Coolant top-up and potential diagnosis.

[cozzykim]

I bought my car, unseen, from a dealer.

When I got around to checking the coolant after a week or two it was below the LOW mark on the filler. I added some water, maybe a pint or so, and the float rose up to MAX.

I've checked it again now it's had a few weeks and miles added to it, and it's below MIN again.

There's some salty deposits on the blue filler cap (and I thought that the caps have been updated from the old 987 caps) which I could clean off, but should I put some silicon grease on the threads (it's a bit stiff to open) and should I:

1. Be looking at buying some correct antifreeze to top it up, recommendations please if so

2. Be looking for a leak, how much if any coolant does a 981 lose over a couple of thousand miles?

If there's a persistent coolant loss it'll probably be going back for repair under warranty to the dealer.

P.S. I don't think that I diluted the original coolant a significant amount, but I now think that I should add antifreeze if topping up.

[iborguk]

Personally I'd buy the Porsche coolant and treat it to a new coolant cap (they have been known to leak) but that's me.

Also check for wet carpet around in the rear boot around the coolant reservoir and if you see fluid on the ground and it tastes sweet that's coolant.

Without telling granny how to suck eggs also check the coolant in consistent conditions e.g. car cold and on the level.

Hopefully it's just the coolant cap.

Edited June 1, 2023 by iborguk

[cozzykim]

1 hour ago, iborguk said:

Personally I'd buy the Porsche coolant and treat it to a new coolant cap (they have been known to leak) but that's me.

Also check for wet carpet around in the rear boot around the coolant reservoir and if you see fluid on the ground and it tastes sweet that's coolant.

Without telling granny how to suck eggs also check the coolant in consistent conditions e.g. car cold and on the level.

Hopefully it's just the coolant cap.

Thanks.

Does the 981 have the same problem as the 987, with the coolant pipes which go the the rads leaking at the joints?

[iborguk]

Just now, cozzykim said:

Thanks.

Does the 981 have the same problem as the 987, with the coolant pipes which go the the rads leaking at the joints?

Yes, there have been a few reports although you'd maybe see signs of this on the floor in the front wheel arch liners with the steering at the extremes.

I'd start with the £20ish coolant cap (ask for discount at the OPC) and monitor, unless you're seeing signs on the floor.

[cozzykim]

9 minutes ago, iborguk said:

Yes, there have been a few reports although you'd maybe see signs of this on the floor in the front wheel arch liners with the steering at the extremes.

I'd start with the £20ish coolant cap (ask for discount at the OPC) and monitor, unless you're seeing signs on the floor.

The car is, unfortunately, always parked on a grassy/gravel driveway, so not much chance of seeing a slow leak as it would soak away immediately.

That's why I asked about the pipes, so that I could (hopeful optimist, I know🙄 ) discount that. 😁

[iborguk]

Just now, cozzykim said:

The car is, unfortunately, always parked on a grassy/gravel driveway, so not much chance of seeing a slow leak as it would soak away immediately.

That's why I asked about the pipes, so that I could (hopeful optimist, I know🙄 ) discount that. 😁

Stick some cardboard under the car.

[cozzykim]

2 minutes ago, iborguk said:

Stick some cardboard under the car.

Why didn't I fink of dat, I is an enjineer after all. 🤣

I suppose it's best to do it after a run out, so that the system's pressurised. 👍

[daz05]

If you don't have a warning on the dash leave it, it is perhaps nothing to worry about.

https://rennlist.com/forums/981-forum/1226935-981-coolant-level-question.html

[cozzykim]

Thanks, I'm probably just mechanically sensitive paranoid.

[cozzykim]

Update:

We were in the car today with the missus driving. Got in a traffic queue in 25C heat for around 20 mins, half of it in a Maccy D's drivethrough.

She suddenly said, someone's car smells hot and I looked at our coolant temp reading... 120C 😬.

At that moment we got a stop engine message. 

Note: she was in 'sport' mode so the stop/start was off.

She turned off the ignition for a couple of minutes, until we had to move in the queue again, and the stop engine light/message didn't come back on.

We moved about 20yds into a garage forecourt and turned off the engine for a couple of minutes, then I suggested that we get onto the adjacent dual carriageway to see whether the engine would cool down again. It did, after about half a mile of slowly dropping in temp, until it was showing 90C, which is normal.

At no time did I hear the engine cooling fans start up, though we also had the air con running, so I might have not heard them.

I'm thinking that I should start to be worried about this car now, and it's still in its six month warranty from the dealer, though they're around 300 miles North of me, so difficult to just 'drop it round' to them.

What do you think?

Edit: Question, which (or both?) coolant caps should I be replacing?

[iborguk]

5 minutes ago, cozzykim said:

 

What do you think?

Edit: Question, which (or both?) coolant caps should I be replacing?

Airlock which shifted when moving again ? Given what happened today and previously, maybe the cooling system needs bleeding.

Re the cap it's the one in the boot which is normally the one replaced but given your issues I'd check both.

 

[cozzykim]

15 minutes ago, iborguk said:

Airlock which shifted when moving again ? Given what happened today and previously, maybe the cooling system needs bleeding.

Re the cap it's the one in the boot which is normally the one replaced but given your issues I'd check both.

 

I was thinking maybe airlock, which might explain why I didn't hear the fans start up.
I think I need to call my (car) dealer.

They took much longer than promised to 'prep' the car when I bought it, and now I'm wondering whether 'prep' actually means 'repair'. 🤔

[Codfanglers]

My quess is you have a leak.

Look underneath to see if there are any wet patches on the trays, drips or crusty white/pinky crystalised deposits.  Fill it up (with coolant if possible) run it, check every few journeys to see if it is still disappearing.

Get a local garage to pressure test the system. If it's pump/reservoir/pipes/radiators claim under warranty for a repair.

The fans will be on if the aircon is running but if you feel under the front arches you should be able to feel the air flow even if you can't hear the fans.

Edited June 16, 2023 by Codfanglers

[cozzykim]

15 minutes ago, Codfanglers said:

My quess is you have a leak.

Look underneath to see if there are any wet patches on the trays, drips or crusty white/pinky crystalised deposits.  Fill it up (with coolant if possible) run it, check every few journeys to see if it is still disappearing.

Get a local garage to pressure test the system. If it's pump/reservoir/pipes/radiators claim under warranty for a repair.

The fans will be on if the aircon is running but if you feel under the front arches you should be able to feel the air flow even if you can't hear the fans.

It's parked on a grass/planings driveway, so I have nowhere clean and dry to do that unfortunately.

It might be possible to get it pressure tested locally though, we have a 'BavarianBenz' garage nearby. 👍

[cozzykim]

Update.

We've been home for about two and a half hours and I thought I'd have a look at the coolant cap etc.

As I opened the cap it hissed, so presumably still pressurised. 

To my surprise the coolant level indicator was at MAX

Put the cap back on an started the engine. Engine bay fans came on and coolant showing 70C.

Scratches head...🤔

Still pressurised after more than two hours presumably means no leaks. I suspect that the coolant level will be down tomorrow morning when the temperature of the whole system, hoses/header tank etc, has dropped, or, maybe that's wrong think and it actually means that there's an airlock and the air expands & contracts with engine temp changing the level?

Hot engine/hot airlock - max level?

Cold engine/cold airlock - below min level?

Duff thermostat, but surely that would be a continuous overheating, if the 'stat wasn't opening?

Weird. 🙄

[Codfanglers]

Not looked into the 981 cooling system and I've only bled my 987 after changing the pump/stat but the basics on mine are take the top engine cover off. There is a separate tank in the engine bay with an air bleed valve. Top up the coolant, get the engine up to temperature and rev it. Top it up, close the bleed valve, let the engine go stone cold and check/top up in the boot. It shouldn't then use any coolant.

If it's been ok and has developed an air lock, it's either

Leaking coolant out somewhere, drawing in air through the pressure cap as it cools, level so low that air has got to the radiators and the water isn't pumping at idle, 

Or the engine is blowing coolant out the pressure cap.

          This could be because the cap is faulty, letting the system boil, then suck extra air in as it cools - (the system runs under pressure to elevate the boiling point)  

          Or - it could be combustion gases getting into the system . To test for this, if you let the engine go stone cold overnight after a run then open the cap in the boot and it hisses/ releases pressure you have an expensive problem. A garage can do a "sniff test" in the header tank to test and confirm if it is this. 

Leaking is the most likely. Look underneath for evidence or have someone get it up on a lift and find the issue. Overheating an engine doesn't do it any favours.

[cozzykim]

14 hours ago, Codfanglers said:

Not looked into the 981 cooling system and I've only bled my 987 after changing the pump/stat but the basics on mine are take the top engine cover off. There is a separate tank in the engine bay with an air bleed valve. Top up the coolant, get the engine up to temperature and rev it. Top it up, close the bleed valve, let the engine go stone cold and check/top up in the boot. It shouldn't then use any coolant.

If it's been ok and has developed an air lock, it's either

Leaking coolant out somewhere, drawing in air through the pressure cap as it cools, level so low that air has got to the radiators and the water isn't pumping at idle, 

Or the engine is blowing coolant out the pressure cap.

          This could be because the cap is faulty, letting the system boil, then suck extra air in as it cools - (the system runs under pressure to elevate the boiling point)  

          Or - it could be combustion gases getting into the system . To test for this, if you let the engine go stone cold overnight after a run then open the cap in the boot and it hisses/ releases pressure you have an expensive problem. A garage can do a "sniff test" in the header tank to test and confirm if it is this. 

Leaking is the most likely. Look underneath for evidence or have someone get it up on a lift and find the issue. Overheating an engine doesn't do it any favours.

Damn right, 👍 and I'm not the slightest bit blasé about risking this. 

 

[cozzykim]

This morning, I called my dealer to notify them of the problem and called a local indy specialist, who's too busy to look at the car at the moment, but very helpful.

The local (35 miles away) OPC answered the phone but then I waited 20 mins for the service desk and had to drop the call eventually.

Checked the coolant level by opening the top cap, and it was still slightly pressurised, no sign of water leaks under the car, at least around the front wheelarches.

So, I started ther car, with no air con or heater blower running to mask the noise of the engine cooling fans, and let it come up to temp.

It took about 10-15 mins and reached exactly 90C on the display. I let it run for another ten mins and then took it for a short run of about 10 miles while watching the gauge like a hawk.

Did some more back roads and dual carrieageway and it sat at 90C the whole time.

All in all I did about 25 miles with no apparent issues.

At no time did I hear the cooling fans start up.

Back home I sat and let the car idle in both normal and 'sport' mode for ten minutes, no fans and the temp gauge never moved from 90C.

Three different people have now suggested that it might be an electrical problem with the fans, combined with sitting in a queue for 20-25 mins at the end of a spirited run on a very hot day.

One person pointed out that modern vehicles don't run the cooling fans unless necessary, and that they'd probably not normally run except in slow or stationary traffic anyway, and they'd be unlikely to be needed at any decent speed on the open road.

So, I still have an open mind...

When the engine/coolant temp has dropped to a safe level of 70C-ish, I'm going to check the filler  cap level again, to see whether it's MAX or not.
 

[BBB]

I’m not sure if it is the same on the 981, but on the 987 the temperature gauge doesn’t actually display the true temperature. The needle rises to 80 and then stays there, regardless of any temperature variation. Porsche think that it’s meant to be reassuring to the owner that it doesn’t fluctuate.

[cozzykim]

39 minutes ago, BBB said:

I’m not sure if it is the same on the 981, but on the 987 the temperature gauge doesn’t actually display the true temperature. The needle rises to 80 and then stays there, regardless of any temperature variation. Porsche think that it’s meant to be reassuring to the owner that it doesn’t fluctuate.

Good point, but, thinking about it, my gauge was definitely showing 1C increments on the way down from 121C to 90C yesterday. 🤔

[cozzykim]

Just checked my coolant level again, after the temp dropped from 90C a few hours ago, to around 68C.

Pressure released when I removed the cap, and level float almost at the top.

At no point during this have I heard the cooling fans running.

Does anyone know how to check the fans and their 'stat, or is it not possible?

[iborguk]

Just now, cozzykim said:

 

Does anyone know how to check the fans and their 'stat, or is it not possible?

A Porsche PIWIS would help there.

If it were mine I think I'd get into it someone who can get it up into the air, check for leaks/airlocks and figure out what's going on.

[cozzykim]

Another update:

I took the top engine cover off (thanks so much for making that so easy - not - Porsche. 🙄😁

The car was still reasonably hot, probably about 75C.

Guess what, as soon as the cover came off I could hear a faint hissing noise. Yep, the inner coolant cap.

I turned it about 5 degrees clockwise and it stopped hissing. It was definitely still pulling in air after the previous run out and the cap and surroundings had white deposits on them.

So, I'm hoping that Codfanglers and others have hit the nail with that suggestion.

I also ran the engine with the cooling system open and opened/closed the bleed valve for about 10 minutes. I couldn't see any air bubbles, but then I was single handed so my legs/arms/neck aren't long enough to rev the engine and look into the coolant tank at the same time.

If I have any more problems I'll get it into my local indie ASAP and I'll also do as I was told and buy two new caps in the meantime.

🤞🤞🤞

Thanks for all the help so far. 👍