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Help Diagnose my engine tick/knock Posted by bobc [Email] (#473) [Profile/Gallery] (more from bobc) on Sun, 12 Jul 2020 05:29:41 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I find myself with a noisey Aero that presents with a loud ticking/knocking. This is a continuation of this thread https://www.saabnet.com/tsn/bb/9-5/index.html?bID=282135
I believe that I have isolated the source of the noise and Im looking for any help or advice and for the more experienced folks here to check my diagnosis. Im new to this so please check my work and let me know if I've made a mistake here.
Here are my steps, my findings and conclusions:
I ruled out accessories:
- removed the serp belt and the noise persisted.
- bonus: I discovered that the water pump was starting to leak.
I ruled out piston slap:
- pulled the valve cover and spark plugs
- no sludge on the top end.
- used a screwdriver through the SP Hole to push the pistons front/back left/right. I felt no play
Lifters:
- I pushed on them with my screwdriver, wiggled them. oil seeped out around the edges.
- I dont know what I was looking for here, or what a good vs bad lifter looks like/feels like.
Cams
- looked bright, shiny, no score marks.
- again I did not know what I was looking for but it looked OK to me.
rod bearings seem to have passed this test:
- Turned the crank with the stethoscope probe pressing on top of the piston feeling and listening for any sort of play, click or knock as I turned the crank
- Here is the test: https://www.google.com/search?q=diagnose+rod+knock&rlz=1CAZJXP_enUS851&oq=diagnose+rod+knock&aqs=chrome..69i57j0l2.4793j1j4&sourceid=chrome&ie=UTF-8#kpvalbx=_uaYEX5XAMduGytMP6vex0A830
- no unusual sounds, and no abrupt motion. Just smooth and quiet.
Buttoned it up started the engine and listened with the stethoscope. I listened first at idle. Then at 1200 RPM and finally with RPM varying from idle to 1200. there was no change in the noise except the frequency which varys linearly with RPM.
- Timing chain area
- quiet, just a whirring sound. no rattling no slapping.
- A faint, distant tap/tick could be heard
- valve cover
- there was a light ticking near 4, the farther away I got the quieter it got.
- at #1 it was just whirring and a distant tick
- exhaust manifold
- quite a racket here
- at #4 the loudest. A tick/tap/clang. the "clang" was heard here only
- moving away from #4 the tapping got quieter but the exhaust manifold was quite noisey
- Oil pan
- whirring. distant tick
- there was no distinct noise here, just a whirring and I could hear a faint, distant tick.
- the sounds on the pan were uniform, no area was louder than any other.
based on this I've concluded that the problem, and the noise, is coming from the head, in particular the valves in the vicinity of #4
and based on this conclusion I've decided to start with a head swap. I'll swap in a known good head.
What do you think?
_______________________________________ '08 9⁵ 2.3T SportCombi, Polar White '01 9⁵ Aero Midnight Blue (benched) '00 9⁵ Aero Midnight Blue (rescued) '99 9⁵ Base model, Cosmic blue '00 9⁵ Aero Silver (RIP - transmission )
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