[DropTop D]

So I recently replaced my tstat, My old one was not opening. Replace it with a new 180. So the new one is not opening, I took it out and put it in some boiling water And it opened right up. The car was running really hot so I know the water was hot enough to open it. Any ideas why it wouldn't open?


Thanks guys.

 

[Philip]

A couple of thoughts, a better test is to suspend it in cold water and raise the temperature to simulate the engine warming up and in the pan of boiling water there is no pressure against the thermostat so it may be binding.

What brand are you using? I tried several and the one in the NAPA box, made by Stant, in the USA has worked great. The 2 before it caused all kinds of grief.

 

[dashboard]

Good luck, I went through three new thermostat's before I got one that worked. It also came from NAPA.

 

[atle]

is it running hot idling? or cruising? can you list engine specs. what kind of fan do you have.... electric or mechanical and do you have a fan shroud?

 

[SWHEATON]

So I recently replaced my tstat, My old one was not opening. Replace it with a new 180. So the new one is not opening, I took it out and put it in some boiling water And it opened right up. The car was running really hot so I know the water was hot enough to open it. Any ideas why it wouldn't open?
================

Along with the questions that are directly above my post what is the actuall temp at idle in traffic and at cruise?

Also,did you have rad cap off rad with motor warmed up/hot and rev motor to see if coolant was actually flowing well with plenty of force out of tubes in radiator?

Are you installing the stat correctly and not upside down which is a mistake i have seen people do before.

Also,if your using the hi flow/hi perf type stats i had 2 brand new defective ones last yr so keep that in mind too.

If you want to try another stat try an autozone 15356 180 deg stat.(Drill bypass hole to ensure air is purged from cooling system)

They are a HD stainless steel stat that works very well,i have installed approx 5-6 of those type stats in mine & other peoples cars over last yr or so with no issues so far.

Could in rare case be impeller in w-pump came off or is loose or shaft broke inside pump not pumping any water both of which i have seen a few times thru the yrs.

Did anyone possibly leave a rag in rad hose to stop leaking with rad out and then forget to remove it when rad was reinstalled?

Scott

 

[LeoP]

Ya know, I've been doing automotive repair for 46 years for a living and i have yet to drill a hole in a stat. I have used many different brands. OEM/Stant etc. If there is something not right in the system, I personally don't think a hole in the stat is gonna be much help. JMHO.

 

[d1_bradley]

The 'hole' allow fluid to bypass stat and lets coolant into well below to make contact with bulb. If there is an air pocket there, the stat won't open. Not always necessary but a good safety mod.

 

[Philip]

I drill a small hole to allow air to escape when filling with coolant. I do not believe it any benefit after that.

 

[onovakind67]

Besides the two aforementioned benefits, a small hole in the thermostat will reduce thermal shock to the radiator under cold operating conditions, and it will reduce the loop gain at the valve crackpoint.

 

[DropTop D]

is it running hot idling? or cruising? can you list engine specs. what kind of fan do you have.... electric or mechanical and do you have a fan shroud?

Both idle and cruising, Its a 454 with a mild cam and oval ported heads, be cool radiator, twin electric fans and mechanical water pump. Car use to run at 190, and now it runs at 200 to 210. Pulled out stat. To make it home and haven't really drove it much. Drove it the other day and got to around 210. Pulled over and noticed that the top hose had a lot of pressure, as if the stat wad not opening... But no stat in it. By the way I'm not that great of a mechanic , Just trying to learn to wrench for myself, Thanks for all the help.

 

[Philip]

Engine temp is hard to control without a thermostat in it. Buy a good 180° and see what happens.

 

[zeke67]

Top hose with a lot of pressure would indicate the stat was open.

SWHEATON makes two good points. Is coolant flowing through the core when fully warm (cap off)? Was the stat upside down?

 

[DropTop D]

Top hose with a lot of pressure would indicate the stat was open.

SWHEATON makes two good points. Is coolant flowing through the core when fully warm (cap off)? Was the stat upside down?

I am going to try to warm the car up and see if I have flow through the core. No flow means bad water pump or clogged radiator?

 

[lsrx101]

Wow! When I read this post 5 minutes ago there weren't any replies showing. After I posted a response, a bunch showed up. Strange.

Deleted my redundant input.

 

[surmin69]

If you start up the car now with no t-stat in it, you will see flow through the radiator right then, won't need to let it warm up. if there is no movement/flow it could be the water pump, radiator, or maybe the lower hose is collapsed not letting coolant flow.

 

[JWagner]

What Surmin says!

 

[bikerdawg]

I don't know if this will help or not. When I had a problem with the top rad hose with a lot of pressure, it turned out the rad cap was bad.

 

[DropTop D]

If you start up the car now with no t-stat in it, you will see flow through the radiator right then, won't need to let it warm up. if there is no movement/flow it could be the water pump, radiator, or maybe the lower hose is collapsed not letting coolant flow.

So I checked out the flow though the radiator cap, I didn't see water flowing at idle, raised the rpms and it starts to flow. Is it supposed to flow at idle. My guess would be yes. But not sure

 

[surmin69]

There should be some flow at Idle, if the rad is full to the top of the neck you might not be able to see it, drop the level a bit so you can see the core,
Then you should see some movement at idle.
What year Chevelle?
Do you have a stock water pump?
Is the rad new/old.
When you can see the core (inside the neck) does it look clean, or is it all scaly.

 

[DropTop D]

There should be some flow at Idle, if the rad is full to the top of the neck you might not be able to see it, drop the level a bit so you can see the core,
Then you should see some movement at idle.
What year Chevelle?
Do you have a stock water pump?
Is the rad new/old.
When you can see the core (inside the neck) does it look clean, or is it all scaly.

Had the levels a 1 inch below core. Didn't see any flow at idle at all. Radiator fairly new. A couple years old.