Temperature gauge acting strange

[twingles]

My temp gauge has always read at the half way mark once it reaches operating temp and never fluctuates. Last week I noticed it was reaching the halfway mark & the heat took along time to get to normal(it has been alot colder so that might be part of it). We had the thermostat changed and while we have normal heat the gauge fluctuates, not past the halfway mark but it drops down when slowing down or driving at 45 & below. The week before this started we had the gas gauge fluctuating. We are thinking maybe a problem with the instrument cluster, how would we check that? If you are idling or going slow & the heat is on it will drop down to cooler, turn the heater off & the temp gauge will go to normal. There has been no coolant loss.

This is a 2001 Windstar with 74,500 miles.

[MT-2500]

Originally Posted by twingles

My temp gauge has always read at the half way mark once it reaches operating temp and never fluctuates. Last week I noticed it was reaching the halfway mark & the heat took along time to get to normal(it has been alot colder so that might be part of it). We had the thermostat changed and while we have normal heat the gauge fluctuates, not past the halfway mark but it drops down when slowing down or driving at 45 & below. The week before this started we had the gas gauge fluctuating. We are thinking maybe a problem with the instrument cluster, how would we check that? If you are idling or going slow & the heat is on it will drop down to cooler, turn the heater off & the temp gauge will go to normal. There has been no coolant loss.

This is a 2001 Windstar with 74,500 miles.

First check the coolant level in rad.
Check the actual running tempt of engine.
Could be a air lock or bad new thermo.

[twingles]

We have no idea how to check the level in the radiator. We can not find a cap anywhere except on the reservoir which is pressurized. Wouldn't air in the system work itself out? I guess probably not since its pressurized, I have no idea about any of this.

[MT-2500]

Originally Posted by twingles

We have no idea how to check the level in the radiator. We can not find a cap anywhere except on the reservoir which is pressurized. Wouldn't air in the system work itself out? I guess probably not since its pressurized, I have no idea about any of this.

I would suggest you find a repair shop that can test things out.
You may have a bad new thermo or a engine air lock or just a bad tempt gauge.
But if you are losing heater heat it does not sound good.
Let us know how it goes.

[twingles]

We aren't losing heater heat anymore, just the gauge drops down when the heat is on. What is an air lock? The hard part is we have had it to the shop & of course it works fine when they have it.

What can it be if you are losing heater heat? I would like some idea of what to have them check. Thanks!

[MT-2500]

Originally Posted by twingles

We aren't losing heater heat anymore, just the gauge drops down when the heat is on. What is an air lock? The hard part is we have had it to the shop & of course it works fine when they have it.

What can it be if you are losing heater heat? I would like some idea of what to have them check. Thanks!

Ask them to check the engine running tempt on a scanner, Also heater operation and tempture gauge operation.
Also remember that when the heater control defrost is on it triggers you engine cooling fan to run all time.
Find a good repair shop and tell them what it is doing.
Tips on finding a good repair shop.
Check around Ask around
Word of mouth.
Family friends coworkers neighbors business people and delivery people.
Mailmen and parcel delivery people get around and notice a lot of stuff.
Even a good parts house knows what shops are good and not good.
Chamber of commerce and better business bureau and city hall.
If you find a good referral to a repair shop go look them over and talk to them.
Look for a clean looking busy place with nice people running it.
Ask a few questions and ask about their qualifications and training.
Not all places have trained tech/mechanics.
If they do not find a place that does.
Even all dealers do not have all trained techs/mechanics.