Low Coolant Light

[ALLSPEED]

HI Gentlemen-Out of all you brilliant people out there someone may help me fix my problem.

I live in the very hot central California Valley and have a 1999 c2 996 6sp. This winter I sent it to a very reputable in Georgia where they replaced my IMS bearing, clutch ,flywheel, WATER PUMP, lifters and some other things. They said when they filled it they did it by vacuum which I believe. The owner said they re-filled the coolant under vacuum but to flip the bail on the bleed valve for fifty miles or so.

I did as he said and everything worked fine. I drive the car little because of my bad back and I've been staying close to home because of my 89 Mother.

Now that summer came and is almost gone my low coolant lamp starts flashes at about 200F which is on the right edge of the 180 on the analog gauge. This is normal for this car. I have verified the coolant temp. with both the Durametric and the HVAC hack. I stop and check and the coolant is not low. I can turn off the key and it will go off but come back on in a few. I think the only reason it waited to do it now is because the ambient temp. is higher outside. May I say I now have it filled to the neck and it does'nt go lower.

I have put the Durametric on it and shows no faults except in the alarm system. I have heard the engine compartment fan come on and activated it from the Durametric. I have activated the low coolant lamp from the Durametric.

Would someone tell me if they have had this problem before or any trouble shooting info as I can get. My wife wants her Audi and I hate to pay the dealer to fix this one. Thanks a lot.

[Loren]

Could be as simple as a bad coolant sensor.

What does Durametric say the actual temperature is?

[ALLSPEED]

I'm going to try and get it to come on with the Durametric and I'll let you know in a little while. It may not be hot enough (ambient). I'll be back in a while. Thanks Loren.

[ALLSPEED]

I'm sorry. I must be mistaken about getting a coolant temp. reading off the Durametric. All I can find on it is to fully activate analog gauge. But as I remember and I will try and use the HVAC again it was about 100 to 102 on HVAC. Is there a way to test the sensor and how do you get to it. Analog gauge seems to be working O.K. Thanks

Edited September 18, 2011 by ALLSPEED

[kbrandsma]

Check radiator cap and if ends in 00 replace. Also, I just cleaned my radiators this weekend and temperature gauge dropped quite abit.

And behind the AC Condenser

Edited September 19, 2011 by kbrandsma

[ALLSPEED]

I can't find a coolant temp. on my enthusiast model of Durametric but I drove it enough to get the get the low coolant light to flash. My analog temp. gauge on dash is lying on the far right side of the 0 on 180. Just for noting my engine compartment was at 78c and the oil temp was at 111. The coolant gauge is about as high as it ever gets and my coolant is filled almost to the neck. Any ideas? PS- This is the temp my car usually runs I just suspect it didn't happen earlier in the year because it was not hot enough and I didn't drive too much because of other problems.

Edited September 18, 2011 by ALLSPEED

[Loren]

But if the sensor is bad it may not even need to be warm to get a coolant light.

As I recall the coolant temperature is in DME actual values - you might have to scroll to get to it.

[ALLSPEED]

I'll go see what I can find and if I do I will try and get it to come on so I can get a read. Thanks, Loren.

[ALLSPEED]

I can't find the coolant temp anywhere on my Durametric. Is it by chance abbreviated. You can chk. your analog gauge (temp) for scaling but thats all I can find. There are several abbreviations that I don't know. It's funny that it keeps happening at about the same temp. Like you said if it was just the sensor why does it come on at about the same temp? Is this where the thermostat opens and this causes something to happen from the flow? Help!

[ALLSPEED]

Any ideas, anyone?

[Loren]

If I get a chance I will hook up my Durametric to my car and see where it is. I was pretty sure you read that at one time.

On PST2 or PIWIS it is called "Engine Temperature".

[ALLSPEED]

Thank you my friend. all help is appreciated.

[logray]

The coolant level sensor (one reason for the flashing of the temp light) is at the bottom of the coolant expansion tank.

#2 in the pic.

Edited September 19, 2011 by logray

[logray]

I can't find the coolant temp anywhere on my Durametric. Is it by chance abbreviated. ...

Depending on your year car and DME you should fine one or both of these values in Durametric...

Engine temperature (this is coolant temp AFAIK)

Oil temperature

[ALLSPEED]

O.K.-I called Durametric and they said on my year 99 996c2 6spd the DME does not give the output of engine or coolant temp. He said that Porsche does not make it available on that year. I did say my oil temp. was 111c and my analog gauge on dash reads where it always does. I'm curios what the engine temp. has to do with this? It does happen at it's hottest but I've stopped right after it came on and visibly checked the reservoir and it was full.

I've read something about the original expansion tanks on early 996's have been updated because the design would let the coolant slosh and the low coolant level would come on. It is kind of strange this just started. My Vin# is WPOAA2995XS621831. I am the third owner and don't know if it has been changed. Is there a way to tell if it has been upgrade by looking at it? I need to get this one fixed. Thanks, Robert.

[Loren]

There have been at least 6 tank upgrades - your guess is as good as anyone's. If your tank is not leaking then I suggest you leave it as is.

Durametric is correct ( I setup my Durametric on my MY1999 996).

The Instrument cluster (which shows the sensor at the coolant tank) does not display. BUT the DME does show the ECTS (Engine Coolant Temperature Sensor) - which should still help you determine if the coolant tank sensor is bad.

The ECTS should be pretty much dead on as the DME uses it. So I would see what it shows. In the end I'll bet you have a bad tank sensor.

BTW a PST2 can show both sensors (DME and Cluster).

[ALLSPEED]

Yes I wish I had a PST2. Someone on this site was going to put one together for me but he disappeared. At least I didn't give him any money.

Back to the car. I hooked up the Durametric and measured the temp. through the ECTS like you show and drove her across town. The low coolant light came on when the temp hit 105c which is 221F and never got any higher. Stopped and chked coolant level, still right below the neck. Not long after that my laptop messed up so I couldn't use it on the way back But it came on three more times driving home which I reset the first two by shutting off and restarting the engine. I did notice that it came on at a slightly(3-5 degrees) lower temp on the way back by looking at the analog gauge. So I know my engine runs a little warm but can someone tell me the correlation between the coolant temp. and the function of the coolant low level indicator. I realize it always happens around max. coolant temp. but that doesn't tell me much. I hate to blindly order a new level sensor and go through the hassle of draining coolant and bleeding just to have it come on again. Any more ideas, please.

Edited September 20, 2011 by ALLSPEED

[Loren]

It could still be a partially fractured water pump impeller (fairly common) or a stuck thermostat.

997.641.503.00 Coolant tank sensor -- US MSRP $27.73

996.106.147.56 Coolant tank -- US MSRP $336.39

The sensor does not touch the liquid - it is on the outside (bottom) of the tank.

So changing the sensor is kind of a pain (because the tank has to come out - at least partially). But you only have to worry about refilling the tank.

Find a shop with a PST2 (or drive to Roseville) and see if the two temperatures are within 5 degrees - if they are then you have water pump or thermostat problem.

[logray]

Try the drive link in durametric to activate the engine compartment purge fan.

Or drive the car until it gets hot again and see if the engine purge fan is running.

If the compartment purge fan is working, then it's probably the fluid sensor because it sounds like your instrument cluster does not think the car is overheating (that happens well above 105 celcius) or a large discrepancy between sensors.

BTW related to your other "wish" I have a KTS500 PST2 clone that I might sell soon, in order to raise funds for an upcoming 3.4 to 3.6 L upgrade of my 996 C2 car's engine.

Edited September 20, 2011 by logray

[ALLSPEED]

I chkd the purge fan with the Durametric and it operated and when I shut it off the fan came on in about ten seconds and ran a few minutes so I don't think it's the fan. Loren- I'm no genius but if it is flashing at full temp would it matter if the thermostat is stuck open. A new water pump was put on less than 2000 miles ago. Also, where are you getting the temp. readings? Is there a float or something in the reservoir or how does it read the level ? Please explain so I will understand this thing better. Does anyone around Bakersfield have a PST2? Is there any way I could have too much coolant as I am filled to the edge of the neck in desperation.

Edited September 20, 2011 by ALLSPEED

[logray]

The function of the thermostat is independent of the temp sensor. The thermostat is already fully open at the temp your light is flashing. If it was stuck open that doesn't have any bearing on what the sensor reads, it will read a temp or it won't.

H20 pump replacement could be co-related, if there is air in the system and the car is overheating, and the sensors are misreporting the temp.

However, 105 C is not overheating (that's around the middle to the right of the 0 in 180 on your gauge).

So there are two "known" conditions left for the flashing light since the car is not overheating and your instrument cluster also thinks it is not.

Purge fan, but you said it works. I'm still a litte suspicious of that though because IIRC 105 might be a trigger point for that fan, or at least that might be hot enough for the purge fan to start running. Perhaps even though the fan can be activated with durametric for whatever reason the dme doesn't think it is on.

Coolant level sensor. You could try to unplug the level sensor and see if the light flashes. IF it doesn't flash when you unplug it get the car up to temp and see if it flashes. If it does flash when you unplug it, you might be able to ground the terminals to trick the level sensor into thinking it is full, although I'm not certain how the sensor functions either, and would have to look at the wiring diagrams and do more research.

Or since you've eliminated two of the three variables you could just get another level sensor and put it in and see if that works.

Also I'm not sure a PST2 would help you here, since I believe Durametic can see all the values the PST2 can in this case for both the DME and instrument cluster.

If I have time tomorrow I'll hook up my Durametric since I have the same year car and see what values I see.

I would also try to monitor the three separate readings (two from dme oil & engine) and instrument cluster (and a/c hack) and make sure they are all in the same ballpark.

IF there is too much coolant it should go out the overflow. Too much coolant is not a condition the light flashes in.

Edited September 20, 2011 by logray

[Loren]

In logray's post above the sensor is item 2 - and as I said it is on the bottom outside of the tank.

For less than $30 you can replace the sensor.

[xmac]

I chkd the purge fan with the Durametric and it operated and when I shut it off the fan came on in about ten seconds and ran a few minutes so I don't think it's the fan. Loren- I'm no genius but if it is flashing at full temp would it matter if the thermostat is stuck open. A new water pump was put on less than 2000 miles ago. Also, where are you getting the temp. readings? Is there a float or something in the reservoir or how does it read the level ? Please explain so I will understand this thing better. Does anyone around Bakersfield have a PST2? Is there any way I could have too much coolant as I am filled to the edge of the neck in desperation.

Get a turkey baster and siphon out some of the coolant and get it back to the MAX level (seam of top/bottom pieces of the reservoir). It doesn't help to overfill the reservoir. If the plastic looks really brownish/yellow in color, it has not been replaced recently. A new/recently replaced one would be milky (opaque) white in color.

As for the main problem, I would start with replacing the coolant level sensor. The coolant sensor is only $22 from Suncoast Updated 997... Coolant Sensor. I would replace that with the updated unit. (Part# 99764150300 ) If you decide to replace it, I would also order the new coolant cap that ends in .04 (Part# 99610644704 ) while you are at it - cheap and eassy update.

In order to get to the level sensor, it is almost the same as replacing the entire reservoir (just replaced mine this past weekend). If your reservoir is yellow, it doesn't hurt to replace it but it is a pricey part. The cheapest I found it online (Part# 99610614756 ) was Suncoast for $239. I prefer to go to my local Porsche Dealer and get them to price match.

Here is a link to a thread with the coolant sensor location and the tank color I am describing:

Coolant Reservoir Leak

Edited September 20, 2011 by xmac

[ALLSPEED]

Thanks xmac.

[ALLSPEED]

Now I am really miffed. I removed and replaced the air pump so I could unplug the coolant level sensor, which I did. I too will have to buy some new nuts with rubber washer. Thank God there is still that upper nut which will hold it for now.

Took her out for a spin with Durametric hooked up. At 105c the light started flashing. The analog dash gauge read on the zero of 180, right edge. Coolant level fine. Sensor not hooked up.

Brought home to garage to chk purge fan. The purge engine compartment fan came on at 78.8c. I've been told the setting is 80c. Kept going to see when light would flash and it started at 97.5c coolant temp and 97.5 oil temp. I guess since I was at idle they came up together. For some reason I cannot get the A/C hack to work. I timed the on time of the flashing lamp and it was 1 sec. Any ideas would be appreciated. I am at a loss.