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Why not get rid of therostat permanently?

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mikekwesell

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1973 Blazer K5 - trying to get rust out of cooling system, multiple flushes... mechanic buddy helping me told me to take the thermostat out and leave it out permanently. Said it does no harm to have coolant circulating through engine immediately upon startup and that thermostat really does not offer any benefits...

I've been running the last week with no thermostat - seems to go ok. Trying to think of reasons to put thermostat back in.

Agree or disagree?

thermostat.jpg
 
find a new mechanic buddy lol.

One function of the thermostat is to slow the flow of coolant so that the air flowing throw the radiator has enough time to cool it. in certain conditions you will overheat just as badly with no thermostat. Many racers will remove the thermostat but install a restrictor to slow the flow but not have to wait for their engines to warm up to operating temperature.
 
Once winter returns you will wish you had that stat back in. You won't get any heat. I don't see any reason to go without. I had a Jeep with a nasty cooling system. I put a flush kit on it with the garden hose. Started it up and ran the hose through it for like an hour. Its clear again but took a long time to run clean. Keep flushing and put a stat back in.
 
The thermostat allows the engine to reach operating temperature faster and maintain a more consistent temperature when running. Also, running too cool can have negative impacts on the engine including lower performance, fuel economy, and can cause carbon build-up. On older carb'd vehicles this isn't as big of a deal as it is on newer fuel injected vehicles (and when I say newer that is most engines made starting back in the mid to late 80's). Overall I don't see any reason to not run a thermostat. If the engine overheats with a thermostat (that is not stuck closed) it's also going to overheat with no thermostat.
 
You can probably get away with it in the warmer months, but it won't run well in the cold months.
 
The oil will sludge up bad in winter if you run without a thermostat,not to mention you'll freeze to death and can't defrost the windshield!..and a 195 degree thermostat is what GM has used since 1968...you can get 180 or 160 degree ones,but I would not use them..

I've had engines that overheated bad when I tried running without a thermostat..as stated earlier,the coolant will rush thru the radiator too fast to ever cool down any..even while flushing the radiator you'll have to let enough cool water from a hose in the radiator to keep it from boiling sometimes..
 
What everyone has already said is true , but another way to think of it , if it really wasn’t needed why did they put it in there in the first place if car makers can save money by not using a part they would. It’s there for a reason.
 
mikekwesell said:
Yes yes yes... thank you everybody for yoru input. Thermostat is back in and staying there :)
Click to expand...
As for rust if you flushed it and you still have rust, I used a product called evaporust, they have a few products all for rust removal, one is for the cooling system, I put it in for a week and it's all clean
 
Make sure your pulling both block drains when doing flush work.. It's not uncommon to have to poke em with a screwdriver or ziptie to knock loose the sludge that builds on each side of the block... With problematic ones I do a few water only cycles, take it for a quick romp, drain... Than I'll dump a quart or so of muriatic acid in, water, run it for 15 min. Dump.. One water only flush.. Than refill 50/50....
 
warrpath4x4 said:
find a new mechanic buddy lol.

One function of the thermostat is to slow the flow of coolant so that the air flowing throw the radiator has enough time to cool it. in certain conditions you will overheat just as badly with no thermostat. Many racers will remove the thermostat but install a restrictor to slow the flow but not have to wait for their engines to warm up to operating temperature.
Click to expand...

Complete agree. If the water flow is too high heat won't transfer into the water while in the engine.
 
i am doing a bit of a custom engine setup for a guy and had to have a custom pulley made or the water pump .

the info i found on just water flow was crazy stuff . std street use and light race thay say 1.20-1.35:1 ratio of water pump to crank speed . if more race only they say go down to a 1:1 ratio .

so yes a thermostat is real important in flow restriction and on how the engine warms up . if its a heat controlled choke and or electronic choke or efi then the longer it takes to warm up the longer it takes for the choke to open / turn off and or the efi to lean out for warm zone of running over the rich zone to simulate a choke .

even race car engines use a special size washer disc to restrict the flow of water were a t-stat would be . but thats for race only .

and newer engines like LS run warmer than older stuff as it burns off emissions better .

keep all these points in mind and make a choice from there .
 
A rusty cooling system is very inefficient. just draining the system from the radiator drain is useless as much of the coolant is still in the block and it is contaminated. I'm old school when it comes to maintenance. What I would do is take one of the heater hoses off, the lower radiator hose at the radiator, thermostat out. Get a garden hose and a pistol grip nozzle, a garden hose repair fitting and screw it on to the garden hose nozzle (This keeps you from getting drenched), put it in the radiator heater hose from the engine and flush thru the heater core. One note to this, make sure your heater valve (if equipped) is OPEN or the heater control is on MAX. This may not work on vacuum operated valves. Give it good flush as a lot of heater cores can hold rust debris. CAUTION! If the heater core will not flush there is a possibility it is badly clogged and will need replacement as the core strength is compromised (Leaks if flushed). Take the garden hose and flush the engine block until the water runs clean. Do the same for the radiator. Reassemble all the hoses, install the thermostat and new gasket and add a cooling system flush additive. Make sure that the flush is compatible with aluminum systems! Make sure you read and understand the directions on the flush product and it's warnings. If the system is real dirty I drive the vehicle to agitate the coolant and warm it up. Let it sit and work then repeat the flush sequence to flush out the chemicals until the water runs clean. Ad 50% full strength coolant and 50% DISTILLED water. Make sure the thermostat opens and coolant is flowing, top off. The coolant reservoir need to be flushed too! Usually the reservoir contains the nasty debris from the radiator. Fill to 50% capacity. In a couple of days recheck the coolant recovery bottle to make sure it is at the proper level when it is COLD.

DISCLAIMER: Used coolant is TOXIC WASTE and should be caught in a pan and properly disposed of according to local and state regulations. DO NOT dispose of on the ground or in rain drainage ditches etc.

If you cannot safely perform this task take your vehicle to a qualified radiator shop and let them perform the proper servicing.
 
This is one of those myths that is apparently harder to bust than the "you need backpressure in your exhaust" myth.

I am going to paste some text from this link here:

https://www.stewartcomponents.com/index.php?route=information/information&information_id=11

A common misconception is that if coolant flows too quickly through the system, that it will not have time to cool properly. However the cooling system is a closed loop, so if you are keeping the coolant in the radiator longer to allow it to cool, you are also allowing it to stay in the engine longer, which increases coolant temperatures. Coolant in the engine will actually boil away from critical heat areas within the cooling system if not forced through the cooling system at a sufficiently high velocity. This situation is a common cause of so-called "hot spots", which can lead to failures.

Years ago, cars used low pressure radiator caps with upright-style radiators. At high RPM, the water pump pressure would overcome the radiator cap's rating and force coolant out, resulting in an overheated engine. Many enthusiasts mistakenly believed that these situations were caused because the coolant was flowing through the radiator so quickly, that it did not have time to cool. Using restrictors or slowing water pump speed prevented the coolant from being forced out, and allowed the engine to run cooler. However, cars built in the past thirty years have used cross flow radiators that position the radiator cap on the low pressure (suction) side of the system. This type of system does not subject the radiator cap to pressure from the water pump, so it benefits from maximizing coolant flow, not restricting it.
Click to expand...

I would like to add, you may want a thermostat for a few reasons:

- you want better heat in the winter
- your stock EFI is looking for a certain operating temp or it won't run as intended
- you want it to warm up quicker
- you need to meet the emissions check
- you want it it to run hotter
- you have one of those older low pressure vehicles with the cap on the pressure side of the pump mentioned above
- something I missed

However, your K5 is not going to overheat because you took out the thermostat as you noticed. Fluid is always in contact with the metal while it is moving because it is under pressure.

Most racers don't use restrictors any more. I don't run a restrictor or a thermostat in my street/strip car because I only use it in the summer, I don't need it. What happens is, it just takes a little longer to reach operating temp, which is whatever happens to be the equililbium where the coolant system can't remove the heat faster than the engine is making the heat. When you think about it, the closer the coolant gets to ambient temp, the less effect the radiator has on it, so there will be some warm/hot temperature it will reach without a thermostat. If I wanted to raise the operating temp I would use a thermostat, but most engines make more power with hot oil and cool coolant. If I remove the thermostat from my truck it still runs about 180 degrees, I run a 160 thermostat and I still get heat just fine for the few times I use it.

Yes you need some sort of restriction in a boat because you have a constant supply of cold water the size of a lake (literally, or maybe a river or an ocean). So if you don't control the temp it may never get up to temp as it isn't recycling the previously heated coolant through like a vehicle radiator. Although some boats do have separate coolant and heat exchangers to keep the dirty water out of the engine block and heads.

Also, some boats like jet drive boats need a pressure regulator on the coolant inlet as the pressure from the jet can reach over 100 psi and blow coolant hoses and cause gasket failures at higher power levels, at lower power levels a ball valve can simply be closed until the engine operates at the desired temp.

With that said, with your rig I would run a thermostat like the guys said, there really isn't a reason not to for you, especially if you want warmer heat in the winter. Fix your coolant system if there is a problem with that, or get a properly operating thermostat if the one you have is stuck shut.
 
Last edited:
folkenheath said:
This is one of those myths that is apparently harder to bust than the "you need backpressure in your exhaust" myth.

I am going to paste some text from this link here:

https://www.stewartcomponents.com/index.php?route=information/information&information_id=11



I would like to add, you may want a thermostat for a few reasons:

- you want better heat in the winter
- your stock EFI is looking for a certain operating temp or it won't run as intended
- you want it to warm up quicker
- you need to meet the emissions check
- you want it it to run hotter
- you have one of those older low pressure vehicles with the cap on the pressure side of the pump mentioned above
- something I missed

However, your K5 is not going to overheat because you took out the thermostat as you noticed. Fluid is always in contact with the metal while it is moving because it is under pressure.

Most racers don't use restrictors any more. I don't run a restrictor or a thermostat in my street/strip car because I only use it in the summer, I don't need it. What happens is, it just takes a little longer to reach operating temp, which is whatever happens to be the equililbium where the coolant system can't remove the heat faster than the engine is making the heat. When you think about it, the closer the coolant gets to ambient temp, the less effect the radiator has on it, so there will be some warm/hot temperature it will reach without a thermostat. If I wanted to raise the operating temp I would use a thermostat, but most engines make more power with hot oil and cool coolant. If I remove the thermostat from my truck it still runs about 180 degrees, I run a 160 thermostat and I still get heat just fine for the few times I use it.

Yes you need some sort of restriction in a boat because you have a constant supply of cold water the size of a lake (literally, or maybe a river or an ocean). So if you don't control the temp it may never get up to temp as it isn't recycling the previously heated coolant through like a vehicle radiator. Although some boats do have separate coolant and heat exchangers to keep the dirty water out of the engine block and heads.

Also, some boats like jet drive boats need a pressure regulator on the coolant inlet as the pressure from the jet can reach over 100 psi and blow coolant hoses and cause gasket failures at higher power levels, at lower power levels a ball valve can simply be closed until the engine operates at the desired temp.

With that said, with your rig I would run a thermostat like the guys said, there really isn't a reason not to for you, especially if you want warmer heat in the winter. Fix your coolant system if there is a problem with that, or get a properly operating thermostat if the one you have is stuck shut.
Click to expand...
I just stopped posting corrections on that, so thanks for saying something.
 
Got out of the Navy n 85. Drove my CJ7 from mayport fl wearing a blanket because of no thermostat. So use to not really needing one & forgetting it was missing! Lol Dumbass rookie mistake!
 
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