Valve knocking a idle?

[89whitepkg]

Background: Engine making a ticking at about 1500 rpm, before and after it stops. And a knocking at idle.

Thoughts: either rod knock or valve noise.

I have checked the cylinders by pulling each plug and the knocking does not go away. It sounds like it is coming from the front of the exhaust valve cover.

Can a poorly adjusted valve cause a knock at idle?

Thanks guys

 

[whitemike]

You say knock, but if it's valve train noise I feel like it would be more of a tick, a higher note than the deep "knock" of a rod against a loose bearing. I vote for taking a stethoscope to the valve cover, or popping the valve cover off and seeing if you popped a shim out.

Hopefully a vet will chime in with some hands-on experience. Maybe what I've recommended can give you a starting point.

Good luck!

Mike

 

[89whitepkg]

I put a screw driver to my ear and put it on the valve cover and I could feel it on my ear. Can a shim pop out that easy?

 

[aznboik1mva]

any smoke, weird idle?

 

[89whitepkg]

no smoke smooth idle.
Okay so I just unplugged and reseated all the wires at the coil pack....knock stops. So i drive home, get home and the knock is back but very faint.
Could a fault in the ignition system cause a knock?

 

[CBatstone]

I am having a similar issue. At idle only an irregular loud metallic knock or detonation is heard. It goes away when the revs come up slightly, but is getting really bad at idle. It affects the idle speed (it drops) and will sometimes do it in rapid succession then be fine and idle quietly for a few seconds. One wet night this week it went away entirely. I was at the track today and had others listen and they guessed it to be an ignition problem possibly a bad coil or maybe.go with a colder plug. I'm going to check the coil specs tomorrow. Does this sound like your issue?

I have a 7m gte BTW

 

[suprafanatic]

post a video of the sound. usually very easy to tell if its rod knock or valve noise.... to people that have had the pleasure of experiencing either lol

 

[aznboik1mva]

a friend of mine was telling me something about if the egr is leaky it will knock or something like this, somebody please correct me if im wrong

 

[89whitepkg]

Supramania,
I come before you today humble and ashamed, but I will not let my pride stop someone else from learning from my errors.
After of hours of inspection, and several sleepless nights pondering the possibility of rod knock I have found the answers I was seeking.
After listening around the engine and coming up with nothing I removed my timing cover, as that is where the sound seemed to be originating from. Still nothing seemed out of place. The next day however my young brother noted that the timing belt looked loose…he was correct. (Hang head in embarrassment)
So, after addressing the loose timing belt, low and behold, the problem has been solved!
Thanks guys for the input as always and hopefully someone else will learn from this.

 

[suprafanatic]

glad you found the problem, did you check your timing after this?

 

[boostcraver]

Even the best mechanic can overlook something from time to time so don't get too down on yourself. Glad for you that it wasn't more severe. In two BHG replacements and one engine swap I have managed the following: left out upper to lower intake manifold gasket, installed CPS backwards (x2), mis-aligned cams by one tooth, left the ecu ground disconnected, forgot to tighten numerous clamps, forgot to replace the injector seals and o-rings (leaked like a mother) and forgot to fill fluids before start-up. That last one was the reason for the swap, lol! Nothing like doing all that work to fix the HG just to fry the motor on start-up due to lack of oil! Talk about your I-feel-like a-dummy moment.