Knocking smokey PD engine

[Gordon Harrison]

My td130 estate has an AWX engine with 200k on the clock. It was running fine until it suddenly developed a suck and blow noise through the air filter; this got worse and now it Knocks badly under any load and chucks out a lot of smoke. The tick over isn't bad but as soon as it revs the engine knocks badly and vibrates like it's running on 3 cylinders. There is quite a bit of pressure coming from the engine when the oil filler cap is removed. I changed the engine wiring loom but no change. When the connectors to each injector is removed there is no difference between the noise on each cylinder. The local garage tester (not VAG) revealed no fault. There is no loss of oil or water and no overheating.

I suspect a blown head gasket, or maybe a valve problem. Anybody got any ideas before the head is removed? Thanks.

[martin1810]

Maybe the cam belt has slipped one notch. Have you looked under the cam cover to check for cam damage/ injector damage. Where in the engine is the knocking coming from and how fast is it compared to revs. Cams tend to knock twice as fast as cranks. Is noise just diesel knock.

[Gordon Harrison]

Thanks for that. I'll go check out the noise source. Trouble is that I don't know what diesel knock is supposed to sound like! Any place I can hear it?

[martin1810]

I can't describe diesel knock, it's the equivalent of a petrol engine "pinking" but sounds more like a knock. That would suggest timing has moved. Engine noise is very hard to diagnose and worse if you are only describing it. Good luck.

[Gordon Harrison]

The knocking sounds like it's coming from within the engine block not the head. There is a corresponding suck and blow sound coming through the air filter and it runs like it's lost a pot.

I've had the cat off - no difference, and am off to get a new fuel filter right now.

Thanks again for your input.

[martin1810]

Might be worth getting the cambelt covers off and checking that everything is lined up correctly. Another thing to try would be a cylinder leakage test or a compression test. I find a cylinder leakage test more useful.

[Gordon Harrison]

Everything seems OK under the cambelt cover, and the belt seems in remarkably good condition considering it has done 45K miles.

How do I test for compression or leakage; where can I get the tool required? Sorry to be pest.

[martin1810]

You will need a garagewith the equipment. You take out a glowplug and fit adapters. Compression test....turn over engine and adapter measures pressure in cylinder on a pressure guage. Leakage test. ..Engine doesn't start..you pump up the cylinder with compressed air and measure how much leaks out. Leakage test is best because it tells you how good the cylinders, piston rings and valves are and by listening you can work out if the valves or rings are the worst leak. If one cylinder is much worse than the others, you know where the problem is. The cam belt needs to be set with timing pegs to make sure it hasn't slipped a notch. Just because it looks ok, don't mean it hasn't moved.

[Gordon Harrison]

Thanks for the really helpful and interesting reply. I'll start with the cambelt check and take it from there.

[Gordon Harrison]

Cambelt is perfect. New fuel filter makes no difference. I still suspect that the head has to come off. See if this video link helps:

http://s378.photobucket.com/albums/o...=SickPD001.flv

Bye for now.