Thermostat Questions

M

Mafia Mustang

Member
Sep 17, 2006
111
0
17
Arizona
#1
Hey Guys I have a 90 5.0 and after a 20 -25 min drive the gauge says its getting really warm like it goes above the N on the normal gauges So I have a few questions
It's not bubbling out of the over flow or anything I'm kinda nervous to let it get all the way overheaded .
I let it get pretty warm and the lower radiator hose came off I don't know it it just wasn't tight or if it could build enough pressure to come off.
I live in Phoenix Arizona and It gets hot as hell here whats a good thermostat to get if that is indeed my culprit?
What Do Most 5.0's set as temp wise once they have reached operating temp?

Thanks guys
 
#2
your stock thermostat should be 195 degrees. Any stock replacement should work fine for you. You could always go to a 180 stat to help it run a bit cooler. You may also want to check that your clutch fan is working properly. If you're changing the stat, do yourself a favor and grab a new radiator cap at the same time.
 
#3
Go with a Stant....stock temp range is 195. If you are gonna go with a cooler stat, go with a 180* but i would personally stay with the stock temp as running a cooler temp tstat isn't really the best way to band-aid a major cooling issue.

However, i'd look at other issues as well before replacing the t-stat. COuld be a faulty radiator cap, or a bad fan clutch or combination of things. Is the coolant fresh? IS it a 50/50 mix? or perhaps 75% distilled water/25% coolant?

Finally, what's the condition of the radiator?
 
#4
Ya fresh coolant and a new Waterpump It's a performance engine I built I replaced all that stuff during the build .. pretty new 3 core radiator new hoses I even replaced the T stat but the car sat for a little but after the build so I'm starting small.
 
#6
The stock temp gauge is highly innaccurate, but if the temp is shooting up that high to popa hose off, then it prob has something grossly wrong.

A tstat is a good start, i'd also consider a new rad cap
 
#9
I've seen them run for a little while spinning the wrong way. Last car I seen like that would run about 10 mins before it was overheated. I believe yes ccw is correct w/ out looking at the car ( it's too damn cold outside)
 
#10
Counter-clockwise is the correct rotation for the water pump. I am also having some puzzling cooling problems except I do not overheat, I have a 180*, new aluminum 2-core radiator, new cap (w/ pressure release), New hoses, New Water Pump, Autometer Electric Temp Gauge, Cobra Water Pump Pulley, and 15" Electric Fan (That constantly runs) and my gauge shows that I'm running 210*-220*, but it takes a good 10-12 miles on the highway to reach that temp before stopping, then going up to 220*-230* very very slowly. Even slower than it takes to get to 210*. I don't want to push it to see if it eventually stops somewhere since I have aluminum heads and 210* is already as hot as it should be. I have a 180* tstat but it doesn't hold at 180* . I do have a/c but don't use it. The fan is pulling decent air since I can stick a terry cloth in front of the a/c condenser and it sucks the cloth to it pretty good, but there is also about 3" between the radiator and condenser. I have an external tranny cooler attached to the front of the condenser too at the bottom. It's in the low to mid 60s here in Texas now and this has been an on going issue since October. I also have an underdrive crank pulley, this is the only underdrive pulley. I'm swapping that back to stock tomorrow.
 
#13
That could be the reason...common for temp to climb on highway when the lower air dam is removed.

Does it drop if you get off the highway and come to a stop and idle in place?
 
#14
Mustang5L5 said:
Go with a Stant....stock temp range is 195. If you are gonna go with a cooler stat, go with a 180* but i would personally stay with the stock temp as running a cooler temp tstat isn't really the best way to band-aid a major cooling issue.
Click to expand...
what he said, if your cooling system is working right a 195 is perfect. I live in phoenix too, have 195 stat, stock radiator and waterpump.
 
#15
What baffles me is in the morning it takes a good 10-15 miles to get up to 200*, but the weather is in the low to mid 50s and the car runs right about 180*. If I went longer it would probably still go up to 200* and more. In the Afternoon when I go home going the same distance and speed the temp takes like 5-6 minutes to reach 180* and will slowly go past 200* to around 220* in high 60s low 70s weather. If I sit at idle it will go down in the morning slowly a bit and in the afternoon it just stops going up if I'm idling. Should I keep the 180* or go with something cooler like a 160* (summers are in the high 90s low 100s here) or a 192(5)*?

Also...could my thermostat be stuck open? I do know that this thermostat has a bypass hole in it that's very small.

Morning:
IMG_0106.webp


Afternoon:
IMG_0110.webp


You are probably thinking why am I worried? I'm worried because if I go farther it will possibly overheat and also it should run cooler.
 
#17
It rises when Im on the highway but stays put when I get off and sit at a light and sometimes it will drop down a hair. I can sit idle all day and it won't overheat or get too hot
 
#18
160s = bad. Provided your cooling system is up to snuff (and it sounds like it isn't), your car temp would hover BELOW the tempurature required to put your EEC into closed loop. Another potential problem is that oil may not be thorooughly heated to operating tempurature keeping it from catlyzing (read: sludge).

180 is as low as you should be going on a street car.

Something else that comes to mind is that switching to a lower t-stat is not going to gain you anything. If your cooling system is not able to remove the necessary heat from your motor at 180* then it's going to be even LESS efficient at removing heat at 160*.

If you're getting rising temps at cruise and cooler temp at a stop then you're not getting the necessary air through your radiator. It's pretty much that simple. The low air pressure area of your engine bay should be behind and below your radiator. That's what that little air dam is for. The high pressure area should be infront of and either above or below or both, from your radiator.

I see from your avatar that you have a hood with a scoop on it. For sh*** and grins, try plugging that hole and go fro a cruise. If that is an active air vent then you're putting positive air pressure inside of your engine bay and probably equalizing the air pressure from the rear of your radiator with the air infront of it. I'll bet a nickle that just plugging that hole will make a difference. A more permanent fix would be to put a decently sized airdam underneath and just forward of your radiator mount.

Give it a try.
 
#19
DontGivaRatz said:
160s = bad. Provided your cooling system is up to snuff (and it sounds like it isn't), your car temp would hover BELOW the tempurature required to put your EEC into closed loop. Another potential problem is that oil may not be thorooughly heated to operating tempurature keeping it from catlyzing (read: sludge).

180 is as low as you should be going on a street car.

Something else that comes to mind is that switching to a lower t-stat is not going to gain you anything. If your cooling system is not able to remove the necessary heat from your motor at 180* then it's going to be even LESS efficient at removing heat at 160*.

If you're getting rising temps at cruise and cooler temp at a stop then you're not getting the necessary air through your radiator. It's pretty much that simple. The low air pressure area of your engine bay should be behind and below your radiator. That's what that little air dam is for. The high pressure area should be infront of and either above or below or both, from your radiator.

I see from your avatar that you have a hood with a scoop on it. For sh*** and grins, try plugging that hole and go fro a cruise. If that is an active air vent then you're putting positive air pressure inside of your engine bay and probably equalizing the air pressure from the rear of your radiator with the air infront of it. I'll bet a nickle that just plugging that hole will make a difference. A more permanent fix would be to put a decently sized airdam underneath and just forward of your radiator mount.

Give it a try.
Click to expand...

Quite possibly the best way someone has analyzed my problem thus far. I've been searching for the problem for a loooong looong time now (October 09). I did however get a 180* T-Stat. Do you recommend me going to a 195*? I plan on buying the air dam for under the radiator from LRS. Also how would you recommend plugging the hole(s) as I have the Ram Air cut out and the vents from the rear cowl?

EDIT: As soon as my 200A 3G Alternator goes on, I'm installing a Mark VIII Fan :D
 
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