991 FAULT cooling system

[eme160]

'Change Over' :frustrated:

 

[Luddite]

Thanks eme160... much appreciated.... Duh or what.. :dont know:

 

[Forrester]

OK, COV redux ...

There are 8 COVs on my C4S:

#1 air cleaner flap (don't know what this does)
#2 sound symposer (I think that's the one deMort is referring to)
#3 heater shut-off (if this fails you will have no cabin heat)
#4 sports exhaust
#5 engine coolant bypass (helps the engine heat up faster, so improves fuel consumption)
#6 tuning flap (no idea)
#7 gear box heating/cooling
#8 PDK clutch heating/cooling

Locations:
#1 & #2 are on the air box
#3 is to the right of the engine near the body at the back
#4,#5 &#6 are under the ECU towards the front of the car
#7 & #8 are on the transmission under the car

The ones that failed on my car:
#1 - no effect, I just found it was dead when checking them all
#3 - no cabin heating. This was the first to fail and it was right in the middle to the Beast from the East cold snap a few years ago. I froze for about a week.
#5 - really wierd. It seemed it was stuck half open and half closed. The effect was that the water temperature kept shooting up to 110+ (normally it's glued to 90) and then down to 85 on a random basis.
#8 - intermittent. No obvious effect apart from throwing a fault. I'd clear the fault and I'd be ok for a few trips, then would fault again. Then it would be ok again for a bit. Finally nailed this one a few weeks ago.

Ease of fixing/access:
#1 &2 - easy, though I found it easier to loosen the airbox so I could get at the retaining tabs
#3 -fairly easy, but more difficult than #1 & #2
#4,#5,#6 - difficult to get at. I found the best way was to remove the ECU (engine control unit, straightforward, but dont touch the pins), then I could get at them quite simply. I replaced all three, even though only one was faulty because I didn't want to pull the ECU again.
#7 - pretty easy
#8 - Porsche (in the w'shop manual) show a nice easy way of removing COVs. You simply press on the retaining tab with a screwdriver and off it comes. If only. Most COVs are not in a position when you can do it that easily and I seem to have required a good bit of futzing around before getting most COVs free. #8 is, however, in a class of its own. The tab that you are supposed to press with a screwdriver is hidden behind a lump of metal, a.k.a 'the axle'. I tried for about 4 hours on my back to get at the tab with no luck. So I had a think, and after a bit came up with this (I'll go through the whole thing)

1) remove rear underbody tray
2) there are two flexible pipes which are in the way of getting at the connector and fresh air supply to COV #8. Unclip these from the dual hose plastic clip and pull the clip off it's retaining bracket. Tuck the hoses out of the way and you've now got clear access to the connector and air line. Undo these (dont ping the retaining clip off the connector - they can be difficult to find if they shoot off: I lost one in the engine and it me ages to find it).
3) remove the vacuum line and actuator lines at the other end of the COV. I used a long bladed screwdriver to work these off.
4) Now, the COV is attached to a thin metal plate. Bend this - it bends easily - a little way out towards the wheel, so that you have a small workspace between the COV and the transmission. Find a small penknife - I used a 3" one, and set the small 1" blade at right angles, so you now have a right-angled thin bladed tool. At the back of the COV, slip the blade between the COV plastic clip near the retaining tang and the thin metal plate. Rotate gently to move the plastic clip away from the metal plate and the tang will come out and the COV released. The COV can now be pulled out easily. Mine came out like it was greased. Extremely simple. In all, the whole procedure took about two minutes! Less time than to describe it in fact. And after 4 hours going at the thing, I was more than a bit relieved.

Finally, I'll just say that I'm not a professional mechanic and I'm sure that someone who does this sort of stuff on a regular basis would find it a lot easier than I do! Still, I've quite enjoyed tracking the faults down - even though it didn't seem so much fun at times.

 

[Luddite]

Many thanks for posting your very detailed and informative write up on the COV ststem Forrester.. :worship:

 

[Forrester]

Thanks, Luddite.

btw, I'm all too rapidly approaching 70 (years, that is) and I've made one concession to my aching bones, which was to invest in a set of Quickjack ramps.

They raise the car body by about 22" which is enough to get comfortably under and waggle a spanner or two. The ramps are *lot* more convenient than a simple jack and axle stand.

I only wish I'd bought them years ago.

 

[Luddite]

Forrester I note you mentioned the w/shop manual is that an official Porsche one for the 991 or some other..? I have been waiting for Streather`s advertised essential companion for the 991, I do have his buyers guide for the 991, but am desirous of more tec detail.

Thanks also for the heads-up on the Quickjack ramp system, I have looked at it, better than struggling with jacks and axle stands and no doubt safer too.

I would still like to maintain my own car but past age 70 and having spent a lot of time in cold and damp my bones ache and I had the benefit of a heart re-bore a few years back, so decided to leave it to my OPC with the benefit of extended warranty as Insurance, which prohibits me chasing the spiders off my spanners, fortunately my OPC have treated me very well.

As suggested by all (and thanks to ALL ) my coolant warning issues were related to the COV circuit, no signs of overheating as such just the alarm triggered and accepted. Apparently one COV with a cracked case, one with high resistance connections and another with an internal leakage, thus three replaced with new and a note to say that three others had been replaced in the recent past, thus six in total of the originals have been replaced to date...Great to have the car back in operation and with no bill to pay, all be it I shelled out for the extended warranty.

Thanks again for all your help guys, much appreciated.

 

[eme160]

Thanks for the detail Forrester.
Just changed a second COV, the one for the symposer (?)
I've now been able to cancel the warning so hopefully will not have to tackle the difficult ones.
They have all actually been changed some years ago for the newer type but still had 2 fail.

 

[Rhodris-dad]

Had the warning light appear on my car.

Coolant level was pretty low (accepted the majority of a 2 litres bottle).

Approximately 20 starts and the message has cleared.

The question is now.....have I a leak or something worse (head gasket) OR did the OPC actually check the coolant level at the last service in September.

The cap was pretty stiff as if it had not been removed for a while.

Could not get an appointment (with a courtesy car) at the OPC until 17/03

I will be monitoring the coolant level up until then.

But now I have another issue.....alarm keeps going off when locked and I'm getting a chattering sound from the driver's door central locking.

Could this be a Battery issue? I have had the car for over 4 years without replacing one. :dont know:

 

[Forrester]

Luddite,

The 'service manual' isn't an official Porsche manual - I think it's a dump of most of the useful bits (330MB!) from the Porsche online service system by some kind person in the USA. It's good for telling you how to pull something apart (and in what order) without damaging things. It's not good for telling you how things work. I don't have a current link, but there's an old thread on Rennlist (https://rennlist.com/forums/991/1043096-991-1-service-manual.html) on where to get it - the location moves around as links get deleted or expire but it's updated reasonably often, so if you look towards the end, you'll find a valid link I think.

However, you may be more interested in the 'technical' manual, the SIT (Service Information Technik) which gives a good overview of how the car is put together. It's a lot smaller and is very readable. You can get it here https://www.dropbox.com/s/4jpmkhmjlupf6w9/991 SIT.pdf

I found this to be far more useful than the 'workshop manual' for finding out things about my 911.

 

[Luddite]

Rhodris-dad, 2 litres reads like a lot, however did you ever check the water level in the past to begin to think you have in fact coolant..? Another thought might be that I think water cooled Porsches can retain trapped air at locations in the cooling system and perhaps it burped causing a slight drop in the coolant level..?

As for the battery I changed the battery on my 2012 C4S as I suffered a fail to start after an 8 day lay up, from the numbers stamped on the top of the neg terminal indicating it was perhaps original to the car...I had Porsche fit and code in a new AGM battery..

Forrester, many thanks for the heads up on the on line 991 info, much appreciated... :worship:

 

[Rhodris-dad]

Rhodris-dad, 2 litres reads like a lot, however did you ever check the water level in the past to begin to think you have in fact coolant..? Another thought might be that I think water cooled Porsches can retain trapped air at locations in the cooling system and perhaps it burped causing a slight drop in the coolant level..?

As for the battery I changed the battery on my 2012 C4S as I suffered a fail to start after an 8 day lay up, from the numbers stamped on the top of the neg terminal indicating it was perhaps original to the car...I had Porsche fit and code in a new AGM battery..



2ltr is a lot and I have done less than 2k since the service in September. My presumption is that after paying £1k for a service that they would have checked the fluid levels, especially as the fillers are both in the same place.
During the service I had the aircon re-gassed too.

You could be right about trapped air. If they have changed the coolant it is a possibility. But I thought they refilled the system under pressure to avoid this problem (i know Hartech do this)
I will check the level again this weekend. There is no evidence of a leak but I will do a more comprehensive search.

Battery.......2 in 3years for my 996, 2 in 4.5 years for my 997 ( 1 because it was non Porsche and they wouldn't give me a warranty). So I am half expecting the need to renew.
Although it has been starting fine even after prolonged stays in France. 5 weeks in October and 4 weeks at Xmas.

 

[Luddite]

Sorry meant to type "to think you have in fact LOST coolant." Unless you checked it prior to service you have now way of knowing..?

It would seem the battery in my 991 lasted 10 years and as one who always self reliant restoring and repairing my own cars, and that I was used to trade prices on parts, it was a bitter pill to pay OPC prices in order to get on to the warranty scheme, but given the history of 996 up to and including 997.1 with issues I need not repeat, I guess I lost a degree of confidence in Porsche engineering from that which I was used to in my air cooled Porsches... When I decided to return to Porsche ownership it seemed wisest to seek the warranty as having to pay out for a replacement engine or gearbox for my 991 would be a hard hit to try to recover from as a pensioner.. For sure there is a price to pay for that sort of Insurance as there tends to be with any Insurance worth the premium...? When I paid up I hoped never to have to claim on it.

I suspect there is a chance you may have overfilled your coolant by some degree..? Removing enough for the indicator to show a level less than MAX might be worthwhile in terms of monitoring for possible loss..?

As for total dependence on others no matter how much you pay...Hmm..? Some things are easier to self check than others, such as brake fluid, water level and pad and disc wear are simple checks before and after service.