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 |
Jax914 |
Sep 25 2009, 05:41 PM
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#2
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Schwienhund Rennenmannshaft Group: Members Posts: 138 Joined: 7-August 06 From: Jacksonville, FL Member No.: 6,602 Region Association: South East States |
You pulled the rocker covers, but did you check the valve lash? There can be a very big impact when the lash isn't correct. The engine must be stone cold - do not run it the day you plan to adjust.
Lots of links out there to how this is done. You only need basic tools and some time. http://www.vwtrendsweb.com/tech/0106vwt_va...ment/index.html http://www.aircooledvwlove.com/how-to-adju...oled-vw-engine/ http://www.vw-resource.com/valve_adjust.html A leaking intake manifold gasket will normally result in a lean condition - spraying starting fluid around the base of the carb and manifold to head should quickly reveal any leaks. Your plugs are showing extreme oil deposits / carbon fouling. http://www.aa1car.com/library/reading_spark_plugs.jpg An improperly gapped plug / bad plug wire / fouled cap or rotor can make the plug not fire. Be aware that under compression, your plug may not fire, even though it fires when you pull it and look at it. It's cheap to adjust your valves, put new a cap, rotor, points (or get a Petronix) and wires. Lastly, pull the main coil wire, and after you've adjusted the rockers to the proper lash, leave the cover off and have someone crank over the motor - watch and make sure the rocker arms are actually moving - it may be a rounded off lob on the camshaft. It's easy to check and see with the cover off. When you're at higher rpm's, it's easy to mask one cylinder not working properly. HTH, |
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