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edebes

Trying to address the tapping sound from last spring

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Loren and Jeff....Using the advice provided last year, I am still trying to solve the tapping sound of my 986S. In review here is a brief report. Car starts fine. I have NO CELs. On cold start, there is no tapping noise. Once started and engine temp is rising, tapping starts on the left side around 180 degrees and continues to become louder as the operating temp hits (210 degrees). Now, here is where I am in my investigation: I have taken a sample of oil and sent to LN for analysis. There were no issues to report. The report had all "green" areas. I was on the phone with a Porsche vendor who  asked if I have Durmetric and have I checked the injectors? I borrowed an "ears" analyzer and I can confirm the ticking is coming from the #5 cylinder on the left side of engine when at OT. When cold, there is no sound, in fact both sides have no noise prior to OT. I went to my Durmetric and used the injector "defeat" feature. I tried all 6 cylinders and when I removed #5 from the circuit, the ticking sound stopped. When I placed it back in operation, the ticking began about 8 seconds later. Have I confirmed that the injector is failing? I plan to replace the plug, coil pack and the injector in that order. Am I thinking correctly here?

 

Ed

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Posted (edited)

Hello again Loren and Jeff!

 

Well, the injectors are all good and not emitting a loud tapping sound, just the typical rattle injectors make. Thought it could be the AC Compressor, so I removed the drive belt and started the engine, the tapping started again at 80 C. I have isolated the sound now in the general area directly below the ac compressor. I understand this is where one of the chain tensioners resides.

 

Further research from prior responses to this topic have the possibilities of bore scoring to worn pads.  

 

So here is where I am with this investigation:

 

I believe I have moved past the high level of damage, but concluding,... No CELs, It is not a noisy injector, Not the A/C compressor, Not exhaust leak, I have a clean oil toxicology report, The sound can only be heard at idle, however, just a slight increase in RPM say 50, the sound is gone. The reality here is increases in oil pressure results from a rise in RPM is worth considering  as a suspect.

 

Here is some data from Durametric from my analysis today all through from cold start and after 30 minutes of driving: (If I need to post other data, just state description)

 

Camshaft Position Variance Offset 1: 1.28

Camshaft Position Variance Offset 2: 1.33

 

I believe a difference of 6 and under is favorable and a difference of 6 and over is a concern.

 

IF I have no other evidence (i.e. CEL's, failed oil report, and positive Camshaft shaft data, etc). I am now down to a  few other possibilities:

 

I replace the tensioner regardless and determine if the problem still exists?

 

Noisy lifter? Do I run an engine cleaner and if so, what do I use? Then a complete change of oil and filter.

 

Check the #4 coil pack and plug. (Number 5 was fine). 

 

Oil pressure issue at idle?

 

Take to Porsche Service Center for cam cover removal and diagnosis?

 

Any other ideas?? I would like to repair the car myself. I have only put a limited amount of miles on the car over the last 3 years. It has remained  mostly in the garage because I am afraid to drive it.

 

Ed

Edited by edebes

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You could have a bad lifter, which is not uncommon.  The design of these lifters require very clean oil as they are a "dead end" design, meaning that there is a passage in, but no passage out for the oil.  Dirt or debris can get trapped, causing the lifter to stick and make noise.  A cleaner added to your oil may clear it, but that also tends to free up other debris in the engine and end up buggering other lifters.

 

If it is a bad lifter(s), this is not really a DIY job as the cam covers have to come off, along with the cams, to access them.  This requires special fixtures and knowledge of cam allocation procedures.

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Loren and Jeff,

 

Thanks for the recent responses. I have additional data to share...

 

Currently, cold start idle is 1100 RPM (+/-10 rpm),  as the engine warms, the idle reduces to around 910 RPM. When the engine is at 90 degrees C (800 RPM)  at full OT at 99 degrees C, the idle is at 650 RPM (+/- 10 rpm). (At 90 C, the tapping noise begins quietly, then becomes louder temp increases and the rpms fall). On the forums, correct idle is 780-800 RPMs. (If I am wrong here, please say so.) If by increasing RPMs by 20 (say 670 to 690), this quiets the tapping 95%. By my data collection, I am not at the factory spec for idle speed, then perhaps I should correct the idle issue first before I condemn the engine to a lifter repair?   

 

First, do both of you agree with my analysis? 2. What could be the cause of the low RPM? 3. My plan would be to start with changing plugs. (Past owner's shop used Bosch 4471's which I believe are  incorrect and for 97-99 2.5 L.) Next, remove TB and clean it. (Here is the data from the throttle area: T-Plate POS 1&2 , 3.9 cold, #2- 2.3 hot; TPS1 (.66) hot, TPS2 (4.35) hot). Any other ideas or data I can provide?

 

Again, I appreciate all the advice both of you have shared!!

 

Ed

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Posted last year...idle speed is 670 RPM, OT-Hot (98 degrees C). If increase in RPM happen, noise disappears....as mentioned on prior post.

 

Ed

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Sorry...this is NOT my car...but has similar symptoms. I used this as an example for the discussion last year.

 

Ed

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2 hours ago, edebes said:

Loren and Jeff,

 

Thanks for the recent responses. I have additional data to share...

 

Currently, cold start idle is 1100 RPM (+/-10 rpm),  as the engine warms, the idle reduces to around 910 RPM. When the engine is at 90 degrees C (800 RPM)  at full OT at 99 degrees C, the idle is at 650 RPM (+/- 10 rpm). (At 90 C, the tapping noise begins quietly, then becomes louder temp increases and the rpms fall). On the forums, correct idle is 780-800 RPMs. (If I am wrong here, please say so.) If by increasing RPMs by 20 (say 670 to 690), this quiets the tapping 95%. By my data collection, I am not at the factory spec for idle speed, then perhaps I should correct the idle issue first before I condemn the engine to a lifter repair?   

 

First, do both of you agree with my analysis? 2. What could be the cause of the low RPM? 3. My plan would be to start with changing plugs. (Past owner's shop used Bosch 4471's which I believe are  incorrect and for 97-99 2.5 L.) Next, remove TB and clean it. (Here is the data from the throttle area: T-Plate POS 1&2 , 3.9 cold, #2- 2.3 hot; TPS1 (.66) hot, TPS2 (4.35) hot). Any other ideas or data I can provide?

 

Again, I appreciate all the advice both of you have shared!!

 

Ed

 

What is your oil pressures doing during the cold start, hot idle, etc.?  There was a notice about excessively low oil pressure at low RPM's, along with a simple fix kit (new oil pump spring and piston).

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Jeff,

 

That was replaced last year upon your suggestion...unless there was an update in the last year, I used the kit purchased at the local Porsche Dealer In Lancaster PA in early 2019.

 

Durametric does not measure oil pressure on a 986...so I need to do a manual setup. Is there a kit made-up to do this for a Porsche 986?  Pedro has one to install in the dash...I just don't have the time now to do that install. I am a college professor and because of Covid19, I have to teach this summer.

 

Ed

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13 hours ago, edebes said:

Jeff,

 

That was replaced last year upon your suggestion...unless there was an update in the last year, I used the kit purchased at the local Porsche Dealer In Lancaster PA in early 2019.

 

Durametric does not measure oil pressure on a 986...so I need to do a manual setup. Is there a kit made-up to do this for a Porsche 986?  Pedro has one to install in the dash...I just don't have the time now to do that install. I am a college professor and because of Covid19, I have to teach this summer.

 

Ed

 

Pedro overcharges for a kit you can make up yourself for a lot less.

 

You do not need a permanent oil pressure installation, most decent shops have a test gauge for just this purpose;

 

spacer.png

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Jeff, It will be a few days until I can pull a kit together and make the test (once done I will report data...Can you ID the possible locations (schematic) of where I can "tap" in on the block?  

 

Ed

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Oh...one follow-up: what is the thread size and standard for the port I will be accessing?

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2 hours ago, edebes said:

Oh...one follow-up: what is the thread size and standard for the port I will be accessing?

 

14x1.5MM, passenger's side cam cover area.

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It is wonderful in this time to hear a concern for data and expert analysis. So often you see a shotgun approach that only starts an expensive spiral.

 

Good luck. These guys are good.

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Thanks, Mike...I appreciate the compliment !

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Posted (edited)

Jeff, Loren, and Mike:

 

Here is my data for my BoxS regarding oil pressure and warm-up condition. As you will note, I observed the car for an hour and took readings over that period. 

 

Summary of results: Cold temp oil pressure was 89 psi at start-up idle (and no knocking sound) and as the engine fully warmed to 98 degrees C, and oil pressure at idle (665) dropped (at the end of the test period, 60 minutes) resulted in a reading of 17 psi with the a very loud knocking sound. The trend data shows a correlation between engine temp and oil pressure and oil pressure and rpm. One aberration is at the the 48:00 minute mark where the engine/ecm voluntarily raised the idle speed to 800 for 3 minutes. The engine had no knocks and ran like a new engine over that 3 minute period. Then the low idle returned to 665 and the knocking was present until end of test.

 

Please refer to the data collection sheet attached to this email for full test results.

 

Jake Raby suggests a few tests and data collection regarding bore scoring using Durametric. Fuel trim, cam deviation,  and rough running index. All  data from these variables  I have observed is within the range Jake has set on his video.

 

Gentlemen, what is the next step? If you require more data, please tell me as I still have the OPG attached to the port and my PC in my garage.

 

Thanks again!

edebesoilpresstest04 BoxS.pdf

Edited by edebes
Spell check

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14 hours ago, edebes said:

Jeff, Loren, and Mike:

 

Here is my data for my BoxS regarding oil pressure and warm-up condition. As you will note, I observed the car for an hour and took readings over that period. 

 

Summary of results: Cold temp oil pressure was 89 psi at start-up idle (and no knocking sound) and as the engine fully warmed to 98 degrees C, and oil pressure at idle (665) dropped (at the end of the test period, 60 minutes) resulted in a reading of 17 psi with the a very loud knocking sound. The trend data shows a correlation between engine temp and oil pressure and oil pressure and rpm. One aberration is at the the 48:00 minute mark where the engine/ecm voluntarily raised the idle speed to 800 for 3 minutes. The engine had no knocks and ran like a new engine over that 3 minute period. Then the low idle returned to 665 and the knocking was present until end of test.

 

Please refer to the data collection sheet attached to this email for full test results.

 

Jake Raby suggests a few tests and data collection regarding bore scoring using Durametric. Fuel trim, cam deviation,  and rough running index. All  data from these variables  I have observed is within the range Jake has set on his video.

 

Gentlemen, what is the next step? If you require more data, please tell me as I still have the OPG attached to the port and my PC in my garage.

 

Thanks again!

edebesoilpresstest04 BoxS.pdf 166.03 kB · 1 download

 

It definitely sound like it is oil pressure related, which ain't good.  Not to start an endless "best oil" argument, but what oil do you run in the engine?

 

As bore scoring is well known on these engines, probably your next step is to have it bore scoped. 

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I was running DT40 until Jack Raby recommended 10w30 diesel to protect the engine from getting worse if bore scoring was the problem.  So I changed oil Fall, 2019. Regardless of what oil I have used, the tapping continues.  I have not used a recommended 5w50. Thoughts on this?  What about the idle issue, 665 rpm is not correct when hot? Can bore scoring create a very low hot RPM?  

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4 hours ago, edebes said:

I was running DT40 until Jack Raby recommended 10w30 diesel to protect the engine from getting worse if bore scoring was the problem.  So I changed oil Fall, 2019. Regardless of what oil I have used, the tapping continues.  I have not used a recommended 5w50. Thoughts on this?  What about the idle issue, 665 rpm is not correct when hot? Can bore scoring create a very low hot RPM?  

 

OK, you are running high film strength and ZDDP oils, which is what you should be doing.  Your idle speed is a bit low (spec is around 775-790), but as yours is an e-gas throttle body, the idle speed is software controlled and cannot easily be changed.  Idle speed can be altered by a variety of factors, so while it is a bit low, I wouldn’t be pursing that at this juncture.

 

Bore scoring could alter your idle speed due to excessive drag at low speeds in the damaged cylinder(s), but it is not necessarily a given that low idle speed indicates bore scoring.  I think it is time for you to bore scope the engine; we have been bouncing around possibilities for long enough, it is time to identify solid data on what is going on and start either eliminating possibles or zeroing in on what is going on.

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Jeff,

 

I concur. However, before I move in that direction, there are a few variables I need to address. It may be a few weeks to provide the results of the bore score scope. My purpose is I don't want to do a repair K$ range..I would rather send to Jake and have him do the entire engine and know I have all the possibles covered going forward. I appreciate your willingness to work with me on this problem and I will keep you advised.

 

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