Thermostat removed...overheating more.

[showman]

Have an 84, 75K miles.

Had water pump and radiator replaced a couple weeks ago. My mechanic removed the thermostat for the summer. Engine got up 245 going up my driveway with a/c on yesterday. Fan goes on around 230.

Runs about 10-15 degrees hotter with a/c on. Was removing the thermostat a good idea?

Thanks!

 

[redvett]

You never ever remove the thermostat, it controls the operating temperature of the engine and prevents thermal shock. You have other problems causing your Corvette to run hot. 195F to 215 is normal. Check out the cooling fan operation after you put a 195F stat back in along with timing,50-50 coolant mix and correct radiator cap and check for plugged cat. or exhaust. Also check coolant temp with a scanner do not rely on the I.P Gauge its not very accurate.
Check that the air dam is there and seals around the radiator and fan shroud.

 

[Rabbit]

Not to be a wise guy, but I would seriously consider getting another mechanic.

Redvett is dead on .

 

[geekinavette]

Ditto on removing the thermostat. BAD idea.

Something else is going on...possibly crud buildup between radiator and AC condenser (VERY common with these cars).

 

[boomdriver]

yep...
IF the fans are running and its hitting those temps, there is a news paper and a dead cat stuck between the radiator and the condensor. Maybe a grocery bag. I had a bird sucked up in there once.


oh yeah, your mechanic is an idiot. (disclaimer) IMHO.

I don;t agree with the 195 thermostat in all climates, but you SHOULD have something in there....a 180 at least. You have iron heads so its not too fragile, but the ECM needs a stable temp near 190 to run right. Old school mechanics should be placed with the cars they trained on.....


A neighbor ask me to give him a 2nd opinion on his car the other day. Said it overheated and had smoke billowing out the exhaust until it actually died and would not restart....
He had it towed to his "mechanic" and the guy put a new water pump on, belts, anti-freeze, t-stat and the works. Also managed to un-lock the seized motor. Neighbor says something about the smoke to his guy so the mechanic adds some (qts?) STP and tells him it'll settle down in a couple hundred miles...

We fired it up and the thing rattled the 1st 30 seconds of running but slowly quieted down a little as the mayonaise viscosity oil started to circulate. As it did, the smoke starts blowing out the PCV port...I mean shooting out! The exhaust is blowing blue smoke everywhere and the guy reminds me that his so called mechanic said it'd be alright.......I felt like the Dr walking out of the trauma ward to deliver the bad news to the family.....

Point being,
That there are countless people walking the streets with some tools that call themselves "mechanics".
Anyone that you would consider working on your Corvette, should be a Technician, not a mechanic.

One thing you CAN do without the thermostat, is see if the coolant is circulating by looking in the radiator filler neck as your rev the motor. Never open the cap hot...Start with the cap off when its stone cold. If all is well with the pump you will see the coolant flowing. No mistaking it.
If ok,

Remove top radiator shroud, let the cat out, remove other misc garbage. That space needs to be as clean as your dinner plate.

 

[Hib Halverson]

A "mechanic" who removes thermostats for the summer isn't a "mechanic".

The thermostat does two things.
1) it controls coolant temperature, so without it the engine has no coolant temperature control
2) it regulates flow through the system. The reason removal of the thermostat can cause the engine to run hotter is that, by removing the 'stat, you increase flow enough that the coolant goes though the radiator so quickly it cannot shed enough heat.

Find a new mechanic, have him/her put a 180 thermostat in the engine then, if coolant temp is still above normal, find out why the engine is running hot.

Look for: a faulty front air dam, debris stuck in front of or inside the cooling stack, cooling fans which aren't working properly, restricted radiator, damaged water pump or other problem.

 

[ex-x-fire]

I like to see if a rag will stick to the front of the rad when the fan is running, I saw one last year that wouldn't do that. The fins were plugged w/ dirt.

 

[crowvet]

I might also add that removing the thermostat causes the electric cooling fan to not come on properly because the sensor doesn't heat up enough to turn it on. Therefore adding to the overheating problem.

 

[showman]

Thanks!

Yep...getting a new thermostat put in and getting a new mechanic!

Thanks!

yep...
IF the fans are running and its hitting those temps, there is a news paper and a dead cat stuck between the radiator and the condensor. Maybe a grocery bag. I had a bird sucked up in there once.


oh yeah, your mechanic is an idiot. (disclaimer) IMHO.

I don;t agree with the 195 thermostat in all climates, but you SHOULD have something in there....a 180 at least. You have iron heads so its not too fragile, but the ECM needs a stable temp near 190 to run right. Old school mechanics should be placed with the cars they trained on.....


A neighbor ask me to give him a 2nd opinion on his car the other day. Said it overheated and had smoke billowing out the exhaust until it actually died and would not restart....
He had it towed to his "mechanic" and the guy put a new water pump on, belts, anti-freeze, t-stat and the works. Also managed to un-lock the seized motor. Neighbor says something about the smoke to his guy so the mechanic adds some (qts?) STP and tells him it'll settle down in a couple hundred miles...

We fired it up and the thing rattled the 1st 30 seconds of running but slowly quieted down a little as the mayonaise viscosity oil started to circulate. As it did, the smoke starts blowing out the PCV port...I mean shooting out! The exhaust is blowing blue smoke everywhere and the guy reminds me that his so called mechanic said it'd be alright.......I felt like the Dr walking out of the trauma ward to deliver the bad news to the family.....

Point being,
That there are countless people walking the streets with some tools that call themselves "mechanics".
Anyone that you would consider working on your Corvette, should be a Technician, not a mechanic.

One thing you CAN do without the thermostat, is see if the coolant is circulating by looking in the radiator filler neck as your rev the motor. Never open the cap hot...Start with the cap off when its stone cold. If all is well with the pump you will see the coolant flowing. No mistaking it.
If ok,

Remove top radiator shroud, let the cat out, remove other misc garbage. That space needs to be as clean as your dinner plate.

 

[Hot Rod Roy]

The thermostat does two things.
1) it controls coolant temperature.
2) it regulates flow through the system. The reason removal of the thermostat can cause the engine to run hotter is that, by removing the 'stat, you increase flow enough that the coolant goes though the radiator so quickly it cannot shed enough heat.

Hib, I really value your input and your opinions, but I wonder if there's more to this story. If the water is flowing thru the radiator too fast to shed its heat, it must also be flowing thru the engine too fast to gain heat. Is there a possibility that by removing the thermostat the internal water pressure at the water pump is reduced because of the reduced restriction at the missing thermostat, therefore promoting cavitation in the water pump?

 

[WillC4]

T-stat removed!!!! One of the dumbest things i have ever heard of. Like others have said, i suggest a new mechanic, or do all the work yourself like i do (service manual from the publisher is an amazing thing, one of the best Christmas gift from my father).

 

[G Winter]

Hib is right on the money.. if the coolant moves to fast it can't transfer heat.


Glenn

 

[Rodney Gold]

If the part was not needed , surely the mnfgr would have left em out , after all it would cost em less.

 

[WhalePirot]

Hib, I really value your input and your opinions

Ditto that. The BeCool techs told me that the water has to stay in the engine (to absorb heat) and the radiator (to cool) long enough. Also recommended that I use different size washers to find the proper restriction for my non-stock car.

Turns out, the Robt. Shaw 180 worked great with the stock fan.

I wonder if the 'mechanic' installed the wrong pump. The Vette's serpentine driven pump turns opposite the V-belters. This, if and only after, the easy and usual things are unsuccessful.

 

[aklim]

My mechanic removed the thermostat for the summer.

You have got to be kidding me. Where did your "mechanic" get his training or certification? Certainly not from the bottom of a Cracker Jack box. Probably something the kid threw away from the bottom of a Cracker Jack box.

 

[boomdriver]

I have experienced the non-cooling effect of a system that moves too fast...
I had mine yrs ago minus a t-stat temporarily for some reason,...I forget, but point is that it would take a while to reach upper temps then stay there with NO cooling and the heating was worse at freeway speeds. The effect was the water was flowing so fast thru the radiator that there was no cooling. Radiators are simple Heat_Exchangers and the coolant has to be INSIDE the exchanger to transfer heat away.

Another thing, most vettes have an orifice either on the water pump, but usually coming out of the intake so it causes water pressure to increase as the flow is restricted. This is done intentionally to make sure that water fills the upper engine area, intake, heads etc so there are no dry or hot spots. If the water were allowed to free-flow out, there would be voids in the heads and that causes aluminum to warp or crack.


After installing my BBK throttlebody the heater hoses had to be changed because that orifice no longer fit under the T-body...so I simply reduced from the 5/8 (think it was) with an orifice, to 1/2" without. This keeps the intake and heads full and creates the needed pressure to make the push thru the heater core and back. Pressure is always created by restriction and fluid metering is always done on the return side of the system, or the exit side.

 

[DailyDriverC5]

right answer, wrong reason

Hib is right on the money.. if the coolant moves to fast it can't transfer heat.


Glenn

I know this is an old string, and I only found it by Google searching something about my C5 thermostat, but I actually joined this site in the hopes that I can right a serious wrong here. I'm sure that you guys are very knowledgeable, and the BeCool tech's are competent mechanics, and I agree that removing the thermostat is a bad idea, for a number of reasons:

The coolant moving too quickly through the engine and radiator IS NOT ONE. To suggest that it is, shows a lack of understanding of both mathematics and physics.

If the water moved through at 1 gallon per minute, or 100, it would make no difference in its ability to absorb heat in the engine or dissipate it in the radiator. I will explain with math, as it's the easiest. for the sake of simplicity, let's assume that, as it moves all the way through the cooling system, a single water molecule would spend half it's time in the engine and half it's time in the radiator (the ratio really doesn't matter, so if you happen to know the actual ratio, it won't change the argument). In an hour of driving, that molecule will spend a half hour in the radiator and a half hour in the engine, NO MATTER HOW FAST IT IS MOVING.

If this doesn't make sense to you, try this simple test of physics. Heat a pot of water, stick in a thermostat, or your finger, with it sitting still. Record the temperature and how quickly the thermostat achieved it, or how badly you burned your finger. Then quickly take the same pot and swirl the water so it is moving quickly in one direction in the pot and stick the thermometer or finger in again, and it will heat the thermometer, or burn your finger, exactly the same. This means that the heat transferred was the same whether the water was moving or not.

 

[roger longman]

So........velocity/volume isn't a factor ? A couple of points come to mind. If the flow through the engine is too fast for the coolant to absorb the heat, where is the heat going ? My logic dictates.....nowhere. The engine overheats. If the flow through the radiator is too fast for the heat to dissipate, where is the heat going ? I say, back to the engine.. I dont need to stick anything into a pan of hot water !.......Roger.

 

[Hot Rod Roy]

This still doesn't compute in my head. If the water is moving thru the engine too fast to absorb the heat from the iron/aluminum in the engine, what is the temperature gauge measuring? Is it measuring the water temp or the iron/aluminum temp? If the water is moving thru the engine so fast that it can't absorb the heat, why does it boil? As the water in the radiator gets hotter, there's more temperature differential with the air stream thru the radiator, so you will transfer more BTU to the air!

I think DDC5 is onto something, but I still don't know what the "mathematics and physic" answer is! My simple logic tells me that if you remove the thermostat, the engine should run too cool, but that is obviously flawed logic. Something else is going on here!

I suspect that during normal engine operation, the thermostat doesn't open all the way. It only opens far enough for the water temp to reach the desired temperature ("medium flow"). During warm up, the thermostat is mostly closed ("low flow"). When you start climbing a mountain with the a/c on, the thermostat opens more in order to maintain the desired temperature ("high flow"). As you continue to climb that mountain, and the t'stat opens all the way ("max flow"), that's when the engine starts to overheat. Therefor, it's the flow rate that controls the temperature of the engine! So what goes haywire when you remove the thermostat ("max + flow")?

:eyerole

 

[G Winter]

DailyDriverC5 read this. Water Cooling Flow Rate and Heat Transfer | Overclockers