Guest herbob Posted July 27, 2003 Share Posted July 27, 2003 My 97 Outback with 2.5 engine has 148k miles with all maintenance performed (know this model is prone to blowing head gaskets from searching this forum). Devleoped rough idle and flashing check engine light. Runs smoothly at higher revs. Dealer diagnosed "collapsed piston" with 25 psi compression on cylinder 1. New engine needed. Not sure I buy this since it runs smoothly at higher revs. There is a slight "ping" sound on acceleration, but nothing that sounds like a piston falling apart. Could this be timing that has jumped a notch or two on one cam? Would this allow the valves to stay open enough to cause low compression on one cylinder? (Not sure they checked all cylinders, think they just checked the one that the diagnosis code showed was misfiring). They did check the plug wires and plugs on the misfiring cylinder and they are OK. Any other ideas? Thanks! Quote Link to comment Share on other sites More sharing options...
Guest meep424 Posted July 27, 2003 Share Posted July 27, 2003 not a collapsed piston. but could be collapsed piston RINGS. Valve failure possible-- cracked, maybe, but not cam slippage. Rebuild engine/replace rings & hone cylinder walls is alternative. mike Quote Link to comment Share on other sites More sharing options...
Guest 1 Lucky Texan Posted July 28, 2003 Share Posted July 28, 2003 Do your plugs look (or have they looked in the past) all carboned up? Any past issue with fuel problems?(too rich) If so, you might actually be lucky enough to have a valve not closing due to a lump of carbon. You could try a Berrymans B-12 or other carbon 'shock' treatment. Just another possibilty. uh - PLEASE let us know what you find - might help someone else! Carl 1 Lucky Texan Quote Link to comment Share on other sites More sharing options...
Guest herbob Posted July 28, 2003 Share Posted July 28, 2003 Mike and Carl, Thanks for your inputs. No problem with fouled plugs--changed them myself about a month ago and the old ones looked pretty good. Have not yet seen the current plugs since problem developed. Will likely be several days before I have access to the car, but will post back when I have a final determination. Thanks, Herb Quote Link to comment Share on other sites More sharing options...
Guest 1 Lucky Texan Posted July 28, 2003 Share Posted July 28, 2003 Another post brought up a related subject. The old wet/dry compression test. You can use it to distinguish poor compression between valves or rings.The idea is to take a comp reading, squirt in a couple tablespoons of oil/STP, take anothe rerading with the pisto/rings wet with oil. If comp is the same, must be the valves leaking. The problem is, how to do this on a horizontal cylinder? Carl 1 Lucky Texan Quote Link to comment Share on other sites More sharing options...
Guest Legacy777 Posted July 28, 2003 Share Posted July 28, 2003 procedure should be roughly the same. I don't think it will be as effective, but it should show some signs of changing/improvement. Quote Link to comment Share on other sites More sharing options...
Guest pkdavis300 Posted July 28, 2003 Share Posted July 28, 2003 I have heard this term a few times, always from a dealer, never an independent mechanic. It is stealership language for "I think you're stupid, and I can scare you into major service or a new car". Run away and seek a professional independent. good luck. Quote Link to comment Share on other sites More sharing options...
herbob Posted August 21, 2003 Share Posted August 21, 2003 Here's the final outcome: Had 25 lbs compression, leak-down test revealed burned/damaged exhaust valves. Given 148k miles on the engine and the tendency to blow head gaskets, decided on a rebuilt engine rather than pulling both heads etc. Emily at CCR (303-293-9230) was very helpful in discussing the alternatives; they supplied the rebuilt engine for $2,695. Strictly Automotive in Denver (303-436-1700, talk to Greg of Steve) did the diagnosis and put in the rebuilt engine. Also put in a new clutch including the "snout mod" to the housing. Runs great and I highly recommend CCR and Strictly. They are straight shooters, competent, and honest. As for Subaru, I'm very disappointed. A well-designed and well-built enigine should go 250k easily, but these engines start having problems with head gaskets as early as 70k. I didn't have the head gasket problem, but it influenced my decision to go with a new motor and more $$$. Bottom line: Subaru is trashing their reputation for reliability. I'll never buy another Subaru unless it's with the old 2.2l that has proven endurance. In Subaru's defense: I neglected to do the valve adjustment at 105k(thought they were hydraulic like the 2.2l, oops. . .), and I suppose this could have prevented the exhaust valve damage. Thanks, everyone, for your past inputs! Herb Quote Link to comment Share on other sites More sharing options...
theotherskip Posted August 21, 2003 Share Posted August 21, 2003 when i did the valve clearance check on my car at 72k, one of the exhaust valves was at .005" (spec is .010"). i wonder if the 105k interval is too long... i just got a letter back from subaru after writing them about my blown head gasket. they said "We are not aware of a know condition with head gasket failures at this time." they seem to care less and less about customer service... Quote Link to comment Share on other sites More sharing options...
iluvmopeds Posted September 2, 2003 Share Posted September 2, 2003 Did you ever find out what was really wrong with the engine? Quote Link to comment Share on other sites More sharing options...
Nug Posted September 2, 2003 Share Posted September 2, 2003 I know on older VW's you needed to adjust the valves every 3k miles. Not that the adjustment changed that much, but you were watching for a valve that constantly too tight. The exhaust valves would stretch, and would eventually break off. Maybe your valve started to stretch, or perhaps the valve was guttering, or the seat was wearing. Worn seats and/or valve guttering could aggravate a burned valve. So can valve guide wear. Quote Link to comment Share on other sites More sharing options...
herbob Posted September 6, 2003 Share Posted September 6, 2003 No, I never found out what was wrong with the engine beyond the fact that the leak down test showed leakage past the exhaust valve(s) on the cylinder with 25 psi compression. I felt I would never trust this engine with 150k on it unless I at least repaired the damaged head and replaced both head gaskets--and this was getting up in $$$ to the point that a rebuilt engine made more sense. So I suppose it could have been a burned valve or a damaged/bent valve or a problem with the valve seats or. . . Quote Link to comment Share on other sites More sharing options...
99obw Posted September 7, 2003 Share Posted September 7, 2003 theotherskip, When I adjusted my exhaust valves at 118k miles, they were all at 0.007"-0.008" IIRC. It's wierd that yours were wearing so much faster. The local stealer gave me the impression that many people don't adjust the valves very often. I have to admit, in this day and age, if I didn't know better and a dealer told me I needed my solid lifter adjusted, I would tell them to go fly a kite. I am curious, do the Phase II 2.5 heads have solid lifters? Quote Link to comment Share on other sites More sharing options...
mazzy111 Posted October 5, 2003 Share Posted October 5, 2003 Well, looks like I have found someone with a similar problem. At 140,000 miles Exhaust valve on Cylinder 4 has zero clearance and I suspect the valve may be cracked in half. Can anyone confirm that a broken valve would cause this? It seems to me that if the valve wasn't seating, the clearance between the shim and cam would be higher than the spec, but I have the opposite. Suggestions? Rebuilt engine? Valve job? Valve job and head gasket? Please help!!! Quote Link to comment Share on other sites More sharing options...
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