914 1.7 Knocking Sound -- New Here, First Post, Horrible knocking coming from the motor |
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914 1.7 Knocking Sound -- New Here, First Post, Horrible knocking coming from the motor |
UberElectricEagle |
Sep 20 2009, 07:20 PM
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#1
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atomic Group: Members Posts: 43 Joined: 10-August 09 Member No.: 10,659 Region Association: None |
Greetings. I am new to the Porsche world and I purchased a 1972 914 1.7 about a month ago. It's a pretty nice car over all, but I think the motor, or part of the motor, might be toast.
When I purchased it, it badly needed a muffler. The knocking noise was harder to notice and sounded more like an exhaust leak over the horrible sound of the lack of a working muffler. The car seemed to run decent even with the poor exhaust and the price was good so I bought it. I just wanted a decent car over all that I could drive around for fun on sunny days before the winter gets here. It came with stainless heat exchangers I installed and I installed a really nice dual muffler from Dave at Triad. When I fired it up with the new muffler, I really noticed the knocking when I drove it since the all the exhaust leaks were now sealed up and I wasn't wearing ear plugs. At idle it's not too bad, but once I get going, the knocking is very noticeable. It's odd too, because it's not real consistent under power in motion. To me it sounds like the noise is coming from the #1 cylinder. I think the cylinder is providing no power, because when I take the wire off the cap, there is really no change in performance. (I put a video link of the horrible sound below.) Any advice on where to go from here would be great. My gut feeling is telling me the motor is going to have to come out. If I'm going to do all that, I might as well put a 2.0 liter in or ????? I'd even settle for just a solid running motor with some minor upgrades to make it a little quicker. Any advice on what route to take on a good used motor would be great. I guess A motor that runs on 4 cylinders would be an upgrade. Thanks for your help, a mildly depressed Sam http://www.youtube.com/watch?v=a5JhEd7SUH4...re=channel_page |
UberElectricEagle |
Sep 26 2009, 03:35 PM
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#2
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atomic Group: Members Posts: 43 Joined: 10-August 09 Member No.: 10,659 Region Association: None |
Probably will be the last progress report because I think this motor has a few internal issues that will need to be addressed out of the car. Probably best fixed with another motor. I'd give it a full tune up and rebuild the carbs, but I don't think it will matter. Thanks for all the help and ideas everybody.
I got the carb linkage sorted out the best I could. Left carb lost a bolt (out of two) that holds the linkage bracket so the bracket was drooping and slightly opening the throttle plate a touch. Bolt was gone because the threads are stripped! Tightened the one up the best I could, but it will end up moving. Adjusted the small linkage so the throttle plate would close. Checked the main jets and they were clean. Adjusted the carbs the best I could and listened to the air going in through a hose and they were pretty dang close. Took it out for a drive and the noises are still there of course. Seemed a little more tolerable though; probably because I don't care anymore if the motor blows up. The car was running a lot smoother though, but smelled rich. It actually felt pretty good. I've actually got it down to two noises. The main noise is more of a quick clacking or rattle type noise which varies depending on the throttle input; and the second is more of a BLAP noise at higher rpm or hard acceleration it seems. I can make the noises disappear at around 3500 RPM on flat ground and in a couple other instances. Kind of nice and peaceful at that moment. I can make the motor smoke a lot like a James Bond smoke screen at 4000 RPM and above. It's a pretty blue smoke and lots of it. If I stay there at the high rpm it will just smoke steady. I've also got clean oil coming out of the top of the motor somewhere at high rpm and bathing everything in the center of the engine compartment. Might be the oil pressure sensor. I'm not even going to look into it at this point. Saw a greenish 914 at the Conway Shell station on my adventure. (I think I've seen it a few times) I thought about going to look at it, but I didn't want to show off my smelly and clacking car if the owner came out. Thanks for the help, Sam |
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