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Join Date: Dec 2007
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How can I turn and inspect the inner valve spring?
I have a noise coming from my 2.7. Originally I thought that it was a ticking valve. So I did a valve adjustment using the backside method and the tick is still there. Using my stethoscope I have located the noise to the #1 cylinder. I listened to #2 as well and also listened to the timing chain. The noise sounds like the valve is slapping the seat. From doing a search I found a thread with a similar problem. So I removed the #1 intake rocker and So far I can not see anything broken on the other spring. I can rotate it using a pair of locking needle nose, however I can not see the backside of the inner spring. Anybody have any ideas on this one?
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Join Date: Mar 2001
Location: Marysville Wa.
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you rarely see a inner spring broken. plenty of outers. if the 2.7 has original copper guides, which will positively be very worn by now, the valve can wobble back and forth about 1/2", which would account for the ticking.
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Thanks for the reply. So in order to check for the dreaded worn valve guide I need to buy one of the "on the head", valve spring removal tools and remove the exhaust valve springs, Then push the valve in? How far? And then wiggle it side to side? Any advice would be helpful. I have not bought the tools yet and I was hoping for a simple broken spring.
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Which usually brake the intake or exhaust?
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the outer spring does most of the work anyway. it would be easy to see if the valve wobbled in the guide if you removed the spring. open about 1/2" and work it side to side, up and down. usually you will see a baked or broken stem seal if it was that bad. some folks like to pry the spring retainer side to side with a couple of screwdrivers. done after establishing rocker clearance, like on that cylinder at TDC. trouble is, most of the guide wear is at the inner end of the guide, but try it.
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One of the things that I just cant figure out is why the valve is so noisy when it closes... Comparing it to all of the other valves, while it is running, there is quite a bit more noise. The sound is very distinct when the valve closes it has a sharp clap to it verses the dull whispers when the other valves close. The sound is similar to a valve assembly being struck with a bronze mallet, it has that sharp crisp sound.
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Location: Canberra, Australia
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FWIW, I had an exchange datsun engine that made a "clang" sound that I could hear from the driver's seat. At first I thought there was something like a loose nut rattling in one cylinder. After doing a thorough check, I restarted the engine and the sound started to subside then finally stopped altogether after the first oil change. My best theory was that the valve stem may have been a bit rusty/sticky and got stuck momentarily on each lift while the rocker backed away, then snapped shut onto the seat without the aid of the cam to control the speed. Only a guess. Don't know whether superior German machines behave the same.
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1982 911 SC coupe RoW moss green SSIs and M&K 2-1 muffler |
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I wonder if it's got a loose seat in the head......They sound like that when the seat slams against the aluminum.
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Paul S "Those who say it cannot be done should not interrupt the people doing it" |
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I wonder if some carbon could be keeping the valve from going back in. That would make quite a bit of sense. The car has sat for two years about 5 miles from the beach and there was quite a bit of humidity in the air. I towed it home a couple of weeks ago and started the resurecting process. Initially cylinders 1,2,5 had poor compression (100-110). I did the sea-foam trick on the vacuum intake and the compression went up to 120-130. I wonder if the valve could have been in an open position for the last couple of years thereby allowing rust and or the expansion of carbon on the valve stem? The only problem I see with that is that would be that within a few cycles of turning over I would guess that the rust would have cleaned off. So far the car has been ran a total of about 1.5 hours. Unfortunately I can not drive it yet as it does not have current registration.
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A few years back when I had the 2.7 in my car, it developed a rattle and and would miss at high RPM's (6000+) under load, it turned out to be the inner valve spring was broken on the #4 exhaust valve.
Does your car miss at high RPM under acceleration ?
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Gary 1975 911S G50 3.5 Twin Turbo |
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I wish I knew if it misses. I towed it home and rolled it off of the trailer a couple of weeks ago. It is running pretty decent right now. So far I have drained the tank, Adjusted the valves (backside method), changed the oil, spark plugs, decarbonized the pistons with seafom. I still need to go through the brakes, smog and registration before this car sees 6k.
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Gary could you hear the valve tapping?
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Quote:
Sherwood |
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I don't think it was the valve tapping, probably the broken spring just rattling around, the car ran normally except for the high speed miss.
I agree with Sherwood, you need to remove the spring and take a look. Make sure to move the piston to TDC and pressurize the cylinder with air, I think I used about 45lbs, put the car in gear so the motor doesn't accidentally turn over from the air pressure. Good Luck.
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Gary 1975 911S G50 3.5 Twin Turbo |
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S far I have pulled the intake rocker arm and there was no up and down movement between the rocker shaft and rocker, just the normal rotational movement. Next week I will get the tools ordered in from pelican to remove the valve springs. I'm in San Diego, does anybody know of any local stores that sell the tools?
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Sherwood, the only thing that I may have left out was checking the exhaust valve by the exhaust pipe.Once I found the noisy clapping valve with the stetha scope I assumed that it was the intake. Bad assumption, now that I think about it. I think that I will reinstall the rocker tomorrow and run the car with the upper valve cover off and definitely locate the source of the noise.
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I tried to post this a while ago, then couldn't get on the network and forgot about it. It may still help:
![]() I had the same experience as you are having. Listen to John Walker, he knows what he is talking about. You will need to take at least 1 rocker shaft out on number 1. I would start with the intake. my understanding is that intake valve springs break with some frequency on this year range. Once you have the rocker shaft pulled out (it is kind of an expansion shaft, if you don't have something like the bentley SC manual (very similar to your car of course) or wayne's engine book you should get a manual of some sort. Anyway, once you have the rocker shaft pulled out and the rocker too, you will be able to see the intake valve spring with a mirror. you can stick an allen wrench or whatever in there and try to turn the outer valve spring, but you may see something out of the ordinary right away, like I did. Mine was a broken outer intake valve spring, which is most likely to be your problem too. To fix this while the engine is in the car, you need a special tool. it's SIR tools P71. this is for the intake but there is a corresponding version for the exhaust. In my case, the outer spring was broken and it had damaged the spring seat, so I replaced that too. I may have also replaced the retainer just for good measure. A key issue is to remove the keepers with a magnet or otherwise carefully, I dropped one down into the exhaust side and it upped my pain considerably. Here is the link to the tools to do this in the car on pelican. if you have any other reason to pull the motor now would be the time to do it, but it's not a tough job even in the car: http://www.pelicanparts.com/cgi-bin/ksearch/PEL_search.cgi?command=show_part_page&please_wait=N&make=POR&model=911E§ion=ENGmis&page=4&bookmark=27&part_number=PEL-TOL-P7E Here is my thread from my similar experience: Engine noise diagnosis help Please - apparent valvetrain If you any questions please don't hesitate to ask.
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