Engine Temperature and Coolant Light - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Reddy Head · 07-11-2014, 10:21 PM

Hello, I'm new to the Boxster world, I just purchased mine about a week ago. Initially I had noticed that coolant was leaking through the cap, as there was condensation on the trunk lid. I went ahead and topped off the coolant and purchased the new coolant cap (part number ending in 04) and installed it. There seems to be no more coolant escaping, and to be thorough I did pull the trunk carpet to check if there were puddles - luckily everything appeared to be dry.

With the old cap on the engine temperature seemed to climb pretty quickly to about 187F and the coolant light would blink.

I took her for about a 35min drive tonight. This being the first time I've driven her at night, and the temperature was low and slowly climbed to the 187F mark - however this time I was pushing her and driving through some pretty twisty roads. I noticed that the coolant light was glowing a very dim red color - it wasn't blinking as it did previously with the old cap...

My questions are:
1. Does the coolant light always glow that dim red color whenever the headlights are turned on? (The dash gauges and everything are lit as expected, I'm thinking that light is supposed to be slightly lit as well)
2. Is 187F a high running temperature?
Keep in mind where I'm staying at the moment temperatures between 90F - 105F in the summer are normal.

The reason I'm a little concerned is that I will be driving her 581Mi. back to my home, as I bought her out of town, and I would hate for there to be a problem on the road.

Thank you in advance, your advice is much appreciated!

Reddy Head · 07-12-2014, 09:31 AM

I just went out this morning and checked the coolant level, it dropped below the minimum level...
The way I see it, is that the coolant reservoir tank needs to be replaced or the water pump. Both the repairs cost about the same amount so we'll what happens.

The question is now, who to take it to?
I'm in San Marcos, Tx right now so I'm thinking about taking it to the Austin Porsche Dealership - or trying to find a good independent mechanic in the Austin area.

At this point I just want to get back home so I don't mind the cost... Luckily, I do my work from "home" so I have the flexibility to extend my stay.

3_Angels · 07-12-2014, 09:46 AM

If there is no obvious sign of water leaks, bleed the system: excerpt from Pelican Technical Article: Boxster Coolant Replacement / Boxster Coolant Flush - 986 / 987 (these cars do not easily bleed themselves)

Now it's time to refill the coolant, and bleed the system. In the trunk, remove the oil cap, lift up the “trap door” panel (Figure 3), and then screw the oil cap back on. Flip up the metal clip that opens the bleeder valve (Figure 4). If you have an automatic transmission car, then you need to remove fuse B1, which is located in the fuse panel near the driver's side foot well (see Photo 5 of Pelican Technical Article: Roof Rack System (Roof Transport System - RTS)). This will disable the ATF cooler shut off valve temporarily. Now, fill the car up with coolant, until the coolant level is visible at the bottom edge of the coolant tank. Start the car and run it at idle, topping off the coolant to the maximum level, until no more coolant can be added. Rev the engine and let it settle down and top it off again if the level decreases. Be sure during the whole process that the car does not exceed 176° F (80° C) while bleeding the system: if the car gets too hot it will interfere with your ability to fill and bleed the system to the proper level.

Now, reinstall the reservoir cap and let the car continue to warm up at about 2500 rpm for 10 minutes or until the thermostat for the front radiators opens up. When the thermostat opens and coolant starts flowing forwards, the electrical radiator fans should turn on. Now allow the car to continue to warm up a bit more, revving the car to about 5000 rpm every 30 seconds or so. Remove the reservoir cap slowly, letting any built up pressure dissipate. There should not be any tremendous pressure built up because the bleeder valve is still open at this time. Top off the coolant in the tank to the maximum level, reinstall the cap, and repeat the process of revving the engine to about 5000 rpm for another five minutes.

Now, allow the engine to idle for a few minutes until you hear the radiator fans cycle on and off at least once. Turn off the engine, and slowly remove the reservoir cap again, relieving any pressure that might have built up there. Top off the coolant until it reaches the MAX level indicated on the coolant tank gauge, located on the side of the tank. Flip down the metal clip to close the bleeder valve and replace the “trap door” panel on top of the tank. If you have an automatic transmission car, then replace fuse B1 in the driver's side door kick panel.

Reddy Head · 07-21-2014, 10:32 AM

It turns out the PO replaced a hose connected to the reservoir tank and NEVER INSTALLED CLAMPS!

I found this out by doing diagnostic work myself - which was relatively easy... This begs the question "What did the mechanic I took my car to even do?!" Had they pressurized the system properly it would have been easily apparent, so in other words they completely lied to me, and essentially charged me $250 for a new $25 Coolant Reservoir Cap. Unbelievable.

Well to say I'm pissed off is an understatement, but I'm extremely happy there was no crack in the tank itself. From now on, I am doing 90% of the maintenance and repairs on this vehicle myself.

Thank you for trying to help, I really appreciate it. Happy Boxstering!

UPDATE
03/14/2020

I am here to publicly call my younger self an idiot (I had been off the forum and forgot to update this many many years ago) it did end up being a faulty coolant reservoir and the hose I had "fixed" actually turned out supposed to be as I found it from the factory and required no "fixing". I have no idea how or why but after performing my non-fix - there was no leakage for awhile which lead me to believe I had solved the problem. I do still still feel the mechanics did not do their job because they should have pressure tested the system and would have easily seen the reservoir was faulty.

Over the years I've been very fortunate, the coolant reservoir has literally been the only issue with the car that was not caused by myself (maybe I'll tell that story another time hahaha).

3_Angels · 07-22-2014, 10:15 PM

pleased to hear that your issue is resolved. Have a pleasant week.

Pdwight · 07-22-2014, 10:23 PM

[QUOTE=Reddy Head;410872]It turns out the PO replaced a hose connected to the reservoir tank and NEVER INSTALLED CLAMPS!

I found this out by doing diagnostic work myself - which was relatively easy... This begs the question "What did the mechanic I took my car to even do?!"

Usually always as little as possible...it is why I learned to 90% of my work myself. I did this by researching, reading and investing a modest sum in tools. If a DIY says the job will take 4 hours you can bet I will take 8. I always clean everything, lube everything that need to be lubed and triple check my work with a checklist that I always prepare before starting the job.