[Chaz1138]

Hey, everyone! I'm having a weird coolant leak in my Bug. (2000, 2.0 GLS, auto) that has seemed to have gotten worse over time.

Last year, I started having my temp light (red thermometer) go off every couple of months or so. Upon checking the reservoir, it would be empty. My mechanic said it was because the quick disconnects for the upper and lower radiator hoses were leaking and he showed me a white substance over the upper disconnect that he said was dried coolant from the leak. Initially, I left it at that because we couldn't find just the disconnects without a hose attached and just kept extra coolant in the car, but I didn't rally have a problem again until this past winter.

Over the Christmas season, I looked for the quick disconnects again and found them being sold separately at a reasonable price. I bought them, had my mechanic install them and my car was good for about two or three weeks. Then the high temp light went off again and the reservoir was indeed empty. I brought it back and he applied pressure to the coolant system and said he could find no leaks. The system functions normally at 15 lbs, pressure and he applied up to 17 lbs. for the test. Now, the temp light goes off every ten days or so, although during the most recent occurrence the reservoir was still half full when the light went off.

Any ideas as to what this might be?

Thanks!

 

[billymade]

Hmm, tough to find coolant leaks can be a challenge; as your mechanic has already done, a coolant pressure test, is the best way to find leaks.

I purchased a test kit from Harbor Freight and seeing how the cooling systems in VWs, have lots of plastic, you WILL use it and continue to have leaks, if you keep your car for a decent length of time. I recommend you get one and do the work yourself. Keep in mind, this is just one source for a kit like this and there are many others available but I own this, it does work, it has the adapter for our VW's.

Radiator Pressure Tester Kit

Pittsburgh® Automotive - Item#63862

https://www.google.com/search?biw=1...sy-ab..3.6.373...0i13k1j35i39k1.0.P2Ki1IHcu7g

So, I had a leak, I could NOT find and had been trying to find the source of the leak, for a long time. I tried the kit for the first time; I pressurized it, found no leaks and got frustrated. Then, I did another cycle of testing; after pressurizing the system a number of time, I FINALLY found the leak, so it may take a number of pressure/release cycles to find it.

Other possibilities; are a head gasket leak or coolant mixing with the transmission fluid, from a failed oil cooler. These can both be checked by looking at the auto trans fluid and inspecting the engine oil. In the case of the engine head gasket; you could try a combustion leak test kit or try a leak down test, to see if things are ok.

Sometimes, taking your car to a shop; for hard to diagnose or intermittent problems, challenge even the pro's. Taking the time to do it yourself; observe the car from a daily use perspective and testing issues, can help find the problem. If this is out of your comfort zone or just don't want to tackle the problem; you might take it to another shop, that is more competent, maybe they can find the issue this time around.

 

[Chaz1138]

Thanks @billymade

I would've gotten back to you sooner, but I never got an e-mail notification about your reply. I'll talk with my mechanic about the clues you've given me, but don't see how it could be a head gasket leak as this same mechanic replaced the valves within the last 18 months.

I have to ask, what is a leak down test? Is that where you put a piece of cardboard under the car?

 

[billymade]

https://mobiloil.com/en/article/car-maintenance/car-maintenance-archive/how-to-do-a-leakdown-test

Anything is possible; when troubleshooting thing, never rule out anything, as a possible problem, this increases your possibility of finding the problem. A process of elimination; is the best way, to work down the list of possibilities, getting the results of methodical testing procedures, confirmed by the correct specifications shown in the service manual. As you eliminate possible problems; eventually, you should find the cause if the leaking, coolant loss issue.