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 |
VaccaRabite |
Sep 20 2009, 07:35 PM
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#2
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En Garde! Group: Admin Posts: 13,465 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
Hey Sam,
(IMG:style_emoticons/default/welcome.png) !! Before you pull the motor, try and adjust the valves. It may be that the rocker arm has come off. It happens, and makes a clatter and the cylinder won't fire. If thats it, it is a simple fix, and will be very noticable when you go to adjust valves. After valves are done, do compression test. (valves need to be right, throttle needs to be open). That will tell you if the cylinder is at least building compression. if you have dropped a valve seat (zero compression on #1 is probably a dropped seat), it is rebuild time. At that point, source a 2.0, or rebuild the 1.7 into a 1911. (IMG:style_emoticons/default/smile.gif) Zach |
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