Coolant Tank Leak Location

[TNT79Bronco]

Just curious, for those of you that have had tanks fail and leak, where did they leak? Is there a seam that leaks? A hole that forms? Just wanted to see if there was any consistency in the failing locations. Thanks!

[jaykay]

Good question and wondering if it is prudent to replace proactively so one is not left at the side of the road.

Mine is 20+ years old!!!

[TNT79Bronco]

No doubt. And on my “good” car, I put plenty of $$ in preventative maintenance stuff and use the good stuff on it. I ask, because I have an older “project” Boxster that I play with and experiment on. I was going to use clear Flex Seal on it, or try and reinforce the trouble area(s) with thick black Flex Tape. If it leaks, then I will replace it. If not, who knows.......

[Newsguy]

Just do it. It's not a particularly fun job with the engine out. You don't want it to go on you in the middle of a national park on a mountain as happened to me.

[TNT79Bronco]

This is not the car I would take to a park. It is an around the town beater to keep miles off of my 911. I paid $700 for it. Lol.

[78F350]

I had small stress cracks at the curved edges. One of those cracks was leaking under pressure. The other leak that seems to be common in older tanks is from seal on the pressure relief valve. Trouble with seams and fittings is usually reported on new aftermarket tanks.

Considering the pressure and temperature, I doubt tape will do any good, but no harm in trying. Carry a few jugs of distilled water.

[Rob175]

My tank (98' original) finally developed "spider" cracks on the very bottom. Once the car was up to temp and the pressure in the system was built up, it would begin to leak. No wet carpet signs because it leaked from the tank's bottom which is below the carpet level. The coolant would collect in a pool under the trunk's floorboard and eventually find its way onto my garage floor in a series of small drops, at first, but eventually growing to an easy to see pool.

My indi Porsche mechanic charged $800 (Genuine BMW part and labor). Stay away from cheaper non-genuine tanks.

[A8ked]

Mine also had small spider cracks at the bottom. Could not see them until I removed the tank.

[TNT79Bronco]

Interesting, I figured it would be around the seams for sure.

[El 3.2S]

I had leaking coolant tank problems a couple of years ago. The above pictures show where the leak was coming from in the tank and how my boot looked with the leaked coolant. It was the original tank and my car is a year 2000 S model with about 80000 miles. I replaced the tank myself, it was a bit of a struggle but managed in the end with a fair bit of online help. I also replaced all coolant, fitted a Pieburg water pump, low temp thermostat and a serpentine belt. Do not know what came over me, as not normally one for ott preventative maintenance lol.

[El 3.2S]

Above is a picture showing where my coolant tank leaked from (circled). This failed a couple of years ago and appeared to be the original as fitted to my 80,000 mile year 2000 S model. I changed the tank myself. It was fairly tricky but I managed it with various bits of online help, advice and videos. Whilst "in there" I also fitted a low temp thermostat, completely changed the coolant, fitted a Pierburg water pump and new serpentine belt. Not sure what came over me with all that extra, not strictly necessary, preventatitive maintenance lol

Below is a picture of how the bottom of my boot looked. The carpets were fine but I often was aware of a coolant smell when opening the boot. Took me some time to figure out what the problem was.

Oops trouble with the photos.