Sudden loss of coolant - 987.2 is in the bad books

[dunc_sx]

So I was at a 2 hour track evening tonight in my 987.2 S. I checked all the fluids before I went and everything was good, the coolant was a smidge below the min so I topped up to between the min and max.

With the air temp about 18 deg at the track it was hot but nothing scary, I took the car on track and did a small 6min stint then came in to check the car and adjust my tyre pressures. Coolant gauge at 80deg and no causes for concern for the car. I was approx three minutes coasting the car prior to coming to a halt and cutting the car off. Still all good at 80deg on the gauge and the car hadn't had that big a work out anyway.

I went round doing each tyre pressure and then there was a massive missing sound and coolant peeing out of the back of the car, all around the engine area. The exhaust was also white around the bottom half at closer inspection.

I'd estimate a litre max came out, probably less. I turned the ignition to check the gauge, still 80deg - fired it up no problems. No dash warnings. My first thought was the coolant had been too full for the temperature and it had spat some out. I had a look at the underside of the engine then got back up to the gauge, it was off the charts and there was a low coolant warning

I turned the ignition off at lightning speed, waited for ages for the temp to reduce, topped up with water. Fired the car up, no obvious leaks, temp perfect, engine sounds perfect. I then proceeded to get all the empty bottles of water I could for the journey home (I didn't want to risk dumping coolant on the track now or busting my engine so no more track stuff). It took approx 2.5 litres to get it to max.

Now I've driven the car 65miles home and it's been perfect, absolutely no signs of leaks now.

So I'm looking for suggestions, I use the car daily and I've got some hardish usage scheduled in less than a months time.

I'm thinking get a pressure test on the coolant system and see what comes up. No noticable change in oil level, or signs of coolant in the oil.

Thanks in advance,
Dunc.

[DarkMatter]

Could be worth fitting new coolant caps, particularly the one under the engine cover, that one caused a loss of coolant on my 987.2.

[Slippydiff]

DarkMatter said:

Could be worth fitting new coolant caps, particularly the one under the engine cover, that one caused a loss of coolant on my 987.2.

^ This. IIRC they're a known issue.

[dunc_sx]

It was the engine area (not sure where, massive mess) and not the actual filler cap, so this is a very good point. I'll give it a google, thanks.

[fozzymandeus]

Coolant pipes are a known failure point as they use mixed metals and suffer corrosion. My 2.9 was losing coolant from the crossover pipes - it was picked up at service fortunately.

[JustGREENI]

Hi, the missus runs a 987.2 S that will become my track car (sooner than she thinks), I'm always interested to learn about any issues and prevent them happening in the future, or just make notes and build up my own catalogue of faults in case i encounter them. Would you share part numbers for the cap and or the pipes please? I've looked at Design911 but not sure which would be the items I'd need.
Thanks.

[dunc_sx]

I think it's no.7 the guys above were discussing, perhaps they could confirm to keep everything clear.

7 = 996 106 447 04

Parts catalogue (for 987.2) taken from:

https://www.porsche.com/uk/accessoriesandservice/c...





Cheers,
Dunc.

[dunc_sx]

fozzymandeus said:

Coolant pipes are a known failure point as they use mixed metals and suffer corrosion. My 2.9 was losing coolant from the crossover pipes - it was picked up at service fortunately.

These were OK when I looked previously (and it has been completely leak free) but I will check again, thanks

Dunc.

[Slippydiff]

Have a read of "Stacy.Chandler's" post in this thread here :

https://www.pistonheads.com/gassing/topic.asp?t=98...

Try the procedure detailed, if that doesn't work I'd look to replace both the coolant filler cap (7) which has vacuum valve in it, and the bleed valve assembly (4) which I seem to recall used to fail on the 996 and cause the cooling system to run sub optimally due to a lack of pressure.

[dunc_sx]

Slippydiff said:

Have a read of "Stacy.Chandler's" post in this thread here :

https://www.pistonheads.com/gassing/topic.asp?t=98...

Try the procedure detailed, if that doesn't work I'd look to replace both the coolant filler cap (7) which has vacuum valve in it, and the bleed valve assembly (4) which I seem to recall used to fail on the 996 and cause the cooling system to run sub optimally due to a lack of pressure.

Great thanks, the problem I've got is it's once again returned to a zero obvious fault situation. If the caps are the no.1 culprit I'd be as well replacing the bleed valve (no.4 - £25 from Hartech) and the pressure cap (no.7 - £17 Frazerparts) while I'm there bleeding the system to rule them out.

Leaving other possible likely causes as expansion tank leak, water pump leak and main coolant hose leak?

Thanks,
Dunc.

[F6C]

dunc_sx said:

Still all good at 80deg on the gauge and the car hadn't had that big a work out anyway.

Worth noting the coolant gauge in your car is heavily buffered. In other words, it will read '80' over a wide range of temps. Can't remember exactly how high the coolant temp has to get to move above 80, but it's in the region of 110 degrees, certainly at least 100. Think it hits '80' before it's actually 80, too. So the range of temperature over which it reads 80 is pretty wide.

That's why it sits top dead centre all the time once you've been running a while. In reality, the temp is fluctuates frequently.

Anyway, that's not say you were definitely running hot or having a proper temp gauge would have helped in your case, but unfortunately the buffered gauge prevents you from seeing moderate abnormalities that sometimes can help.

[Andyoz]

^^^ Yes, I think it was setup that way so as to not concern casual drivers. It's basically a switch not a guage and will go from 80 degrees to off the scale in seconds.

Useless really as the live data is there if Porsche had decided to use it and not treat us like Snowflakes that can't handle the truth...

[stevemcs]

Not sure if it’s the same setup as a 986 S but the one we did the other week would dump all of its coolant out of the thermostat, 911 design sell the housing and the thermostat although it’s available from Porsche for the same price.

[dunc_sx]

F6C, thanks I was aware of that and annoyingly it's the case with most cars now. I also read the gauge goes full max (including warning light) when the fluid level low sensor triggers. This ties with the temp gauge still reading max after leaving it for half an hour, then instantly going to approx 80 when only a small portion of the fluid was topped up. Before topping up the rest.

I think in my case I lost the fluid but didn't overheat the engine.

Andyoz, yup - same with most other manufacturers, they mostly are correct to assume this though Saying that the dead zone shouldn't be as large IMO

stevemcs, thanks - I changed to a lower temp thermostat on a my old gen 1 997 c2s but never bothered doing it on this as it's a gen 2. Also I think the water was coming from higher up than the thermostat, the whole engine was a mess. I over reacted and thought head gasket at the time but having driven the car 150 miles since this I'm fairly certain it's something less critical.

Thanks folks

Dunc.