Thermostat - how do I know if it's an issue?

[King_V]

All,

Well, ok, this may be a somewhat dumb question, but how do I know, if I don't have a gauge on the dash, whether the thermostat is opening at the correct temperature, or opening too early.

I know the computer expects 195 degrees - is there any way I can get the info from the ECU or in some way while driving, so I know if the system's in closed or open loop, or get an absolute number somehow of what the coolant temperature is?

It's too effing cold out and I don't want to swap the thing if I don't have to put the time and effort into it!

Thanks in advance.

[gadget73]

install a temperature guage would be the best way. Next best way is to tap into the ECT wiring with a voltmeter, and monitor it. There is a chart to translate the ECT voltage to temperature at fordfuelinjection.com. Its a lot easier to just install a guage though.

[85crownHPP]

the IR laser thermometers are getting pretty cheap, Ive seen cheap ones at harbor freight for 30ish bucks...

[86GmLsCoupe]

I was wondering the same thing myself since from what I read the sensor could be pretty much dead without setting any code off but you will notice it at the pump. My car's heat will fade out driving on the highway mainly then comes back so from what I was thinking the the thermostat is sticking open at times? Mines original so I'll probably test it but end up just replacing it anyhow and saving the old as a good spare. Gadget's gauge idea is right on track though. I'd just love to get temp, oil, & tach. I could even go for a trans temp and vacuum but those aren't so common.

[Tiggie]

I noticed problems with mine in the winter. The heat would go away on the highway. Installed a temperature gauge and it never moved.

I poped the thermostat housing off and found this:


Change it if you suspect problems. Otherwise you'll have a sludge bomb inside your engine before long.

[1987cp]

What the heck is that in the picture? It doesn't even look like a thermostat!

[Tiggie]

What the heck is that in the picture? It doesn't even look like a thermostat!

LOL, it was a thermostat. In two peices, it obviously wasn't doing much to regulate temperature.

[gadget73]

looks like an OE Ford one that someone broke apart.

Cold engines do get very nasty inside. They don't come up to tempertature and cook off the impurities in the oil, which causes sludge buildup.

[86GmLsCoupe]

I get that crappy water droplet stuff on the cap now and then plus the heat issue. After seeing that picture and with knowing mine is original I'm definitely putting replacing the thermostat on the to-do list.

[Rob Roy]

The thermostat on our Navigator is starting to hang open, during the last week or so I noticed it takes forever to warm up and will actually cool back down if you leave it running. The fuel economy has taken a pretty big hit as well. Guess I have a project for this weekend...

[packman]

I think I might tap into the rear coolant plug and run my old temp guage from there. I know it's not the best place for a temp guage reading, but it's better than nothing.


Packman

[1987cp]

rear coolant plug? If it's a pipe plug, remove it and get a pipe bushing to install the sender!

[King_V]

install a temperature guage would be the best way. Next best way is to tap into the ECT wiring with a voltmeter, and monitor it. There is a chart to translate the ECT voltage to temperature at fordfuelinjection.com. Its a lot easier to just install a guage though.

Ok, so, um, what's the correct way to hook up a gauge? Does the gauge get the info from the ECM, or from some sender already on the engine? Sorta lost here....

[86VickyLX]

Ok, so, um, what's the correct way to hook up a gauge? Does the gauge get the info from the ECM, or from some sender already on the engine? Sorta lost here....

Stick it where the sender with one wire coming out of it was. That's the coolant temp switch. It'll trip the check engine light if the engine overheats. It's on the drivers side of the lower intake. But be warned, coolant will come out of the hole when you remove the switch. So have extra coolant ready.

[gadget73]

yep, replace the idiot light sender with a guage sender. If you're using an electric temperature guage, the sender will look similar. If you're using a mechanical guage, the sender is on a long wire permanantly attached to the guage.

The rear coolant ports also work, but the flow back there is not so great, so the guage responds a bit slow. I used to have one back there, it warmed up slow and cooled off slow.