Regardless of the temperature gage working, I would change the T-stat. If you are going to start towing with it and it has that many miles, you shurely would not want it to fail in the closed position while you were out and about. Also, as previously discussed, running cold can kill the gas mileage. The big thing to be concerned about if you are going to tow is keeping the tranny cool. If it does not have a separate tranny cooler and you are going to be pulling a good sized trailer any distance, you are going to need one. I pull a 6,000 lb trailer with mine and I have two tranny coolers.

 

Thermostats are SUPPOSED to fail in the open position; however, some, failing closed, have started to appear.

 

There is a radiator cap available that has a built in gauge, install one and see if the temp differs from the dash gauge

 

Stant? Who? Either way, the t-stat needs to be pulled and inspected.


BTW - to the original poster, if you do have a t-stat present, drop it into a pot of boiling water (assuming the t-stat is in the closed position) and see how far it opens.

Seriously, I think you have a t-stat that failed open.

 

You are right VW, they are supposed to fail open, but I can personally vouch that they will fail in the closed.

 

Yes, and that is ****-poor design. My dad was an automotive design engineer for many years, and has been into cars longer than anyone on this board (he's 84). He told me that he's seen, in the last 15 years, t-stats failing in the closed position, and he cusses out the engineers and bean-counters who put those turds on the market.

 

JC Whitney has one at this link. Another way to crosscheck your dash gauge is to use a ob2 interface and software. It will give you real time readings on your water temp, oxigen sensors, manifold pressure, fuel pressure, etc, but if your sending unit is out of wack, it will still read wrong. The cap is only $20.00. I do'nt have alot of faith in the accuracy of dash gauges. If you do'nt want to spend the 20 and want to check when your thermostat opens, pull it out, stick it in a pan of water, place it on the stove and heat the water. Insert a pocket thermometer in the water. As the water heats check to see at what temp the stat opens. ( calibrate the pocket therm in a stirofoam cup full of crushed ice water for about 5 minutes, keep tip in center of cup, 32* F) This is as accurate as it gets.

http://www.jcwhitney.com/autoparts/P...001468/c-10614

 

If you open up the t-stat housing and there isn't, one put in a new one.
If there is one, I'd still replace it while you are there and since it sits a lot there is a good chance it's sticking.
If the gauge bounces around occassionally when stopping and turning, then the coolant is low and the sensor is not always in coolant to read. Not sure about ours but haveworked onother vehicles with the sensor on the top of housing/jacket and would jump when splashed and read low other times.
If it still reads low, either replace the sensor or put a temp gauge on the tap and see if they are close. Quick check. The gauges are cheap and most gearheads have atleast one laying around from a past project.

 

So I'm looking for a 16 psi cap with temp guage? Advance Auto only had 13 psi caps.

 

# 11331 is the 16 psi cap you need from advance auto.