woofe Posted December 20, 2008 Share Posted December 20, 2008 Bought this car from my brother. It is an 03 legacy with 69000 mi and has the 2.5 motor. It seemed like a REAL good deal. The car runs quite well. I don't hear it inside the car when the widows are up. It is very audible when the windows are down. The issue is that it has a nasty tinny tapping sound at idle. It goes away above about 1200 rpm. It seems to be loudest on the drivers side of the engine compartment and seems to be associated with just one event per (or every other) engine revolution. I assumed that one (or more) of the valves had the lash set far too loosely. In the "old days" of messing with air cooled VW engines this issue is clearly identified as something in the valve train. I have heard a lot of rod knocks and piston slapping in my time. I don't (so far) think it is such a problem. I got the books and reviewed the procedure to check/set the valve lash (this is very much like setting valve lash on a VW engine). When the valve covers were removed, I noticed the inside of the covers and the head and valve train were spotless (I took this to be a very good sign). While the engine was cold I followed the procedure in the book and checked all 16 valves for correct lash. I set (or reset) intakes at .008 to .009 and exhaust to .009 to .010 inches lash. I did not find anything that was grossly loose. I did find the exhaust valves on #3 cylinder to be too tight at about .007 inches and corrected the lash. I did not expect that I had found and solved the problem. I reassembled all the parts and pieces and started the engine. I appear to have had some impact on the problem as it does not appear to be as loud as before. The tinny ticking noise is still matching the engine speed at idle and is clearly only one "tick" per cycle. I'm beginning to consider that the cam may have a defect that is generating the noise. I've seen such things before on both VW engines and in a few early 80s Hondas. I plan to get the stethoscope out tomorrow and go hunting (again). Any thoughts are greatly appreciated. woofe Link to comment Share on other sites More sharing options...
idosubaru Posted December 20, 2008 Share Posted December 20, 2008 highly unlikely the cam is to blame. that stethoscope should at least help you narrow down which cylinder is the cause. sounds like you're fairly confident that it's not something else up front, like a timing belt tensioner? and keep piston slap in the back of your mind too. it usually is loudest at start up and quiets down as the engine warms up. don't think any other tapping would do that. Link to comment Share on other sites More sharing options...
woofe Posted December 20, 2008 Author Share Posted December 20, 2008 highly unlikely the cam is to blame. that stethoscope should at least help you narrow down which cylinder is the cause. sounds like you're fairly confident that it's not something else up front, like a timing belt tensioner? and keep piston slap in the back of your mind too. it usually is loudest at start up and quiets down as the engine warms up. don't think any other tapping would do that. The issue with piston slap seems to be a very common problem. After doing a google search last night and reading a bunch of posts and listening to a lot of recordings, I have to admit several of them sound like what I have going on. The issue for me is that, piston slap I have heard in the past had a more massive "sound" to it. Slap I've heard in the past was not as sharp as the sound I'm currently hearing. Hence it is suggestive of two less massive hard surfaces (objects) banging together like what I think a valve head and rocker would sound like. Of course that was in a different style of motor. Also, can anyone explain if it is normal for piston slap to "go away" with an increase in RPM above about 1200 - 1500 RPM. When driving with windows down, I usually don't hear the tapping until I decelerate to under 1000 RPM . From what I have read, the tensioner seems to be a source of trouble also. I would think the tensioner would cause a higher frequency tapping than something corresponding to the frequency of one valve set tapping or one (or even two) pistons slapping cylinder walls. Can anyone describe to me the typical failure mode of the tensioner??? thanx woofe Link to comment Share on other sites More sharing options...
ocei77 Posted December 31, 2008 Share Posted December 31, 2008 It's engine noise that's hiding the slap. My BE had a case. Noticed it at @26K. Diagnosed at 35K. Not fixed still 55K (by dealer under warranty). The car will run indefintitely like that, but it is annoying and you always have that what if question in the back of your head. O. Link to comment Share on other sites More sharing options...
idosubaru Posted December 31, 2008 Share Posted December 31, 2008 piston slap is loudest at start up. that it goes away with increasing RPM is true of lots and lots of engine noises just due to tire, trans, engine...all sorts of other noises drowning it out. i'd just ignore that "fact" for the moment. Link to comment Share on other sites More sharing options...
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