QuestionI own a 2003 VW GTI (65,000 miles) with the 1.8T engine that I have owned for about a year and maintain it exactly according to the manual. About 2 weeks ago I was cruising at about 55 mph with the cruise control on when I heard a beeping sound. I look and see that the temperature warning light is on and the temp gauge is at the top. I pull over straight away and as soon as the car returned to idle, the temperature quickly dropped to normal (within about 15 seconds). The rest of the drive was uneventful. After this, I have been looking at the gauge trying to figure out what's going on. It never happens in stop and go traffic and only seems to happen when cruising in 5th gear (and I'm not climbing any big hills). Now, when I see the gauge go up, I just press the clutch in and coast with the engine idling and the temp drops quickly. I first assumed a sticking thermostat, but then why wouldn't it happen all the time? Could it be an air pocket in the cooling system somewhere? Could it be related to altitude (I live in Santa Fe, and the problem always seems to happen on the stretch of road at the highest altitude -- 7500 feet -- on the way to my home)? The cooling fan is working well; I can hear it come on. The coolant level is fine and the coolant appears clean. I am mystified by this problem and with it being so intermittent, I don't want to spend a fortune on "trial and error" fixes.
AnswerHello James...my best recommendation with the current symptoms is to replace the engine coolant temperature sensor. Unfortunately, at 65,000 miles it is no longer covered under warranty. I appreciate the fact that you are so attentive to the surrounding environment, and can succinctly describe the conditions. If you have a local garage that your service is done at, I would take it to them, and have them retrieve the conditions where this event takes place. Volkswagens store DTC's....(diagnostic trouble codes) for every system. So, have the technicians look for DTC's in the instrument cluster, or driver information display, or whatever they call it there, and I promise you there will be one. It may not be stored in the ECM....(engine control module), but it will be stored in the instrument cluster, at least. How long ago was the coolant flushed, and refilled? I have had several questions lately related to the coolant system, and I don't think people are doing it correctly. The cooling system needs to be drained, and closed. Then the cooling system needs to be evacuated to 1.5, to 2 bar....(ie. 1.5 to 2 atmospheres) of vacuum. Then the cooling system need to rest for 5 to 15 minutes while the vacuum/pressure gauge is monitored, and then, provided no leaks, refilled...WHILE STILL UNDER VACUUM!!!!!!! There are no fittings, or bleeder screws, or other such devices whereby a pocket of air can be released from the cooling system. If you decide to go back to where you have had service done before, ask them what kind of FLUSH, AND REFILL system they use. If there is no mention of vacuum...go someplace else...where they use the vacuum refill system...it is the only one that is proven to work in Volkswagens. I hope this description gives you the information you need to keep your GTI going strong...one of my personal favorite models! Good luck, James.
