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Variocam thoughts and questions
Ok, so I did my homework and I have read through a a lot of threads and articles on this variocam fail topic and I learnt a few things that were new to me but maybe obvious for most of you all. I still have some questions that I thought are worth to share. First, what I learnt: 1) The actuators are all the same in all 5 chain engines, from 2.5 to 3.4, or at least they have the same part number. 2) The two units are different though, variocam 1-3 and 4-6 move to the opposite direction when they actuate, and it seems only actuator 1-3 has this large green O- ring that has a tendency to disintegrate. At least in all the threads I`ve looked at the first sign was the appearance of green rubber O-ring fragments. Actuator 4-6 has no such large green O-ring shown on the few pictures available on the web.
I noticed that when the actuator is not filled with oil the piston moves freely between the two endpoints. When the camshafts rotate and the valves open and close the load alternates respectively between the small chain`s upper and lower side, resulting in tugging the actuator`s piston between the two end points pretty badly. I uploaded a video of this here: https://www.youtube.com/watch?v=F069qIpI3_U When I fill the actuator with oil with a syringe, the piston no longer moves. So I assume the tugging is gone once the actuator is pressurized. Also, normally the oil can`t escape from the actuator easily, because there`s a check valve in the actuator`s oil pressure line which rectifies the oil flow. So, is it possible that the check valve remains open because of dirt or something and the tugging at start up eventually destroys the O-ring?**** In this case, dying of the actuator should be preceded by a rattling noise at every startup. Is that true? Why is it that only the 1-3 actuator fails (if that`s true)? I`ve read some hints somewhere here on the forum about that in engines with****DOF****where the IMS is punched through, the actuator may be more vulnerable and more likely to fail. This makes sense to me because oil might leak through the IMS at the pump and the oil that gets lost has to be pumped back at startup. So, is there a real statistically significant relationship between DOF and actuator failure? And again, why only actuator 1-3? Opinions? |
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Just following this discussion as my car had the green debris in the oil filter
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1) IF the green debris (in oil filter) is just an O ring mashed up then the potential risk of future issues (of oil feeds clogging) is relatively minimal (as clearly, my old filter had done its job and there was about an O rings worth of tiny bits) and claims that I need to "tear down the entire engine and have it rebuilt" (from some UK specialists) may be an overreaction? 2) If the one O ring is now gone and the actuator is still functioning then how long will it continue to function without the lost O ring? And in what way will it react (wear or break) over time OR maybe it will go on working because there are also other internal seals in the actuator? 3) Add the massive cost of the brand new OEM parts and the labour to fit (£2-3k?) in a £4K car that has a RMS leak and will need a clutch and maybe the dreaded IMS doing soon costing £1.5k+ |
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2) Good question. Perhaps others will chime in who had the same problem and know the answer. I wouldn`t use the car for too long like that, you can see in the video what happens if the actuator works with no oil. Probably your actuator is not there yet, the remaining O-rings may still hold the pressure? The small timing chain rail bits in the filter on its own would be a good reason to pull the valve covers to prevent future failures. 3) Yeah, tough decisions you need to make here. If you want to keep the car for long it`s worthwhile to fix all these issues. If you are a DIY person. If you are not, I`d consider selling the car to someone, who is... |
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Timely post for me. My 2000 2.7 just threw a 1341 error code (cam timing). The newly remanufactured engine was just installed last fall after Sitting in a garage for years. After reading this thread, seems conceivable the O-ring could have dried out and failed. I am still holding out hope it’s the sensor or solenoid, but after reading this.... probably not.
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I am not clear on the work to replace these 0-rings and the actuator. Is this something a competent shop can do with the engine in the car? Is this a $3k repair or $6k? |
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Ok, I don’t get this. Just received my new OBDII scanner yesterday. I cleared the 3141 error code (Camshaft Adjustment Bank1 below limit value) that threw the CEL. I cleared the code with the engine running. The moment the CEL cleared, the engine idled down maybe a hundred rpm. In addition, when I start the car after the CEL was cleared, the car does not really “rattle” the 1st second or two after starting as it had. Other than this anomaly, it runs normally otherwise.
Why does the car start and idle differently with the CEL on than off? Why would the chain “rattle” be different? Is that the nature of the 3141 code? |
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I have an appointment to bring the car into the shop next week to address the cam issue. Am guessing it is the solenoid anyway. |
Failed Actuator causes fried ‘computer’.
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Did they record and tell you by how many degrees the cams were out of time? Pretty simple to do. Did they show you the faulty actuator and explain the fault with it? If a DME -ECU- computer is fried how does it throw a code? Or keep the car running?? Just a few questions that enter my mind;) |
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Depends on how far out of time they are. If you have one actuator not working your cams can still be in time until around 1500 RPM when the actuators are supposed to actuate. Then the cams on one bank will be out of time. Then the actuators kick back out around 5000 RPM so the cams will again be in time. If the shop can not tell you if the cams were out of time and by how much before they replaced the actuator. And if they are not showing you the faulty actuator and what the issue was with it. That they charged you big money and didn't fix anything Also now they want to replace the computer. For more money. Sounds to me like 1. they don't have a clue as to what they are doing. 2. they are taking you for a ride. |
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This is a high end shop. Between the race cars, turbos and both newish 911’s And air cooled 911s. But I’ve never seen Boxsters in that shop. When it comes to the vario cam system for 986s, is it the same as 996s? I assumed it was. |
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I do know that they only used the twin actuator style in the Boxster from 1997-2002. In 2003 they went to a different method of varying cam timing. Keep us posted on the outcome. Always interested on end results. |
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30 miles after picking up the car, the 1341 CEL returned. So I guess I’ll do the engine flush, but seems a long shot. Otherwise, I may just drive the car with the CEL. Hopefully I can clear the CEL and it will still pass smog next year. |
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Hard to give any further advice without having the car at hand. Giving advice over the net is kind of a crap shoot at best. |
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Hence they want to do this engine flush in the hopes of clearing an oil gallery to increase oil pressure in the actuator. Again, that sounds like a Hail Mary. But after your syringe experience, maybe the flush might clear out something. Must say, I am stunned at how little difference the vario cam seems to make. If as they said, it wasn’t working at all on bank 1-3 when I brought it in, and it’s not working well now, why does the car run so well? I can’t tell the difference. Seems like a lot tech for not much performance. |
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It could have been tested with a multimeter via back probing the wiring connections. Also the function of the actuator can be tested with a OBDII scanner that has test functions. With my $175.00 Foxwell scanner I can trigger my actuators then not only hear the difference in how the engine runs. I can also see the cam timing change and by how many degrees. Very simple tests that verify function. |
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It is the Foxwell NT520 Pro I went out and hooked it up to my 2000S so I could refresh my memory on how I do it. I will attempt to talk you through it. Hook up the scanner Go to the Porsche program and hit enter. Go to manual selection and hit enter. Go down to 986 Boxster/Cayman hit enter. Go to Diagnosis hit enter. Go to control units hit enter. Go to DME (its the top choice on my scanner) hit enter. Go down to actual values hit enter. Go to all data hit enter. Now you should be looking at a list of all the data the DME sees. With the car running you can watch all this data under different driving conditions. You can watch all the data the DME sees in real time. You just have to learn what your looking at and what it means. I have hooked mine up and watched various data over a 320 mile run several times. Now go down till you see camshaft deviation for each bank Below that is actual camshaft angles. so if your at idle watching camshaft angle you should see changes when your Variocam timing actuator kicks in. I think that is around 1500 RPM. then I kicks back out around 5000 RPM. Not positive on those RPM's but I should be in the ballpark. You can graph it with the graphing feature and see changes over a short period of time. I think you can also Data log with this scanner but I have never tried it. Now You can back out to where you found actual values and go down to Drive links active. Hit enter Now you can activate your fuel injectors and your Variocam timing Actuators. sort of a test mode. You will hear and feel the difference when you activate the injectors or the actuators with the engine running. Now simply activating them does not tell you that everything is within spec. but it will tell you if they function, or not. So that is how it works with my scanner on my 2000S Hope this helps Let me know how you go;) |
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