Is my thermostat stuck open?

[Greg_B]

I have noticed that for a long time my engine temps never get above 170. I thought it was just my gauge. I have the stock gauge and the 89 mustang sender... but this morning I drove it to work... it never got above 170 in 16 miles. I got here I took one of those infared heat gun and check the temp at the thermostat housing and it read only 142.

I dont know what themostat the 89 stang came with but it is the original...

I guess changing it out is simple enough but what temp thermostat should I go with?

**Actually it is a 93 stang engine with an 89 harness.... not that it makes any difference here...

Greg

 

[Skiddy]

on an EFI 195* thermostat

 

[Explorer]

For what it's worth, I'm running a 195* in my Bronco and my son's 66 Mustang, both 200ci I6. Neither one really comes up to temp in the winter. I just changed the one in the Mustang this weekend trying to get him some more heat.

 

[Socal Tom]

Either the thermostat is stuck open, or the heater is on ( or bypassed with no valve)
Tom

 

[Explorer]

That was what I thought too. Problem is, Bronco has aluminum radiator, aftermarket gauge and control valve, all new. Mustang has original radiator, does not use a heater valve and stock gauge. Both run too cool for my liking.

 

[Greg_B]

I am running the stock Bronco radiator with NO fan shroud... I have the 17" flex fan... no clutch. I have a new heater valve and it is closed. I can squezze the top hose and it seems to have no pressure on it.

If changing the thermostat doesnt help I may try an electric fan.

One of the guys here at work asked me why I wanted it to be hotter, he thought it was a good thing. besides actually having heat in the cab I thought the engine was designed to be more efficient at a higher temp... Isnt this true?

Greg

 

[Explorer]

No shroud on either of mine. Yes, I would like to get the temp up to 180* at least. Both always run good temps in the summer, never overheating. Heat is fine in the Bronco since I realized I had put the heater hoses on backwards! Still lost on the Mustang heat. If you get it figured out let me know. I've tried everything but blocking the air flow. Good luck.

 

[Bartonatl]

A warm engine does run better. I went with an electric fan with a 195 degree thermocouple. The fan will not come on until it gets hot. As soon as the fan comes on, the temp. stabilizes right at 200.

 

[73azbronco]

wait, you are saying an engine in a Bronco is "too" cool?

 

[Greg_B]

wait, you are saying an engine in a Bronco is "too" cool?

Exactly...

I did a little research... the taurus fan is in the 1990 to 1995 years and is also in the same years for the Sable and the Continental. Rock Auto.com has the Dorman brand replacement for $95.00 and the Motorcraft replacement for $331.00.

I am going to drive to the junk yard at lunch and see what I can find. What do these use for a sending unit? Do I need some kind of thermocouple or the other items from the car to make it work?

Greg


*** Little more research... seems to be conflicting posts on here on whether ther Taurus fan will fit with a Mustang serp setup or not. I do not want ot cut my core support. Anyone know for sure?

 

[Viperwolf1]

Thermostat is bad if temp only gets up to 140. Mustang sender is probably not correct either.

 

[Skiddy]

Exactly...

I did a little research... the taurus fan is in the 1990 to 1995 years and is also in the same years for the Sable and the Continental. Rock Auto.com has the Dorman brand replacement for $95.00 and the Motorcraft replacement for $331.00.

I am going to drive to the junk yard at lunch and see what I can find. What do these use for a sending unit? Do I need some kind of thermocouple or the other items from the car to make it work?

Greg


*** Little more research... seems to be conflicting posts on here on whether ther Taurus fan will fit with a Mustang serp setup or not. I do not want ot cut my core support. Anyone know for sure?

i had to cut mine for the fan

 

[Greg_B]

Viper... I drove it up to the autoparts store a few minutes ago and got a new T-stat. When I got back the highest the temp got on the gauge was a little over 170... I got out with the engine still running, popped the hood and used the infarerd gun on the T-Stat cover area... it read 164.

G

 

[Greg_B]

i had to cut mine for the fan

So you have the same setup I have? Mustang serp and stock radiator?

G

 

[Explorer]

I've got a spare mechanical gauge I'll throw on the Mustang. Bronco runs about 160* when cruising, but location of my sender may have a lot to do with it. It's in the thermostat housing and is measuring temp of coolant entering engine. It doesn't register till thermostat opens. Forgot about that.

 

[jw0747]

your thermostat is stuck wide open. change it to bring operating temp up to where you get max. performance from your engine and add a metal shroud and you won't need an electric fan.

 

[broncnaz]

I've got a spare mechanical gauge I'll throw on the Mustang. Bronco runs about 160* when cruising, but location of my sender may have a lot to do with it. It's in the thermostat housing and is measuring temp of coolant entering engine. It doesn't register till thermostat opens. Forgot about that.

water doesnt enter the engine from the t stat housing. It enters through the water pump inlet.

I had similar not getting warm enough issues a couple of years ago. in my case I pulled the T stat it was a high flow one and found that it wasnt closing all the way. When I testerd it it seemed to open very fast so I think it was staying fully open at way below its rating. Swapped it out for a new regular flow t stat and temps came up to where they should have been. Sometime T stats will just open and stay open so the engine doesnt build heat. The T stat is supposed to maintain the engines heat to about what the t stat is rated for so if your engine is not getting up to the temp rating on the t stat the the t stat is not functioning properly. Now in the winter you can have issues with the engine not reaching the t stat temp when its really cold out and you have the heater on.

 

[Skiddy]

So you have the same setup I have? Mustang serp and stock radiator?

G

Yes i have the same setup

 

[Greg_B]

ok thanks... I was hoping to be able to use the Taurus fan without mods.

Cooling issues or not I am not thrilled with my setup. The fan is way too close to the radiator. I run one of those wire radiator guards hoping it will help keep the fan out of the radiator. I may have a little over 1/2" gap. The wire guard also makes a whining noise as air rushes around it... sounds kind of like it is super charged.. but it gets on my nerves.

I may have to break down and find an Explorer setup to get more room. Not sure even where to start looking for that or exactly what I would need.

Greg

 

[jw0747]

those wire fan protectors are junk and if your fan is too close to it your first good motor/frame flex will cause your fan to hook it and it'll destroy your radiator. ask me how I know...