15 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHVery strange coolant behavior
Reported or suspected cause
working itself out
Suggestion or failed attempt
No successful repair reported for this finding.
0
Identified cause
1
Suspected cause
0
Reported fixes
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Discussions that suspect a cause
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Leading evidence: 'working itself out' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'working itself out' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Run engine at at least at load a few times' (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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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion
and run the engine at at least at load a few times.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
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Suggestion
Did you use an airlift or similar to refill the system ?
Outcome qualification: Negation, uncertainty or missing explicit repair resolution overrides the raw extraction signal.
Coverage and how to read this overview
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
15 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 1 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T091943Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I flushed my coolant a few days ago to change a lower rad hose, and now something very strange is happening.
After driving a decent distance (20mi+) the coolant light starts to flash, indicating a low coolant level.
I pop the rear lid and can see no coolant in the overflow tank. I slowly(!) unscrew the blue reservoir cap and hear hissing air, while at the same time the coolant reappears in the expansion tank! Now the cap is off and the coolant level is at the max line.
I add no coolant, put the cap back on, and it's good for another 50 miles before a repeat occurrence.
WTF is going on here?
1 suction cycle only..
Are you following the factory bleeding procedure when you pull the cap off?
The system will self bleed if you follow the directions its just annoying.. LOL
please elaborate ... what are you saying I should do?
i�m not sure if that little bleeder plunger on the reservoir tank is doing anything. Should it be possible for pressure to build in the system with the plunger in the upper position? Because it is. If it�s meant to operate like a vent then I don�t think it�s working.
Make sure the cap is the most current version, there are leak and pressure control issues with the older cap.
Should be Blue IIRC..
You need at least a Haynes manual on the car just for the maintenance details,,
or you will spend a lot of money or damage if some minor things are not handled right..
The bleeder "should" be open till you've heated the motor up to full temp a couple times
and run the engine at at least at load a few times.
Not only should the coolant cap be blue, but the P/N must end in "04", although I still had an OLDER blue coolant cap on my 2002 996 up until this summer when I finally replaced it with the latest "04" version. Never had any leaks or strange coolant behavior though with the older cap...guess I was one of the luckier ones.
I appears you still have air trapped in the system....time to do an old school burping.......I would go for a 10 mile drive with the coolant tank expansion cap off (or very loose)......bring the coolant with you........stop and refill as needed....drive some more with the cap off or very loose.....stop and refill as needed.....until the expansion tank is midpoint when hot....
Keep a close eye on engine temperature as you do this
You have air trapped in the system. The bail must be left up for a couple of heat cycles. Refilling when cold. It is not a “vent” per say. It is more of a vacuum break that allows the system to vent during cool down when the bail holds it open. You have probably noticed that it rises and falls on it’s own during normal operation.
I’ve been following the advice here, driving with the vent open, topping up as necessary. I believe the problem is working itself out. I’ll let you know.
Air is compressible; water is not - which is why the system is behaving differently between hot and cold / pressurized and not pressurized. The liquid in your cooling system always occupies (roughly) the same volume; the air volume decreases when the system is pressurized, displacing the coolant in heretical ways God didn't intend.
This is a source reference. Confirm exact model applicability in the original material.
