Rotmilky

I'm currently traveling to visit my parents and got stuck in a weird hail storm that closed I40 for a few hours last night. Who gets stuck in an ice storm in July? Anyway, the road was closed for about 4 hours. As I sat in my car idling, I started to smell coolant. I checked and i could see dripping just below the cool reservoir. I thought it was maybe coming out of the overflow tube, but when I pulled it, it looked dry. Drip rate was maybe 2 drop per second.

I shut the car off, turned off the A/C and the dripping stopped. When the road finally opened, I had to drive the car another 1.5 hours to get to the hotel. This time with the A/C off. No more drips during the remainder of the trip. I stopped every 10-15 minutes to check. Didn't smell burning coolant and didn't see any sign of leak after that.

Since I'm stuck away from home, I'm hoping you guys can help me sort this out. I do have a set of tool and my workshop manual, so I can do a fix in the boonies. But I need to figure out where it's coming from pronto and get the right parts moving my way double pronto. Based on the location, I'm thinking potentially coolant cap, bad coolant reservoir or bad connection to reservoir from one of the coolant lines.

1) Are there any known leaks caused by running the AC while idling? Not running the AC while I idled 'seemed' to fix it.

2) When a faulty coolant cap leaks, where does the coolant actually leak out? Could it be the coolant cap?

3) If it's a bad reservoir, is there a way to know it's the reservoir without simply replacing it to test?

4) Are there any known issues with the coolant lines connecting to the reservoir?

Any suggestions to help me figure this out and fix it would be greatly appreciated!

LexVan

What are the last 2 digits on your coolant cap? The newest ones end in "04".

997_rich

Even if you have the "04" coolant cap it can still fail (soft, not hard failure). You'll see a little residue around the perimeter of the cap and then it spills down the sides of the tank eventually.

AC on just puts more heat in the engine (more load, more heat off the condenser, etc). So that increases the coolant temp slightly which increases the coolant pressure. Same thing for idling in place rather than crusining.

Renzsport

I've experienced the mysterious coolant leak once as well, but haven't seen it since. I think it might be a design flaw with the tank? Make sure your coolant is topped up and keep an eye on the temp gauge, but can't help much beyond that.

LexVan

Early signs of a pending waterpump failure? A 2005 is getting pretty close (over) to the edge on the waterpump.

USMC_DS1

As a temporary fix since you're in the boonies... fill up the coolant reservoir with distilled water assuming you cannot gain access to VW or Porsche coolant. https://rennlist.com/forums/997-foru...-porsches.html

2) When a faulty coolant cap leaks, where does the coolant actually leak out? Could it be the coolant cap? If it's the cap then it should leak out around the coolant cap although it may be leaking on the back side... use a white/light cloth to wipe around the cap area and reservoir to help determine where the coolant fluid is leaking. If that's clean then apply the same method to check the tank.

3) If it's a bad reservoir, is there a way to know it's the reservoir without simply replacing it to test? There are coolant fill tools, such as the Airlift, which will help to fill the coolant system properly and have the critical secondary function of checking for leaks within the coolant system.

http://www.amazon.com/UView-550000-Airlift-Cooling-Checker/dp/B0002SRH5G

http://www.amazon.com/UView-550000-Airlift-Cooling-Checker/dp/B0002SRH5G

4) Are there any known issues with the coolant lines connecting to the reservoir?
Some background
We have extensive amounts of coolant lines running front to back. All those lines should be inspected/tested as part of regular maintenance... This requires that all the panels beneath the car and the front bumper are removed to visually inspect the keyed hose connectors and the hoses for wear/tear/condition. BTW, this does not test for a system under load... Only a tool similar to the Airlift or run time conditions such as you've experienced will stress the system for leaks at load. So it's good maintenance SOP to flush the coolant system... plus I personally don't buy into the "lifetime coolant" marketing spill nor does my SA and the parts manager at my p-dealer. FWIW, most p-dealer tech's will indicate that they inspected your lines and reservoir for leaks when you take it in for service... that's a qualified "inspected"... they likely did not remove the under panels and certainly did not remove the front bumper. And obviously they did not test your car under load unless you paid for a complete coolant flush. If you've never had your coolant system flushed, tested for leaks, etc... well it's a good time to consider this especially after 8 yrs. I did a partial flush and leak test at the 4 yrs mark... and plan on flushing more every other year from now on. Here's a DIY and some more background re this topic. https://rennlist.com/forums/997-foru...-part-1-a.html

Try to determine exact where the leak is occurring before you hit the road again. If you cannot determine this with the current coolant over flow then clean off all leaked coolant, do a short drive, then check for initial signs of run off/over/leaks. Focus on the WP and coolant tank areas for leakage. If the leakage is truly at or near the coolant tank then you may be OK to nurse her home or the p-dealer if it's not adverse... check regularly on the road and just have it towed if you start loosing any significant amounts of coolant. If the leak occurs below the coolant tank then be very careful... If it's a hose then replace if at all possible... overnight the part from pelicanparts.com if you have to. Small leaks on a hose or the WP can get by under normal conditions but then get exponentially worst after a heavy load similar to what you just experienced... a small breach can become a big gusher in the worst of environmental/driving conditions and it's all downhill from there. The WP's are known to fail after 40K-50K miles. If it's the WP then have it towed or replace it before you drive. Don't take any chances with that one. Better safe than $26K+ lighter for a rebuilt engine from Porsche. GL and keep us posted on your outcome.

Rotmilky

Thanks for responses. I did make it to my destination and am trying to find the leak now. Unfortunately, the leak has stopped and has not leaked any (that I can tell) since. I think I may go start the car up and idle it in the driveway with the AC on. Summer in Texas (where my parents live) should put more stress on it than summer in the mountains of NM.

The leak is coming from near the coolant reservoir. Exactly where is hard to tell because it drop down onto the muffler baffle (or whatever that big muffler expansion thing is in the rear wheel well) and then it drops off of the bottom of that.

I replaced the WP about 3000 miles back (using your excellent DIY guide USMC) and refilled the coolant using and airlift. At that point in time, the coolant system would hold a vacuum to the point that I noticed nothing abnormal. I didn't actually pull a vacuum on the system and then see how long it would hold. I pulled the vacuum to what the directions specified, then swapped from vacuum to fill mode. I do seem to recall that the directions specified pulling the vacuum to some value before filling. I couldn't get to the value specified. It was a little shy of that. I figured my gauge read wrong. Maybe I had a small leak then? What happens on an airlift when you have a leak and you try to pull a vacuum? Do you still pull a vacuum but just not as high? The other possibility is that the cap could be bad. With the way the airlift works, you can't test it with the cap on.

In any event, I've ordered a reservoir and cap. Since they are known to be problem areas, I'm looking at it as preventative maintenance even if they don't fix the problem.

Edit: When I saw the leak, I stopped off and grabbed several gallons of distilled water. I don't have my P-approved coolant on me.

USMC_DS1

Very nice... you have the right tools and you've already swapped the WP so you're well ahead of the game! I like your approach of swapping out the reservoir tank and cap at this point... cheap insurance. Let us know the postmortem re condition of the tank. This is something I've been contemplated as a preventative measure myself. FWIW, the airlift should hold it's PSI setting provided everything is airtight. I believe 21 PSI was the target setting... but double check the instructions.

FiatCoupe

I had the coolant reservoir replaced under warranty, not sure of the exact mileage but around 50k - 60k miles. There was a vertical split in the side nearest the engine that was difficult to identify or see anything directly leaking from it. I initially replaced the coolant cap but that didn't help. I would clean up the dry pink deposits underneath but they would reappear. I head that others have had problems with the reservoir splitting so I had a closer look and could see the problem area.

John

user 72902

Did you check you coolant recently? Sometimes the caps are a little tight and when you think they are 100% seated they aren't and will leak.

PelicanParts.com

You're headed in the right direction with solving this problem! Sounds to be a minor leak either hose, tank or cap.

Rotmilky

Managed to get home today. A roughly 600 mile trek and not a single leak during the trip. Talk about intermittent.

As luck would have it though, I pulled into the driveway (which is sloped) and unloaded the frunk. When I came back out to put the car in the garage...there was coolant leaking. I yanked the air intake assembly and could see a stream shooting out of the reservoir across and hitting the engine. The leak itself was behind the hose support bulge in the tank that is roughly halfway down the long side. I grabbed a mirror and could finally see it shooting straight out of the reservoir. Around the hole was a little bit of foamy looking matter that had collected I suppose during the previous leak.

So, in this case, the leak is caused by a leaky expansion tank. Fortunately I have a new one on the way. When I yank the old one, I'll post some photos of the location of the leak and the foamy stuff I see around the hole.

--Von

Hella-Buggin'

I had this happen occasionally. It turned Out to be a small crack in the reservoir tank. Mine wouldn't do it unless it was parked up my driveway on a really hot day.

M

Rotmilky

I wonder if it needs to be parked on a slope to do it consistently? When I first noticed the leak last week, I was parked on a slope at a gas station waiting for the interstate to open. No leak again during about 900 miles of driving over 3 days. Then it did it again while I was idling parked in the driveway on a slope. <shrug> In any event, I'm just happy to find out where it was coming from.

Renzsport

I recollect mine happening on an inclined driveway as well, yet ever since then nothing at all. Glad to hear you've identified the exact location of the leak and I'm looking forward to pics. I guess I'll be ordering a new tank for myself!!