to prevent contamination from oil or other fluids which can make a mess of the rubber in the belt and cause premature failure. Are you sure you are not thinking of the aux/fan/alternator belt? Generally i go with manufacturers recommendations for belt change intervals, unless the engine is having other major work which makes it easier to change the belt and tensioners at the same time to save time later on. Post a pic if you like, its fairly easy to see if a belt is worn or damaged.

Looking forward to seeing any other pics of broken engines anyone can find. I'll get some pics of the really bent valves from another Iveco head next week, when i have finished beating them out of the guides!