G50 3.2 Carrera Tapping sound
 

Hey everyone, currently working on my 87 911 Carrera 3.2 that sat for 21 years. We’ve replaced soooo many things like: fuel tank, fuel pump, flushed the fuel lines/hoses, injectors, plugs, all filters, ignition coil, distributor cap, ICV, alternator, belts, o2 sensor, and adjusted the valve timing for exhaust and intake. No oil leaks so far but the idle surges. It used to surge a lot (up to 2-2-5k rpm) but now it’ll increase and decrease from idle by ~400 rpm.

The bigger area of concern is the tapping sound at idle and lower rpm’s. I attached a link video of a cold start and idle. It sounds like a top end issue since it’s a higher pitched tap rather than a knock. Would love some input on the severity and some ideas on what to check/ or change. TIA

https://youtube.com/shorts/EWHfv3t-DOU?feature=share

well? it definitely sounds bad..i would not even drive it.
You have to do valve adjustment--who did this-as you say adjust valve timing exhaust and intake..??
Did they know what they were doing?
Anyway..that is 1st thing you should do by a mechanic who knows how to go about it...after it`s quite possible you have broken one or 2 valve springs by the sound of it.
But ,as i said 1st adjust the valves

Ivan

We did the valve adjustment (using the feeler gauge to adjust the clearance) and definitely took our time and very confident we did that correctly. Made sure the crank was at the correct position for each respective cylinder. However that’s as far as we went.

ok ,let`s assume you did it correctly..next would be to use stethoscope and pin point where exactly is the noise..my guess as i was saying you might have a broken valve spring or 2...

just don`t drive it..that could be more problems to come

Ivan

Thank you for the advice. We didn’t check the valve springs too closely so that’ll probably be the next step on top of using a stethoscope to help pin point the issue.

Thank you

We got a stethoscope and think we pin pointed it to the exhaust side on cylinder 6. Valves for cylinders 1-3 sounded perfect. Going to take the valve cover off tomorrow and find out. First time using a stethoscope and had no idea how well they work.

Also- after hearing the engine in person after listening the video… it sounds much worse in the video. Not as noticeable in person.

BlueG - I'll be following this thread with anticipation. I think I may be experiencing similar issues.

My 83 SC sat for 3+ years. I just got it started two weekends ago, after: dumping old fuel and adding fresh/new, and replacing: fuel pump, fuel filter, oil change, spark plugs, distro cap & rotor.

Once I got it started, it belted out loads of black smoke, and idled very rough. I also hear a clattering noise. The idle could be due to vacuum leak, so I'll be chasing/checking that. But the clatter is worrying. Could need valve adjust or something else. Check out my video here at the 1:35 mark: https://www.youtube.com/watch?v=GOm80FNjPGM

QUESTIONS: where did you buy the stethoscope, which one, and where to apply on the engine to listen?

Thanks!

your engine is running on 5 cylinders.I would suggest to locate the death cylinder 1st.
To locate the death one unplug one at a time spark plug connector.If the running of the engine does not change that will the one.
Also you idle is way too low you need to increase that.
When was the last time you check your engine distributor timing.
But 1st replace the spark plugs.Remove all the heating pipes to get access..disconnect the a/c compressor get a thick blanket and place it on the right side of the fender...this way you will have a room to work on it.

For this you do not need the stetho.
If you do not have the stetho.you can use long screwdriver handle in your fist and the other place on each intake pipe....that is if you have any noise....later

Ivan

@proporsche --- thanks for engaging w my post, watching the video, and recommending steps to assess/remedy.

5 Cylinders - I think you are on to something. I also suspected that. First thing for me will be to revisit all the spark plug wire connectors --- both at the plugs and at the distro rotor cap.

CONTEXT: A few weekends ago, I changed the spark plugs - my first time at this job for this car. I also changed the distributor rotor and cap. Through all this, I may have not reassembled all the spark plug wire connectors properly. So will check that first.

I like your suggestion to check the plug wires while engine is running and listening for changes (or no changes). The idea of reaching into the engine bay to get to the plugs while engine is running seems too adventurous for me. So, I will first try my way. And, if I need to I will attempt your suggestion LOL.

Low Idle - the car sat for 3+ years in the garage. So definitely time to check idle. I'll need to figure out how to do that. I have both Bentley manual for 911 SC and Wayne's 101 project book. There's probably a 'how-to' in there somewhere, and specs for proper idle RPM.

Spark Plugs - as mentioned, I changed them a few weekends ago. It was a real pain, especially @ cylinders 4/5/6. I did not remove the AC compressor, but will take your suggestion going forward. It would be much easier. For cylinders 1/2/3 I removed the heater ducts/hoses and access was better, but not great, it never is!

BTW - I follow most of your posts here and watch the videos of your drives across Germany (Austria/Czech?) --- great stuff!

yup it is much easier if you remove the compressor.Thick blanket on the side of the fender will do..wipe the dust 1st-thou;-)
And yes it is possible that you have mis the correct order of the wires to the plugs..once you find the culprit the idle might just go back where it is supposed to be..

let us know ..glad to help
oh ya too bad i did not do any videos while living 27 years in L.A.;-)) no time , just playing hockey at the beach , traveling and diving those days;-)

I had an adjuster lock nut come loose once, and the adjuster unscrewed a turn or two. Sounded just like that. Readjusted the rocker and it was good thereafter.

We did a second valve adjustment and even though none of the valves were off by much. It did solve the issue.

super..glad you got is fixed..;-)
Ivan

Let's hear it.

Mine kind of sounded like this before the most recent valve adjustment. Not quite as loud, but very much like a noisy sewing machine.

Agree with pmax, would like to hear it now.