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You can unplug the ECT electrical connector for test drive but what's the factory default temperature is questionable and I highly doubt it will go above 170 degree and that's not the appropriate way to test it. ECT hardly fail and it has a long lifespan perhaps as long as your vehicle. It's the electrical connector that needs routine (perhaps every 5 years) cleaning when you see corrosion build up. That's why I mentioned just cleaning the electrical connector of it, also check for any damage to the wire and the connector.
Check the cooling system diagnosis procedures above to see if you have a bad tstat. If the procedures are not so visible just save it and enlarge it it's just a jpg file. Even if you have a bidirectional scanner, unfortunately, tstat is a component you can't use your scanner to operate its opening/closing on demand. Additionally you can tell if your heater works or not hot or it takes long time, that's also a good sign of stuck open tstat. You can also check for operation of your radiator fan. Just drive a bit longer and monitor the ECT and see if it maxes out at 170 still.
If your tstat is determined to be bad just buy a new one, but don't blindly grab any, there are quite a few, some with lower opening temperatures those are for racing cars, you want OE temperature around 195 degree, especially in Colorado. If you live in Arizona you probably can go a bit lower around 185.
Find below "Water_Pump-Service-Repair.pdf". When you change water pump it's highly urged to change the tstat together, when you change just the tstat it's not necessary to change the water pump. But since you mentioned you haven't changed both of them for a while it's recommended that you change them both plus the water outlet as well. Check rockauto pretty cheap.
You can unplug the ECT electrical connector for test drive but what's the factory default temperature is questionable and I highly doubt it will go above 170 degree and that's not the appropriate way to test it. ECT hardly fail and it has a long lifespan perhaps as long as your vehicle. It's the electrical connector that needs routine (perhaps every 5 years) cleaning when you see corrosion build up. That's why I mentioned just cleaning the electrical connector of it, also check for any damage to the wire and the connector.
Check the cooling system diagnosis procedures above to see if you have a bad tstat. If the procedures are not so visible just save it and enlarge it it's just a jpg file. Even if you have a bidirectional scanner, unfortunately, tstat is a component you can't use your scanner to operate its opening/closing on demand. Additionally you can tell if your heater works or not hot or it takes long time, that's also a good sign of stuck open tstat. You can also check for operation of your radiator fan. Just drive a bit longer and monitor the ECT and see if it maxes out at 170 still.
If your tstat is determined to be bad just buy a new one, but don't blindly grab any, there are quite a few, some with lower opening temperatures those are for racing cars, you want OE temperature around 195 degree, especially in Colorado. If you live in Arizona you probably can go a bit lower around 185.
Find below "Water_Pump-Service-Repair.pdf". When you change water pump it's highly urged to change the tstat together, when you change just the tstat it's not necessary to change the water pump. But since you mentioned you haven't changed both of them for a while it's recommended that you change them both plus the water outlet as well. Check rockauto pretty cheap.
I was a little premature in my report I guess. I saw 170 in idling in the driveway, and it was about 15 degF out. But I just took it for a drive around the block to make sure it was warmed up, and it did indeed get to 190. It varied between 190 and 198 which I'm sure is expected given the mechanical nature of the tstat. Bummer, that would have been an easy fix.
If you can see 198 degree and your heater is working properly then it's time to move on and forget replacing any part that's not broken. Check the MAF if you get a chance. And lastly never forget to run a proper fuel pressure check.
Engine off key out then unplug the electrical connector of your MAF (not MAP which your van doesn't have), then start it up and get a CEL (ignore it) and get rough idling (ignore it) and drive uphill again. If this helps then you either have a bad MAF or bad wiring that needs cleaning or repairing. It's fine to drive without MAF for diagnostic purposes since the factory default air-fuel ratio will be used when your ECU can't locate the present of your sensor. When the test is done just plug the connector back in then the CEL will go away. This test takes just a few minutes to complete.
Another easy test is to remove the ECT (Engine Coolant Temperature) sensor (for ECU, not for cluster), remove just the electrical connector, then clean using electrical contact cleaner or 91% isopropyl alcohol. And of course you can also use a scanner to verify for proper temperature.
I finally got around to the test drive with the MAF disconnected. I did not notice any difference.
If MAF appears to be good there are many other possibilities still. You should check the easiest test first like vacuum-Test.pdf below then jump to the one that has higher chance, namely the fuel system.
If MAF appears to be good there are many other possibilities still. You should check the easiest test first like vacuum-Test.pdf below then jump to the one that has higher chance, namely the fuel system.
Wow, thanks for all of this! I really do appreciate it. I'm heading out-of-country in 2 days, I'll be away for a month, so I won't get to any of this until March. I'll report back once I start looking into this. Talk to you then!
