A 7 PSI cap is just like any other cap but it vents at a lower pressure. This means the cooling system internal pressure will be 7 PSI instead of 15-16 PSI as it is with a "regular" cap. The reduced pressure means the hoses won't be as hard, which is what it sounded like you were worried about. The reduced pressure will decrease the stresses on the radiator and hoses so weak spots are less likely to rupture. The lower pressure will also reduce the boiling point of the coolant but not by a huge amount.

Your local auto parts store should have one.

 

This is for everyone... not anyone in particular.....
In response to this pile of internet-amplified nonsense I've spewed....and said laws of thermodynamics (in which I'm degreed), this problem has proven to go both ways, several in fact. Hashed out as many times as it will be and has been, try opening the mind hole. This "nonsense" was not gleaned by reading a thick book or weenie cyber surf learning or by being a know-it-all or one THAT THINKS HE IS. This was learned by experience.

Thank god there are no kings here.

Some times when one runs into a troubleshooting problem you try different approaches to solve it. Especially when there's seven digit figures ridding on solving the problem quickly. When what you have tried FINALLY solves the problem YOU HAVE LEARNED (mind hole enhancement).

When I learn I like to pass it around to help others. So by shooting it down right away cuz you didn't read about it doesn't necessarily mean its garbage.

I can take criticism but not disrespect, especially when my sole purpose is to enhance everyone's enjoyment and experience with our muscle cars. That is the true intent of this site not sparing. Thankfully, I do have a day job and thick skin.

By playing around with pressures, flows (aqueous & air), dwell, concentrations, additives and other various trade tricks in various cooling systems I have solved many cooling system problems in the last 35 years.
From 4 cylinder offshore junk to 16V92s to Waukesha 9390s, ATs & GLs with 300-1000+ gallon systems.

Just one example we can relate to; My current stock 68, 4 core, auto, with air always ran hot for me. 205-210-215. I tried everything from no stat to a 180 in keeping with the same closed minded thought train as seen in this thread. The temp went down a whopping ~5 degrees with a 180 but fluctuated between the stat and 205*F with several brands of 180* stats. Yes NIST temp gauge too. I installed a 190-195 HD stant for ***** the car now runs at a consistent 195 regardless of ambient conditions. Thats the only item changed.

Whys that I wonder how could that possibly work...humm lets ponder.

I run 7 or 10 psi caps on most all my vehicles, fleet & private.

So in conclusion I hope this bit garbage helps someone.

 

If you're degreed in thermodynamics....which either means mechanical engineer or HVAC repairman with a votech degree, I'm sure you know the perils of basing scientific theory off of one data point.

Just to look at your example, you have a ten degree variance that you're basing an entire theory off of. How many gauges did you test with? Is your gauge even that accurate? Did you account for the cross sectional area difference of the orifices of the thermostats. Did you notice the one you have is a heavy duty marked one; it may have a larger flow rate?

Let me dust off my masters degree in mechanical engineering, here. If you really want to be precise, radiators aren't thermodynamics; they're heat transfer (which, despite meaning the same thing, it's actually two different subjects, where thermo is a macro view and heat transfer is a micro view of each element.) My heat transfer book is back in my junk room, but, just going by memory here, heat transfer is directly related to delta T, as in the difference between the reservoirs.

Delta T affecting cooling is intuitive, because people can grasp that your car runs colder on a cold day. Your engine is still making the same heat, but the equilibrium of the system is lower because the radiator is doing a better job since ambient is lower.

This works both ways. You get more heat transfer from hotter coolant to ambient, then cooler coolant. This is why your casserole out of the oven is nuclear for a few minutes, and warm for 30, then ambient. Delta T. You don't care what the temp of the individual cups of coolant is, you care about heat transfer from the engine, to the radiator, to the ambient.

So, as coolant proceeds through the radiator, it dumps most of its heat early, which is why there is a hot side and a cold side to the touch. Sticking around longer may result in more heat loss per unit volume, but per unit TIME, it won't, because that plant is still making the same heat, and you want to get as much coolant through there as possible and get the low hanging fruit of the quick, big Delta T, heat transfer.

So, your theory is bogus for two reasons. One, the above, and two, your miracle thermostat actually has the water moving FASTER, since it is a heavy duty one with a bigger orifice and the flowrate can be faster. Remember, an open thermostat flows the same when it's open, regardless of what temp it opens at, as long as it is open, and the HD one will flow more. The only thing keeping your temp better with that stat is more flowrate, not the hotter stat. What was your data with no thermostat?

Also, since we're giving anecdotes here, I have a Chevy with an original radiator that would get quite hot on the road, enough that I doubted the stock gauge. An aftermarket, additional gauge (two data points) showed correlating data, so out came the, believe it or not, original, low emissions, high temp 200~ish thermostat, and in went a stant superstat 160. Temp has the same behavior on idle vs street vs highway, but everything is globally about 25 degrees cooler now.

Flow. It's what it's about.

 

Electrical/Mechanical/Chemical Engineer, seven years worth. Apparently you missed the 30 years in the field comment. 30 years of data points hardly adds up to one. This path of installing a hotter TStat proved successful on a number of vehicles not one. To complement the education is something called common sense hands on in the field experience, with dirty hands when needed. But Im not here to boast my accolades as some see the need to do. Sometimes you cant apply logic to all solutions and have to go against whats written or studied. So while were all impressed with your knowledge and the need to jump on the sparing wagon I'm not impressed with your lack of respect for me or for something thats is just real plain and simple for the OP to try with out turning it into a science experiment. Too bad I thought this site was a step above the other elevated testosterone ridden sites.

To the op. Try a 190-195 stat and see what happens. Please report back with the results. Happy motoring!

 

If going this route, there needs to be an overflow tank. That reduced pressure needs to go somewhere besides spewing on the ground.


On the thermostat, it does not regulate max temp in a cooling system. The thermostat rating regulates the minimum operating temp. So whether he has a 160 or a 190 and no other changes were made the engine will still go to whatever temp it will reach based on cooling capacity and outside air ambient temp.

 

Temps sound ok But I'm no expert. Although I did stay at a Holiday Inn Express last night

 

Dr. Oldsmorland, You are correct that my earlier post was not respectful. I had a strong personal reaction to the content and phrased my post in a way that I shouldn't have, and I apologize for that.

I respect both your engineering training and your experience in the field, and I do not dispute that your solution of using a higher temperature thermostat may work.

However, I must and do continue to disagree with your explanation for the reason why it may work ("... [T]he coolant isn't spending enough time in the radiator rejecting heat. It will then dump it right back in to the engine. The 190*F stat will allow more dwell in the rad for full heat rejection").

Increasing the temperature gradient by increasing the coolant flow will absolutely increase the amount of cooling obtained, all other factors being equal.
I suspect that the reason this solution has worked for you in the past, and the reason why it may help in this case (as you say, it's not hard or expensive to try) is due to one of the many "other factors" not being equal. Perhaps in a particular car's system, flow is disrupted due to a rough casting or piece of flashing at a critical point, leading to increased turbulence, which creates a situation where increasing the flow pressures can actually decrease the flow, so that restricting the flow at the thermostat leads to more laminar flow, and better cooling. Perhaps it's something else.

Regardless, though I respect your experience, I believe that you do a disservice to our members by using decreased flow to explain the success of your solution, when, as I'm certain you are aware from your training and experience, decreasing coolant flow, in isolation, will decrease heat transfer and cooling ability.
Reducing flow may aid cooling in certain specific cars or systems, but cannot be said to increase cooling capacity as a rule. Telling people that it does is misleading, and can cause them to do useless or even harmful things in their attempts to improve their cars' cooling systems.

- Eric

 

Cannot stop laughing.

 

You are correct - I was assuming this was a system with an overflow tank.


Agreed. If someone's engine is running at 220º with a 160 thermostat, the thermostat is wide open. A 180 or 190 thermostat would be wide open as well.

 

To get respect, you must show respect. If you're getting bent over the word bogus, then I'll apologize, because that's the only thing I can think of that was anything other than clinically dry in my reply.

Common sense says a heavy duty stat flow better than a normal one. You still haven't said what the car did without a thermostat.

 

Well maybe thats my problem I have no overflow tank and I have a 160* tstat I appreciate all the info that I get from everyone on this site I hope that we all can get along here because none of us are perfect we all have had experiences and handled them different when you look at it we are all olds brothers helping each other so let keep this together and not ridicule one another I need to either find a overflow tank or make one anybody got any suggestions

 

hahahahaha, well let me wipe the bird poo off my shoulder and tell who I am, lol. I started this thread,,, After HS I took aviation maint for two yrs then found poontang and had a starter marriage and stayed in auto world and last 15 yrs until doing my own thing I was a Mercedes/BMW Master Tech. And what I am reading over all this is that No one is happy or can get happy with the ability of keeping their Olds cool!

 

Mine stays cool.

- Eric

 

Not true, people don't understand whats hot and whats not.

 

Eric (MDMechanic) referenced this thread earlier,
https://classicoldsmobile.com/forums...i-running.html
in which I had posted this link,
http://www.flowkoolerwaterpumps.com/cooling_faq.html which debunks a lot of the internet nonsense.


Again, IMHO, any time removing a stat or installing the incorrect stat "fixes" a cooling system issue, all it is doing is masking the REAL problem.

 

Oh, hell, I agree with that statement totally. My 72 was getting hot with the original thermostat, and I believe the problem is a gunky radiator. Putting in the 160 stat just gave it more of a head start on the heat. Although, it doesn't seem to mind hours of 70 mph in the summer anymore.

 

Here are some from O'Reilly's Auto Parts:
http://www.oreillyauto.com/site/c/se...0186/C0331.oap

I have one of the Interdynamics overflow reservoirs on my car and it works quite well.

 

Well I dontvhave an overflow tank on my car and cant find one at least not a reasonable price and every since I busted my heater core hose and bypassed the heater core the car has been running running 185- 190 with the 160 tstat in it but I kkow im gonna need an overflow tank because when it gets hot fl uid just sprays out the the hose.what can I do about that ?

 

You can make sure you have a "pressure/vacuum" radiator cap, instead of a one-way "pressure" cap, get a half-gallon soda bottle, mount it to the fenderwell with some nylon ties, drill a hole in the cap, slip a hose through the hole all the way to the bottom of the bottle, push the other end of the hose onto the overflow barb on the radiator, and pour a few ounces of water into the bottle.

- Eric

 

Did you look at the link I posted above?

$8.99 for 1.5 quart capacity



$12.49 for 2.5 quart capacity

 

The reason why it's spraying fluid is not because it's overheating. It's because the radiator is over filled. The level should be just over the automatic trans cooling coil or about 1 inch below the neck. Water expands with temperature so there needs to be some head space in the radiator otherwise it blows it out the overflow.


With an overflow tank and the proper radiator cap, all you have to do is maintain the level in the plastic tank.