Engine I think I broke my coolant temp gauge

[AnthonyA1234]

My coolant temp gauge always read perfect in the middle. Ever since I took out the cluster to put LEDs and dusted the cluster my coolant gauge always reads low. It goes up to about the first tick mark and won’t go up anymore no matter how much I drive. I was very gentle cleaning it I don’t know how this could’ve happened. I also changed the ect sender which was already new and that didn’t help. Is there anything I can do or am I screwed?

 

[90sickfox]

You need an infrared thermometer to take readings of how hot your engine actually is. It may have been a bad connection previously at the cluster plug. If you ground the temperature sensor wire to metal on the engine it should peg all the way up.

 

[AnthonyA1234]

Where should I shoot the thermometer?

 

[rednotch]

At the thermostat area intake side.. The stock guages are pretty much idiot lights with levers, they also tend to peg the temp gauge if the keys off and you turn lights on with the poor wiring ford did on them... one it mine sits at 2 bars up to about 210 on an actual gauge before it will go any higher. Only gets that hot after a long drive and parking it to where it heat soaks the coolant when its off like running into a store for a few mins, goes right back to 190-195 when running and driving, still has a clutch fan on it.

 

[Mustang5L5]

Coolant gauge doesn't use the ECT sensor as a reference. There is another small sender on the front driver's side of the lower intake with a single plug on top. That's the sender for the guage.

 

[AnthonyA1234]

Coolant gauge doesn't use the ECT sensor as a reference. There is another small sender on the front driver's side of the lower intake with a single plug on top. That's the sender for the guage.

Yea that’s what I meant sorry for the mixup

 

[AnthonyA1234]

At the thermostat area intake side.. The stock guages are pretty much idiot lights with levers, they also tend to peg the temp gauge if the keys off and you turn lights on with the poor wiring ford did on them... one it mine sits at 2 bars up to about 210 on an actual gauge before it will go any higher. Only gets that hot after a long drive and parking it to where it heat soaks the coolant when its off like running into a store for a few mins, goes right back to 190-195 when running and driving, still has a clutch fan on it.

I know this is old but I haven’t had my car for a while and I was finally able to check the temp of the engine to be able to compare it to my gauge.

It seems like my gauge is accurate, the car is running cool. Yesterday I drove it around a while and the peg made its way up to 1 tick below the middle and when I took the temp it read about 175 so it checked out. Also today I drove it just for a few minutes around the block and when I got back the peg was low at the first tick and the engine was 150.

My car has a sve aluminum radiator and a new fan clutch so that’s probably why it’s running cooler. I would prefer if the car ran at the temp it’s supposed to. Is it possible my thermostat is bad and is staying open too much?

 

[Kid wita 5oh]

Sounds like it's stuck open

 

[Mustang5L5]

So does it somewhat line up with this?

 

[AnthonyA1234]

So does it somewhat line up with this?

Yea pretty much spot on.
That’s a useful picture to have thanks for that btw

 

[Mustang5L5]

Take it with a grain of salt. Those gauges aren't known for being completely accurate, but they get you somewhat in the ballpark.

 

[AnthonyA1234]

Going to be changing the thermostat tomorrow. Any tips or tricks I should know for that install? I read that it can be tricky to keep everything lined up when putting in the Tstat. You guys have any tricks to keep it all together or should I be alright?

 

[keel]

You can use a little RTV to hold the gasket in place on the water neck when you install it.

 

[AnthonyA1234]

You can use a little RTV to hold the gasket in place on the water neck when you install it.

Great, good to know. I don’t have any rtv lying around in the garage but I do have a bottle of 3m super 77 spray adhesive. You guys think a little bit of that on that gasket is ok to use?

 

[keel]

Personally I wouldn't risk doing it that way, but I imagine it would probably be fine.

 

[General karthief]

Great, good to know. I don’t have any rtv lying around in the garage but I do have a bottle of 3m super 77 spray adhesive. You guys think a little bit of that on that gasket is ok to use?

I wouldn't use that type of adhesive, it's more of a permanent glue, RTV blue works very well.

 

[slow84lx]

It's a good idea to put your new thermostat in a pot of water on the stove to verify that it opens and closes correctly before starting that work. I learned this lesson the hard way.

Doing thermostat a second time is no fun.

 

[AnthonyA1234]

I wouldn't use that type of adhesive, it's more of a permanent glue, RTV blue works very well.

Ok, I’ll pick up a bottle of rtv blue tomorrow. Should I just do a little dab of it to stick the gasket to the tstat housing or should I put a thin layer on both sides of the gasket?

 

[slow84lx]

A thin layer on both sides has been more effective for me than other methods.

Permatex used to sell an adhesive / sealer that was perfect for usage on one side of the gasket to hold the stat in place while getting it all back together. Haven't seen this in some years now.

 

[AnthonyA1234]

So I pulled out my thermostat and it’s a 160 degree. That explains why I’m running so cold now that I upgraded my radiator and fan clutch. Now I’m thinking my car might run too hot with this motorcraft 197 thermostat I’m putting in. @General karthief I remember you live in Florida like me, do you run a stock thermostat and does it work for you in this FL heat?