Car is running cold... been through 2 stats. Help?

[JasinC19]

Hey guys,

Looking for some help here. I put an OEM replacement Stant superstat 195 thermostat in my 5.0 and ever since then the temp gauge will *occasionally* reach normal operating temp, then divebomb down to the 2nd mark from the bottom. (which i estimate to be 165f) It will then hold steady for some time.

As the title states, I've replaced the thermostat with another exact replacement, everything is sealed up well, i bled the system according to shop manual, and made sure the spring side of the thermostat was facing firewall.

Can anyone give me some advice?

The Stant t-stats do NOT have a bleed valve, but I've noticed that many other brands do not (including Mr. Gasket which everyone loves)

NOTE: I did pull a code (no SES light on) that said something about the A/C switch output being too high or something. Not sure if this could possibly affect it.

Thanks!
Jason

 

[bmo37]

sure your sending unit is working right or the gauge is accurate. I actually have the opposite problem I run overheating under load or cruise. I would verify temps some other way like an IR heat probe gun. Could use under drive pulleys to slow the water pump hence making it run hotter and not pump as much coolant. Do you run electric fans? Sure you installed the stat the correct way, could open up and get stuck open which would continuously cycle coolant not letting the engine get up to temp.

 

[lxman]

Try getting your radiator cap tested and pressure test your system. You should test your t stat before you put it in to make sure it operates properly.

 

[JasinC19]

Hey bmo,

No, not electric fans yet. Everything relevant is stock.

Before I switched out the oem t-stat (from '93), everything was fine; Temp gauge in the middle of the range with little movement.

I'm starting to think I either got a MASSIVE air bubble in there somewhere or something.

What would be the best way to check the cooling sending unit? Can I do it with a multimeter?

Would a bad cooling sending unit throw a code?

Jason

 

[Kdubslugga]

I would think an air bubble would cause overheating? I dunno could be wrong

 

[JasinC19]

Yeah... I know that's the norm.

But seeing as how I'm not 100% sure why it causes overheating, I am guessing it could cause the opposite as well.

It's seemingly not a very common problem...

The thing is, when the engine cannot reach normal operating temperature, fuel economy is basically crapola. (12-15 mpg)

That's why I've been driving my Civic until I figure this dumb problem out.

 

[Beasty306GT]

I would replace the temp gauge sensor and go from there there pretty cheap at autozone

 

[jka]

If you still have the stock gauge...that may your problem not the t-stat. If you are still using trhe stock gauge... please install an aftermarket temp gauge... because the stock gauges are almost wrong all the time. Your normal temp with a 195 degree t-stat should be 195-210 in the summer and a bit lower than that in fall and winter.

 

[HISSIN50]

Though you're doing a relative comparison with the same gauge, I do agree about using an aftermarket or alternative means of checking the absolute coolant temp. You can interpolate the ECT for free if you have a DMM.

 

[JasinC19]

Though you're doing a relative comparison with the same gauge, I do agree about using an aftermarket or alternative means of checking the absolute coolant temp. You can interpolate the ECT for free if you have a DMM.

Hi can you clarify this? What is the ECT? Cooling Temp?

What is a DMM? Digital Multimeter? If so, is there a writeup for this somewhere?

Thanks,
Jason

 

[Noobz347]

I would think an air bubble would cause overheating? I dunno could be wrong

+1

 

[HISSIN50]

Hi can you clarify this? What is the ECT? Cooling Temp?

What is a DMM? Digital Multimeter? If so, is there a writeup for this somewhere?

Thanks,
Jason

Yes and yes.

With the ECT connected, carefully backprobe the output wire (one wire will read 5 V. You want the other wire).

At 194*F, you should read .61V. At 212*, you should read .47V

 

[88gt373]

check out this post i just did..... same problem with my cooling system and my w/p was running the wrong way...... mine has to run counter clock wise like most......


check here for post

you want the routing like this:

alt-tensioner-a/c-p/s pump-water pump-crank-smog-alt

or if you dont have smog stuff or ac just make sure the w/p is COUNTER CLOCK WISE... MAYBE THAT HELPS.. GOOD LUCK

 

[JasinC19]

Just a quick update guys:

Changed out coolant temp sensor... no luck

Then I changed out coolant temp sending unit and took her for a spin. Gauge works perfectly now.

Thanks for the advice.

 

[Dave2000GT]

Just a quick update guys:

Changed out coolant temp sensor... no luck

Then I changed out coolant temp sending unit and took her for a spin. Gauge works perfectly now.

Thanks for the advice.

Any progress on the low mpg issue ?