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I will jack the rear up again, let it settle, maybe run the car a bit. But it’s almost full of coolant...
How do you know it is almost full of coolant if it is over-heating? What came out initially is what has to be replaced...then you know it is full.
I do not know what your driveway is like (flat or sloped) but place the front of the vehicle at the lower end of the sloped driveway and jack up the rear. I had absolutely no issues with my fill that way. Chock the front wheels when doing so.
How do you know it is almost full of coolant if it is over-heating? What came out initially is what has to be replaced...then you know it is full.
I do not know what your driveway is like (flat or sloped) but place the front of the vehicle at the lower end of the sloped driveway and jack up the rear. I had absolutely no issues with my fill that way. Chock the front wheels when doing so.
So about 9L came out when I initially drained with the car jacked up.
About 6L went in and about 1L probably got wasted as it spat it back out.
This is how high it was jacked on initial drain and refill.
Therefore the coolant must be about 4L less than full right now. I’m thinking I jack it up, let it run so air might come towards the back, then drain it at the rear again. Then try vacuum fill it.
So about 9L came out when I initially drained with the car jacked up.
About 6L went in and about 1L probably got wasted as it spat it back out.
So about 1/3 of the total capacity was initially drained. That is what I also drained while performing the "fix". I have seen 26.3-27.5 liters and 29-32 liters listed on coolant product web sites.
As for your pic, driveways usually slope towards the road. I would have parked the car accordingly and then lifted the rear. In my case, the rear of my 991 was quite a bit higher.
By the way, you have two coolant temperature sensors in the system; one at the engine and one in a coolant pipe midway under the vehicle. I would think the coolant gauge shows the one at the engine.
In addition to the other tips, I mentioned in my other posts above I would also have the bleeder (comfort valve) in the upward open position when you are doing your vacuum bleed with a relatively full system. The small lines shown as orange on the below diagram are on the high spot of each radiator and heat exchanger and connect to the comfort valve and should be able to remove some of the trapped air when you are pulling the vacuum. At least that makes sense to me???
Jim
Comfort valve #5 and expansion tank #6 with the small orange bleeding lines shown connected to the comfort valve.
Several months ago I did replace the gasket at the plastic coolant pipe on the thermostat due to a drip. The job was tedious and frustrating. The filling procedure was quite straight forward as It is made simple by placing the rear of the car on ramps or some other method, filling the coolant reservoir completely and leaving the bleeder metal clip on the cap in the open position. I then drove the car several times letting the engine come to temperature, each time the coolant dropped at which time I filled the reservoir only to the ' full line'. On the 4th fill it did not move so I then put the metal clip back in the closed position.
I’ve pulled the vacuum today. Didn’t manage to pull 25PSI. I got to 11PSI in just a few seconds and it wouldn’t really move much after. Started to draw coolant in, got in about 2.5L.
The car ran for about 15mins, all got to temp, managed to drive round the block. After this it went to 99c, and I turned the engine off.
I think I’m closer, so once it cools off, I’ll repeat it. The bleeder valve has been left open the whole time so far.
The pipe is still dripping, but very very slowly now.
Edit, after it cooled, I barely pulled any vacuum, maybe 250ml went in. It is still breaching 90c after about 15mins, and heaters won’t get hot. Not sure what’s next other than taking it to the shop.
Edit, 12hr later, pulled vacuum again, and got about 2L in. This time I let the car warm up with the coolant cap open, hoping it might burp. About 1L coolant creeped out over 10min. But still no heat from the heaters and eventually hit 94c. I might drain and start over with the car on jacks at the rear.
Edit, 6hr later, drained it on jack stands at the rear. About 8L came out. Pulled a 25psi vacuum this time and refilled about 10L. It’s taking about 20min and hits 94c, heaters still cold. Well I’m defeated now.
Porsche advised to pull the vacuum for 45min. And also to rev the car (throttle blip) to 3000-4000rpm.
I didn’t drain and re-vacuum fill, just tried the throttle blip.
Leaving the car jacked up at the rear, I tried this today. We have some success. Heaters started to blow hot air, the coolant temp got to 90c, and I kept blipping the throttle. Coolant temp dropped to 89c *jaw drop*.
I did this process after the temps were at 60c, so not to damage the engine.
Later I will open the coolant cap, maybe some air will release, and repeat it another time. I hope this does the trick once and for all.
If your car is old like mine and weathered in, there’s probably no way the steps in the DIY will work, it’s just too difficult to get those pipes out. I ended up following what my Indy said, undo the 3 bolts on the plastic pipe, and undo the retaining clips on the other pipes, as well as the thermostat housing screw that secures it to the engine. There’s also one screw that is via a retaining bracket into the thermostat housing, unscrew that one too.
That will allow you to wiggle the thermostat housing away from the plastic pipe. Then get some spanner’s and slot them between the pipe and the thermostat housing. I put the spanner’s flat between the part on the pipe where the screws go in and the housing, so that they don’t get in the way of the pipe face.
At this point I had maybe 10-12mm of a gap to work with. I then used a very small screw driver to pick the old seal out. Clean it as best you can and slot the new seal in, ensuring that it’s sitting in its housing all the way around.
Now tighten it all up again. Vacuum fill the coolant, the parts I bought were sufficient to refill 8-10L of coolant.
Make sure to open the bleed valve, it’s under the plate that’s covering the coolant and oil fill caps. One bolt is holding it on. Lifting the metal clip on the bleed valve to the vertical position allows it to bleed air.
Start the car, keep it on the jacks at the rear and rev to 2500-3500 rpm. Do this till coolant gets to 90c and hopefully you can keep going until oil hits 90c too. That should get the heaters hot. I repeated that 3x, each time letting it cool off for a few hours. You should be able to close the bleed valve now. Keep monitoring the coolant level and top up.
My seal was very very slightly still leaking, but seems like after bedding in, it’s fixed the leak.
I have done 2 drain and fills and used a vacuum fill tool so I’m not a lot of help with you air bleeding issues but I recall a valve on top of the coolant reservoir tank that can be flipped up in an open position to help bleed air from the radiators and the system. It bleeds air to the top of the sealed reservoir tank and not externally so I think it would probably take multiple heating and cool down cycles??? Porsche and most of the DIYers recommend the vacuum bleeding tools as there are multiple heat exchangers and valves in the system that can trap air and make a complete fill very difficult without the vacuum tool.
Porsche issued a service bulletin on “Reworking Coolant Pipe” with a kit that has a water tube retaining bar and bolts that puts more uniform clamping force on the coolant pipe that is installed without removing the existing pipe. There are 2 other recent threads on this repair and I posted the below repair and added to some previously posted installation tips. The parts were about $40 and I installed them as a preventative measure to avoid a leak in the future. This repair does not require draining the coolant but a small amount will come out when the bottom bolt is replaced so you need to work fast.
Jim
Thank you.. Great info.. Perhaps i don't need pipe replacement and this is the fix to s slow leak. How much does Porsche or shop charge for repair (how many hours needed)? Thanks
05-08-2024, 10:47 AM
