Cayman 718 2.0 Base Overheating issue - Page 2 - Boxster/Cayman - PistonHeads UK

Hi, I have the 2.0 Base 718 Cayman, 2017 which has an overheating issue and its driving me insane. The problem first happened around 3 months ago, all of a sudden the car developed an overheating issue, it would run up to temp and sit happily at 90o and then all of a sudden the temp starts to rise, fans come up, temp keeps going up and then wham... overheating message. There are no water leaks and before its mentioned its not a head gasket problem either. Every time it overheats i check the coolant level and although i have to top it up its never that much.. just what has been evaporated really. At first i thought it was an air block, so it been to an independent that i trust and its been vacuum filled several times. After this it was fine for several days and then back to overheating. Next on the list was water pump. Changed that along with the thermostat and filler cap. No better After this i took it to my OPC ( Leicester ) to have the coolant filled properly using there computers to ensure it was filled properly having read that you need the proper Porsche system to open all the valve ensuring there was no air blocks. Total disaster, they wouldn't touch the car without having it checked over first at a cost of nearly £300 only to tell me yes the car overheats and there is a bulletin to replace all coolant pipes.. They never even tried to bleed it as "the computer" says change the pipes at a cost of just shy of £2000... to say i went ballistic at them is an understatement as all they done was charge me 300 quid to tell me what i know and then as the computer says no they didn't even bother to carry out the work i requested. .. anyway moving on Latest work was to replace the coolant vacuum valve as it was suggested that could be sticking and as its only a £30 part thought may as well try. That's been done but made no difference so we removed the vacuum pipe from the value, sealed it off and it seemed to be OK.. well for a week and a half... now back to over heating. One thing i have noticed is when it overheats there is no heating.. heating and fan turned up to max and its like the air con is on.. I'm sick of the car to be frank, never want a mid engined car again but even if i were to sell it, it needs fixing.. so hear i am... I have read of similar issues on other posts... no one seems to have a definitive answer so i am hear to ask the collective... Any idea's please .... other than cremation that is

First of all, coolant should not be evaporating. So if it needs topping up regularly, then it means there's a leak. If you have no heating, then it means that coolant isn't making it to the heater matrix, or it means coolant isn't being pumped around the system. And that suggests eeither a low coolant level, and airlock in the system, or a failed water pump. As you've replaced the water pump, I'm going to suggest that one of your coolant hoses has a split in it. That would explain the loss of coolant, and how air is getting into the system. And Porsche saying there's a service bulletin to replace colant hoses suggests that it's a known issue. Take the car to a specialist, tell them what the issues are and you'll probable end up having to spend £500 plus parts cost to replace the hoses. It COULD be a head gasket failure allowing coolant into the cylinders and exhaust gases into the coolant. The syptoms might be the same, but I'd expect rough running at times too. If the car has ever actually overheated, then one or both blocks or cylinder heads might have warped causing leaks past a good head gasket. In which case it's going to cost a lot more than £2000 to fix.

Thanks @LunarOne, although i appreciate where your coming from i'm afraid i have to disagree When water gets to over 100o it turns to steam and some will evaporate... the overheating warning kicks in at 122o.. that HOT.... the car stinks and some of the water will turn to steam.. the filler system is not sealed so it can deal with any overflow therefore the steam / condensation.. call it what you want.. it will disappear. Its not a lot that i add back in, just enough to get it to the fill limit I do agree with the Heater Matrix issue but then again i know for a fact its been vacuum filled several times so how can there be an air lock still.. this is why i took it to the OPC but they were useless. I personally still think an air lock is the issue... just no idea how to resolve it The reason i do not believe its a head gasket is when it is running properly it is perfect.. no issue's with running at all.. admittedly its not been checked but i know the car, i also ( currently ) run an Vantage and Supercharged RR but have had Maserati's, TVR and RS Audi's ... i know when a car is running properly and this is one of them ( apart from when it becomes a steam engine ), i'm sure with just 4 cylinders if it was engine related I would know about it :-). However i would be the first to say i'm no mechanic but i do work on my cars.... happy to replace parts etc and get my hands dirty... just going to have to take it that its not an engine related issue, sorry. Finally i know there are no leaks because i have a polished garaged concrete floor... when its overheated before i have left the car inside.... checked it the day after an nothing.. no water strains anywhere.. I'm not afraid to spend money on it, i just want it fixed..... i don't trust the OPC, they refused to let me actually speak to the engineer and had to relay the symptoms via the front desk ( i don't personally believe the engineer who worked on it even knew why it was in ). The bulletin refers to a damaged waterpump feeding water into the vacuum lines hence them wanting to replace it all. They assumed that as i replaced the water pump it was at fault, where in fact when we did replace it there were no symptoms of it actually ever leaking. Unfortunately they came across someone that actually has an idea of what they are talking about and i let them have both barrels.... it is unacceptable to carry out a vehicle check which pretty much was simply checking a computer, noticing there was a bulletin and using that to assume that's the reason.I have no issue if that is actually the case... but i know for a fact they didn't even remove a pipe to check if its was an issue or not. I digress... they really annoyed me as you can probably tell. Thank you for your input, i appreciate you taking the time to respond .. i think a specialist is the way to go.. just hoping someone on the forum has had a similar issue and can let me know what was done.

It’s unlikely to be a pipe unless they can collapse and reduce flow somewhere which seems pretty unlikely. The coolant system is sealed but there will be a pressure release that allows a controlled escape of coolant at a certain point. The coolant will need to be well above 100 degrees before it can evaporate or vaporise because the boiling point is raised significantly by being kept under pressure and probably by the ingredients of the coolant as well. Actual running temps well over 100 are not unusual on modern cars. Most likely cause would be a lack of flow which could be caused by either a pump problem or sticking stat, both of which you have done but are you sure there’s only one stat and pump on these engines? I think there is an auxiliary electric pump for the chargecooler (which wouldn’t cause your issues) but I don’t know if there is any others. I have replaced the front crossover pipes on my 2.5 718 and had the coolant system drained a few times on my 2.0 but I’m not sure how the various controls are set up other than to say it’s a fairly complex system and I wouldn’t be surprised if there were additional pumps or valves that can add to or restrict flow. Vac filling is generally a pretty reliable way to go on these but when I have had airlocks filling them it is usually fairly obvious straight away and the easiest way to actively bleed them that I have found is to release the trapped air by pulling the top pipe partly off each of the radiators. Once you have most of it out it starts to circulate properly and seems to self-bleed any little that remains. Finally, it’s worth knowing that the temperature gauge tells lies. It will go to 90 degrees and stay there to reassure you, it will only read a higher temperature once it goes above a certain threshold. If you want to see the actual temperature get a cheap obd reader and you can see the true reading in live data. This might give you some idea of how much the temperatures are actually varying even when the dash says everything is ok.

Surely, if the system's been vacuum filled to rule out air locks, then during that process, they could/should have seen that the system did or didn't hold a vacuum...? A small leak around a hose clip (where its cut in to a pipe) would leak in a cold system under vacuum. Its conceivable that the leak partly seals as it heats up but then sucks in air as the whole lot cools and contracts, and you're back to another air lock. But the pressure test should surely show that cold leak?

Discombobulate said: Coolant / water mix boiling point is around 105 C. But in a pressured system it is more like 130 C - obviously the higher the pressure release valve / cap setting, the higher the boilng point. But I don't know what the 718 system is set to. Obviously it can start evaporating at much lower temperatures but not in a closed system. Needing frequent top ups - even very small ones - is a sign of a leak or air lock. I agree. I have a 2014 981 S with the 3.4L engine. It's never needed coolant topping up between services. Once it gets up to temperature, it generally sits at 90C according to the gauge and once, when I was driving in Seville in 52C ambient temperature, I saw the engine coolant temp climb to about 96C. I have no idea what the pressure release valve is set to but it will be regulating pressure and not temperature. According to this old thread the thermostat is electronically controlled depending on whether you're in sport mode or not. I'm not sure how that works, but if it's true then such a system may also exist on the 4-cylinder models. That might add an additional layer of complication, but my money is still on a good old-fashioned leak in the system. https://www.pistonheads.com/gassing/topic.asp?h=0&...

Thanks to everyone that has replied so far. I'm going to give my local specialist a call and arrange for the car to be taken in to them and see what they come up with. I do feel there is a slight obsession with a leak. I appreciate why a lot of you are coming to that conclusion but i personally don't think that the case. When the car goes out and it overheats its literally no more than 100ml of coolant that goes back in and if i park the car in the garage overnight after a run there are no signs of a leak. However i do understand that it could be so small that the water is evaporating before it hits the ground. That said.. if there is a leak it has to be so small it can not be the cause. My money is still on an airlock and as the heating is cold when it does overheat i think that backs that theory up.. but as its been Vac filled so many times how can that be.... time for someone else to look at it i think and see what they come up with.

Steve H said: It s unlikely to be a pipe unless they can collapse and reduce flow somewhere which seems pretty unlikely. The coolant system is sealed but there will be a pressure release that allows a controlled escape of coolant at a certain point. The coolant will need to be well above 100 degrees before it can evaporate or vaporise because the boiling point is raised significantly by being kept under pressure and probably by the ingredients of the coolant as well. Actual running temps well over 100 are not unusual on modern cars. Most likely cause would be a lack of flow which could be caused by either a pump problem or sticking stat, both of which you have done but are you sure there s only one stat and pump on these engines? I think there is an auxiliary electric pump for the chargecooler (which wouldn t cause your issues) but I don t know if there is any others. I have replaced the front crossover pipes on my 2.5 718 and had the coolant system drained a few times on my 2.0 but I m not sure how the various controls are set up other than to say it s a fairly complex system and I wouldn t be surprised if there were additional pumps or valves that can add to or restrict flow. Vac filling is generally a pretty reliable way to go on these but when I have had airlocks filling them it is usually fairly obvious straight away and the easiest way to actively bleed them that I have found is to release the trapped air by pulling the top pipe partly off each of the radiators. Once you have most of it out it starts to circulate properly and seems to self-bleed any little that remains. Finally, it s worth knowing that the temperature gauge tells lies. It will go to 90 degrees and stay there to reassure you, it will only read a higher temperature once it goes above a certain threshold. If you want to see the actual temperature get a cheap obd reader and you can see the true reading in live data. This might give you some idea of how much the temperatures are actually varying even when the dash says everything is ok. Coolant / water mix boiling point is around 105 C. But in a pressured system it is more like 130 C - obviously the higher the pressure release valve / cap setting, the higher the boilng point. But I don't know what the 718 system is set to. Of course, it can start evaporating at much lower temperatures but not in a closed system. Needing frequent top ups - even very small ones - is a sign of a leak or air lock. Edited by anonymous-user on Sunday 27th July 21:02 Edited by anonymous-user on Monday 28th July 15:45

rodrayner said: Thanks to everyone that has replied so far. I'm going to give my local specialist a call and arrange for the car to be taken in to them and see what they come up with. I do feel there is a slight obsession with a leak. I appreciate why a lot of you are coming to that conclusion but i personally don't think that the case. When the car goes out and it overheats its literally no more than 100ml of coolant that goes back in and if i park the car in the garage overnight after a run there are no signs of a leak. However i do understand that it could be so small that the water is evaporating before it hits the ground. That said.. if there is a leak it has to be so small it can not be the cause. My money is still on an airlock and as the heating is cold when it does overheat i think that backs that theory up.. but as its been Vac filled so many times how can that be.... time for someone else to look at it i think and see what they come up with. My money is on air lock too. Not sure how, but... Keep us posted.

rodrayner said: Thanks @LunarOne, although i appreciate where your coming from i'm afraid i have to disagree When water gets to over 100o it turns to steam and some will evaporate... the overheating warning kicks in at 122o.. that HOT.... the car stinks and some of the water will turn to steam.. the filler system is not sealed so it can deal with any overflow therefore the steam / condensation.. call it what you want.. it will disappear. Its not a lot that i add back in, just enough to get it to the fill limit I do agree with the Heater Matrix issue but then again i know for a fact its been vacuum filled several times so how can there be an air lock still.. this is why i took it to the OPC but they were useless. I personally still think an air lock is the issue... just no idea how to resolve it The reason i do not believe its a head gasket is when it is running properly it is perfect.. no issue's with running at all.. admittedly its not been checked but i know the car, i also ( currently ) run an Vantage and Supercharged RR but have had Maserati's, TVR and RS Audi's ... i know when a car is running properly and this is one of them ( apart from when it becomes a steam engine ), i'm sure with just 4 cylinders if it was engine related I would know about it :-). However i would be the first to say i'm no mechanic but i do work on my cars.... happy to replace parts etc and get my hands dirty... just going to have to take it that its not an engine related issue, sorry. Finally i know there are no leaks because i have a polished garaged concrete floor... when its overheated before i have left the car inside.... checked it the day after an nothing.. no water strains anywhere.. I'm not afraid to spend money on it, i just want it fixed..... i don't trust the OPC, they refused to let me actually speak to the engineer and had to relay the symptoms via the front desk ( i don't personally believe the engineer who worked on it even knew why it was in ). The bulletin refers to a damaged waterpump feeding water into the vacuum lines hence them wanting to replace it all. They assumed that as i replaced the water pump it was at fault, where in fact when we did replace it there were no symptoms of it actually ever leaking. Unfortunately they came across someone that actually has an idea of what they are talking about and i let them have both barrels.... it is unacceptable to carry out a vehicle check which pretty much was simply checking a computer, noticing there was a bulletin and using that to assume that's the reason.I have no issue if that is actually the case... but i know for a fact they didn't even remove a pipe to check if its was an issue or not. I digress... they really annoyed me as you can probably tell. Thank you for your input, i appreciate you taking the time to respond .. i think a specialist is the way to go.. just hoping someone on the forum has had a similar issue and can let me know what was done. What you have failed to take into account there is pressure. Water boils and turns to steam at 100 C at atmospheric pressure. Cooling systems are pressurized, Google suggests the Cayman is pressurized to 33psi, which seems very high to me, but lets go with it. That means the boiling temperature of water in the cooling system is 167 C, so the water doesn't boil and there is no steam to evaporate. Therefore if you having to top up, there is a leak.

Megaflow said: What you have failed to take into account there is pressure. Water boils and turns to steam at 100 C at atmospheric pressure. Cooling systems are pressurised, Google suggests the Cayman is pressurised to 33psi, which seems very high to me, but lets go with it. That means the boiling temperature of water in the cooling system is 167 C, so the water doesn't boil and there is no steam to evaporate. Therefore if you having to top up, there is a leak. I do understand why you think that but it doesn't explain the overheating issue. The Cayman takes around 19 litres of coolant, i'm topping it up with no more than 100ml... therefore there is still ( if it is actually full and no airlock ) over 18.5 litres of coolant in the system,.. that's surly is enough to stop it overheating.

It seems odd that it can sit happily at 90°C then 'suddenly' increase rapidly. These have an electronically controlled stat dont they ? and a complex High Temp and Low Temp loops with a check valve ? Given it looks like the water isn't flowing through the heater matrix, check the check valve isn't passing maybe or the other water pump ?

You mentioned the heater doesn't work when the car is overheating. Fairly obviously the engine in a mid-engine car is some distance from both the radiators and the heater matrix. Some relevant diagrams on this link, https://www.718forum.com/threads/cooling-circuits.... This implies that when you're overheating there's either, 1. Coolant in the pipes but it's not moving round at the front of the car, or 2. There's no coolant in the pipes. Are you able to access the pipes and feel along them to see what's hot and what is not?

The described behaviour of car running fine, then overheating with the vents running cold sounds exactly like the issue I had on my v. Old G reg Vauxhall Carlton about 30 yrs ago. I never did get to the bottom of it! The car would run fine, then randomly and all of a sudden, vents would go cold and the engine temperature would rocket. I tried everything.. New Thermostats, radiator out, cleaned & tested...I think I even replaced the heater matrix... Nothing fixed it... We though it could be a blocked radiator or airlocks, but couldn't sort it I think I even redid the head gasket.. And that was a simple front engine / radiator setup.

rodrayner said: the filler system is not sealed so it can deal with any overflow therefore the steam / condensation. I think you mean it is sealed but when the pressure gets too high the valve in the filler cap will let some blow out. Your issue is that water isn't reaching the front of the car and the engine is trying to fry itself, overheating and blowing steam/coolant through the cap. I understand your frustration with OPC but there's nothing a technician enjoys less than being handed a car that's already had someone else working on it who hasn't been able to fix the problem. All they can do is work through the recommended order of work which means either repeating stuff that's already been done or trusting the first work was done right and starting where they left off. Hence the quote for coolant pipes.

Panamax said: I think you mean it is sealed but when the pressure gets too high the valve in the filler cap will let some blow out. Your issue is that water isn't reaching the front of the car and the engine is trying to fry itself, overheating and blowing steam/coolant through the cap. I understand your frustration with OPC but there's nothing a technician enjoys less than being handed a car that's already had someone else working on it who hasn't been able to fix the problem. All they can do is work through the recommended order of work which means either repeating stuff that's already been done or trusting the first work was done right and starting where they left off. Hence the quote for coolant pipes. I think you've put it very politely. No technician is going to trust the work that was previously undertaken elsewhere, or the diagnosis of armchair forum Porsche mechanics, because if all of that worked and was useful.. you wouldn't be taken a car with issues to them. In short, the technician is never going to trust the guy that came before him: If the last guy was able to fix the issue, he would've done it. How to fix anything: https://youtu.be/ic5R4C5HRUg?si=ckvzmCwtzaxyjNmd

There are known issues with water pumps and thermostats on the 2.0. As a side note, if the picture you posted is of the car stationary and not under full load, I'd have a look at the way your exhaust sits as that definitely isn't right.

scrounger73 said: As a side note, if the picture you posted is of the car stationary and not under full load, I'd have a look at the way your exhaust sits as that definitely isn't right. I hadn't focused on the photo but you're absolutely right. The car has clearly been "got at" at some point in its existence.

Panamax said: scrounger73 said: As a side note, if the picture you posted is of the car stationary and not under full load, I'd have a look at the way your exhaust sits as that definitely isn't right. I hadn't focused on the photo but you're absolutely right. The car has clearly been "got at" at some point in its existence. Is it possibly a track exhaust? They often seem to point down. Does look odd I agree.

John D. said: Is it possibly a track exhaust? They often seem to point down. Does look odd I agree. There is a good chance the 2 exhaust clamps on the tail pipes are corroded and have split. My exhaust looks exactly the same and is getting repaired next week.

I take it there's no signs someone has put rad weld in it to cover up a leak?

I may have missed it but if the pressure is regulated by a valve the coolant cap, as it is in most cars, has that been changed? The cold heater is an air lock for sure, but what caused it, air goes where it wants to and generally stays there until you flush/suck it out. If the coolant pressure is being released early and lower than it should be it will overheat, once it overheats it will chuck coolant out, once that goes it will be replaced with an air lock and so it goes on. If you have a look under a car there may be stains of where the coolant is being chucked out. It would be a bit daft to get to crack testing the heads over a faulty two bob coolant cap.

rodrayner said: Megaflow said: What you have failed to take into account there is pressure. Water boils and turns to steam at 100 C at atmospheric pressure. Cooling systems are pressurised, Google suggests the Cayman is pressurised to 33psi, which seems very high to me, but lets go with it. That means the boiling temperature of water in the cooling system is 167 C, so the water doesn't boil and there is no steam to evaporate. Therefore if you having to top up, there is a leak. I do understand why you think that but it doesn't explain the overheating issue. The Cayman takes around 19 litres of coolant, i'm topping it up with no more than 100ml... therefore there is still ( if it is actually full and no airlock ) over 18.5 litres of coolant in the system,.. that's surly is enough to stop it overheating. It might very well be. Because while the pressure in the system is design to stop boiling under normal running and therefore not produce any steam, thus producing a fully sealed system that should not require any tops up. if there is a leak, regardless of how small, that leak will also relieve all pressure in the system and make it easier for it to over heat. What I do know with the Cayman's is the coolant gauge will go to max if the coolant level drops, even though the car isn't actually overheating. My 987.2 had the radiator pipes changed and after about 100 miles a big chunk of air bleed its way to the header tank, the level droped and the gauage immediately went to max... Some poo came out when it did! A coolant top up and a check by the garage that did the work and it was all fine.

981Boxess said: I may have missed it but if the pressure is regulated by a valve the coolant cap, as it is in most cars, has that been changed? rodrayner said: Next on the list was water pump. Changed that along with the thermostat and filler cap. No better. Sometimes it's helpful to read the thread and see what's already been done. OP also reported no leaks onto newly painted garage floor. Yes, it sounds like an airlock and with this complicated cooling system the process to resolve it will need to be followed religiously. Whether an "indy" has the ability to do that appears to be what's in question.

Panamax said: 981Boxess said: I may have missed it but if the pressure is regulated by a valve the coolant cap, as it is in most cars, has that been changed? rodrayner said: Next on the list was water pump. Changed that along with the thermostat and filler cap. No better. Sometimes it's helpful to read the thread and see what's already been done. OP also reported no leaks onto newly painted garage floor. Yes, it sounds like an airlock and with this complicated cooling system the process to resolve it will need to be followed religiously. Whether an "indy" has the ability to do that appears to be what's in question. Yes I missed the new cap, the marks on the floor mean nothing, it could have dried off whilst driving. The stains I am refering to are under the car, as in get under the car and look up, not on the floor, I should have been clearer.

You can download the Porsche workshop manual for the 981 6-cylinder models here (213MB, 6087 pages): https://drive.usercontent.google.com/download?id=1... And then look at procedure "WM 193817 DRAINING AND FILLING COOLANT (ALL MODELS)" starting at the bottom of page 4102. On page 4110 you'll see some interesting details, including that bleeding the system requires use of the PIWIS II tester. So if whoever replaced the water pump didn't have access to this, then you might find the system wasn't properly bled. I'm sure the procedure is either similar or identical for the 4-cylinder models. Workshop Manual said: Information The filling device 9696 is used for filling coolant The system is bled using PIWIS Tester II 9818. Information The quantity of coolant available should exceed the amount required to fill the system by about two liters in order to prevent air being sucked in . An antifreeze content of -35 °C corresponds to a mixture of 50:50 (coolant: water).

That procedure can be done with various aftermarket diagnostic tools as well and there are some fairly straightforward manual ways of bleeding as well. As the OP has been through having it bled more than once and there can be days between occurrences of the fault I don’t think this is an airlock.

Why would there be an airlock in the first case - eg before any fixes were tried? I think the first thing to consider is the circumstances around the first case of overheating.

Just remembered, I had a similar issue with a Mk1 MR2 When it warmed, the radiator cap lifted light, dropped the pressure, the coolant then boiled and voided part of the system and that seemed to cause pressure locking and the temp would climb. That car had to be primed using valves and plastic tubes.