82SC Tapping Sound

[booyah911]

Time to play, what's that noise? I just went through a major service of this 82SC, including tightening the rocker shafts and verifying the head studs are tight. The sound comes primarily from the right side and underneath. Could this be an exhaust leak?

https://youtu.be/gEmVJls_3SA

I took a stethoscope and the chain tensioners don't sound loud. The loudest sound was when touching the scope to the exhaust and along the exhaust rocker cover (right side). Any suggestions for tracking this down would be great.

[Schulisco]

Does the sound also appears while driving, especially under load? Opening the inner and outer shift coupler rubber boot covers will help hearing it better while driving.

I had years ago a similar sounding, also after checking & adjusting the valve clearance. The ticking noise on idle appeared not much different than before, but while driving and esp. under load/accelerating the noise were more and more noticeable and hearable. Long story short - the fuel distributor was out of balance and the cylinder (in my case #6) ran too hot due to a too lean mixture...this let the valves proonging that much that they fill the gap and they start tickering ... So check amount of fuel delivered on every cylinder (sensor plate set on WOT, jumped fuel pump) and let flow 30secs each injection valve into it's own measuring cup and compare the volumes. Tolerances >5% are not tolerable. You can try turning the screws your FD has on every output, but I suppose that they won't help as they're for fine tuning in very narrow limits only. I tried to balance it by that for two afternoons without success. At the end I let overhaul the FD by a pro. After that ticking noise was completely gone.

Other possible reasons:
- bad ignition
- valve clearance not correct set

Thomas

[booyah911]

Thanks, Thomas. I just verified the FD flows a few weeks ago when overhauling the CIS but I can double check.

To rule out an exhaust leak I'll smoke test the exhaust. After that, I'll recheck the valve clearance on the bank 2 exhaust side. I rechecked the intake side last night but that didn't make any improvement. I put off the exhaust side because I have to drain the oil (again). I'll also triple check the rocker shafts/head studs while I'm in there. Frustrating, because I'm so close to having it back on the road and now this.

If anyone else has other thoughts, I'd appreciate it.

[911obgyn]

You can check exhuast valves by draining engine oil while one side of car is up. You dont have to drain tank.

[Schulisco]

Originally Posted by booyah911

I just verified the FD flows a few weeks ago when overhauling the CIS but I can double check.

With or without the injection valves?
The valves self also may be worn over time and the opening pressure range is quite widely specified by Porsche from factory between 2,5 and 3,6 bar / 36 and 52psi ...
How is the spray pattern? Should be a fine mist with cone pattern. If they haven't this any more, add a fuel injection cleaner additive in the fuel and drive the car carefully and see if it's getting better...

Thomas

[booyah911]

Originally Posted by 911obgyn

You can check exhuast valves by draining engine oil while one side of car is up. You dont have to drain tank.

So, lift from one side and drain just the sump? That's good to know.

[booyah911]

Originally Posted by Schulisco

With or without the injection valves?
The valves self also may be worn over time and the opening pressure range is quite widely specified by Porsche from factory between 2,5 and 3,6 bar / 36 and 52psi ...
How is the spray pattern? Should be a fine mist with cone pattern. If they haven't this any more, add a fuel injection cleaner additive in the fuel and drive the car carefully and see if it's getting better...

Thomas

Tested with and without injectors, but I can easily retest to confirm. Spray pattern looked OK, but admittedly they were in graduated cylinders so it was tough to tell. Also don't have perfect knowledge of a normal spray from these injectors. I didn't test the breaking pressure of the injectors but they all seemed to come on at the same time when lifting the sensor plate.

I'm not against replacing the entire set with new injectors if this could be the issue. I'll start knocking this off the list.

[proporsche]

Originally Posted by booyah911

Time to play, what's that noise? I just went through a major service of this 82SC, including tightening the rocker shafts and verifying the head studs are tight. The sound comes primarily from the right side and underneath. Could this be an exhaust leak?

https://youtu.be/gEmVJls_3SA

I took a stethoscope and the chain tensioners don't sound loud. The loudest sound was when touching the scope to the exhaust and along the exhaust rocker cover (right side). Any suggestions for tracking this down would be great.

Is it the same cold and warm engine? If yes it is possible you have broken one(of the pair)) valve spring.If the sound is not there while cold--only warm it is the valve adjustment.
If you take the valve cover off check on the each valve -you should not be able to push them.Also use small mirror to look for the broken spring....
Here is how the engine should sound on SC .This one just finished , complete rebuild...

https://www.youtube.com/watch?v=EGWlKtAwdTs.

[booyah911]

That engine sounds great. I'll check my valve springs.

The tapping sound is present immediately at startup and persists after a 10-15 minute warm up. I'm avoiding driving it until I know this won't cause catastrophic damage.

[proporsche]

Originally Posted by booyah911

That engine sounds great. I'll check my valve springs.

The tapping sound is present immediately at startup and persists after a 10-15 minute warm up. I'm avoiding driving it until I know this won't cause catastrophic damage.

Thanx.........
Ok, save yourself time lift the back of the engine-you can use the middle where the strainer plate is-with rug or paper..drain the oil and check them all intake & exhaust.After put back the oil..easy done ....If you will find broken valve spring-let`s hope not-that is also easy fix with a special tool .It is doable without removing the engine...Are you using feeler gauge for the adjustment?
Here is how i do it past 40 years....you can try it out..
people will say it is easier with the engine out but i like it better with the engine in the car -i get better leverage...for my hands
Ivan

https://www.youtube.com/watch?v=O_ypBn_u7g8

[booyah911]

I'll check it out and report back. I've been using the valve adjustment tool below. I double checked a few with a feeler gauge but I found messing with the feeler with the engine in the car is tricky.

https://www.pelicanparts.com/More_Info/RENT23.htm?

[ahh911]

Valve clearance. Every time I do an adjustment there is always one valve that I don't get nice and quiet. My right bank ticked from cold similar to yours, I know because the sound would bounce of the cars in our driveway as I backed out in the mornings and it bothered me, that's when it was time to re-adjust. I nailed that side and it's now perfectly quiet all the time but my left side post valve adjustment is making a tick, but only when warm, so it's okay to me. (not as deep sounding as yours, but that's squabbling). I think one of your valves is close to the max spec limit, near 4 thou one valve may tick but it's a little less deep sounding.

Phil

[booyah911]

Thanks, Phil. I think it's valve clearance too. Last night I pulled the valve cover from intake bank 2 to inspect. Valves were all fine and readjusting clearance them didn't help. I also verified the intake springs are intact and pulled the rocker shafts to inspect because I recently shifted them to address an oil leak. They were perfectly smooth and not causing chatter. Started the car again and the sound is definitely coming from exhaust valve 5 or 6. I'll drop that cover this weekend. Here's hoping it is that simple!

[booyah911]

Oh and I also smoke-tested the exhaust to rule out an exhaust leak. Assuming smoke can pass through the cat, I had the smoke machine pushing smoke into the tailpipe for a good while and no leaks in the system.

[booyah911]

Crack a beer, fellas. She's purring beautifully now. Exhaust valve 5 and 6 were way out. Adjusted all valves and tapping is gone. Thanks for the help!

[pmax]

Congrats !
Too loose ?

[proporsche]

i had a feeling you can do it..

ivan

[booyah911]

Originally Posted by pmax

Congrats !
Too loose ?

Yes, way too loose.

[$yncro]

You inspired me.. I did my valve adjustments today
and retorque my headstands too. I noticed the same
5 and 6 a tad loose as well. Ticking is gone.