Coolant system troubleshooting - 986 Forum - The Community for Porsche Boxster & Cayman Owners

sickbananas · 03-09-2015, 01:42 AM

Hi All,

I have replaced my waterpump, fitted a low temp thermostat, done a coolant flush and re-filled the system with porsche coolant/distilled water 50/50 using my airlift.

The car swallowed +-18 litres. Its a 2000 S and yes the heater was on while I pulled the vacuum.

I checked for leaks and took the car for a drive, after a short drive the filling bottle was almost empty and I refilled it, so all in all I have about 19-19.5 litres in the system is that the correct capacity? The system is sealed with no leaks and the bottle level has stayed on the max mark. I have opened the bleeder valve and let the car idle as well as rev'ing her.

Next question is what temperature should my needle be on with my new low temp thermostat installed? It seems my car is running too hot (my temp gauge is in degrees Celsius)

When at idle, the temperature rises to 100 degrees (212F) after a while, when driving the temperature sits just above the 80 degree 176 mark +- 90 degrees(194F) at 12 o'clock. The front fans do kick in and work properly.

I must add, when I open my coolant cap slowly when the car is at idle and at 100 degrees according to the gauge, the water does not seem to be close to boiling or letting off a lot of steam.

Is a temperature gauge probe into the filling bottle a option to check how accurate the cars gauge is?

any ideas will help, thanks!

JFP in PA · 03-09-2015, 02:36 AM

Quote:

Originally Posted by sickbananas

Hi All,

I have replaced my waterpump, fitted a low temp thermostat, done a coolant flush and re-filled the system with porsche coolant/distilled water 50/50 using my airlift.

The car swallowed +-18 litres. Its a 2000 S and yes the heater was on while I pulled the vacuum.

I checked for leaks and took the car for a drive, after a short drive the filling bottle was almost empty and I refilled it, so all in all I have about 19-19.5 litres in the system is that the correct capacity? The system is sealed with no leaks and the bottle level has stayed on the max mark. I have opened the bleeder valve and let the car idle as well as rev'ing her.

Next question is what temperature should my needle be on with my new low temp thermostat installed? It seems my car is running too hot (my temp gauge is in degrees Celsius)

When at idle, the temperature rises to 100 degrees (212F) after a while, when driving the temperature sits just above the 80 degree 176 mark +- 90 degrees(194F) at 12 o'clock. The front fans do kick in and work properly.

I must add, when I open my coolant cap slowly when the car is at idle and at 100 degrees according to the gauge, the water does not seem to be close to boiling or letting off a lot of steam.

Is a temperature gauge probe into the filling bottle a option to check how accurate the cars gauge is?

any ideas will help, thanks!

The temperature display in these cars is both inaccurate and non linear in its movement; making it little more than an idiot light that moves.

healthservices · 03-09-2015, 06:49 AM

I must add that even thought the thermostat is lower the fans will kick on at the same temps as they will still switch on at the same temps as before.

Smallblock454 · 03-09-2015, 07:59 AM

Hi,

i don't know the exact amount of cooling water for your car. But why do you guys never the amount that you drain off the car. It is so easy to measure the fluid you drain off the car and than you'll know exactly how much to fill in.

As you micht know the cooling system of the Boxster is a little bit complicated. That's why Porsche does the refill with overpressure.

If everything is OK the water temp should be constant a little bit lower than 90 degrees celsius with the lower temp thermostat. There are a lot of people over here in germany that have done this conversion and all said that the gauge temperature corresponded to the temperature of the water temperature valve.

The fans get their signal from an electronic sensor. So they will allways start at the same temperature. Are you shure you understand why you did the water temp valve modification?

If you have air condition check if the grids on air condition radiators are OK and are not worn. Also check if the water radiatos are OK. Sometimes that causes temp changes.

But if you haven't had temperature issues before i would recommend to refill the cooling water with the process Prosche recommends to make shure you have no air in the cooling system. Because this air will cause massive damage to the engine.

steved0x · 03-09-2015, 08:03 AM

That sounds about right and mirrors what happened when I did a refill of my coolant. The amount sounds right as well, I started with 3 gallons of undiluted coolant and 3 gallons of distilled water and I have left 1 gallon of 50/50 so I have about 5 gallons in mine.

Here's my thread which sounds a lot like yours:
http://986forum.com/forums/general-discussions/55388-sanity-check-my-coolant-went-about-quart-low-after-wp-thermostat-change-air.html

Steve

woodsman · 03-09-2015, 11:08 AM

I found the same numbers after WP and low-temp stat install : 80 generally and at 12:00 o' clock for the fans to kick on when idling. It would be nice to get the fans to turn on sooner...

san rensho · 03-09-2015, 08:45 PM

With the AC on, and both fans on high, the temp should be significantly lower than with the AC off, even in stop and go traffic. Use a durametric but if you dont have one, for reference, with the ac off, the hot temp in stop and go was in e midle of the 0 on the 180 scale, with the AC on, it was near the 1.

70 mph, 5th (or 6th) ac off, you should also get a temp near the 1.

steved0x · 03-10-2015, 07:24 AM

In between autocross runs I idle with the AC on, which helps keep me cooler and it keeps the needle down, during a 60 second run at high RPM in 2nd the needle will be up a little off its usual mark when I go to grid for my next run, and after the run if I idle for bit with the AC on the temp goes right back down.

I am going to search now to find if the fans run on low or high when the AC is on but the water temp is below the high fan threshold.

sickbananas · 03-10-2015, 09:27 PM

Thanks for all the helpful information and experiences. My level in the water bottle has stayed on the max mark and the needle doesn't seem to raise much over the 12 o'clock point so I think I can put this one to bed. As a matter of interest I put a very accurate thermometer into the water bottle. The car was idling for about 5mins after a hard drive, the needle was sitting on where the 100 degree C mark would be (212 degrees F)-just over 12 o'clock. The thermometer was 89 degrees C (192 degrees F)