Purekoryo

Been driving my 991.2 GTS just fine but then this morning the water temp just skyrocketed. I immediately turned on the heater but no heat. I limped back home and noticed the two radiators in the front were cold.

Coolant level is good. Did see some residue of a very very small leak but not enough to drop onto the floor.

Is my thermostat stuck? I just installed sport cat yesterday and drove for 20 miles and it was fine. Did I maybe touch something in the process?

I checked the PSE valve and seems to be operating correctly (opening and closing, I can feel more air and less from both tailpipes and sound of course).

Josh(PA)

Very interested to hear if you find a solution. This has happened to me 3 times on my .2 base since I got it in February. The first time was the day after i had a leaking water pump replaced. I took it in for service and was told they had to "burp" it. The second time was one of the first cold days of the year about a month ago, I thought maybe the water level was a little low (due to the cold ambient temp) and then it happened for a 3rd time yesterday. All three times it has been within 4 miles of starting out for the first time (ie car is cold), the water temp sky rockets to 250+ and the red water temp warning shows on the screen. Meanwhile, the oil temp stayed below 150F.

I made an appointment at my local dealer for tomorrow, I'll let you know if they diagnose anything. Please post if you find a solution.

Purekoryo

Unplugged both vacuum lines to PSE and back on. Checked lines above it as far as i can see (not much) wiggled it a bit to feel if anything was loose. Then started it up, turned the heater back on and now it’s blowing hot air and temperature seems normal after driving for a few minutes and a couple of wide open throttle.

still need to find the root cause. Not sure if by opening the coolant reservoir cap i released any air gap.

going to go for a longer drive (while staying close to home) and see what happens.

Jack F

So you added sport cats but didn’t mess with the coolant system? Have you don’t anything to the coolant recently? Weird that air bubble would show up suddenly. Keep us posted.

Purekoryo

no I haven’t messed with the coolant system.

I just got back from driving about 15 minutes this time and brought oil temp to around 230F (normal mode). Water temp stayed at a steady 194F the whole time. Switched to Sport mode and the oil temp dropped quickly to 196F. This was while doing WOT several times and just cruising.

I’m stumped as to what happened. I did notice that on the passenger side i did not secure the vacuum line to PSE valve to one of the small holder/bracket to keep the hose from wiggling.

Would a partially leaky PSE vacuum hose cause this to happen? ie not allow the crossover valve to work correctly? This may be the case as the mechanical vacuum pump is connected to 8 different valves all within same system, with the coolant valve and PSE valve being 3 of them.

btw, my sport cat is getting broken in well getting louder

Purekoryo

I’m starting to think it’s a loose vacuum hose upstream of the PSE connected to the heater/coolant COV. Do you guys know where this is?

Of this is indeed the case, I can’t believe something fragile like this would be part of the system that prevents your engine from blowing up! At least have a a fail to open to constantly cool the motor.

Josh(PA)

I spent about 3 hrs driving mine today and it performed as expected. I'll see what Porsche Main Line says tomorrow.

Fullyield

First system of Change Over Valve issue is heater blowing but not hot. Sounds like your coolant shut off valve did not open. There was a recall on these valves in early 2013. Google it as there are diagrams available identifying location of the valves.

Purekoryo

Thanks for confirming this. Makes sense as I plugged and unplugged the PSE vacuum lines and know that they are connected to the COV for coolant shutoff valve. But shouldn’t it fail open?

I saw that the diagram but it looked like it was for 991.1 only. Is the location the same?

Purekoryo

The problem came back this morning. Then I let cool down for couple of hours and did the unplug plug dance with the pse hose again and seemed to be ok. But then I got home let it cool and started again and the issue came back yet again even after I did the dance.

I also have a lithium battery. Would this prevent the solenoid to coolant shutoff valve from working? It seems like everything else is working so I don't think the battery is an issue but want to hear your thoughts? I just don't see 13.2V dropping below 12V as it travels to that particular solenoid, if everything else around is operating fine.

97supratt

I seriously hate the fact that porsche uses vacuum lines to control vital parts of it's vehicle components. Sorry for your overheating issues OP. Check for leaks or COV. I'm sure there's a diagnostic procedure.

Gus_Smedstad

I had this problem a couple weeks ago in my 991.2 GTS. I pulled over and had the car towed the dealership immediately when it overheated.

It turns out there's a technical bulletin for these cars about the water pump. They checked it out, and sure enough, the water pump had leaked into the vacuum line controller block. They replaced the pump and the vacuum valve block (since it was contaminated with coolant). Car's been fine since then.

Josh(PA)

this was my diagnosis as well. I added the info to the water pump thread. Replacing vacuum hoses and the valve block is now part of the water pump replacement procedure. Coolant from the leaking pump gets in the vacuum lines and fouls the control pumps

Purekoryo

Thanks folks! I have an appt next week to bring the car in. I’ll share what you guys have stated with my SA. Although I think he did mention something about coolant possibly leaking into vacuum so obviously this is happen quite often.

Purekoryo

I was thinking the same thing. As someone who spent almost entire career in Reliability Engineering, AND having owned and modded a few dozen “beater cars” and expensive one’s, Porsche really needs to step up their game. I would’ve convinced myself that maybe it’s just heuristics. But my six year old can figure out that the stats on this is pretty profound, relative to its six figure price tag.

Vital systems like the coolant system should have failsafes that are better designed or at least have redundancies within the system. Can’t believe this system is designed such that water and electronics can be contaminated with each other.