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Car Forum / Volkswagen / Air Cooled Volkswagen Cars / June 2005Valves Rattling
Greetings group, Something new has started in my engine and I'm not sure what else to do. When I hit the gas hard, the valves are rattling. At first, I knew it was timing, as we discussed here a few weeks ago and when I backed the timing off to where it should be, 7 btdc almost 30 full advanced, 009 diz, everything was just fine. Bought a tank full of cheap gas (I know...stupid) and it started again, not as bad but bad enough to notice. After about 150 miles I decided it was bad gas so I filled up again with the good stuff. Got better but still very noticable. I filled it up again after another 100 miles or so and it's the same. I adjusted the valves and put in new plugs and points this weekend. I've really only driven it to the store and back since because of all the rain this week but it's still rattling away. Any suggestions? <>< TC > Greetings group, > [quoted text clipped - 16 lines] > <>< > TC I am a total bug newbie, so just thinking about the things learned thus far (so could be a mile off base): Could it be that the head bolts are loose (not torqued properly) or you need some case savers? Or maybe worn (cupped in) cam followers? Bent or rubbing rods? Not sure, but wouldn't that make the valve adjustment near impossible to make? > Greetings group, > [quoted text clipped - 16 lines] > <>< > TC Sounds like predetonation to me(pinging) from the cheap gas. Anything else changed around the time the "rattling" started? No, nothing changed and I should have been more specific, yes it's predetonation, pinging, whatever you want to call it. I know "valves rattling" is not accurate but I figured everyone knew what I meant. I checked torqued on everything when I adjusted the valves, as I always do. And it being a fairly new engine, have been checking such often. I'm going to keep using the mid grade branded gas for a while to see what happens. Thanks, <>< TC > No, nothing changed and I should have been more specific, yes it's > predetonation, pinging, whatever you want to call it. I know "valves [quoted text clipped - 5 lines] > I'm going to keep using the mid grade branded gas for a while to see > what happens. .............OK, I'm going to take a stab at this. A 'fairly new engine' could have finally seated-in its rings which should dramatically raise the effective compression ratio. Too high a compression ratio would require a combination of high gasoline octane and/or less ignition advance to prevent pre-detonation. Without actually knowing anything about this new engine other than what you've posted, I'd get rid of the middle-octane stuff if possible and put 2 or 3 gallons of 93 octane in your EMPTY tank, add a bottle of octane booster and back the ignition timing advance off to maybe 3 or 4 degrees. If it then runs without 'rattling', you'll have a starting point to work from that isn't continuing to potentially damage your engine while you're figuring out why this has happened. You might be looking at a teardown if I'm right about all of this to recheck your deck height/combustion chamber volume and make some changes that would lower the compression ratio. "I adjusted the valves and put in new plugs and points this weekend. I've really only driven it to the store and back since because of all the rain this week but it's still rattling away. " Did you re-set the ignition timing after installing the new points? Chris > "I adjusted the valves and put in new plugs and points this weekend. > I've really only driven it to the store and back since because of all [quoted text clipped - 3 lines] > > Chris I checked it but it was still spot on so the answer to your question would be no. Points are gapped .016 and it was 7 btdc and just a hair under 30 full advanced. Thanks, <>< TC >>"I adjusted the valves and put in new plugs and points this weekend. >>I've really only driven it to the store and back since because of all [quoted text clipped - 11 lines] > <>< > TC Maybe you are running plugs that are sticking out too far. I've heard that can cause problems with the electrode getting very hot and causing pinging and other problems. -Kevin |
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