Road Test of Stant vs. Shewman Thermostats

[Old Henry]

I wasn't really interested enough in such a comparison to do it but have received several repeated PM requests to repeat the test I did last year comparing no thermostats to Stant thermostats (here: https://www.fordbarn.com/forum/showthread.php?t=113979) but this time comparing Stant thermostats to Shewman's "High Flow" thermostats. So, I did it exactly the same way I did it last year but on two consecutive days rather than a few days between. The ambient temperature on the first day when the Stant was tested was 92° and on the second when Shewman's was tested 90°. The details of the test are otherwise described in last year's thread referenced above. The data from the test is in the attached PDF file. Hopefully VeryTangled will graph them again for us like he did last year.

The data confirms what I predicted about Shewman's stats last year here: https://www.fordbarn.com/forum/showthread.php?t=112889 Post # 85. Because Shewman's stats do not completely shut off the water flow when closed the engine takes much longer to warm up to proper operating temperature (3 miles/7 minutes longer) and that operating temperature is not maintained (it drops 40° below the stat setting) when going down a long descent with no throttle. (Many have not even been able to get their engines up to operating temperature in the winter with Shewman's stats. See here: https://www.fordbarn.com/forum/showthread.php?t=121447) Then, on the other end, because Shewman't stats have a much lower flow than the Stants when fully open (33% less) they allow the engine temperature to raise much higher faster than the Stants, up to 10° higher. That is enough difference to boil or not boil over (and was for me). One other big difference - the Stant stats are $18.00 a pair compared to Shewman's at $50.00 per pair. I'll be putting the Stants back in.

NOTE: THIS TEST WAS ONLY OF SHEWMAN'S STATS FOR THE 59A ENGINE NOT THE ONES FOR THE 8BA.

Here is the graph of the data later created by VeryTangled with his graph of the elevations he made last year added by me and the numbers re-aligned by 51 MERC-CT to read a little easier.

[Ross F-1]

Nothing like real data, thanks! I've had no issues with the Stants.

[34PKUP]

Originally Posted by Ross F-1

Nothing like real data, thanks! I've had no issues with the Stants.

"THIS TEST WAS ONLY OF SHEWMAN'S STATS FOR THE 59A ENGINE NOT THE ONES FOR THE 8BA"
Really?

[Old Henry]

Originally Posted by 34PKUP

"THIS TEST WAS ONLY OF SHEWMAN'S STATS FOR THE 59A ENGINE NOT THE ONES FOR THE 8BA"
Really?

Really. Although they both start with the same stat, they are modified very differently for the two different applications. What Shewman has done is taken the Robertshaw 330 stats, that are perfect for the 8ba engine, and drilled holes in them for that engine which is most likely going to make it run cold in the winter and adds nothing for the summer since, once the stats open in an 8ba, the water flow is unlimited by the stat. Then, for the 59A, since the stats mount differently than for the 8ba, he trimmed off the stat flange, after drilling the holes in it, and brazed a tube onto it to hold it in the upper radiator hose just where it goes into the radiator. That's the real rub since the cup that moves out of the way of the water flow in the 8ba just stays in the way in the hose of the 59a. Two very different applications for which Shewman tried to make one thermostat work.

So, for allowing the highest water flow at high temperatures in the 59a, Shewman's stats can't be beat. For fast warm up, particularly in cold weather, the stock Robertshaw (without the holes drilled in it) would be better. For 59a, Shewman's stats have no advantages, only disadvantages.

[Old Henry]

Later today did a 150 mile round trip to Mirror Lake climbing up over 10,000 feet. On the way down the Shewman stats let the engine get clear down to 120° for the 30 miles coming down the mountain, 60° below their rating of 180°, the temperature that they opened when tested before installing them. So, the holes drilled in them really do defeat the purpose of a thermostat.

[JM 35 Sedan]

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Sorry....but with all the previous posts on the mechanical and electrical issues with this test vehicle and some of the "fixes" that were made, plus the previous negitive posts that were made by this same person about Skip Haney's and Bob Shewman's products, I would not rely 100% on these test results. Of course this is just my opinion

[JWL]

Well, as they say in the movie "Used Cars"---this "blows the hell out of those high prices".

[V8COOPMAN]

Originally Posted by JM 35 Sedan

Sorry....but with all the previous posts on the mechanical issues with this test vehicle and some of the "fixes" that were made, plus the previous negitive posts that were made by this same person about Skip Haney's and Bob Shewman's products, I would not rely 100% on these test results.

Thank you, thank you, thank you!

Could not have said it any better. DD

[VeryTangled]

Chart

[Old Henry]

Originally Posted by JM 35 Sedan

Sorry....but with all the previous posts on the mechanical issues with this test vehicle and some of the "fixes" that were made, plus the previous negitive posts that were made by this same person about Skip Haney's and Bob Shewman's products, I would not rely 100% on these test results.

. . . not to mention the very few actual miles the person drives his vehicle.

It's pretty easy to criticize without any contradictory data or even personal experience. Not very persuasive though.

If you don't have any way to refute the message all you're left with is to kill the messenger.

It doesn't take a rocket scientist to do exactly the same thing twice, changing only one thing, record the data and report it. Interpretation of the data may vary but the data itself are facts that can't be disputed.

[Old Henry]

Thanks to VeryTangled for graphing the test results for us. I added his graph of the elevations he made for the identical test last year and the numbers were re-aligned by 51 MERC-CT to read a little easier.

[gearhead1952]

The graph does not look right to me as the bigger numbers should be on top all the way along.

[Old Henry]

Originally Posted by gearhead1952

The graph does not look right to me as the bigger numbers should be on top all the way along.

[Numbers rearranged by 51MERC-CT] The numbers for the Stant are above its line and the ones for Shewman's below. So, when Shewman's line goes above the Stant line the numbers look upside down but are still in the same orientation to their line as for the entire graph.

[bobH]

Old engineer's 'creed'... If you have something that is working well, and you try to make it better, if you screw with it long enough, eventually you will f**k it up.

I ran this same test several years ago, on another engine (the other brand, sbc350). It's a vehicle/engine that has always had overheating problems during the 40+ years that I've owned it. I got exactly the same results. Stock stat went back in.

[VeryTangled]

Hi Everyone, gearhead1952, I agree. [edit: Oops I see Prof. Henry beat me to the comments.]

The numbers below the data point are for the Yellow/Shewman's stats. Numbers for the Magenta/Stant are above the data point.

Because the lines cross in a couple of places, the numbers where they cross look weird. A good example is the last two points. The yellow is 189 and the magenta is 182.

[51 MERC-CT]

Originally Posted by VeryTangled

Hi Everyone, gearhead1952, I agree. [edit: Oops I see Prof. Henry beat me to the comments.]

The numbers below the data point are for the Yellow/Shewman's stats. Numbers for the Magenta/Stant are above the data point.

Because the lines cross in a couple of places, the numbers where they cross look weird. A good example is the last two points. The yellow is 189 and the magenta is 182.

Is this a little better?

[gearhead1952]

Originally Posted by VeryTangled

Hi Everyone, gearhead1952, I agree. [edit: Oops I see Prof. Henry beat me to the comments.]

The numbers below the data point are for the Yellow/Shewman's stats. Numbers for the Magenta/Stant are above the data point.

Because the lines cross in a couple of places, the numbers where they cross look weird. A good example is the last two points. The yellow is 189 and the magenta is 182.

Gotcha, thanks for the clarification.

[FlatheadTed]

The statement . So, the holes drilled in them really do defeat the purpose of a thermostat I go along with .The idea of a thermostat is it opens and shuts to maintain and maximise working tempt ,From my experience you only need to drill one hole in it to screw up its function ,Ted

Originally Posted by Old Henry

Later today did a 150 mile round trip to Mirror Lake climbing up over 10,000 feet. On the way down the Shewman stats let the engine get clear down to 120° for the 30 miles coming down the mountain, 60° below their rating of 180°, the temperature that they opened when tested before installing them. So, the holes drilled in them really do defeat the purpose of a thermostat.

[Mart]

The results look pretty convincing to me, I use stock type 'stats in mine, with a very small hole drilled to allow filling and air purge.

When I say stock they are the common type found on UK Minis and the like from the sixties.

Mart.

[flatjack9]

Common sense prevails here.

[FlatheadTed]

Most have a hole in them but if non then a purge hole is needed ,I drilled 3 1/8 " holes in one and it wouldn't get up to Temperature, The idea is to have a Radiator larger or more efficient than what's needed then the thermostats keeps it up to the ideal temperature . Hats of to Shoeman for trying to solve a over heating problem by increasing flow ,A more efficient Radiator would be one answer .

[Old Henry]

To illustrate how critical it is that the thermostats shut the water flow completely off to maintain the water temperature, the stock thermostats actually have a check valve in the burp hole that opens to let air through.



But closes when water tries to come through.



That's the one weakness of the Stant stats - no burp hole. I drilled a 1/6" hole for such which may account for the minimum temperature being 10° below the stat's rating of 170° on the graph. But, the Shewman stats allowed 40° below their rating of 180° in this test but 60° below later in the day on a longer drive.

[Cecil/WV]

So tell me, what's the big deal about having a bleed hole? For the last 60 yrs. I have just filled my radiator and let the engine warm up and then top off the water and it is good to go, never a problem.

[Mart]

Many stats have a small indentation in the seat that the inner part seals against. This allows air to vent out and limits water leakage to an acceptable minimum.

Others have a small hole, others have a jiggle pin like pictured. Some have nothing.

Mart.

[Ross F-1]

Originally Posted by Mart

Many stats have a small indentation in the seat that the inner part seals against. This allows air to vent out and limits water leakage to an acceptable minimum.

Mart.

The Stants have a wavy edge in (I recall) 3 places to allow air to escape. If you hold them up to the light it's easy to see.

[bobH]

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Originally Posted by Cecil/WV

So tell me, what's the big deal about having a bleed hole? For the last 60 yrs. I have just filled my radiator and let the engine warm up and then top off the water and it is good to go, never a problem.

So, it's NO big deal if you never have a problem. I was probably close to the same 60 years into my own engine 'career', when I encountered MY first problem. I had a fresh build, with an air pocket that didn't allow the t-stat to open soon enough (on first start-up), and I got that fresh engine hot enough to burn the new paint. So, starting then, I put in a 1/16 hole like Henry shows, if the stat does not already have a built-in bleed. JMO

[Old Henry]

Originally Posted by Mart

Many stats have a small indentation in the seat that the inner part seals against. This allows air to vent out and limits water leakage to an acceptable minimum.

Others have a small hole, others have a jiggle pin like pictured. Some have nothing.

Mart.

Originally Posted by Ross F-1

The Stants have a wavy edge in (I recall) 3 places to allow air to escape. If you hold them up to the light it's easy to see.

I think I see one of those little "notches" you're talking about on the Stant on the right (the left one is a stock one with the jiggle pin). Wonder if they work? Might have skipped drilling the hole in mine. Good to know if I ever have to replace them.

[Mart]

Yeah, prof there looks like a small divot out of the od of the inner part, just to the left of the end of the spring. The ones I have seen have been on the outer part, but they achieve the same.

I imagine it is a latter day cost saving. A little notch is probably cheaper than making and assembling a jiggle pin.

Mart.

[HCO41]

First, I want to thank Old Henry for taking the time to do this test and put the data together. I learned a lot about thermostat function from most of the posters.
Seems that JM35Sedan and V8COOPMAN would rather criticize the condition of the test vehicle and repair methods used on same than accept the efforts in putting the data together.
I look at it this way. The tests were done on successive days with the engine in the same condition for each test. If the tests were done on a "perfect" engine in a "perfect" car I can only assume that if the data were even slightly different, the results would be relative. Where the numbers on the graph may be confusing, the impact of a graph is visual and data can be generalized by paying attention to the x and y axises. My first take on the graph was that the yellow line (Shewman's) was taking some radical dips when the function of a thermostat is to keep the engine temperature as constant as possible.
Old Henry is another asset to this forum. If we didn't have those who did this kind of testing and shared their knowledge with us through this forum and their writings a lot of us would be lost. So, thanks to: JWL, Pete, Gofast, 'Ol Ron, Walt, Charlie NY, V8Bob and all the others who take the time to gain knowledge of our interests and share it.
Howard

[John R]

Originally Posted by HCO41

First, I want to thank Old Henry for taking the time to do this test and put the data together. I learned a lot about thermostat function from most of the posters.
Howard

Yes! Thanks,Old Henry.

[FlatheadTed]

GM promotes this product ,no disrespect meant but I think ,they need rethinking

[G.M.]

Originally Posted by FlatheadTed

GM promotes this product ,no disrespect meant but I think ,they need rethinking

How do you know if you never used them??? The test information provided is from an unreliable source who bad mouthed Shewmans stats before he ever saw one. I doubt if he tried them he followed instructions on how to install them. The chart looks phony to me. I KNOW the Stant stats he promotes cause the engine to run at elevated temperatures in 90 degree outside temperatures. I have probably the coolest running stock radiator flathead that exists. A 39 P/U stock radiator, Skips hi flow pumps, 6 blade industrial fan, 4 lb pressure cap and a shroud. This truck was run in the flea market at a EFV8 meet on a day over 100 degrees at a fast idle for over 2 hours and never got over 180 degrees with no stats. When raced a little the temperature came down. I went to lunch and left Ken ct watch it for me. This was run with no stats. Later that summer driving the truck it was running at 165 so I tried the same Stant stat with and without holes in the flange to help increase the flow caused by the small flow opening. The 6 or 8 3/16" holes in the flange helped cool a little better but caused the truck to run above 190+ on the road at driving speeds and hotter in traffic.
The truck now has Shewmans 180 stats in it and runs at 178 to 182 at all times. I have his stats in several other 30's Fords and they all run very close to 180 in hot summer. I only tested them in temperature above 45 or 50 degrees and they ran in the 170 range. My testing is uniform under the same conditions most of the time. The best most accurate testing is done with the car in a stationary position with a large house type fan against the grill at an engine speed in the 25 MPH range. I find that the temperatures I get in this type of test are exactly what I get on the open road. Idle and traffic temperatures on stock radiators varies greatly because of the poor fans on most of these cars. I use and promote Shewman's stats because they are the only ones I know of that don't restrict the flow of coolant. G.M.

[HCO41]

GM, while I and others appreciate your experience, there's no reason to criticize Old Henry's ability to install his thermostats properly unless, of course, you were there to see the process. Same goes for the graph!
I suggest that you and Old Henry get together and perform the same tests and share your data with us.
Seems to me that would be more productive than knocking his efforts!
Howard

[Old Henry]

Shewman's stats were installed per his instructions. One can't really screw up the installation unless one puts them in backwards which is unlikely since Bob marks on them which end goes toward the radiator.

Every piece of data on my data chart was photographed, i.e. I watched the odometer and at every mile took a quick digital picture of my watch for time, the ambient temperature thermometer, the odometer, the water temperature gauge, and the GPS giving the altitude. Each picture has it's built in date and time stamp verifying all data both digitally and photographically. That data is on the table in PDF format attached to my first post (and this one) for all to see and analyze and is what VeryTangled used for his graph.

Although any old thermostat will probably work fine just driving level roads in hot temperatures near sea level, I needed one that would be best for extreme driving which I do - from 10° F in the winter to 100°+ in the summer and at altitudes from below sea level to over 14,000 feet and inclines up to 10%. That's part of why I did the testing and have reached the conclusion that I have reported.

[Old Henry]

In response to G.M.'s emotional irrational tirade, I say again what I said before: "If you can't refute the message, all you can do is kill the messenger."

[Mart]

It's a thermostat guys, no need to get mega emotional about it and start bringing peoples efforts into question.

Just use whatever works for you and what you are happy with.

My 75 degree C Mini stats work just dandy, thanks.

Mart.

[Old Henry]

Here is one set of data photographs mentioned in case anyone is interested.

[51 MERC-CT]

Originally Posted by Old Henry

Here is one set of data photographs mentioned in case anyone is interested.

Ya! I sort 'a like the GPS.
Some times I deliberately make wrong turns just so I can hear the GPS lady say "recalculating"

[flatjack9]

Old Henry does real world testing. Gm's test are done in a static, controlled environment.

[G.M.]

Originally Posted by flatjack9

Old Henry does real world testing. Gm's test are done in a static, controlled environment.

Initial tests are done static which provide consistent results. Then the driving tests which were also done with the same distance traveled over the same route dozens of times. Also Shewman's stats were in during the entire vapor lock testing and stayed at 180 + or- 2 degrees on all of those tests. Henry showed pictures of his Stat installation and the condition of the insides of his heads which wasn't very impressive. Based on his prior trouble shooting and blotched repairs I don't have much faith in what he does. G.M.

[Old Henry]

I don't recall ever "blotching" a repair. Or, was that just "blotched" spelling?

Should we doubt everything that you do or say because you can't spell?

I rest my case.

[russcc]

Henry - Thank you for the facts.

[flatjack9]

Henry is not pushing a product either.

[Ryan]

A few of you guys are worse than school girls. I swear.