Rabs

I've been doing a valve adjustment and various seals on the engine. Had previously started the engine with exhaust minus the cat and this noise wasn't noticed. Have installed a decat today and when started this noise was there. It doesn't sound like a blowing noise. Pretty concerned that the knocking could be doing damage to the engine so worried to have it running to try and diagnose. Any thoughts on what this could be?

http://s1168.photobucket.com/user/ra...vkifn.mp4.html

Earlydays

Knocking at idle, or when running under load?

Zingari

Have you tightened the rocker shaft bolts up tightly? Difficult to hear properly on the video clip but there is a metallic tappet sound there?

One of mine came loose resulting in a loud tappet sound. Fortunatley I caught it in time and once re-tighened and clearances checked AIO.

Having witnessed this I'm convinced that this act is what leads to engine rebuilds, noisy tappety engine due to rocker shaft coming loose, lossens further and rocker goes on to foul the cam

Rabs

Knocking at idle. Less noticeable under load I believe

crg53

Have you checked that the cooling fan is not touching the shroud.

Rabs

On further review I have identified that the distributor belt has broken for secondary distributor. Could this account for the noise? I stopped going back and checking the valve adjustment as until this is fixed there is no point. With the distributor belt being broken and the second distributor rotor arm being able to spin freely could this have affected the timing and would that account for the noise?

Earlydays

Does not effect timing, but can definitely cause a knock. It happened to me, though I could only hear the knocking under load, not at idle.

Goughary

Disconnect the coil to the distributor that isn't spinning and see if the noise goes away.

Rabs

Goughary thanks for the advice. Removed the connection from coil to secondary distributor and recorded this.

http://s1168.photobucket.com/user/ra...97uha.mp4.html

I know there is a blow from the exhaust and I still think the valves need to be adjusted properly but it's a definite improvement. Do you agree?

What are the thoughts should I still have the engine apart to check the Pistons etc?

JasonAndreas

For future reference you can avoid all chances of zapping the crap out of yourself (or grounding the coil to the engine which is the cause of the infamous christmas tree) if you remove the low-voltage connector between the ignition coil and the ECU. Instead of the connector between the coil and the distributor.

Undo the connectors at the bottom of the image and ignore the red arrow...

It sounds like a loose valve. A stethoscope will really help pinpoint the valve location to lower/upper and the cylinder. And something like the makes things even easier.

Goughary

Well there is clearly something different from one video to the next...so you already know your disty belt needs to be changed. While that's out, pull the valve covers and check the tolerances...zip it all back up and when the new belt is in, see if you still have your issues. I hope it's nothing serious.

J richard

Concur, Sounds like a mis-adjusted valve. All it takes is to not get your adjustment exactly on the heal of the cam.

A small bit of hose can work as a stethoscope in a pinch. A mechanical tap can be separated from a exhaust leak by resting a long screwdriver on the valve cover and against your ear. Listen for the loudest tick and you can narrow it down.

Rabs

Thanks guys I will get the dizzy fixed and check the valves again and pray!!

VR6-er

Matt cut your losses, I'll give you 18k for it and a curry.

HiWind

bump for this one ... although there are about a zillion knocking noise re fan/alternator bearings etc...
Did you solve it?