Coolant Smell Help?

Hello all. I have a 2002 c2 Cab, with about 28k miles. Recently started noticing a coolant smell from the rear left after driving. I have replaced the coolant cap, used a pressure tester to confirm system will hold pressure (it does). I have a boroscope and looked around under the coolant tank and didnt see anything obvious down there (but it would be pretty easy to miss something with one..) I also pulled off the serp belt to check the water pump. No lateral/wobble movement on the pump. Very little fore/aft movement (i.e. much less than the alternator). Turns fine, no binding, grinding, appropriate amount of resistance, etc. Didnt see anything we around the snout, but also didnt pull the pulley to get way up in there... Temp is normal when driving, all else seems fine. So, question for the experts is; what did i miss? What else can I look at/check? Any thoughts would be really appreciated before i start swapping parts...or take it to an indy. By the way, before anyone asks, the IMS has been addressed Thanks!

Do you have any dried white or greenish seepage under the engine? Mine started with a light smell and over time got a little more pronounced. Then a drip, then a quarter sized puddle, then a bit more. Engine was dropped and I had all the coolant fittings TIG welded. More items were replaced for maintenance during that time as well. Edit to add: Mine is a TT and the culprit was the fitting behind the alternator.

Quotes source post: 11648444

With the smell there's a leak. You need to get the car in the air and carefully check the water pump for any signs of coolant leaking. It might be just a large white residue stain. Or it can be, as was the case with my Turbo, a large greenish blob of dried anti-freeze residue under the pulley. No need to remove the pulley just get the car in the air and with a bright flash light check the area of the water pump thoroughly. Be sure you check the water pump where it bolts to the block for a leaking gasket/seal. Look at the hoses and their fittings for any signs of coolant leak. The tank might have a split that opens up a bit when the engine is shut off hot. What you can do is a poor man's pressure test. Be sure the coolant tank level is ok, not too low, but not too high either. Use distilled water to top up. Then with the AC off drive the car around until it gets fully up to temp. When I hear/feel the radiator fans come on that's a sign the engine's fully warmed up. (My car's fans come on at 212F.) Back home open the engine compartment lid and expose the engine. Start the hot engine and raise the RPMs to 1500 and hold until the fans come on. Turn off the engine and get out of the car. Carefully check around each radiator, along the length of the car, at the water pump and the hoses that connect to it, everywhere, for any signs of coolant dripping. You'll have to lay on the ground and use a flashlight and maybe a mirror on a stick/swivel to really check the hoses/connectors and water pump area. Carefully check the top of the engine for any signs of coolant. The oil/water heat exchanger can leak. Keep in mind the engine is really hot and as the hot engine sits this will raise the coolant's temperature and pressure. If there is a leak it can appear with no warning and gushing hot coolant so keep a safe distance and wear eye protection -- I like a full face shield -- when you get close to the engine.

Tracerline UV dye kit. Amazon. Win

First tell me what pressure tester you used, how much pressure you used and for how long you tested it? Forget about visual. There are many places that can crack at the bottom of the tank. You won't see the cracks on the tank even if it's in your face.

Quotes source post: 11649808

While a pressure test might reveal a leak by the pressure dropping it won't reveal where it is. For this one has to turn to visually looking for leak sign. All pressure tests I'm aware of have the engine cold. The several coolant leaks my car's have had all really only made themselves known when the engine is hot.

Obviously if you pressure test it, you need to rely on visual and feeling around with your hands. My comment was without a proper pressure test, don't expect to see cracks visually as the cracks won't look obvious at all without coolant leaking out.

Guys, THANKS for all of the responses! I have a coolant system pressure tester. Tested at 23lbs (cold). Held steady for over 5 minutes. Used an OTC 7991 Cooling System Pressure Tester I think I still have a UV leak kit somewhere in the garage. IF I can find it, I may try it. Was hoping to find it without going through that hassle though. I also haven't really noticed any loss of coolant in the reservoir (i.e. haven't seen the level drop), but that may be a function of whatever is leaking being very small....

Look with a mirror under the expansion tank. Bet there is a hairline crack, I see it a lot. Drips down onto the exhaust.

Quotes source post: 11652151

23 lb is more than enough. In fact Porsche calls for 19psi only. 5 minute definitely too short. Try 20~30minutes and you should see the leak.

Quotes source post: 11652208

Thanks to everyone, this is really helpful! I will try what you said this weekend (I couldn't find the official Porsche spec, and I had thought 5 mins was enough). Ill re-do the test this weekend. Also, I will grab an inspection mirror and look under the coolant tank too....that may work better than the boroscope. Ive been meaning to replace the water pump (due to age) anyways...so I just ordered it from suncoast (under $300 for oem!). If it gets here this weekend, ill do that and run the pressure test and report back what I find. In the meantime, since the WP bushing wasn't wobbling, going to keep driving it while the weather is nice! THANK YOU again to all who have replied, I really appreciate it!

I had the same smell for quite a while and even got a new coolant tank cap that helped some. After a while the smell came back but this time it wasn't the cap and I could not figure out where the hell it was coming from. Until the day my AOS gave out in the parking lot at work and spewed coolant all over the parking lot Turns out it was a very tiny crack or hole that just grew over time.

Check around the oil cooler from underneath with a mirror. That's where mine was. Seen in this thread. https://rennlist.com/forums/996-foru...orth-it-2.html

Ok, so I spent some more time on it this weekend. Pressurized it, and it lost 1 psi over 35 minutes. Im assuming that's not good. However, still no visible leaks anywhere (that I can find). Went underneath with lights/mirrors, didn't find anything. Also put a large sheet of white paper under the car after a long drive, and there were NO drips. There are a few spots under the tank that look suspicious, but I cant tell if its from a slow leak or just dirt/grime, etc Im planning on doing the waterpump this weekend. I may just do the tank as well, as I believe both are original to the car (its a 2002). Short of using dye, any other thoughts/recs? As for the AOS, was inspected by my indy in april when I had the LN IMSB installed...I know it was a while ago, but at that time they claimed it looked great, and no need to replace it..... Thanks again!

I would get a wiff of coolant smell once in awhile. Then almost every time I drove. I still couldn't find the "leak". Then one day after almost a year of this there was a puddle under the left rear muffler area. My tank looked like this:

Well, the coolant smell has been getting progresively worse. I now have some crusty residue on the drivers side exhaust, so looks like its probably the tank. I did the water pump yesterday. Pretty easy, except when the neighbor helping broke one if the bolts. Luckily, easy to remove, and no damage. For anyone thinking about this as a diy, its pretty easy IF you get a 10mm swivel socket in 1/4" drive. 3/8" drive is just a little too big. After the pump, tried to do the tank. Just cant get it out all the way. Dropped the engine about as far as it can go with undoing just the rear mounts, and still couldnt get it out. Not sure what i was doing wrong....but very frustrating/disappointing. Unless anyone has any tips/tricks to share, i may have to take it to an indy...i just hate to give up on something i should be able to do!

Hang in there. Just remove the black bracket holding the tank (two bolts) and it should come out with some wiggling. Install is reversed and you should be able to install both bolts with some patience.

Yeah, just couldnt seem to get the tank in a position to get the bolts out of that black bracket....when i started thinking about using hammers, i knew it was time for a break! The worst part is that i figure this is one of thise things that if you do it once, the next one is probably easy! Any tips on how to get to that bracket?

Yes, slide the tank off the bracket completely then push the tank all the way toward the left front of the engine compartment as much as you can.

Dang it! I was right there yesterday! Argh! I may give it another shot today, even though its all buttoned up. Any idea how many hours a shop would need for this if i cant get it done?

Sorry, no idea how many hrs a shop will charge. I would think at least 2 if not more.

I just noticed you have a cab (I have a coupe). Not sure if that adds more issues. Hopefully someone else with a cab will chime in.

Only special stuff ive read about a cab is that it is harder to do than a coupe. Have to lower the engine a little more for the clearance. Thanks for all of the replies, i really appreciate it!

I did mine. I lowered the engine and pushed it as far to the right as possible. I was able to slide the tank off the black mount then towards the firewall and engine enough to get at the 10mm mounting bolts. Look at your new tank it has a series of tabs that slip through spaces on the mount so that you don't have to slide the tank over too far to get them to disengage. I used a 1/4" drive ratchet with a wobble extension and a universal to get at the bolts. Once the mount is out the tank comes out pretty easily. Take the level sensor off as soon as you can reach it. It turns clockwise to loosen it. When you lower the engine take the oxygen sensor wires out of the channel so that you don't break them. Also undo the clamp that holds the hoses to the bulkhead above the power steering pump.

You probably need new motor mounts anyway... Do them at the same time and it will let you drop the motor slightly for better access to the tank. The other thing I'll mention... Some 996's just like to burp out extra water/coolant to a bit below the marks on the tank which will definitely cause the coolant smell. When I first got my car, I topped off the coolant a few times, it always burped it out to the same exact level, under were the marks on the tank are. New cap, same issue. Bleeding, same issue. I finally just let it stay at the slightly lower level, and no more disappearing coolant, no more coolant smell, and perfect coolant temperatures. Evidently a common issue...