What happens when a thermostat goes bad? - CorvetteForum - Chevrolet Corvette Forum Discussion

Register FAQ Search Today's Posts Mark Forums Read Vendor Directory

C3 General
General C3 Corvette Discussion not covered in Tech Sponsored by
Corvette America

What happens when a thermostat goes bad?

Reply
 
 
 
Thread Tools Search this Thread
Old 08-01-2005, 10:36 PM   #1
BKbroiler
CF Senior Member
Thread Starter
 
BKbroiler's Avatar
 
Member Since: May 2002
Location: Lebanon Township New Jersey
Posts: 3,675
Thanked 36 Times in 33 Posts
Default What happens when a thermostat goes bad?

Can they just open partially? My car, with new radiator, all shrouds and seals in place, and clutch fan that spins half a turn by hand, gets up to 230 or higher. The radiator gets hot all the way across and the lower hose does not collapse. A partially open thermostat might explain this. Right?
BKbroiler is offline   Reply With Quote
Old 08-01-2005, 10:53 PM   #2
MYBAD79
CF Senior Member
St. Jude Donor '05
 
MYBAD79's Avatar
 
Member Since: Oct 2004
Location: Orlando Florida
Posts: 5,194
Thanks: 0
Thanked 0 Times in 0 Posts
Default

No, with a partially open thermostat (that is stuck in it's position) the water in the engine would get very hot (not enough flow), the water in the radiator would have all the time in the world to cool down.
I may be wrong but my guess is that you don't have enough air flow across the radiator.
MYBAD79 is offline   Reply With Quote
Old 08-01-2005, 11:23 PM   #3
rihwoods
CF Senior Member
 
rihwoods's Avatar
 
Member Since: Feb 2005
Posts: 16,098
Thanks: 0
Thanked 3 Times in 3 Posts
Default

Put a new thermostat in.Cheap and easy to do...you have alot invested in the rad..at least you will have eliminated that as an issue...
rihwoods is offline   Reply With Quote
Old 08-02-2005, 12:36 AM   #4
BKbroiler
CF Senior Member
Thread Starter
 
BKbroiler's Avatar
 
Member Since: May 2002
Location: Lebanon Township New Jersey
Posts: 3,675
Thanked 36 Times in 33 Posts
Default

I will change the t-stat. Just wondering if anybody thinks that is really the problem.
BKbroiler is offline   Reply With Quote
Old 08-02-2005, 01:26 AM   #5
71SoCal
CF Senior Member
 
71SoCal's Avatar
 
Member Since: Apr 2005
Location: San Diego CA
Posts: 339
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Quote:
Originally Posted by BKbroiler
I will change the t-stat. Just wondering if anybody thinks that is really the problem.
It's hard to say. If the t-stat is stuck mostly open, then the car will take a long time to warm up. If it's mostly closed, it's more likely to start overheating.

They're cheap. Get a new one and eliminate that question.
71SoCal is offline   Reply With Quote
Old 08-02-2005, 01:28 AM   #6
carbster09
CF Senior Member
 
carbster09's Avatar
 
Member Since: Oct 2002
Location: Hagerstown Md
Posts: 860
Thanks: 0
Thanked 0 Times in 0 Posts
Default Air in the system ..

I have a similar problem. I replaced my water pump and now the car runs at 230! I really did not have a BIG problem before, however in my quest for the perfect cooling system I added a high flow pump. Now I have this issue of it running at 230. I think I have not purged all of the air out. I am going to replace the T-stat and purge it yet again.

carbster
carbster09 is offline   Reply With Quote
Old 08-02-2005, 03:28 AM   #7
rihwoods
CF Senior Member
 
rihwoods's Avatar
 
Member Since: Feb 2005
Posts: 16,098
Thanks: 0
Thanked 3 Times in 3 Posts
Default

In my opinion,no...if your thermostat was restricting flow,you would heat up fast....and overheat above 230...(but put a new one in anyway)..personally,I'd check that fan clutch again...rotate it slowly by hand,and if you feel resistance in one spot and it feels "free" in another,it is toast...I learned the hard way...install a thermo clutch..they operate on underhood temps...
Rich

Edit.... http://www.haydenauto.com/fce2.htm
rihwoods is offline   Reply With Quote
Old 08-02-2005, 04:35 AM   #8
DMONSVETTE
CF Senior Member
 
DMONSVETTE's Avatar
 
Member Since: Mar 2002
Location: On an island surrounded by sharks Hawaii
Posts: 8,571
Thanks: 0
Thanked 1 Time in 1 Post
Default

Pretty sure it's the clutch fan. That is where my problem was about a month ago after replacing the radiator, water pump, t-stat and all hoses. Run the car for awhile then turn it off while someone watches the fan if it continues to spin for 3 or more rotations the clutch is out.
I was able to hold my fan with my hand to keep it from spinning.
Put on a flex fan and spacer and Vette runs very cool now.
DMONSVETTE is offline   Reply With Quote
Old 08-02-2005, 10:34 AM   #9
GDaina
CF Senior Member
Support Corvetteforum!
 
GDaina's Avatar
 
Member Since: Feb 1999
Location: In Dreams There Is Truth Ohio
Posts: 16,975
Thanks: 0
Thanked 0 Times in 0 Posts
Default

as others have mentioned, 'stats are dirt cheap. If you want to eliminate sthe 'stat as a problem...take it out, and observe if it's cold...place it in a pot of boiling water...if the 'stat opens, it's good, if not, get a new one...oh yea...use some pliers to take the stat out...
GDaina is offline   Reply With Quote
Old 08-02-2005, 11:31 AM   #10
Pete76Shark
CF Senior Member
Support Corvetteforum!
 
Pete76Shark's Avatar
 
Member Since: Jan 2003
Location: Columbia SC
Posts: 383
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Sometimes it helps just to get it out of the circuit and test.

suggest you remove the thermostat completly and run the car, on the road, see what she does. It is either going to get better or stay the same. If it gets better then go down to your local Chevy parts place and but a new thermostat. I learned the hard way to never buy this part from anybody except the dealer.

If it stays the same temp then you have another issue.

FYI.....
I have others that replaced a stock water pump with a "high flow" water pump and have had high temp problems as a result. Nothing else was changed just the water pump. I think the high flow pump creates cavitation and as such slows down the water flow.

With no thermostat in your car (for testing only) the engine will stay as cool as possible. So if you still have high temps then something else is causing it. Like air finding an easier path around the radiator, or a radiator problem, or a fan clutch that feels ok by hand but does not lock up completly.
Pete76Shark is offline   Reply With Quote
Old 08-02-2005, 11:36 AM   #11
jonny4523
CF Senior Member
St. Jude Donor '05-'08
 
jonny4523's Avatar
 
Member Since: Nov 2000
Location: Lafayette Indiana
Posts: 896
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Here is a different suggestion. Do you have the air dam on? Underneath your front bumper? From the picture, it looks like you do, but I didn't know if you took it off or not. I had replaced everything and I was still running hot. Then I found out that you are supposed to have that air dam on there and I didn't. Put one on and the problem went away. It was all a matter of bringing enough air across the radiator.
jonny4523 is offline   Reply With Quote
Old 08-02-2005, 11:46 AM   #12
tigers123
CF Senior Member
 
tigers123's Avatar
 
Member Since: May 2004
Location: belle plaine ks
Posts: 1,100
Thanks: 0
Thanked 1 Time in 1 Post
Default correct

Quote:
Originally Posted by GDaina
as others have mentioned, 'stats are dirt cheap. If you want to eliminate sthe 'stat as a problem...take it out, and observe if it's cold...place it in a pot of boiling water...if the 'stat opens, it's good, if not, get a new one...oh yea...use some pliers to take the stat out...
This quote is right, but have it hanging from a thread through the opening. [just push it open cold and drop thread through] and a thermometer in the water to see when it opens. You would be surprised to see how many don't open when they are supposed to. I learned this from an old GM line mechanic at a dealership I worked at a few years back. He said he got burnt on a service call one time because of a new 'bad' thermostat and decided he would check them from then on.
tigers123 is offline   Reply With Quote
Old 08-02-2005, 01:10 PM   #13
BKbroiler
CF Senior Member
Thread Starter
 
BKbroiler's Avatar
 
Member Since: May 2002
Location: Lebanon Township New Jersey
Posts: 3,675
Thanked 36 Times in 33 Posts
Default

Quote:
Originally Posted by jonny4523
Here is a different suggestion. Do you have the air dam on? Underneath your front bumper? From the picture, it looks like you do, but I didn't know if you took it off or not. I had replaced everything and I was still running hot. Then I found out that you are supposed to have that air dam on there and I didn't. Put one on and the problem went away. It was all a matter of bringing enough air across the radiator.
I do still have the air dam in place, with all seals.
I think I will try it without the stat to see what happens.
Thanks guys.
BKbroiler is offline   Reply With Quote
Old 08-02-2005, 01:26 PM   #14
rihwoods
CF Senior Member
 
rihwoods's Avatar
 
Member Since: Feb 2005
Posts: 16,098
Thanks: 0
Thanked 3 Times in 3 Posts
Default

Question to anyone here...re testing without thermostat...agree engine would run cooler...but would this "mask" an issue with the clutch fan ? Just wondering...these clutch fans are not easy to check when they are going out...I got lucky as I felt resistance then it would feel free...turned out the bearings were gone...another I had on my Trooper was "wobbly",and that was obvious..
Rich
rihwoods is offline   Reply With Quote
Old 08-02-2005, 02:49 PM   #15
Pete76Shark
CF Senior Member
Support Corvetteforum!
 
Pete76Shark's Avatar
 
Member Since: Jan 2003
Location: Columbia SC
Posts: 383
Thanks: 0
Thanked 0 Times in 0 Posts
Default

On a hot summers day the stat opens up and stays open so removing it for testing will not change the engine temp at all. I have a 180 stat and my engine runs at 210 or a little under all the time in the summer.

This does not apply to a winter day of course as the stat will maintain the engine temp at whatever it should be.

Also I had a bad clutch and it was very difficult (for me anyway) to tell that is was not working. I replaced it on a guess and sure enough the new one works alot better then the old one.
Pete76Shark is offline   Reply With Quote
Old 08-02-2005, 03:44 PM   #16
rihwoods
CF Senior Member
 
rihwoods's Avatar
 
Member Since: Feb 2005
Posts: 16,098
Thanks: 0
Thanked 3 Times in 3 Posts
Default

Good point on stat staying open on real hot days...and in my case that occurs mostly at highway speeds with temps at 200....in traffic it modulates cause the fan kicks in more often...I have a 180,as well...
rihwoods is offline   Reply With Quote
Go Back   CorvetteForum - Chevrolet Corvette Forum Discussion >
Reload this Page
  • What happens when a thermostat goes bad?
  •  
     
    Reply

    Related Topics
    Thread Thread Starter Forum Replies Last Post
    I think I have a big problem Roco71 C3 Tech/Performance 11 02-05-2011 06:08 PM
    wierd thermostat thing baxsom C3 Tech/Performance 15 12-31-2008 01:40 PM
    How does a fail safe thermostat work? bweaver999 C1 & C2 Corvettes 3 10-13-2008 06:38 PM
    Correct thermostat 327 motor please? Kensmith C1 & C2 Corvettes 23 06-04-2007 07:42 PM
    thermostat 101, not the usual culprit aminnich C4 General Discussion 13 07-05-2006 11:02 AM


    Tags
    bad, car, changed, corvette, dies, eliminate, fan, fuel, happen, open, partially, pump, stays, thermastate, thermostat

    Thread Tools Search this Thread
    Search this Thread:

    Click for Advanced Search

    Posting Rules
    You may not post new threads
    You may not post replies
    You may not post attachments
    You may not edit your posts

    BB code is On
    Smilies are On
    [IMG] code is On
    HTML code is Off
    Trackbacks are Off
    Pingbacks are Off
    Refbacks are Off

    Forum Jump


    All times are GMT -4. The time now is 10:26 AM.