JFP in PA

Questions are what we are here for. The answer to yours totally depends upon the condition of the metal surfaces; if they are perfectly true and free of imperfections (scratches, etc.), the gasket should be enough without sealants. However, if there are marks on the metal surfaces, or the surfaces are not completely flat, a small application of sealant would be advantageous. Just don't go nuts with the sealant, you would be surprised at how often we find gobs of excess sealant jamming up oil pump pickups.

Please do not double post, it is against forum rules. Your second post has been removed.

Welcome to RennTech :welcome: Are you sure the difference in pedal feel is entirely due to the use of a different pressure plate? It could also be the result of the mechanics in the pedal itself (pivot point, helper assembly, etc.) and have nothing to do with the pressure plate.

I don't see why you can't make you own, providing the material is oil resistant gasket.

I stand corrected: Pat number 93010519801, about $2

What year?

No, that is the correct name, it is just for the earlier version or the 911, which is why it is always important to included the year and model information in such questions. What are you working on?

The IMS flange on the M96/97 engine's uses in internal seal, so no gasket is necessary:

The factory procedure to get air out of these systems is by pressure flushing them with the system activated by a diagnostic computer (dealers use a real PIWIS which is a lease only item and will set you back just shy of twenty thousand dollars for the first year, which makes the Durametric system a relative steal by comparison). Once air gets into the ABS/PSM control network, it is very difficult to impossible to get out without doing it this way

P1341 Camshaft Adjustment, Bank 1 – Below Limit Potential causes: – Short to ground – Actuator faulty – Open circuit in triggering wire – Open circuit in B+ supply

Without actually seeing the car, I would start by having the control network for the ABS/PSM checked out. There are a lot of valves and controls in that system, which are susceptible to build up from corrosion and can jam or malfunction. I would also try pulling the vacuum line to the brake booster when the brakes are locked and see if that releases them.

Welcome to RennTech :welcome: When you mention that you previously had a problem with the brake pedal not returning, was that corrected with new booster, or was the car still doing it after the new unit was installed?

Or a couple of good compression seals to go under the bulkhead fitting nuts.

Why even bother? We flush these systems almost daily, and we do not siphon off the reservoir first, the way the Motive system works it simply is not necessary, and more paint jobs have probably been ruined while doing this than anything else.

You will also need a small diameter barbed end bulkhead fitting to put into the cap.

On your car, most likely the two small paddles that sit in between the two cams, just behind the cam chain sprocket.

I would not be alarmed just yet, the range for these values is -/+6 degrees, which is a large window. Take the car for a good run, and then recheck the values before deciding anything, and if the values are still out, you need to replace some tensioner paddles.

Did you thoroughly warm up the car (as in take it for a ride for 20 min. or so) before you checked your deviation values? Checking them on a just started car will often give you erroneous values. Even if these are your final numbers, only one is out of spec, and then only by a little bit. Normally, this is as the result of worn chain tensioner paddle pads, which can be replaced. And as the values are steady, there is not sign of impending IMS issues.

I'm not fan of fixing cracked parts unless there are no replacements. Usually, they just crack again.

Sorry, but there are no real "magic Band-Aids" for this, if you have a cracked component, it needs to be repaired or replaced.

More than the data this could yield, I'd still like to know what the crankcase vacuum level is on your car; one min. of diagnostic time would immediately confirm or deny the AOS is going bad. I'd be willing to bet that we would see a vacuum signal somewhere between 5 and 10 inches of water; enough to be annoying and causing running issues, but not yet shot enough to disable the car and turn it into a mosquito fogger. Oh the joys of long distance diagnostics...........

John, this is interesting. Why will AOS leak make MAF read higher? Even I have a setup like that at home :) You have hit on the $64 dollar question. We know from direct experience that MAF's on their way to "aging out" often read higher than expected air volume flows; we have seen this on Porsche's as well as other brands, so it is not an unexpected event. So when we saw higher than normal MAF air volume numbers on cars with obviously dying AOS units, we kind of wrote it off to an aging sensor. But then someone brought it to my attention that they had seen similar high air flow volumes on cars with bad AOS units, that subsequently (but not always) dropped back into range when the AOS was replaced, so it was not always a dying sensor. Always intrigued by a new mystery on these cars, and not wanting to needlessly be replacing expensive MAF units, we started looking at cars we got in that failed the AOS vacuum test (vacuum signal at the oil fill caps greater than 5 inches of water). And what we saw mimicked what the other observer noted, the air flow volume often changed, which set us scratching out heads. On the 986 in question for example, the AOS line to the intake system enters behind the throttle body and ahead of the intake plenum, and the MAF is located a couple of feet "upstream" of the throttle body, near the air filter box on the driver's side rear fender; so intuitively it would seem rather too remote to see a change in the vacuum signal level where the AOS line enters the intake. But it apparently does under some conditions. Why this happens remains an item of speculation, and the amount of air volume change is not always large, but always seems to be in the same direction when it happens. An interesting experiment would be to set up a car to mimic a failing AOS (which would require being able to "throttle" the AOS crankcase vacuum level up or down, while monitoring both the intake plenum vacuum levels and the MAF air flow volumes) and collect some additional data points in an attempt to see what is going on. Unfortunately, in the shop we are nearly always in a time crunch to figure out what is wrong and get the car back into the owner's hands, so we have not attempted this. It would be an interesting R&D experiment however. Thanks John for the detailed reply. My thinking is as follows: Suppose everything is working correctly on a warmed up idling engine. Now all in a sudden the AOS diaphragm cracks. That allows MORE crankcase gas (oxygen deprived and even fuel-enriched) into the throttle and LESS fresh air from intake, Both effect will create an instantaneous rich condition. Engine will start to stumble due to wrong a/f mixture. To maintain a minimum rpm, the DME compensates by opening up the throttle a bit more to let more fresh air (oxygen) into the engine to achieve the correct a/f ratio. At the end the MAF will see more flow (in mass per second) and the rpm may be raised a little too (not sure about this though). When you observed the MAF read a bit higher than normal, I assume the rpm was at a normal value and not raised? I mean if the rpm was also raised, it's just natural the MAF read higher. I think it will be quite difficult to simulate the crack inside the AOS precisely. One will need to build an adjustable bypass valve between the AOS vent tube that's connected to the crankcase and the AOS vent tube that's connected to the throttle body. Will be an interesting experiment nonetheless :) I would expect that if the your scenario were correct, the idle should go up and down, and with the repeated A/F issues, the car would also code because the mixture would eventually have to swing out of range one way or the other more than once. We observed the higher MAF volume numbers at a normal (and steady) idle speeds. The basic problem with the AOS design is that it is way too complicated, too fragile, and has too many ways of going south on you. We thought about how you would have to modify one to test our observations and it quickly turned into a plumbing and electrical nightmare. Sometimes the view just ain't worth the climb.............

I will repeat what I have said many times before: I have never seen one of these engines blow a head gasket, nor have I ever heard of one from a credible source. These engine's use a multi layer steel head gasket, which is way stronger than either the cylinder head or engine case castings. You have a crack somewhere.

John, this is interesting. Why will AOS leak make MAF read higher? Even I have a setup like that at home :) You have hit on the $64 dollar question. We know from direct experience that MAF's on their way to "aging out" often read higher than expected air volume flows; we have seen this on Porsche's as well as other brands, so it is not an unexpected event. So when we saw higher than normal MAF air volume numbers on cars with obviously dying AOS units, we kind of wrote it off to an aging sensor. But then someone brought it to my attention that they had seen similar high air flow volumes on cars with bad AOS units, that subsequently (but not always) dropped back into range when the AOS was replaced, so it was not always a dying sensor. Always intrigued by a new mystery on these cars, and not wanting to needlessly be replacing expensive MAF units, we started looking at cars we got in that failed the AOS vacuum test (vacuum signal at the oil fill caps greater than 5 inches of water). And what we saw mimicked what the other observer noted, the air flow volume often changed, which set us scratching out heads. On the 986 in question for example, the AOS line to the intake system enters behind the throttle body and ahead of the intake plenum, and the MAF is located a couple of feet "upstream" of the throttle body, near the air filter box on the driver's side rear fender; so intuitively it would seem rather too remote to see a change in the vacuum signal level where the AOS line enters the intake. But it apparently does under some conditions. Why this happens remains an item of speculation, and the amount of air volume change is not always large, but always seems to be in the same direction when it happens. An interesting experiment would be to set up a car to mimic a failing AOS (which would require being able to "throttle" the AOS crankcase vacuum level up or down, while monitoring both the intake plenum vacuum levels and the MAF air flow volumes) and collect some additional data points in an attempt to see what is going on. Unfortunately, in the shop we are nearly always in a time crunch to figure out what is wrong and get the car back into the owner's hands, so we have not attempted this. It would be an interesting R&D experiment however.

I went to the largest Porsche dealership in the area, and they seemed familiar with the AOS when I asked them to specifically check it as well. Just remember one thing about dealerships: Good techs typically leave dealerships and go to work for independent shops, both because they can make more money, and don't have to toe the corporate line. A lot of dealerships out there will still tell you that it is impossible to replace the IMS in one of these cars without tearing the engine apart, even though it has been done everyday of the week for over eight years now in the field.