Thermostat temps
 

Long story short I live in Arizona and recently changed my thermostat from a 160 to a 180 high flow speedway degree thermostat. I burp the coolant and at idle it's between 180 to 190 degrees. When I drive and stopped at a red light it will jump to 210. I'm thinking I still need to purge the system or is the new 180 thermostat the problem? Or a faulty temperature sending unit? I run dual radiator fans that come on at 180. Before with the 160 degree thermostat it would get up to temperature kinda quick but didn't have a issue at a red light. Any information will be GREATLY appreciated.

Thanks Chris

Re: Thermostat temps
 

Might be the start of a water pump issue. Loose belt? Cavitation?

Have you drilled your thermostat?

Re: Thermostat temps
 

Perhaps the flow rate is the culprit, given that the old thermostat wasn't high flow(?). My truck had issues with heating for decades, until a high flow rate thermostat was installed.

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Ac or no ac?

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The thermostat doesn't regulate temp. It just opens at the stated temp.

Re: Thermostat temps
 

What???

Re: Thermostat temps
 

i too live in phx.

every late model vheicle has around a 200 t hermostat

Post a few pics of your set up.

Its 60 degrees out nealry daily, are you over heating?
what happens when its 118 degrees out?

you might just be having the 'i cant stop looking at the guage' syndrome instead of enjoying the driving experinces..

Re: Thermostat temps
 

The thermostat opens at and above stated temp and closes below stated temp. which (if the rest of your cooling system is up to the task) fully regulates the temp of your engine.

Re: Thermostat temps
 

Why did you change the thermostat temp?
What temp did the truck run at before?
Is the thermostat the only part you changed?
Can you adjust the temp that your fans come on at?
You need to make sure the system is fully purged before trying anything else.

Re: Thermostat temps
 

Yeah i only changed the thermostat. I went from a 160 to a 180 thermostat. Thinking I had a 180 all along I might go back to 160. I thought my thermostat was sticking open or closed cause it got to temp kinda quick thats why i switchedit out. I tried purging the system a couple of times without success but I don't have the right funnel. I drove the truck without a thermostat last week and it didn't overheat stayed between 170 and 180. It just started overheating with the higher 180 thermostat. Didn't have any issues with the 160 in the summer time. Will get hot at a traffic light but goes down when I drive again. Water pump is fairly new. Thanks.

Re: Thermostat temps
 

In all reality 210 isn't that bad, not close to overheating, so not too much to worry about there. I'd still be a little concerned about the temp jump at red lights. Not sure why changing thermostats would change things, unless you got a bum one....which is more and more common these days. What's the condition of the other cooling system components? Where's the temp gauge sending unit plugged in at? Where's the vacuum advance hooked up at? Where's the thermostat for the fans hooked up at? I'd have the fans come on at 170 with a 180 stat. When you refilled the radiator and tried to purge it, did you also fill the engine through the theromstat hole?

Re: Thermostat temps
 

A thermostat will never cause an engine to heat up faster. The thermostat only reacts to coolant temperature. It won't add heat to the coolant

The thermostat should be closed when the coolant is below the rated temperature of the thermostat. The job of a thermostat isn't to keep the engine from overheating, that's the radiators job, the thermostat is there to regulate the coolant flow, so the engine stays in its most efficient temperature range. The thermostat does its best work when it is cold outside.

However because thermostat is not an off on switch it may take 5 or 10 degrees of temperature change to get the thermostat to completely open (or close). So it may be rated for 180 degrees but it could start opening at 175 or 184.

If the thermostat is stuck open it could cause the engine to take longer to reach operating temperature.

As previously stated you may need a high flow thermostat. As inadequate flow may cause the engine to run warm. This would be noticed when driving on the highway in hot weather or when the engine is heavily loaded for extended periods

The rule of thumb for temperature creeping up at idle is caused by not enough cool air flowing through the radiator. Whether that is from blocked fins in the radiator or insufficient draw by the fan or hot air being recycled from under the engine to the front of the radiator. (3rd gen F-bodies suffered from this if the small air dam under the radiator got torn off or removed).

In hot weather being too close to the car in front of you at the traffic light of can cause the engine temperature to rise, if the vehicle in front of you has their exhaust feeding directly into your radiator.

Re: Thermostat temps
 

Franken is just a smart ass going around to post with criticism. Smart remarks every day.

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I stated nothing but a few facts w/o emotion, though I did neglect to say the thermostat closes below the rated temp. I didn't criticize anyone.
Lighten up Frances.

Re: Thermostat temps
 

The OP seems to think that the thermostat has something to do with the temp getting to 210--it doesn't. Once the temp gets above the opening point, the thermostat opens and as long as the temp remains above that point, it has no impact on cooling.

People sometimes think the thermostat keeps the temp at it's rating, which it doesn't and isn't the purpose of the thermostat.

Re: Thermostat temps
 

WTF are you smoking? That is exactly what a thermostat is for. To REGULATE the temperature of the coolant. Get yourself a dictionary and look up the words regulate and thermostat. You apparently don't know the meaning of either.

Re: Thermostat temps
 

With a 180F tstat and the engine is running at 210F, how is the tstat regulating? It's wide open and out of the loop. And of course it allows the engine to reach operating temperature quicker because at less than 180F it's inhibiting the flow of coolant through the radiator until it opens. That's what it is for.

Franken is absolutely correct.

Re: Thermostat temps
 

Seems some of you need to read the bold part again.

Editing to say that if you were to run NO thermostat and the rest of your cooling system was functioning properly, the most likely thing to happen would be it would take longer to reach operating temp and in some cases the engine would never reach operation temp, and in fewer cases running no thermostat can cause overheating due to the speed at which the coolant is flowing through the system, not allowing time for the coolant to cool in the radiator.

Re: Thermostat temps
 

I guess I’m still not clear why you were changing the thermostat. You started you changed it because it was getting to temp quickly. I would think this is a good thing. The engine is going to run most efficient when it is at temp. As long as the engine wasn’t getting too hot I’m not sure what the problem was.

Re: Thermostat temps
 

My temp sending unit is on the intake I have not had a chance to move it to the block so is the temp for the fans. No I didnt top off the engine through the thermostat housing. It seemed like it was stuck open. Since I'm in Arizonai was wondering what temp thermostat should I be running with my fans coming on at 180 degrees?

I running a 160 degree thermostat now and it seemed to fix the issue.
Thanks

Re: Thermostat temps
 

You & Franken are quite wrong. Go ask a mechanic, an engineer or even Google what a thermostat does.

Re: Thermostat temps
 

100% did not fix anything.
our high was 74 degrees yesterday. You should physically be able to remove your fan assembly and sit it in the grgae and go drive your truck all day long. Unless of course you get stuck on grand and have to wait for a train.
There is an issue with your system. The issue could range from the driver thinking its too hot. The temp sensors in the wrong position making it seem to hot. The gauge and or sensor are showing incorrect temps. Or there is a hardware issue such as plugged rad, bad water pump=tstat etc.
It appears you have a basic SBC. Is it stock? Where is the timing set? Fuel injected? Carb? When was it last tuned on a dyno? Distributor recurved?
Unless youre trying to get every HP from the engine and are down to the last race and trying everything possible, a 160 t-stat is doing more harm than good.
If an engine doesn’t get hot, it wont burn off the condensation inside of it. That turns to bad stuff that kills bearings.

It’s yours, you can leave the 160 in it and never look back, or you can find the cause of the issue and correct it now, before its 118 outside.

-fellow zonie

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Ok what would you suggrst?

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If you are getting a moderately correct temps while running at speed, and heating up at idle at a stop light I am inclined to think it is something to do with the fans. You have two fans. Are both running? Is it possible you bumped one of the leads when installing the Tstat. I had a issue with my fans a while back. The connectors do not have a catch tab on them and will wiggle loose but not completely disengage. That will compromise the amperage to the fan. It will slow the fan, eventually overheat and damage. You will eventually start popping fuses. Make sure both fans are running strong. Champion sells replacements at a reasonable price.
The other idea, is the stat in correct orientation, and have you tried switching back to the original just to be sure the new stat is not causing the issue?

Re: Thermostat temps
 

Fans and Radiator are champion brand and are fairly new like 2 years old. I did go back to 160 thermostat and is driving good and not overheating bit am I using the right TempStat? With my fans?

Also will move temp sending unit to block and see what happens but might be after the holidays.

Re: Thermostat temps
 

Temp sending unit was in the driver's side cylinder head from the factory. ;)

Gary

Re: Thermostat temps
 

I agree. It's pretty straightforward. However, this particular t-stat may be sticking before it fully opens. Since it's the only thing that was changed prior to the problem, it needs to be tested in boiling water on the stove. If it doesn't open before the water starts bubbling, then it's not working as a 180 t-stat.

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I agree with that.

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I am a mechanic and engineer. Perhaps if I use Google I'll come across your opinion. :smoke:

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So tell me sir what company do you work for as an engineer. I want to make sure not to buy any of their products. If you don't understand what a thermostat does, I can't trust your engineering ability!

Re: Thermostat temps
 

This!


And as I stated before, your fans need to turn on at least 10 degrees before your t-stat rating.

Re: Thermostat temps
 

Well, that's just a little childish!

And I still don't understand the disagreement. You said the t-stat's job is: "to REGULATE the temperature of the coolant." Others have said that once the coolant temp soars up to 210, there is no regulation happening at all. Both of you are correct!

In the OP's case, I would normally say his cooling system isn't up to the task, but we know it worked OK with another t-stat. And since there were NO other changes, the only conclusions we can draw is the new t-stat is NOT fully opening, or the coolant level is very low.

Let's see, what else?

Is ambient temperature the same before and after the t-stat change?
Was the coolant temp sender or gauge changed?
Any changes to the radiator fan or shroud?

To the OP: When you find the problem, please get back to us.

And to the rest of you: If you don't agree with me, Im gonna take my ball and go home!

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They used the "lighting up a smoke" emoji so you know they are correct and you are dismissed now. :lol::lol:
Dude's so right about this, I bet They've never been wrong in their life. :lol:

Re: Thermostat temps
 

i dont know where you live.

But go get on loop 101 and drive 15 miles one way, tunr around and go back home.

For those not in PHX, loop 101 usually runs about 75 mph constanlty, up to like 95 mph.

a good 15 mile drive will get your engine up to operating temp and at around 75 mph there is no need for any fans to be on.

This will completley stabilize your engine temp. -what does the engine temp gauge read while driving this distance?

This test will tell you hw efficient your system is while driving.
-now be aware, on my v8 s10, i would overheat above 65 mph. What i found out is i had a bubble form under my truck in the engine compartment and no cool air was going through my rad. it was recirculating the air out of the rad under the truck and up into the rad again. If i slowed down, instant cool down to correct 200 temp.. i sped up to 70 itd heat up to 230 quickly.

SO, for your truck, you have to do several tests to figure out what and where your issue is.

Simplest is the freeway test.

Report back and let us know what your temps at speed are. Dont drive 2 miles, go the full at least 15.

When I do test runs, i go from my home i17 bell road up to cave creek and back. Thats almost a good two hour drive there and back, and roughly 30 miles one way.

Re: Thermostat temps
 

It's my water pump slowly going out. Purged the system again today and looked at the hoses really good and see some coolant coming from the seep hole on the water pump leaking onto the lower rad hose. Thanks for all of your suggests and support through this post.i appreciate it

Chris

Re: Thermostat temps
 

In my 67 C20 with 402BBC TH400, I run 3 core radiator, 180 high flow stat, clutch fan, Shroud. I can Drive it a distance 20mi plus, it runs at 185F, sit and idle, will slowly creep up to 195, drive and its right back to 185. but ambient Temps are below 90deg F in Summer past 2 yr. Pleased with the cooling sys. Still have room for 4core, but may not need it, unless I was in TX, AZ. CA. high ambient...

My cooling system is basically OEM... no elec fans, no Alum rad, trans cooler in rad. It works as designed.

Re: Thermostat temps
 

Here are a few things to try: 1) Take the old thermostat and the new one and test them in boiling water with a thermometer. When the water hits 160, the old one should open. When it hits 180, the new one should open. If they both do, then it isn't the thermostat. 2) Check the radiator. I don't know how old it is, but could it be plugged? Usually a plugged radiator will make the vehicle run hot while cruising down the road, but will idle at normal temps. 3) Collapsed hose? Rare, but it happens. Usually the lower hose because it is neglected the most. 4) Last, remove the overflow tube on the radiator and attach a piece of hose. Fill a beer bottle about half way with water and put the hose in the bottle in the water. Start the engine from cold and watch the bottle. You will get a few bursts of bubbles. This is the thermostat opening and closing until the engine get to temp. After that, is should stop. If it does not, you have an engine problem, most likely a blown head gasket and it is allowing gasses to enter the cooling system.

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How I check guages. Can do thermostats as well.

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Conduit nuts fit nice on senders.

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Great idea hanging them, instead of setting them in the pan! Keeps the metal pan bottom out of the loop.