Thermostat Wahler or OEM Volkswagen

It has been two weeks since the repair without issues, so I am going to call this one solved. If I was paying for this out of pocket in the future, I would only replace the thermostat and not the pump as that is what was closing and causing the issue.

Spend slightly extra and get a quality OEM Wahler thermostat.

I did the timing belt water pump thing on my MK4 last year, and shortly after the test drive with fresh genuine VW antifreeze and while patting myself on the back for a job well done it occurred to me that I hadn't changed the thermostat. Sure enough a month or so ago when the first of the really cold whether started around here the temp gauge would only get to about halfway to normal during a trip to town and back. I tried the ol' cardboard in the grill routine for a couple of days until I got a chance to change the thermostat and that brought things back to normal.

Got the Wahler on my 2008/2011 and it was identical to the MB part except the area that had the MB logo on the original one was ground out.

I've had the thermostat on my M272 engine replaced by an indy mechanic. OEM was Wahler, looking at the original the the Wahler I got, the only difference was the spot where the MB logo was on the original, it was grounded out by some grinding disk on the replacement one.

My 2007 MKV 2.5 Jetta is still having overheat problems even after changing the tstat to a OEM (Wahler) and the waterpump to one with metal impeller, which works way better than the original.

I've replaced my thermostat with a new wahler one and I have the same problem which is that it openes at around 70°C and cools my engine to almost 50°C, from what I understand the thermostat is mechanical and electronically assisted to open faster/wider

I just replaced the original thermostat at 90,000 miles because at highway speeds it would run slightly cold and took a while to warm up from cold. The new wahler replacement takes just as long and will actually run cold intermittently when not on highway. Occasionally it won’t deviate from center on the highway.

My tstat is wahler. People said that it was better than Mahle. But I found it similarly poor.

After getting mine back together, and filling it back up with coolant, i found the new thermostat from the dealership was stuck wide open and the car wouldn’t get over 110*F.