I shared in February that I was watching what I suspected to be an oil migration problem. I was finding a sludge in my coolant reservoir. It was not obviously oil, but it certainly was something that didn’t belong there! My primary suspicion was that one or more of the gaskets between the oil cooler, accessory bracket, and engine block had split. My mechanic is very pragmatic and wasn’t convinced that I was seeing oil in the coolant reservoir. You see, oil leaking into the coolant often results in a frothy mess in the reservoir. My leak was slow enough to question what was really happening, perhaps just a few drops per day, and it didn’t present as a froth. I decided to monitor the coolant while I awaited a report from Blackstone Labs.
Oddly enough, the coolant that I flushed from my engine was clean because the sludge in the reservoir floated to the top and then was not sucked back into the engine so long as I removed it periodically. The reservoir was behaving as an oil separator for the cooling system. I managed to tolerate scooping sludge from the reservoir from time to time for about 10,000 miles before I felt compelled to flush the system again. Even then, the coolant itself was clean; only the reservoir was a mess. I even used the old coolant from 10,000 miles ago to reflush the engine. Replacing the reservoir with an aftermarket unit was about $20 and far more convenient than trying to clean out the old double-walled reservoir. I continued to watch the situation and planned for when I’d have enough of a leak to justify the expense of replacing the gaskets. Then a new problem arose.
I’ve had a minor air conditioner issue for years. I think I first noticed hints of a problem in 2019. The AC worked, but would seem to stop blowing after about an hour of driving. I eventually concluded that the system was freezing when I discovered that turning off the compressor for about 10 minutes seemed to restore proper airflow. This behavior can happen if the refrigerant is low. My mechanic removed the refrigerant to weigh it, said everything was normal, and then put it back. Ironically, my freeze-over issue disappeared for about two years. In 2023, the AC’s performance became poor enough that I suspected a leak. So, I had the system recharged and UV dye added.
Unable to find evidence of a UV dye leak after a few weeks, my mechanic and I agreed that there may be a leak in the evaporator behind the dash. Given the great expense of replacing the evaporator and high likelihood of new dash rattles afterwards, not to mention all of the additional wiring that my radio equipment has throughout the dash, I decided that I could recharge the AC system every year until the car dies for less than the cost of replacing the evaporator! 😀 Yes, it’s both expensive and time-consuming to do this job!
New oil cooler…
Coincidentally, I continued to search for oil leaks in the vicinity of the oil cooler. It’s impossible to see the oil cooler flange directly, but I looked for signs of oil leaks nearby. There was a suspicious drip near the compressor and accessory bracket, never enough to drip on my driveway, but enough to be seen from under the car. The drip was neither light brown like fresh oil nor thick black like contaminated oil. Instead, it was light gray and had the consistency of light penetrating oil. As I continued to clean and monitor, I noticed that it was becoming time for another AC recharge. The previous charge lasted two years, which wasn’t too bad!
I shared my discovery about the gray oil with my mechanic and asked if the compressor has its own sealed lubricant source. He agreed that I may have compressor leak and inspected the area with a UV light. Sure enough, there was an invisible splatter all over the engine bay. Apparently, the 2-3 week inspection that we did in 2023 was too soon to detect a leak. Now, it was clearly time to replace the AC compressor! It wasn’t difficult to convince him to replace the oil cooler and associated gaskets during the job since it’s “only a few more bolts” with the alternator and compressor already removed. Doing the work now probably saved me some money in the long run.
Once the accessory bracket was out, it was clear that I had a gasket failure. Photos like this one show a split in one opening and evidence that other areas of gasket were compressed enough to eventually leak. I’ve shared more photos of the gaskets, new oil cooler, and new AC compressor in an album below. The job was expensive since I didn’t do it myself, but worth the price for the fast turnaround, restored comfort, and overall peace of mind. The AC blows cold enough to freeze my face off! I had forgotten that I prefer to have the vents pointed away from me since the airflow can be uncomfortably cold. Still, the overall temperature in the cabin is great! It will be much-appreciated as the temperatures exceed 90°F this weekend. For what I paid, the new compressor clearly is not a genuine VW part. Instead, it’s by Sanden and made in the USA. Genuine or not, I’ll take the savings if the air blows cold for another eight years!
Frost-bitten,
Scott
