What Matthew said makes perfect sense. But most of us Southerners have never even seen -40 degrees! As he also said, the engine water temperature is dependent on heat transfer eficiency, ambient air temp, and BTU's generated by the engine. Unless the cooling system is very efficient, and the engine is small, and the weather is hot and humid, (like today) the temp will probably run around 190 to 210, even with a 160 degree thermostat. I guess that was my point. A higher rated thermostat will cause faster warm up, but a lower rated thermostat won't necessarily make the engine run cooler.
If your hoses are super soft, they are old and worn out. Replace them! And warming up quickly is not a bad thing, as long as the running temp doesn't exceed 210 or so. If it's not puking water out, it's probably fine. I would recommend a overflow reservoir, so you don't have to refill the radiator as often. I know the old trucks only came with a puke tank. My engine, fan, radiator, and shroud are all mid 90's. They were designed for a closed system, and 195° thermostat. That's what I run. Haven't driven it much yet, but with extended idling, it runs about 210°.

 

Exactly if you increase the the thermal efficiency of the Radiator either through a bigger rad or lower ambient temp etc. You can out strip the engines capability to replace those lost BTU's as quickly, For example in -40 the temp of the coolant may be 170F leaving the engine but maybe as low as 40F going back in to the engine. In that instance the the engine would not be able to keep up replacing the lost heat. So the engine cools and the T-stat closes till the engine heats back up. So your Engine op temp may only ever reach 170F . Drop a 205F stat in now not only have you added another 35F of worth of BTU's to coolant, it will now enter the engine closer to 75F and the engine has much less lost heat to replace The T-stat will close if the coolant temp falls below 205F keeping the engine close to that 205-210F range of operating temp. They sell 205F stats for that exact reason, extreme cold weather operation.

In the southern US you probably do not even a T-stat and could just get away with a restrictor plug (a t-stat with no valve in it just a hole, as they use in some race applications) it will slow the warm up time of the engine but it will have no effect on over all engine operating temp.


And it is not a rare circumstance In sub zero weather T stats cycle all the time opening and closing and restricting coolant flow in effort to keep the engine at Op temp. This is very easy to observe with an infrared thermometer you can even do it on a cooler day and watch the temp of the outlet change as the thermostat cycles, the colder the day the more frequently it will cycle between open and closed, it is also a super fast way to verify if your stat is opening early or late or at all, with out pulling the stat or to check for restrictions in the rad, restricted tubes will show a temp variation (usually lower) from surrounding tubes.

So yes the T-stat does directly affect engine operating temperature, but it might not affect it under all conditions like Spdcat said.

 

When the Tstat is closed there is no (or little to none) flow through the rad so the engine is NOT being cooled the coolant is just cycled through the engine black via the by pass hose/ passage and heater core (if equipped) . The coolant in the engine will heat up since it not being cooled by the rad. When the coolant reaches the open temp of the T stat is will open allowing coolant in to cycle through the rad to be cooled. It does not matter what temp it is out 120F or -40 that operation will not change. What changes with ambient conditions and or vehicle speed is the temp of the coolant leaving the rad and entering the engine that is what is affected. See the above post for more clarification on that.

 

Did not meant to hijack your thread. Sorry

The bulging hoses is not a bad thing. it proves that the cooling system is functioning as it should and is sealed tight.

As the coolant and engines cools things contract and the system pulls in air (no purge tank) or Coolant (purge tank) in to the system. As the system heats up things expand and when the pressure exceeds the rad caps rating it burps out excess air and coolant. The purge tank catches this coolant and recycles back to the rad when the system cools down. With out a purge tank it is a strait loss.

Your rad hoses should be firm and not spongy or brittle and cracking. As was previously stated.

When you shut the vehicle off cooling flow has stopped but the engine still has all the latent heat in it from when it was running. The engine will actually get hotter until that latent heat dissipates. At this point the pressure will increase in the cooling system, causing the rad hose to bulge a bit more than when it was running, when the pressure exceeds the rating of the rad cap the excess pressure is released giving you that burp of coolant. It is also when a cooling system can potentially see it's maximum pressure. This is why a lot of hose failures occur some time after you shut the vehicle off.

As was suggested if you are unsure or suspect of the condition of the hoses replace them, Also change the t stat as you have no idea how old it is and they do eventually fail.

Checking the new T stat for operation as was suggested is a good idea, as on occasion they can be NFG out of the box.

The T stat mod is a good idea to release trapped air. It is more critical in vertical orientation than a horizontal one
The hole need not be any larger than 1/8" Some of the better quality T stats will have a hole with a little dongle in it to release the trapped air. If cooling flow is consideration with a standard T Stat high flow ones are available from Robertshaw (OE supplier) these stats also negate the need for the air hole.

 

Well done, Matthew. I have thought a lot about what you said and I am convinced that you are correct. It is just that I have never faced -40* weather.

Stay around. You are a smart guy. Let's hear more from you on the tech issues.

I suggest that you move to CA to get away from -40*. We are the land of +40*, low taxes, open freeways, diversity, clean air, cheap housing...

Semper Fi

 

Aw John you must be taking about the wonderful place called Rice Ca. where it has cheap housing like you say non crowded highway.
Orich

 

Good, Orich.
On a technical note, I never understood- in fifty years- the purpose of the bypass hose until Matthew. If it were not for the bypass and no circulation until the thermostat opens, we would have local boiling on the cylinder walls and steam explosions.
Again, hang arround Matthew.

 

I started working in a Auto repair garage at 17 so, I was well versed in what does what rebuilding many type of engines. I was handing my dad tools at 4 yrs he told me what number where on them an I hold it up yep son that's it.

I started young!
Somethings you never to old to learn, as long as has nothing to do the ABC
Orich

 

Yup that is exactly the purpose of the by pass hose. Race engines for most part do not have by pass hoses or T stats, (less parts to fail) and just use a restrictor plug to control the coolant flow rate through the rad to insure it releases the maximum amount of heat with out over cooling the engine. The diameter of the restriction will will be sized to the ambient conditions expected for that race day. Some race engines (F1) can not even be turned over till they are at or near operating temperature due to the very close tolerances in them, and are warmed up by external coolant and oil heaters before start up.

And no problem John glad I was able to help. And Ya I will be hanging around no worries. I know sometimes my posts tend to ramble a bit and can come off as seeming a bit in your face. But that is never the intention.
A literary genius I am not, even at the best of times (one of my many failings lol) , I just try to pass along information as best I can. So sorry in advance if they seem a bit arrogant or in your face, that certainly is not the intention ever.

And thanks for the kind words John

 

Good explanations Matthew! I'll buy it!

 

2X Cougar John here. This is exactly what I would do with only one exception. I would use distilled water for the 25 mile flush run rather than tap water. Distilled water is pure so it will be more "thirsty" for crud,rust, or contamination in general that you want to flush out of the cooling system. Tap water already has things added to it according to your local water company. Like chlorine, fluoride, calcium, etc. Tap water has already grabbed these additives where as pure distilled water hasn't grabbed anything yet.
And buy quality hoses. That upper hose might have been a cheapie Po bought. All rubber with no reinforcing webbing in the rubber. Rubber hoses, belts, etc. are just like tires. A no name brand made in China tire is NOT just as good as a Michelin, right?

 

Someone might have already suggested this but I'd check the temp sending unit.

 

2X. I want you to hang around here also. The more heads on a problem the better. Separate, none of us knows everything. But collectively, we know most everything. And your knowledge and experiences can and have added to this. Which reminds me to REP ya here in a second. We do appreciate your explanation of your style of "delivery". Just one word of caution. We will now understand it but a newbie may not. There has been times a newbie or someone rarely here had a problem. Then jumped all over one of us because they didn't like that person's delivery. We would have your back. But just lettin' you know.

 

I think you may have Distilled water and Deionized water mixed up.
Distilled water is exactly that water that has been distilled it removes all organic impurities and dissolved inorganic solids but does not remove mineral impurities.

Deionized water removes all mineral impurities down to the molecular level the ions of iron, calcium,sulfates,sodium,chlorides, copper and other minerals that have attached themselves to the water molecules are stripped away.
Chemically it is more pure than distilled water. But deionization water does not significantly remove uncharged organic matter such as dissolved organic solids bacteria viruses etc.

Distilled water will be sterile deionized water may not be.


There has always been an ongoing argument what to use in your cooling system. Distilled or deionized water..


As some useless info chemically pure H2O is the strongest solvent known.

Deionized water as soon at is contacts the cooling system will start trying to replace the ions it lost in the deionization process pulling them from the surrounding strata Iron from the block, Copper from the rad, calcium and sodium from internal deposits etc.

Distilled water has basically zero dissolved solids and no organic matter (bacteria virus's etc) but will not have the mineral ions removed from it's molecules. Distilled water will pick up dissolved solids, salts, calcium etc till saturation.


Deionized water will also pick up dissolved solids, salts, calcium etc till saturation. but will also attack these minerals on the molecular level as it try's to replace the the ions it lost in the deionaztion process.


My take on it has always been distilled water in a new system and deionized water in an old system. Just cause you do not want the deionized water pulling Ions from the fresh new surrounding materials (copper Iron etc). Once the system has been in service for a bit deionized water will help keep things cleaner as it pulls Ions from the oxidized surfaces it comes in contact with and from any mineral deposits as well picking up dissolved materials till it reaches saturation.

That is my take on it. But your mileage may differ.

 

Thanks JEFFFAFA it is appreciated. And you are absolutely right none of us know everything, (lord knows I don't lol) but as a group we damn near do.

My line of work deals very much with black and white there is no little to no grey area things are ether F'd up or not. So over the last few decades my written reports dealing with schedule updates, financial tracking, engineering F ups contractual omissions and like are very factual based with little room for emotional inflection in the writing, Unfortunately this very direct to the point style of writing has crept in to my everyday written style of communication and can come off as cold and arrogant. (not that I have ever been accused of that in my written word lol ). My goal is to just pass information along, so it is going to be a process as I relearn to do it in manner that can communicate the information in a manner that is shall we say more appeasing to the reader.

And ya I have seen it on the board where people get a stick up their @$$ when someone was just trying to help. I don't think anyone really intentionally tries to be d*** but most of us on here I suspect are not literary geniuses and are just trying to communicate the best we can. So I really do not not pay much attention to the style of delivery but more to the content. But then again that is what I do at work also... so it can be bit of a double edged sword. Unless of course they are intentionally being a tool then all bets are off ,lol.

Communicating in the written word is a bit of an art form (I'm more of math and science guy to be honest).
I'm sure all of us have sent a text that was taken out of context. And in today's world as we communicate more and more by the written word (texts, FB, twitter, email, forums ect) and less face to face, for some us ( early gen X and older) we did not grow up doing this on daily basis and perfected our communication skills using body language and voice inflection to determine the tone of the conversation. Expressing tone with the written word I find far more more challenging since we were not brought up doing it daily with every day communication. That is my my take on it at least for what it is worth.

So do appreciate the patience and understanding.