16 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHSolved - Knocking noise (let's speculate...)
Leading reported evidence
Replace oil
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
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1
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Read evidence and context
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Leading evidence: 'Replace oil' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check gauges - 5 bars' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion · Original poster
Check all gauges - 5 bars on oil pressure, 14v charging and no CEL.
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Suggestion
I will be changing the my oil very soon to the same oil you have in your car, Total 5W40.
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Suggestion
Lifter noise happens after the motor has been run for a while as the valves that are open are continually exerting pressure on the lifters trying to get them to colapse and evacuate their oil supply.
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16 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Drove the car 1,200 kms last week. Washed car and put it away on Sunday and have been using the Subaru.
Went to start car and move it this evening.
Loud knocking noise from engine area appears immediately. Not a ball bearing noise, but rather a hard clack like knocking rod or really loud lifter / tappet which is engine speed sensitive.
Check all gauges - 5 bars on oil pressure, 14v charging and no CEL. Shut down. There appears to be a bit of oil smoke in the garage. Check for leaks etc. nothing. Oil level is fine and clean. Coolant level is a bit low, but at the minimum level.
Oil was changed 2 weeks ago (Total 5W40). Filter inspection showed no metallic parts and a few small pieces of brown plastic that I would attribute to chain tensioner pads.
Engine is factory remanufactured, installed in 2008 and have about 40K miles on it.
I am desperately hoping this is a collapsed lifter. Any other thoughts?
Syn oil will allow lifters to bleed down when not driven for several days. Not hearing the noise, it's hard for me to advise you what to do. If you feel comfortable running it again, the noise should gradually go away in a few minutes or less. I'd just let it idle and don't rev it up. If the noise starts to diminish you can increase the rpms slightly which will increase oil pressure and help to fully feed and pressurize the lifters at which time the noise should totally be gone.
Generally catistropic related noises start and occur while the motor is running and not happen all of a sudden after being parked. Lifter noise happens after the motor has been run for a while as the valves that are open are continually exerting pressure on the lifters trying to get them to colapse and evacuate their oil supply. When this happens you get clatter until the refill and get full pumped up.
small animal trapped in the belt?
heck, I am hoping for simple fixes
coils is a good guess, CAT(s), loose muffler?
did it stop, did it repeat? maybe a lifter...could also be a tensioner stick, but with a reman motor those parts should all be fresh.
I will tell you I have seen a valve come thru a lifter...but that noise did NOT go away until the lifter was changed
I just idled it again and noise appears to have diminished some. It's still loud, but not nearly as bad. I will let it idle for a while tomorrow morning.... Hoping it is a lifter.
I will be changing the my oil very soon to the same oil you have in your car, Total 5W40.
How long have you been using this oil and have you noticed any differences compared to others?
Just a lifter that had collapsed. After running for a while the noise vanished as it pumped back up. Took it to my indie for a check and all the coils and plugs are fine.
And Ed, no small animals were discovered.
Really! I had a grindy, flappy noise the other day. Panic
I was sure that it was dreaded IMSB FAILURE and had it towed to the dealer.
It was a flat rear tire!??!
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FWIW I had a sticking lifter on my 996...occationally on an autoX run it would act up the next time I started the car...was a little scary but since I knew what it was I just monitored it...for a LONG time, it only showed itself to me about 4-5 times in a year and only for a short while, sometimes stopping quickly, sometimes making me think...it gave up - but it never did
