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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHAdvice on AOS replacement job
Leading reported evidence
Replace coolant expansion reservoir
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
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1
Discussions
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Performed · outcome unconfirmed
In addition to what you've listed, I replaced my coolant expansion reservoir.
Leading evidence: 'Replace coolant expansion reservoir' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'replace them as well' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Replace air oil separator' (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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Suspected cause
If the plugs are due (or "soon" will be) do the plugs and of course if the coils look suspect replace them as well.
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Suggestion
If the engine has a good number of miles on it and you believe in being proactive then consider replacing the water pump and the T-stat.
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Suggestion · Original poster
My question is, what else should I replace while in that deep in?
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12 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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So I'm about to dig in and replace my AOS. I know it's not for the faint of heart, but I feel I can tackle it.
My question is, what else should I replace while in that deep in? I'd rather not make return visits to this part of the engine bay in the near future if it can be avoided (that place is like my in-laws). I really want to get a comprehensive parts order in before I take the car apart. I am already planning on replacing the parts for the Secondary Air Injection check valve fault as I'd like that light to go away.
Any advice is appreciated, thanks again!
-Brock
I did mine when I did the IMS/RMS on a '00 C2. Watch out for the coolant hoses. I was warned but didn't think it was in the AOS. Got a little wet. Kinda a pain to clamp from underneath. Might be easier from top. Good Luck, other than that it wasn't too bad.
Rick
Stock up on tape and batteries for your digital camera. No joke!
There are so many vacuum hoses and connections that need to be pulled out of the way so when you try to put it back together it can get confusing. Document EVERYTHING!
What MY and what mileage?
Generally whatever needs to be done.
If you have a CEL with error code (or codes) pointing at something specific with the fuel tank venting system, address that.
If the plugs are due (or "soon" will be) do the plugs and of course if the coils look suspect replace them as well.
If the engine has a good number of miles on it and you believe in being proactive then consider replacing the water pump and the T-stat.
Needless to say if there are any leaks: spark plug tubes, camshaft covers, RMS; address the leaks.
What else? Well, there's the intake air filter, the fuel filter, the serpentine belt.
Thanks for all the feedback guys. The car is a 1999 C4 coupe, just turned 100k. I've had the car just over a year and it's been a joy to own. Aside from some issues getting the drain plug off on the front dif (still sorting that one out) working on it has been pretty simple compared to my wife's Audi.
I'm for sure planning on doing the spark plugs and tubes as there seems to be a small leak in that area. I'd also like to do the fuel filter since it's on the way. I'm also addressing the secondary air pump fault so I can get rid of the CEL (P0410 if I recall). Since I am about to move to Cali, I'll need that sorted for emissions testing.
The air filter I already replaced with a K&N assembley, so I should be good there. I will likely do the accessory belt while I'm in there. Is it a big stretch to get to the water pump and thermostat? RMS was done at 60k per the service records and I wasn't planning on bothering with that until the clutch went unless it starts spewing oil. Of course then I will also do the IMS upgrade.
I'm hesitant to drop the motor and will likely try to keep it in for the festivities. Maybe once I get more comfortable with working on a Porsche the thought of dropping the motor won't seem so foreign haha.
In addition to what you've listed, I replaced my coolant expansion reservoir. It wasn't leaking but I had similar mileage and figured it would go eventually. Removing it gives you some more working room when dealing with the AOS. I wish I had done the fuel filter while I was in there but it sounds like you're already doing it.
That's very good advise. As for dropping the motor, just loosen the motor and trans mounts and drop them down a few inches with your floor jack(s). This gives you more access to the AOS from the rear.....
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