Coolant Leak - Need 2nd Opinions

[Spannerhead]

Hi guys. New here. Working on a coworker's '02 Tiptronic Boxster S, trying to track down a coolant leak. I've already replaced the water pump & thermostat (pretty straightforward), but there's a leak that's dripping from the corners of the splash tray, more so on the right side. See below:



All the hoses above it are intact and dry from what I can tell. I removed the forward rear fender liners, and there's coolant on this brace, both sides:



I removed the engine top cover, and firewall access panel behind the seats, no leaks.

Then I removed the trunk liner and saw this:





(yellow is old coolant, red is newer coolant)

The tank is leaking, right? If so, how does the coolant make its way down on the chassis braces in front of the rear wheels? And over that far to the left in the trunk?

Any input welcome. Thanks!

[JFP in PA]

Yes, by gravity

[Spannerhead]

Right, but where is the path? Are there drain holes at the front of the trunk? It just seems like a long way to go from the front edge of the trunk to the chassis braces in front of the rear wheels (and then onto the splash tray)? It makes me think there might be something else/besides the tank leaking.

[JFP in PA]

There are about a dozen or so places where it can leak thru.

[Homeoboxter]

Originally Posted by Spannerhead

Right, but where is the path? Are there drain holes at the front of the trunk? It just seems like a long way to go from the front edge of the trunk to the chassis braces in front of the rear wheels (and then onto the splash tray)? It makes me think there might be something else/besides the tank leaking.

Why does it matter? Just replace the tank and call it a day.

[Spannerhead]

Originally Posted by Homeoboxter

Why does it matter? Just replace the tank and call it a day.

Because the drips are a long way from the tank, and I was wondering if there were other common sources of leaks closer to the drip locations that I should look for and address in addition to the tank.

[Raji]

The leak could be coming from anywhere

[Spannerhead]

Originally Posted by Raji

The leak could be coming from anywhere

No kidding.

OK, let me try this a different way. When your 986's coolant tank is compromised, where does it typically drip from under the car?

[JFP in PA]

Anywhere it wanted.....................get on with it and replace the tank

[Spannerhead]

Amazing introduction to the Porsche owners community. Wow.

Guys. The tank is compromised. I get it. I will replace it.

BUT. Do the drips in front of the rear wheels (a long way from the tank) point to a bad tank? Or is there a hose closer to the drip location that could be leaking?

I'd feel pretty stupid if I replaced the tank only for the car to still be leaking from somewhere else. That's what I'm trying to determine.

[Marc_986]

Well, I think they are saying (with different forms of humor) it could be just the tank and coolant will find a way to somewhere.

I'd take the advice, replace the tank, clean everything up and see if it persists. If it does, you have at least solved one issue.

[JFP in PA]

Originally Posted by Spannerhead

Amazing introduction to the Porsche owners community. Wow.

Guys. The tank is compromised. I get it. I will replace it.

BUT. Do the drips in front of the rear wheels (a long way from the tank) point to a bad tank? Or is there a hose closer to the drip location that could be leaking?

I'd feel pretty stupid if I replaced the tank only for the car to still be leaking from somewhere else. That's what I'm trying to determine.

If you are that concerned, add some UV dye to the cooling system, after circulating it for a while, pressurize the system with something like the Stant system test tool, put the car up in the air and look for where it is coming from with a UV light.

[Homeoboxter]

A less sophisticated but simpler test is to pour about a quart of water into the trunk below the coolant reservoir. You will need to clean up that mess anyway. Then you just follow the route. If you see the water accumulate at the same places where the coolant did before, you can be almost 100 percent sure you have only one source of a leak. Good luck!

[Starter986]

I've been here since 2017... and there's one thing I learned and that is to listen to the more than several knowledgeable members... JFP being one of them. It has saved me a lot of time and money.

OP... change out the tank. See you soon. Welcome to the board.

[78F350]

Originally Posted by Spannerhead

Amazing introduction to the Porsche owners community. Wow.

Guys. The tank is compromised. I get it. I will replace it.

BUT. Do the drips in front of the rear wheels (a long way from the tank) point to a bad tank? Or is there a hose closer to the drip location that could be leaking?

I'd feel pretty stupid if I replaced the tank only for the car to still be leaking from somewhere else. That's what I'm trying to determine.

There are multiple hoses that connect to the coolant tank at the firewall. You will have to disconnect them all when you replace the tank that is clearly failing. Those hoses are short and connect to metal tubing that leads to the front of the right rear wheel. Inspect them when you replace the tank. They rarely fail.



Using 'flexible hose clamp pliers' and ensuring that spring clamps vs screw clamps are used will make the job go much better.

[Rob175]

Once the coolant leaks out of the tank it moves all around the truck as you drive the car. Ever hear of "centrifugal force"? Liquids will slosh around as you drive....trust that it will always find a place to leak out of since the car isn't sealed "water tight".

Replace your old, yellowed plastic coolant expansion tank AND BE DONE!
(of course while you're at it I suggest you change out your water pump and buy an OEM replacement tank....not a cheaper aftermarket substitute .....you usually get what you pay for these days.

[Spannerhead]

I replaced the water pump & thermostat about a month ago.

Got the new tank in. Not too hard.







Looks like some stress cracks in the base of the tank.

I reattached the hoses through the engine bay top opening because that way I could be sure they were snug against the plastic plate. The oil filler tube was a pain.

Still find it weird coolant managed to find its way all the way in front of the rear wheels from the trunk. Also, this is probably the most overcomplicated cooling system I've worked on. And I've owned 4 BMWs, lol.

No leaks I can see. The low coolant warning in the tach flashes (the slow flash) for about 10 seconds on startup, but then goes off, though. Even after a few drive cycles. From what I read, the sensor is kind of flaky?

[Smallblock454]

What is that? Looks like something has worked itself into the plastic.

[Spannerhead]

Originally Posted by Smallblock454

What is that? Looks like something has worked itself into the plastic.

[img]

No idea. Maybe some gunk accumulated on the inside of the tank in the crack seam? It's the original tank AFAIK, ~67K miles on the car.

[theWalkinator]

I just replaced water pump and thermostat, while doing coolant flushing, I over filled distilled water and water dripped down in front of rear passenger side like you said, and water find a pathway somewhere.

There are 4 hoses going to expansion tank through a bulkhead and hoses are clamped to the bulkhead on both side, so that might be another source of leaks. If you have a coolant system pressure tester kit you can test pressure and see where the leaks is, you can rent one from you local auto part stores.