1987 Porsche 911 — footwell gets wet only after heavy rain

I'd want a measurement, not a hunch. If a shop can't duplicate it on the 1987 Porsche 911, bring a video plus freeze-frame data, not just a story. If the cheap test changes it, stop and reassess. Happy to compare notes if your setup is different. Not trying to scare you — just skip the expensive first guess. I'm in no rush to be a hero on it.

Log the conditions before you spend. A pressure test beats staring at a dry driveway if the 1987 Porsche 911 is losing coolant with no puddle. Save the big job until that test fails. On “footwell gets wet only after heavy rain,” that was the fork that mattered for me. Had a similar mess a couple years ago and that's what finally sorted it. That's my plan before I call anyone.

Intermittent stuff lies if you only catch it once. Get a real battery/charging test on the 1987 Porsche 911, not just resting voltage, before blaming a module. Don't erase codes until someone who can help has seen them. On “footwell gets wet only after heavy rain,” that was the fork that mattered for me. Had a similar mess a couple years ago and that's what finally sorted it. This is the filter I use when the thread starts repeating itself. Heat soak after errands is the other window.

Start with the test that can prove you wrong. Capture voltage while the 1987 Porsche 911 is actually failing — after it restarts you've lost the clue. That's the branch I'd chase this week. This is from a 1987 Porsche 911 in Portland with 245,000 miles. Learned this the expensive way on a previous car. I've seen both outcomes, which is why I'd test instead of assume. Happens in gear, not in park, for what that's worth.

I wouldn't throw parts yet. Write temp, speed, and in-gear vs coast when the 1987 Porsche 911 does it — then decide on parts. Save the big job until that test fails. Was this after sitting overnight? If that fails I'll eat the diagnostic fee.

If it were in my driveway, two 1987 Porsche 911s can feel identical and have different causes, so measure before you copy someone else's repair. You'll know quickly if you're on the wrong tree. If they can't show the line item, I assume it's hiding. This is me being the wet blanket on purpose.

Ask what changed right before it started. A pressure test beats staring at a dry driveway if the 1987 Porsche 911 is losing coolant with no puddle. If the cheap test changes it, stop and reassess. Had a similar mess a couple years ago and that's what finally sorted it. No warning lights, which is why I'm documenting it.

OP update: scanned the 1987 Porsche 911 again and still only have the one pending code, no new lights. Doing the boring step first on purpose.

This is usually cheaper to test than to guess. A pressure test beats staring at a dry driveway if the 1987 Porsche 911 is losing coolant with no puddle. Don't erase codes until someone who can help has seen them. Happy to compare notes if your setup is different. I'll update if anything new shows up.