Ideas on engine failure?

My Octavia (1.8 20v petrol) broke down on Friday night. Ran for 5 miles, parked up, got back in 10 mins later, and there was a diesel type rattling for 5 seconds, then the engine died. Tried to start again, but it just turned over fast, as if there was no compression, or the cambelt had gone.

I presumed it must be the cambelt, but on inspection this morning, the cambelt is intact and turned fine. There is the opposite end cam chain on these engines, which may have failed, though unlikely. (the cambelt runs only the exhaust cam, then there is a chain at the far end to run the inlet off the exhaust cam).

What are the likely faults? Some I can think of are cambelt skipped a tooth or 5, and valves now bent, so no compression. A holed piston, though as there seems to be little compression, it is unlikley to be this unless all cylinders are holed. Head gasket split badly, though that seems unlikely to cause such a big failure, with no clues to its demise beforehand.

I cannot see any way of finding out the fault without taking the head off (apart from a compression test, which will not tell a great deal I think). Are there any other tests I can do before stripping it down?

Thanks Alan.

Reply to
A.Lee
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Quite possible that the cambelt has torn off some teeth and then caught again and continued turning, I had a peugeot diesel that did that, luckily without damage. So you need to actually check the cam timing. turn it to tdc (there is a mark on the pulley or on the flywheel teeth or both) and check that the cam mark lines up at the top, if it doesn't then turn it to the tdc again and have another look.

honest john remarks: "Plastic water pump impellers on early 1.8 20v engines fail flinging off timing belts. Newer water pumps have metal impellers. 1.8 20v engines can snap their timing belts at 70,000 - 80,000 miles and the extensive damage this causes is not repairable. The car will need a replacement engine. 1.8

20v timing belt drives waterpump and belts are difficult to replace on transverse engines (£500 job).

All engines need new timing belts, tensioners and on 1.8 20v waterpumps every 4 years or 60,000 miles whichever comes first. TDI waterpumps also prone to failure, but driven by an auxiliary belt so not so much of a disaster. Essential, however, to replace all ancillary belts at the same time as the timing belt because if they break the can interfere with the timing belt at take the timing belt off."

So I am afraid it doesn't look good.

Reply to
Mrcheerful

Well, yes, I am debating whether to scrap it, ebay it, or repair it. I replaced the cambelt 18 months ago after a tensioner failure. That time there were only 3 valves bent, despite it running for a minute or so.The downside was that the waterpump was not replaced then, so it may be that that caused this failure. It looks like I'll have to strip it down to see the fault. Ta Alan.

Reply to
A.Lee

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