Bender6502

I recently bought a 2002 996 Turbo. The car was very clean with just under 36,000 miles. This is my weekend car, so it gets rarely driven. Recently, I noticed that the coolant level has dropped about 1/8th inch in 4 months. I didn't notice any leaks on the garage floor. So, first thing I checked is the coolant tank. This tank was replaced in 2019, so it is fairly new. I did notice some dried up crud by the cap.


I know this isn't genuine Porsche cap, but it is an OEM cap manufactured by Blau (996-106-447-04-M8). I decided to top off for now, so I bought a Porsche coolant (000-043-305-15-M100) and genuine Porsche cap (996-106-447-04-M100). I mixed the coolant with distilled water (50/50), and noticed that coolant in the car was orange VS. the coolant I just mixed was pink. Do Porsche coolant change color over time? If not, is it okay to mix these two?

For now, I decided to just add distilled water (no coolant), it took about 7oz to top off.


After a coolant top off, and with the new cap in place, I took the car for a short drive (10 miles). When I returned, I noticed coolant drips on the drive way. When I checked the tank, it has overflown.

Coolant level was about 1/8 inch above min line. Can this still cause overflow? After doing some research, I read that after topping off, you should pop the bleed the valve up, and go through several drive cycles to burp the system. This sounds reasonable, this is something I can try next. Has anyone else experienced similar issue?

Bernard IV

Is the car stock? Drive the car hard for a few runs and then pull over. Release the pressure with that bleeder valve and then take off the cap. Check for exhaust gas smoke or whatever in the tank.

SSDVC

I had the same issue with my C4 Cab. Indy was doing a lot of work on my car and while he was at it, I had him replace the tank and cap and flush the coolant. After I got the car back, she kept on puking coolant after she got hot. Not a significant amount, but I kept smelling it and there was always a puddle on the ground, or a trail of it leading up the driveway to the garage. We looked everywhere and finally determined that the fluid was coming from the same place as is yours and realized the new cap was defective. Indy FedEx'd a new cap to me, I put it on and haven't had a single drop lost since.

Lazurus

As suggested it will probably desist once you top it off and open the breather clips until it equalizes. This will happen most every time you drain coolant and top off again as in a radiator swap.

Provided there are no hairline crack(s) on the expansion tank itself which seems to be how they fail as they are not known for their longevity. I believe I'm on my third tank after 18 years. I've never had an issue with the exp tank caps. Only the system needing to be "equalized".

Bender6502

Thanks everyone, I appreciate your feedback. To answer Bernard's question, yes, the car is stock, no X50 nor any mods. It is good to know that most likely that system needs to equalize. I hope that cap is not defective, this will make diagnosis much more difficult. At least I still have the Blau cap to try.

So, it consensus points to opening the bleeder valve for a couple of hot-cool cycles. When done, is it better to put the bleeder valve close when the engine is hot or cold, or does it matter?

Lazurus

One brisk run with the breather unclipped after topping it off should be sufficient, Then close it, and just check it again ( visual level and for any residue ) after your next drive. Hot cold doesn't matter, but it'll be hot pressure after the run, and that's when to close it. I always peek occasionally to look for residue accumulating near or at the motor mount under the tank. But that's just my third exp tank "paranoia"!

Bender6502

Thanks Lazurus, that makes sense. I'll do this and keep my eye out. I don't blame you, I would be paranoid too, if I went through that.

Bender6502

I finally got a chance to take the car out again. I left the bleeder valve UP and drove gently for about 10 miles. Upon my return, I noticed a faint trail of coolant on the driveway again. It wasn't as heavy as my first run, but it was there. I checked the coolant tank again, and sure enough there was some leakage.



It's much less compared to my first run, however, the coolant level dropped down even further this time (about ~1/4 inch). During my first run, it dropped about (1/16 - 1/8 inch).



I'm not sure what's going on. According to the records, this tank was replaced in 2019. It's not yellowing and still has that bright white color to it. You can see the part # in the picture (996.106.057.04), so it seems to be genuine.

I topped it off with distilled water again. So far, I've added about 16 oz. total. I would top it off with coolant, but the color didn't match. The coolant in the tank is orange, whereas the genuine Porsche coolant I bought is pink.

QUESTION: How much more can I top off with distilled water before it becomes a concern? I calculated I added about 2.2% to 2.5% of distilled water so far.

I noticed there are others out there who had this exact same issue. I just hope this isn't a defective tank. I didn't notice any cracks or leaks coming from the tank itself. I also heard the rubber seal in the cap is sometimes not completely sealed. I checked for this, and it looks properly sealed. However, I did notice there's a lot of play at the cylinder part of the cap.



My OEM Blau (black) cap had a tighter tolerance. For now, I wrap some Teflon tape around the neck of the expansion tank and put back on the Blau cap back on tight. As much as I love this car, this is just anxiety-inducing..

Any suggestions? Thanks!

Bernard IV

You need to diagnose the car for a blown head gasket. If you have a leaking head gasket some weird stuff can happen. Sometimes it will seal fine cruising around but when you accelerate hard it will push exhaust gasses through. Sometimes your car will slowly eat coolant in the cylinders. Sometimes it will push the water past the seals on the cylinder liners and you wind up with water in the oil, the classic milkshake situation. Maybe for you it is over pressurizing the coolant system and blowing it out of the vent. So like I said earlier, take you car for a hard pull and then immediately pull over. Open the vent and take off that cap carefully to check for any exhaust smoke or smell in the tank. Maybe take your oil filter off and see if there is any water in the oil too. You could also try one of those head gasket test kits that test from the tank opening, but like I say it could be sealing fine at low speed and only leak under load. Don't worry about the level for now, you'll be fine as long as the tank isn't empty. The orange coolant is probably the Valvoline Zerex stuff, that's what I run in my car. But that also indicates that someone has changed out the coolant at fairly low miles, and not at the dealership. Another clue.

vtec_

i wouldnt worry about adding some distilled water to the coolant tank, that isnt the problem.

Are you sure it isnt just overflowing from the hose next to the cap?

Carlo_Carrera

That hose is just a drain.

Bernard may have it right. The OP might have a head gasket leak. It is the first thing that should be checked. They sell detector kits at parts stores and Amazon.

garrett376

You've got blown head gaskets, cracked tanks, bad caps being thrown out there... if there is a faint trail of coolant, jack it up and watch where it's coming from (from below) while it's running; it should be easy to trace and confirm exactly where the leak is from while it's occurring.

Bender6502

First, thank you for all the feedback provided. Wow, this started as a $25 cap to possible blown head gasket, *nervous chuckle..

I called local indy shop to make an appointment. His take after describing my situation plus condition of the car, he doesn't think it's a blown gasket, but I need to really tighten the cap down, use 2 hands.

So, I made an appointment with them to check out the car. The earliest appointment available is 2.5 weeks away..

I did get the car inspected 2 months ago at a Porsche dealer who specializes in classic Porsches. I do believe they've already done pressure test. He did point out minor things here and there, but nothing relating to cooling. His assessment is that this is a very honest clean car. Again, this doesn't mean that everything is fine.

s65e90

Coolant system is sealed, you shouldn't be losing any. Are you sure the wet you see around the reservoir isn't from filling it up? If you see on the floor, you have a leak. I'd doubt the headgasket is bad, but when they do fail between cylinders, the car can push coolant under boost and cause you to lose it. Again, doubtful, I'd start with the simple stuff, change the reservoir and cap. You fill it to the line(s), leave the cap tab open for a day or so, then close it and drive. Use the car and watch the temps, but drive it.

Bender6502

Thanks for your reply. Yeah, I'm positive that spill isn't from the filling up. I made sure that I wiped any exccess clean before driving. I didn't notice any leaks on the floor either. I haven't checked the expansion tank closely for any cracks. I currently have 2 caps, Blau (OEM cap, black that came with the car), and a genuine Porsche (blue) that I just purchased. I can contact the vendor for an exchange, this is an easy task. Again, my indy mechanic told me to close that cap real tight, "use two hands" <- his exact words. I just hand tightend it before.

It didn't occur to me to check the coolant level regularly. The engine felt solid, and I didn't see any white smoke, hesitation, or overheating. I'm just not familiar with this car, but I'm learning as I go.