Subject: Re: Flappy, number 2 From: "Fred Rourke" Date: Sun, 10 Oct 1999 15:23:32 X-Message-Number: 31 Adam, If your flap does not work and you know the flap is free to move then there are three main possibilities: 1. The solenoid actuated valve is naff. 2. The actuator on the underside of the manifold is naff. 3. Your vacuum system is naff. To diagnose: 1. Solenoid valve [just in front and below the inlet manifold]: Disconnect the plug. Apply 12 volts over the two terminals on the valve. You should hear the solenoid engage and disengage. You can also disconnect the vacuum lines and when the solenoid is open you should be able to "blow through" the valve. If the tests are positive move on. When the car starts the system should transiently put 12 volts on the solenoid terminals for a second or so. You can try to measure this on the connector terminals. If the solenoid valve is functioning O.K. move on. 2. Disconnect the vacuum line that runs from the solenoid valve and disappears into the front of the inlet manifold. If you apply very light pressure to pull the line towards you, you should feel resistance from where it connects to the flap actuator. If there is no resistance the vacuum line has come away and it will pull straight out [ I stress very light resistance!!]. If you suck on the free end of this line you should be able to actuate the flap. If you cannot move the flap this way then the problem is with the actuator under the inlet manifold or the vacuum line has disconnected. Move on. 3. If your "passive vacuum system" has a problem you can diagnose this by sticking a vacuum gauge on the vacuum line that runs into the solenoid valve from the 4-way connector. When you disconnect the vacuum line from the solenoid valve for this test, if things are O.K. you should hear the vacuum system sucking in air. Run up the engine for a couple of minutes to build up the vacuum in the system. The vacuum gauge should now indicate about 500mm Hg [Hg = mercury]. The flap needs about 250mm Hg vacuum before it thinks about moving. When the vacuum has maximised switch off the engine. The system should hold vacuum for ages. If the vacuum decays rapidly [i.e. you can see any change in the gauge reading within an hour] you have a problem with the vacuum system. If the vacuum is insufficient it will be because of one of the following: a] Vacuum reservoir collapsed [inspect in the driver side wheel arch]. b] leaky 4-way crossover, c]leaky check valve [the litle device mounted on the inlet to the brake booster] d]Your inlet system in general has bad leaks and you cannot pull a decent vacuum anywhere [possible but most unlikely] e] You have a leak [probably an actuator] somewhere in the hv/ac system. My S4 suffered a] d]and e] simulataneously!!! Next step: Disconnect the single tube leading to the hv/ac system at the 4 way crossover and plug the empty connection- if you can hold vacuum now the problem is in the hv/ac system. If you cannot hold vacuum at this stage the problem is in the vacuum reservoir or the suction system from the inlet manifold. If the problem is in the hv/ac system re-connect the vacuum line and proceed as follows: The hv/ac system is more complicated to diagnose and a pain to fix properly. You need to enter the side of the centre console by pulling back the panel to the right of the drivers leg. You will see the nylon vacuum tubes running from the row of vacuum valves out to the actuators [the tubes are colur coded]. I isolated the tubes one at a time and stuck on the vacuum gauge. I found that I needed to snip some of the vacuum tubes to get good access and used vacuum connectors to re-instate them. One by one you test the lines until you find the faulty one. When the main system holds vacuum the actuator you have disconnected is the one that is faulty [unless of course you have more than one faulty unit at the same time!]. There are 5 actuators in the hv/ac system: Heater valve [acessed from the engine bay] Footwell Flap By-pass flap [used for a/c duty] Main closing flap Defroster flap If you are really unlucky the problem could be elsewhere under the dash regrettably you will have to fathom this out for yourself. The heater valve is easy to diagnose as you can put the vacuum gauge on in the engine bay. I have two leaking actuators in my system. I disconnected both of them hence I do not get air into the footwell and the main flap on the blower discharge is permanently open [I do not know why it was there in the first place]. To help diagnose which actuator is leaking you need a copy of the vacuum schematic. I could scn this and e-mail it to you if you like. One little modification I have considered is to stick one of those little check valves on the line to the vacuum system. By doing this you can protect the flap from failing if you have a problem in the hv/ac sub system. It surprises me that Porsche never fitted this in the first place. Hope the above is useful. I am sure it has all been said before but I worked all this out the hard way. Regards Fred R Oman 1990 S4 auto -gradually plugging the leaks! From: clay zbar [czbar@mindspring.com] Sent: Friday, May 26, 2000 8:00 PM To: 928 Subject: [928] flapper fixed...more power...next project after i read the phil's post regarding the "test turn of the flapper during start up" i wanted to really check things out before i attempted to "bypass" the flapper. here's what i discovered: 1. the selonoid to the flapper is a is not reversable in terms of the way the vacum lines are connected, as i orginally thought. i had them backwards and the "blowoff" valve is there of course to allow the flap to close back when the revs fall below 3500 or so. not knowing that, i had some time back "capped" it off thinking it was another "leak". 2. it is easy to get vacum lines reversed, if you decide to replace vacum connectors (as a project) so don't make the same mistake i did. remember to identify by taping if you remove more than one at a time. 3. ok...after going through all tests, i connected the selonoid back up properly and verified that the flap moves 1/4 turn after staring up, and reving up to about 3500 caused the flap to move "open" as well. pretty cool to see it "flex" as i peaked through the windshield as i reved the motor. (the ole paper sail attached to the top of the flapper trick). 4. another mind twister fixed, i went for that "drive" to see/feel/experience the difference...well the difference was pretty impressive. much better across the rev range...one of the things worth while to look in to if not funtioning as designed...well off to the next project...my air/fuel meter arrives next week, stay tuned to the possible rising rate fuel pressure regulator. clay 87 s4 auto just waiting for another dyno chance! black/black rmb, 17" ATP 17-8/10 momo runner koni/Eibach's corbeau gt7's, cat bypass (roar) Sony 200 watt eXplod system rear sway bar links (really cool) nitrous 150hp system dynoed at 352hp/434 torque 928OC member -----Original Message----- From: Ralph S. Smith [mailto:rssmith@easystreet.com] Sent: Wednesday, February 20, 2002 2:12 AM To: 928 Subject: [928] Flappy Bearings BTDT Finally something I can contribute, just a moment to thank the collective wisdom and especially the core experts for many little bits of knowledge over the years. OK, flappy bearings are supposed to be INA F-957762, but HK10 10 bearings fit perfectly at about $3.00 per bearing. Now the caveats. The Porsche part has a seal incoporated into the bearing, the ones I used don't. There is a need for a seal of couase since this is the intake manifold. BUT, vacuum leakage would be pretty minor since the shaft clearance is pretty small and on the top end the cap completely seals the hole anyway. A better solution than the HK10 10 bearing might be the HK10 12RS (rubber seal) which has a seal and is 12 mm thick as is the original. Unfortunately the RS was not available from the local suppliers, the story I got was that it was something that was not in high volume so they built them once in a while, probably when a mega order came in, but in between builds you were just SOL. Add a 10x2 O ring behind the HK10 10 and viola we have a seal again. The O ring probably is fine in Buta alhough I was trying to get Nitril, I can't actually remember what I put in I think Buta. The seals go in first then the bearing, the retention lip for the bearing in on the interior side of the intake manifold and the bearings press in from the outside. Be careful to only press the bearings into the flush level. In other words the O ring should be touching the lip and the bearing, but you don't want the bearing crushing the O ring. I can't tell you about the long term reliability for sure, but I have been running this arrangement since February 2001 with no apparent problems. I was most worried about too much friction with the O ring instead of the seal, but after a little hand testing and then observation of the vacuum actuator at startup I am pretty sure that the O ring does not inhibit the flappy motion. I would guess that any leakage would show up as idle problems. I was suspecting leakage a while back and did the test of preasurizing the intake discribed in the manual and found no leakage. Well, good luck, if someone else tries it, let us know how it goes, also let us know if the RS is available this year. RSS -----Original Message----- From: mlschmidt@sprintmail.com [mailto:mlschmidt@sprintmail.com] Sent: Thursday, February 21, 2002 1:28 AM To: 928 Subject: [928] Re: Flappy Bearings BTDT When looking for the original INA F-957762 bearings, I couldn't find anything. I looked for bearings of that same type, with the same exact dimensions. (An open end drawn cup needle bearing for a 10 mm shaft, 14 mm outside diameter, 12 mm height, with a seal on one end) I also came up with the HK 1012RS bearings. Bearings like that are apparently made by INA, FAG, NTN, SKF, MCR and some other manufacturers, all using the same HK 1012RS number. The first local bearing supplier I called and asked about INA HK 1012RS bearings, said no problem, and took the order over the phone. They should be here by UPS in a day or two. They're probably available from a lot of places. I happened to order from Berry Bearing. They have locations throughout the country, or you could just get them by mail. Their phone number is 1-800-BEARING. Mike Schmidt '88 928S4 Auto Black/Black "PORSCHE" cloth 928 Owners Club Charter Member PCA Chicago Region From: mlschmidt@sprintmail.com [mailto:mlschmidt@sprintmail.com] Sent: Wednesday, August 07, 2002 1:48 AM To: 928 Subject: [928] Re: Rough idle when warm >Where did your mechanic get the replacement flappy bearings? I got mine from Motion Industries (www.motionindustries.com), but you should be able to get them from any number of bearing suppliers. The part number you want is HK 1012 RS. Bearings like that are made by several manufacturers including INA, NTN, and others. They all use the same part number. Mike Schmidt '88 928S4 Auto Black/Black "PORSCHE" cloth 928 Owners Club Charter Member PCA Chicago Region