2001 Boxster Coolant Leak - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Greetings: I recently purchased my first Porsche, a 2001 Boxster with 120k miles. Previous owner replaced IMS, RMS, water pump, clutch, spark plugs and coils very recently. I have noticed a robust leak of pink coolant out of the overflow tank hose once the car warms up, confirmed by placing the back of the car on a ramp and observing fluid coming from the lumen of the tube. I have driven the car around 600 miles or so since purchasing, and have not noticed a "low coolant" light. There is no visible leak around the water pump, hoses, or thermostat housing. The heater works as it should, and the car does not overheat, which leads me to believe that both the water pump and thermostat are functional. There is no white smoke from exhaust and no unusual color (white/creamy) on the oil dipstick. There is a -04 series radiator cap installed, a dry trunk, no corrosion in the bottom of the trunk, no wet area on rug, and no corrosion around the bleeder valve bolts. Nevertheless, I attempted to manually raise the bleeder valve with the small metal tab on top, which promptly came off in my hands. It appears that there is wear around the rubber where the metal tab sits on the bleeder valve, and I am uncertain whether this valve is working at all. I was going to replace the radiator cap (despite being an -04) and the bleeder valve with a genuine Porsche part (around $85 or so, as the aftermarket parts have not gotten the greatest reviews). Notably, if I remove the radiator cap while the engine is warm, I don't get the sense that there is any pressure/steam/etc. escaping from the overflow tank. I wonder if the hoses were ever removed from the tank (it doesn't look old/yellowed), and if so, were placed back on the right nozzles? What else might I be missing? The coolant system seems to be unique on Porsches (i.e. I'm just getting used to it). I have done quite a bit of work on other cars, including Alfas, Maseratis, Cadillacs, Mercedes, etc., so I am rather handy. Before I start throwing $$$ at head gaskets, etc., was curious what others more experienced with these cars might think. Any help appreciated. Best Dave

Before throwing parts at it the first thing to do is a system pressure test. That should help you locate the fault. The burp valves can be rebuilt.

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The bleeder valve tab should not come apart. There should not be visible wear on the rubber where the tab sits. It sounds like your vale is worn out/damaged and dumping coolant before it reaches normal operating pressure. I'd watch that area when you do the pressure test.

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Attached pressure test kit to overflow tank cap with a tight seal, cold engine. System holds *no pressure*. Heard air leaking around the bleed valve. Put some water around the valve, and saw bubbles near one of the screws where bleed valve cover attaches to overflow tank. No obvious cracks and no pink fluid in trunk. Bolts are tight so didn’t feel the need to overtighten. Are next steps replacing the bleeder valve, o ring, etc, or ? Dave

You can replace the bleeder valve. I have pulled one apart on a bad tank out of curiosity and it's not too complex. Here's a thread that I've read before: http://986forum.com/forums/performance-technical-chat/47325-my-first-question-bleeder-valve.html I would recommend replacing the entire tank unless you know that it has been done in the last several years. The tank will wear out eventually. Why not do it now. There are lots of complaints about aftermarket tanks. Many of them are flawed right out of the box. Best to go with Porsche brand even though it costs (much) more. The easiest way to replace the tank: http://986forum.com/forums/diy-project-guides/56334-diy-coolant-tank-replacement-under-2-hours.html

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Many thanks for the links... fingers crossed that this is the source of the problem vs. a red herring. Any other reasons why I shouldn’t have any pressure (ie cannot even pump it up to 2-3 lbs)? Dave

I discovered that my bleeder valve was leaking when I attempted to use a vacuum lift tool to replace the coolant in my 987.1S. I purchased a new bleeder valve kit and It was straight forward to replace. Just be careful not to over tighten the screws as they go into the plastic reservoir. I used silicone grease on the rubber seals to seat them properly. Sent from my Pixel 3 using Tapatalk

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Replaced the bleeder with a new kit. Haven’t noticed any leak from underneath car, through the overflow pipe nor is there a coolant odor anywhere. Interestingly, when the car is hot (180) or so, unscrewing the cap still releases no pressure. Dave

There's another place that I have found small coolant leaks. Both radiators have a small connection for a tube at the top corner. Those tubes join and run back, under the car to the tank. The connection at the radiator is fragile and I have found them cracked on a couple radiators. Hopefully yours is good now. Have you tried a pressure test again?

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Update: replaced bleeder valve, system still holds no pressure (using pressure tester) and I can still hear air seemingly near bleeder valve during pressure test. O rings are on it properly. System also dumped a ton of coolant through overflow again today after a spirited run. No evidence of coolant in trunk. Is there anything potentially serviceable underneath bleeder valve? Stumped on this one. Dave

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Slightly off topic but appropriate.... I have a slight coolant leak from the front passenger side and I was thinking to remove the underside panel and check around but looking at this pic its probably checked from the top? How do I take a look at the top of the radiator? thanks Nevermind, I found a write up, but is there any way to see a possible source of a leak without taking the whole front end off?

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Simplest things first. are you sure the bleeder valve is in the down position? If yes take it apart again and make sure you reassembled it correctly.

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Took apart again. Everything seemed in order... cleaned around new o rings. When cold still had difficulty holding pressure. If I pumped up to 4psi I could hear a high pitched squeal coming from around bleed valve housing. Nevertheless I started the car and once it began to warm up, I was able to pump pressure tester to 5-7lbs and it would hold pressure. As engine warmed up pressure increased as well. Wondering if I’ve finally seated the bleed valve correctly. Popping up tab on bleed valve reveals a burbling sound which goes away with tab down. System still holds pressure and does not leak out overflow valve. Despite having an .04 cap I think that is now the culprit. Off to dealer to grab new cap. Fingers crossed! Many thanks for all of the great suggestions. Dave

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With things working correctly you should be able to pump the pressure up to around 14 PSI and it should hold the pressure. If you do a search on the forum someone has probably listed the spec for pressure but 14 PSI is in the ballpark

I purchased a new cap (another .04 cap) and appears to hold pressure now and release steam when loosening cap (something that never happened previously) when engine is hot. There was no additional output via the overflow tube after spirited driving or letting it idle. I will pressure test again to see if I am able to get it up to 14PSI or so, but cap seems to have been the ultimate culprit. Sincerely appreciate all the comments and support on this forum. Best Dave

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Hey glad you came good.