Noise on One Cylinder, Sounds like a knock... Options

[sgetsiv]

The engine was noisy so I adjusted the valves. I also replaced the push rod tubes and used new Vitron seals. I thought I had valve noise but that wasn't the case.

I then isolated the knock to Cylinder #2 by pulling each spark plug wire. Using a stethoscope with a tube to listen, it was clearly an exhaust leak right at the head.

I have a set of Triad headers on the car so it should be pretty easy to pull the drop and check everything. Of course, this is also the head where I had two poorly repaired exhaust head studs. I retapped for 10mm and used step studs I got from Auto Atlanta.

The other common symptom I have is backfire on decel, of course. This is typical with an exhaust leak.

So hopefully it will be obvious when I pull the drop. I've already tried tightening the drop to get rid of the leak but I think something is messed up with the copper washer (which was annulled) or possibly the head itself.

Just thought I would post in case some one else was experiencing something similar.

Ya, I'm a newbie so even though I owned a 914 for 4 years back in the early 80's, I am relearning everything.

I'll post again once this is resolved or if I can't get it sealed.

[sgetsiv]

Got it sealed. There was a 2mm chunk of aluminum right on the outer edge of where the washer fits; it was impeding the complete seating of the copper washer.

Now, it is on to hunting down the rest of the engine noises. Valves are adjusted but still not as quiet as they should be.

Could be some intake noise as well - running a single carb. I don't even know what kind it is.

I am thinking of installing a Raby kit this winter and switching to dual carbs.

I guess I should buy the carbs from Jake since I want to use his engine kit, eh?

[wertygrog]

I just pretend I don't hear my angry engine noises. Your mileage may vary. (IMG:style_emoticons/default/wink.gif)

[Mark Henry]

T4 engines are noisy and they do sound a bit like they're knocking, it's normal.
It's if the knocking sound get louder and louder then it's time to say OH-OH!

Your single carb does suck, but dual carbs won't stop the noise.

[rjames]

T4 engines are noisy and they do sound a bit like they're knocking, it's normal.
It's if the knocking sound get louder and louder then it's time to say OH-OH!

Your single carb does suck, but dual carbs won't stop the noise.

Jack stands will. (IMG:style_emoticons/default/happy11.gif)

[r_towle]

T4 engines are noisy and they do sound a bit like they're knocking, it's normal.
It's if the knocking sound get louder and louder then it's time to say OH-OH!

Your single carb does suck, but dual carbs won't stop the noise.

With dual carbs and a decent stereo you wont hear anything..

Rich

[Jake Raby]

Do not ignore the noises. The engine is telling you that it's sick and if you ignore it's symptoms you may have enough parts left after the imminent failure that could be waiting just around the corner for you. If the noise goes away when a spark plug wire is pulled it's not normal.

Find the problem before it finds your wallet in a big way.

[sgetsiv]

Last weekend's work: Dual carbs (Empi 44mm's from Jake) installed. Mallory Unilite installed. Triad headers pulled and re-installed with new gaskets. Tightened down header drops without breaking any exhaust studs.

Still had noise but couldn't tell if it was exhaust, valves, or something inside.

So I had my neighbor come take a listen. He's the proud owner of a 1987 911 - he spent a year rebuilding the engine. He says valves, so we popped off the valve covers and started adjusting.

Some of the rockers themselves had a little slop - you can actually pull outward on the top of the rocker and get a few thousandths more clearance. I adjusted the exhaust valves down so they were tight with the feeler gauge in, being sure to pull outward on the top of rocker.

No more noise! Finally. I've driven the car 5 or 6 times this week and everything is working great.

Next step is to fine tune the carbs. Still waiting for my Synchrometer tool to arrive.