New Thermostat advice

OK, my 2004 BEW is showing 173f degrees on my Scangauge. I've checked with the dealer about a new stat - they want over $50. Not gonna do that. So I've located a couple of stats with the 87c/188f OE temp rating. However, there is a standard stat and a high-flow stat. I've never seen that designation before. Can anyone explain why one is better than the other?

Buy the VW thermostat as well as the VW housing for it. You WILL break the tabs on the old housing and there is a good chance an 'OEM' thermostat will be bad out of the box. In my experience, even simple parts like these differ based on brands even though they are OE spec. I ran an 'OEM' thermostat in my 1981 1.6TD Rabbit and the temp would be all over the place. I switched to the VW thermostat and it warms up and keeps a rock solid temp.

When you break down ~$50 over 100,000 miles of use... that's pretty cheap and I don't have to think about it for a good chunk of time and mileage.

To answer your question: "High-flow" thermostats allow a small amount of coolant to circulate before fully opening, thus supposedly allowing the engine to warm up quicker. The old hack to this is drilling two small holes in the thermostat unit... aka: high-flow.

There are a couple of high-temp thermostats available for our ALH's. Mine is out of a 1.8T gasser a MK2 IIRC. It is rated at 192*F and I commonly have temps of 194-196F even when on the highway.

My thought initially was that 173f may not be considered full operating temp in VW standards. So, it may affect the MPG to a degree. My other VW's were spot on at 190f and would only vary by a degree once in a while. If the non-VW stats are unreliable then the choice is pretty clear.

Thanks for the thoughts guys!

ffemtp said:

My thought initially was that 173f may not be considered full operating temp in VW standards. So, it may affect the MPG to a degree. My other VW's were spot on at 190f and would only vary by a degree once in a while. If the non-VW stats are unreliable then the choice is pretty clear.

Thanks for the thoughts guys!

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You're exactly right. The ECU likes to see the car up to 190 or it will adjust fueling to keep trying to warm things up. If you do some digging there are folks that have experiented with higher temp thermostats as well as running 'waterless coolants' to try and get the operating temp up and increase efficiency. From what I've read, though, the ECU will try to make adjustments when you are outside of that 'full operating temp' range, regardless if it's high or low.

I put one of the aftermarket stats in the car, it never was right. Yes, it's expensive from the stealer (or one of the trusted places) but put the OE in there. This is one of the places on these cars that I've had experience with in both directions and wound up doing the job again.

The other problem with doing it twice is you get to buy coolant twice because there is no "low block" drain on these cars, so when you pull the stat you WILL dump a fair bit of coolant on the ground -- no way around it.

Once again, thanks for everyone's input. I picked up a stat and gasket from the stealer yesterday. Also grabbed a gallon of G13 concentrate. Going to do the job in a day or so. As a tip to anyone buying stuff from a stealer, many will give you a discount if you mention "VW enthusiast pricing".

I really appreciate the guidance and other personal experience shared here.

Good work, always ask the dealers to reduce their price.
I don't know if the 2004 housing is different than the VE motor, did you read Post #2?

I asked the parts guy about that at the stealership. He said they don't usually change the housing. He actually talked me OUT of buying the housing. He was actually honest about it, and was a mechanic himself. He said it won't be needed, even with the clips being broken. I watched a YouTube vid on this. The guy in vid said it wasn't needed either. So, no new housing. Anyone feel strongly about this, please jump in...

ffemtp said:

I asked the parts guy about that at the stealership. He said they don't usually change the housing. He actually talked me OUT of buying the housing. He was actually honest about it, and was a mechanic himself. He said it won't be needed, even with the clips being broken. I watched a YouTube vid on this. The guy in vid said it wasn't needed either. So, no new housing. Anyone feel strongly about this, please jump in...

Click to expand...

One could argue you don't need the housing. On the ALH it's helpful to have the tabs in place as it holds the thermostat in the right spot when seating it on the head. I think on the BEW you might be able to fit it in there better as there isn't an IP blocking your view.

Conversely, I have seen plastic housings start to weep over time, regardless of using a new o-ring. For me, adding in a new housing to the job is worth the added cost so I don't have to touch it again until the thermostat starts to die. I put in my thermostat 102,000 miles ago and it's still going strong with no leaks.

Don't overtorque the flange and it'll probably be fine. Frankly, the housing is so darn cheap that I'm not sure it's worth not replacing it, but then again the tabs don't really make that much of a difference; I've never had trouble getting the thermostat correctly placed.

Good tip, thanks.

You can always return the part if not needed. I have the same issue on the car where 173 -181 is what it gets. I even took the thermostat off along with 2 others and put in water and brought to a boil with a thermometer in there. All opened the same and correctly. There is always circulation in the heater core and oil cooler and the thermostat is in a different spot then the sensor. Honestly not going to lose sleep over mine as I get 46-47 mpg every tank.

And with the housing. Even the bew the clips are needed and almost impossible not to break with the mount for the alt, ac, power steering in the way. If you twist just right (3rd time for me) you can do it without breaking the tabs.

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