Here's a scenario. You're zipping along the Highway, and your car starts to overheat. Not enough to set off the idiot light yet, but you know it's coming from the temp gauge. You pull over, and open the hood. No steam yet, but when you squeeze the top radiator hose, its not pressurized, or even warm. Ah ha! Someone has a dead thermostat.

Question: Can you remove your thermostat and safely proceed to the nearest parts warehouse without damaging your vehicle?

I am not worried about damaging the vehicle (it will run just fine without a thermostat); but you. That coolant is still hot and pressurized. As soon as you crack the radiator cap you will be getting a scalding shower unless you have a vented cap and your overflow tank can handle the stress of the escaping steam and water.

Big Dave

If the radiator hose is soft, how can the coolant be pressurized?

Clay where are you coming up wiht this stuff??? Do you like, lie awake in bed every night thinking this stuff up :D

Sleep? I don't need no stinkin' sleep!

Just two gallons of joe a day. one cream, 1/2 sugar please?

http://www.freesmileys.org/smileys/excited001.gif

If the radiator hose is soft, how can the coolant be pressurized?

You've never had a bad thermostat, have you? :confused:

Sleep? I don't need no stinkin' sleep!

Just two gallons of joe a day. one cream, 1/2 sugar please?

http://www.freesmileys.org/smileys/excited001.gif


l:) I dont drink coffee :noway:

i'm kinda with Mike on this one... if it's getting hot then expansion is occuring... the water flows in a circular fashion so to speak and even though ya drop the gate and close it off (stuck thermostat) the system is still pressurized... now let's get molecular... if it's NOT really hot then maybe it's not boiling over, not AS pressurized as it could be etc... but heat is caused in a running engine and everything expands with heat... which equals pressure.

now, if it's not really hot and it's not really pressurized (yet) and you're lucky enough to know the thermostat is stuck then i'd say yeah, you're OK to remove it and drive to the part house...

but i'd venture to say if it's stuck, it's going to get hot REAL quick and i'd sit around for whatever time it takes to cool down before i'd attempt the job.

hopefully you just happen to have a spare thermostat housing gasket somewhere in your car, or a tube of silicone, cause your going to have a problem sealing it back up after you remove the stat so you can drive it to the parts supplier

a brown paper bag, scissors and a dab of grease work in a pinch :rolleyes:


jus' don't be runnin' with 'em or slip in da grease :eek:

a brown paper bag, scissors and a dab of grease work in a pinch :rolleyes:


jus' don't be runnin' with 'em or slip in da grease :eek:


yep, but how often do you just happen to have a paper bag, scissors, and a dab of grease in your car while you zipping down the interstate?

If it where me I would put the heater on full to help with the temp of the motor and limp off the interstate ASAP.

hopefully you just happen to have a spare thermostat housing gasket somewhere in your car, or a tube of silicone, cause your going to have a problem sealing it back up after you remove the stat so you can drive it to the parts supplier

Um, I have a water neck gasket that's been riding around in my glove box for a year and a half :D. just cause I haven't put my 160 degree thermostat in it yet (which is also in the glove box). So I'm set for a bad thermostat! :disco:

Um, I have a water neck gasket that's been riding around in my glove box for a year and a half :D. just cause I haven't put my 160 degree thermostat in it yet (which is also in the glove box). So I'm set for a bad thermostat! :disco:

ok you got me on that one :p, but I'll bet most people dont have one in their glove box:)

ok you got me on that one :p, but I'll bet most people dont have one in their glove box:)

I must not be most people either then :o

It's in my trunk tho, so does that count? :cool:

You can run the car with the pressure cap removed (put it on the dash to remind you)and it will not leak just bolting on the old thermostat housing again reusing the torn up old gasket.

You can have steam in the system caused by a low coolant level and the hose will be collapsed by the water pump suction. It is still above atmospheric pressure (4-6 psi) on the discharge side of the pump waiting for that thermostat to be removed which will flash boil the remaining coolant. The hose is cool because there is no coolant flowing through it and the fan is blowing air in it to remove what heat builds up.

I had a 1961 one ton Chevy Apache truck that had more lead than brass in the radiator, It was constantly loosing coolant to the point that the thermostat closed for lack of heat and the top radiator hose collapsed. I would turn off the truck and because the coolant in the radiator was below the inlets in the block what little water was in there (it leaked too much to waste antifreeze on the old beast when it never freezes in Florida anyway) would boil in the block. It would percolate for a half hour or more, but eventually cooled off enough for met to top off the radiator with the two gallons of water and one gallon of oil that I carried to keep up with the leaks.

Big Dave

I must not be most people either then :o

It's in my trunk tho, so does that count? :cool:


see, I told ya most people dont have it in their glove box:rolleyes::D

Here's a scenario. You're zipping along the Highway, and your car starts to overheat. Not enough to set off the idiot light yet, but you know it's coming from the temp gauge. You pull over, and open the hood. No steam yet, but when you squeeze the top radiator hose, its not pressurized, or even warm. Ah ha! Someone has a dead thermostat.

Question: Can you remove your thermostat and safely proceed to the nearest parts warehouse without damaging your vehicle?

If the radiator hose is soft, how can the coolant be pressurized?

You've never had a bad thermostat, have you? :confused:

Let's see - I'm going down the highway and my engine temperature apparently starts going up. I want to pull over to see what's wrong, so I stop along the highway. Being smart, I shut the motor off so it won't do any further damage, and I open the hood to look at the engine. I feel the radiator hose and it's soft, which to me would mean that the pressure inside the radiator is less than atmospheric. I need some rocket scientist to explain to me how there would be a non-uniform pressure inside the block.

All I can say is that it has happened to me before. I felt the hose for heat and pressure, and had neither. I had been driving for 20 mins or so, so the thermostat should have opened up by then. I let it cool down a bit, and took the thermostat out. Went to the parts house, got a new thermostat and installed it.

Problem solved. It was a bad thermostat.

I can only type what I know. Sorry if I can't explain this via mathematical formulas and charts, but that's not my job.


It's Dave's :D

Why would you assume that I've never had a bad thermostat in response to my question about the coolant being pressurized in a soft hose?

Why would you assume that I've never had a bad thermostat in response to my question about the coolant being pressurized in a soft hose?


Look. We've gotten off on the wrong foot here.

Hi, my name is Clay. Thanks for responding to my QOD. If I am wrong in my ramblings, please feel free to correct me. Any input you may have will be appreciated.

As far as the question of whether or not a top radiator hose will be under pressure when a thermostat goes bad, lots of crazy things can happen to vehicles. I'm sure many scenarios are possible, and I would love for anybody to share their personal experience here.

Thanks

I ran my old 78 Delta 88 Royal with an Olds 350 without a thermostat for several years and it didn't cause any damage. The one problem I will note of course is I could never get the heater to blow heat and that made the trip to school in the morning cold in the dead of winter.

You should definately let the engine cool before doing any work on a sealed coolant system. If your young dumb and stupid you can use your AC/DC T-shirt as a cover over the rad cap if you have to bust the system open while still hot, (not that I would ever do anything like that) but you have to also remember all the water that comes out will need to be replaced. If you are on the side of the road it could be difficult to get replacement fluids. Additionally make sure you check the weep hole on your water pump. Building all that pressure in the engine has probably loaded it up pretty good and if it was close to going it probably would go during this event!

Also if you in car tool box (if you don't carry a tool box you couldn't remove the thermostat housing to begin with) does not have a tube of red RTV in it you should consider adding it. Red RTV can be used as a temporary substitute for all kinds of gaskets and in some cases on beater cars it can be used indefinately.

Also if you are just trying to get an old junker home and the issue comes up and all you have is a screw driver you can get it done also. Wait till the engine cools. Remove the upper hose. Get your screw driver in the housing and pound a bunch of holes through. You may have to bend the screw driver to get the right angle! (Note: This will probably cause small metal particles to become present in your cooling system. Since it is on the discharge side these will more than likely enter the radiator and could block off some tubes. This is not a long term fix and probably not a fix I would do on a rare engine or even a common engine whose numbers were matching something special!)

Look. We've gotten off on the wrong foot here.

Hi, my name is Clay. Thanks for responding to my QOD. If I am wrong in my ramblings, please feel free to correct me. Any input you may have will be appreciated.

As far as the question of whether or not a top radiator hose will be under pressure when a thermostat goes bad, lots of crazy things can happen to vehicles. I'm sure many scenarios are possible, and I would love for anybody to share their personal experience here.

Thanks

One thing to remember in automobile engines is that the laws of physics apply uniformly everywhere. If you have no coolant flow in your engine, i.e. the water pump is not turning, the pressure throughout the cooling system will be constant, minus the slight differential due to the depth.

If you want to see the effect of operating the engine with the thermostat closed, just fire it up early in the morning and get right under the hood. Does your upper hose collapse when you rev the engine?

One thing to remember in automobile engines is that the laws of physics apply uniformly everywhere. If you have no coolant flow in your engine, i.e. the water pump is not turning, the pressure throughout the cooling system will be constant, minus the slight differential due to the depth.

If you want to see the effect of operating the engine with the thermostat closed, just fire it up early in the morning and get right under the hood. Does your upper hose collapse when you rev the engine?

It will if it is soft and spongy from rot! You can buy silicone rubber hoses that will last the life of the vehicle. Unfortunatley someone feels they have to be colored other than black as I have seen them for Chevy's only in blue (GoodYear HighMiler), or green (the factory color).

Big Dave

i don't think onovakind67 Mike is here to get anyone upset or anything... i think the purpose is to teach and help us understand. there's a reason for the questioning, that's to get us all to think.

be open to the questions to the question and i'll bet my bottom dollar (seems to be the one on the top also) that we'll all come away a little smarter ;)


good luck to all :thumbsup:

JR

Don't the majority or upper radiator hoses have a spring inside? What is this spring for?

In an air conditioning system Freon pressures can vary greatly even though the system is a closed loop. Isn't this due to orifice sizes, tubing sizes, and pressure valves? If you take a closed loop of piping and put a pump in the loop. One section of piping is 1" diameter and it feeds into a 2" diameter pipe that feeds the pump and the pump pushes the fluid out into the first 1" section which pipe is going to have more pressure? Now throw heating, cooling, conversion of the liquid from liquid to gas, and you get a new equation that throws vapor lock into that equation. Isn't this vapor lock the reason the top hose will pinch itself together (if it does not have the spring in it) on a car!

Now granted this isn't my discipline. I'm electrical and I try to leave the boiler stuff to the guys with those disciplines. I do however get sucked into baby sitting contractors working on the plants boilers and in these cases I have to actually crawl in and look at the thousands of tubes of which I couldn't tell the difference between a primary reheater tube and a pendant reheater.

I'm sure Dave will correct my multiple mistakes though! :beers:

The spring is usually in the lower radiator hose, the low pressure side of the radiator and the connection to the suction side of the water pump.

Pressures can vary greatly in an air conditioning system, but we're discussing a closed loop water cooling system here. If there is no prime mover of water in operation, e.g. a pump, the pressure inside the system is the same throughout the system. There is no way to trap differential pressure anywhere in the system, as the water pump is not a positive displacement pump and leaks off as soon as it stops.