Thermosat

LarryW

LarryW

Well-known member
Mar 28, 2002
6,028
756
113
Menomonie, WI.
How are they suppose to work?

I have three thermostats in hot water. A Stant 195, a brass Robetshaw 195, and a steel Robertshaw 195.
Here is how they open

Stant begins opening at 190, full open at 195. (This one ran at 195 unless ambient was above 85, then ran to 200.)
Brass Robertshaw begins open at 175, full open at 1985. (This is an old one I took out because engine ran colder than I wanted. Hard to get heat out
of dash in cold weather)
Steel Robertshaw begins open at 194 full open at 204. (This is a brand new one, not run yet)

How is a 195 suppose to operate?

IMO a 195 should being open at 192 or so with full open 197 or something like that.

What do ya all think?
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
 
There is no precise opening and closing as it is reliant on the wax that
expand and contracts.
It is automotive grade so not worth the time to be measuring.

On Tue, Jun 9, 2020 at 7:54 AM Larry via Gmclist
wrote:

> How are they suppose to work?
>
> I have three thermostats in hot water. A Stant 195, a brass Robetshaw 195,
> and a steel Robertshaw 195.
> Here is how they open
>
> Stant begins opening at 190, full open at 195. (This one ran at 195
> unless ambient was above 85, then ran to 200.)
> Brass Robertshaw begins open at 175, full open at 1985. (This is an old
> one I took out because engine ran colder than I wanted. Hard to get heat out
> of dash in cold weather)
> Steel Robertshaw begins open at 194 full open at 204. (This is a brand
> new one, not run yet)
>
> How is a 195 suppose to operate?
>
> IMO a 195 should being open at 192 or so with full open 197 or something
> like that.
>
> What do ya all think?
> --
> Larry
> 78 Royale w/500 Caddy
> Menomonie, WI.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502
 
> There is no precise opening and closing as it is reliant on the wax that
> expand and contracts.
> It is automotive grade so not worth the time to be measuring.
>
> On Tue, Jun 9, 2020 at 7:54 AM Larry via Gmclist

>
> > How are they suppose to work?
> >
> > I have three thermostats in hot water. A Stant 195, a brass Robetshaw 195,
> > and a steel Robertshaw 195.
> > Here is how they open
> >
> > Stant begins opening at 190, full open at 195. (This one ran at 195
> > unless ambient was above 85, then ran to 200.)
> > Brass Robertshaw begins open at 175, full open at 1985. (This is an old
> > one I took out because engine ran colder than I wanted. Hard to get heat out
> > of dash in cold weather)
> > Steel Robertshaw begins open at 194 full open at 204. (This is a brand
> > new one, not run yet)
> >
> > How is a 195 suppose to operate?
> >
> > IMO a 195 should being open at 192 or so with full open 197 or something
> > like that.
> >
> > What do ya all think?
> > --
> > Larry
> > 78 Royale w/500 Caddy
> > Menomonie, WI.
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> --
> Jim Kanomata
> Applied/GMC, Newark,CA
> jimk
> http://www.gmcrvparts.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

I know it is not a precise thing, but both Robertshaws are 195's, were purchase from you (several years apart) and are opening at such radically
different temps, and the new one doesn't fully open nearly as far as the old brass RS. Changing the thermostat in the Cadillac engine is not an easy
task, and I don't want to be putting a faulty RS in, only to be taking it out again a week from now. Just say'n.

--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
 
> How are they suppose to work?
>
> I have three thermostats in hot water. A Stant 195, a brass Robetshaw 195, and a steel Robertshaw 195.
> Here is how they open
>
> Stant begins opening at 190, full open at 195. (This one ran at 195 unless ambient was above 85, then ran to 200.)
> Brass Robertshaw begins open at 175, full open at 185. (This is an old one I took out because engine ran colder than I wanted. Hard to get heat
> out of dash in cold weather)
> Steel Robertshaw begins open at 194 full open at 204 but does not open as far as the brass RS. (This is a brand new one, not run yet)
>
> How is a 195 suppose to operate?
>
> IMO a 195 should begin open at 192 or so with full open 197 or something like that.
>
> What do ya all think?

This guy boiled a pot of 195's and they were all different
https://youtu.be/WQWIop3ZM8o
https://youtu.be/WQWIop3ZM8o

--
Wally Anderson
Omaha NE
75 Glenbrook
Megasquirt III injection
Bob Stone hydroBOOOOST
Manny reaction arm system
Branscombe Kelsey Hayes park brake
http://wallyandsue.blogspot.com/
 
What are you guys using for coolant? What % of ethelyne glycol and water
are you using? Name brand glycol, or brand XX? Distilled water or whatever
runs out of your garden hose?
Reason for asking. You seem to be messing with thermostats a lot more
frequently than we do out West. I put in a new one, "just because" I was
replacing new hoses and a water pump. That was 4 or 5 years ago. Engine
still seems to run at about the same temperature as it always did before.
Is it the humidity back there higher than it is out here? I don't know.
Jim Hupy
Salem, Oregon

On Tue, Jun 9, 2020, 11:46 AM Wally Anderson via Gmclist <

> > How are they suppose to work?
> >
> > I have three thermostats in hot water. A Stant 195, a brass Robetshaw
> 195, and a steel Robertshaw 195.
> > Here is how they open
> >
> > Stant begins opening at 190, full open at 195. (This one ran at 195
> unless ambient was above 85, then ran to 200.)
> > Brass Robertshaw begins open at 175, full open at 185. (This is an old
> one I took out because engine ran colder than I wanted. Hard to get heat
> > out of dash in cold weather)
> > Steel Robertshaw begins open at 194 full open at 204 but does not open
> as far as the brass RS. (This is a brand new one, not run yet)
> >
> > How is a 195 suppose to operate?
> >
> > IMO a 195 should begin open at 192 or so with full open 197 or something
> like that.
> >
> > What do ya all think?
>
> This guy boiled a pot of 195's and they were all different
> https://youtu.be/WQWIop3ZM8o
> https://youtu.be/WQWIop3ZM8o
>
> --
> Wally Anderson
> Omaha NE
> 75 Glenbrook
> Megasquirt III injection
> Bob Stone hydroBOOOOST
> Manny reaction arm system
> Branscombe Kelsey Hayes park brake
> http://wallyandsue.blogspot.com/
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
The second one is a 180 degree thermostat or at least it is acting like one that is going bad. The steel Robert Shaw acts I see most 180 thermostats
only for the 195 range. They at open at 1 or 2 degrees before and fully open at 3 to 5 degrees after their temperature rating.

I do not have anything that I run a 195 in, but I assume they are similar in design with with a 180 with a different wax pellet.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
According to a GM 1970 big book Buick factory service manual “the 195 stat starts to open at 190 and is full open by 212F”.
It’s not an on /off switch but a variable throttle plate that modulates to try to keep temp at or above the rated point. Above that open is open
and it’s not controlling temp rise.
Today’s stats are mostly cheap junk and not packaged well to survive drops in shipping etc with just an unpadded thin box. I have had best luck with
Stant Superstats which throttle more accurately and I just put in the Flowkooler 195 from JimK in the 455. Only 100 highway miles so far but seems
very steady.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
For coolant I mix Advance's glycol antifreeze half and half with distilled water from the grocery. The water is a dollar a gallon, ikf you buy ready
mixed coolant you pay about 2.50 for the water.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
This is all no surprise to me. Even the durability engines run in dynoland are not run with a thermostat. Years ago it was discovered that the
manufacturing variability was too wide to be acceptable.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
Matt, did you use a washer to restrict flow to an open 'stat, or run totally without?

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
I drove cross country twice in August of 2011 with a Mondello Washer instead of a thermostat, I had no problems.
Once winter came, it did not get warm enough to heat the interior, so I put a thermostat in.
I tried many, and in my opinion, no matter which one I used, it always ran hotter.
I am having other issues now that may be the cause of it running hotter, but I am very tempted to put the washer back in for the summer.
--
1973 GMC 26' Glacier - Unknown Mileage - Has a new switch pitch transmission with Powerdrive
 
Just call me and I’ll replace it n/c
You do need to return.

On Wed, Jun 10, 2020 at 5:51 AM Michael via Gmclist
wrote:

> I drove cross country twice in August of 2011 with a Mondello Washer
> instead of a thermostat, I had no problems.
> Once winter came, it did not get warm enough to heat the interior, so I
> put a thermostat in.
> I tried many, and in my opinion, no matter which one I used, it always ran
> hotter.
> I am having other issues now that may be the cause of it running hotter,
> but I am very tempted to put the washer back in for the summer.
> --
> 1973 GMC 26' Glacier - Unknown Mileage - Has a new switch pitch
> transmission with Powerdrive
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502
 
> Matt, did you use a washer to restrict flow to an open 'stat, or run totally without?
>
> --johnny

Johnny,

Very early on we tried to run some without any thing at all and it caused all kinds of problems. Ever after that, we either ran with a blocked open
'stat, or a restrictor as specified by the client.

It was strange and took us a while (and a couple of durability engines) to find out what the problem was. Without the restrictor, temperatures looked
good, but we saw over-heat damage on tear down. We later surmised that the issue was that at high crankshaft speeds (and high loads) the coolant was
going through the passages such that it did not always pick up the heat. This was a boundary layer issue. I doubt it could happen in the real
world.

Matt

--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
I can tell you it happens, if racing is real world. The Spridget we sponsored at Mac's (the inspector was the driver) would overheat with no 'stat.
Mac did some destructive testing and we used a washer a bit bigger than the 'stat opening. Worked fine.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
I’ve also seen overheat problems on several vehicles that had the thermostat removed. Upon installing a good thermostat, the o/h problems went away.

I have always had the belief that removal of the thermostat allowed coolant velocity to increase, causing the coolant to pass through the radiator too fast. This I figured would result in the coolant not being able to shed the heat due to reduced “dwell time” in the rad. With Matt’s comments, i now realize that velocity and dwell time in the engine is also a factor.

I’m thinking that the test described by Bob may not be a reliable method under certain conditions. High flow water pumps, high ambient air temps, poor airflow through rad, etc. can all cause varied results.

Les Burt
Montreal
'75 Eleganza 26'

>
> I can tell you it happens, if racing is real world. The Spridget we sponsored at Mac's (the inspector was the driver) would overheat with no 'stat.
> Mac did some destructive testing and we used a washer a bit bigger than the 'stat opening. Worked fine.
>
> --johnny
> --
> Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
> Braselton, Ga.
> I forgive them all, save those who hurt the dogs. They must answer to me in hell
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
When I use to Drag Race , we had to put a restrictor when we ran the 455 to
not overheat.

On Thu, Jun 11, 2020 at 7:26 AM Les Burt via Gmclist <

> I’ve also seen overheat problems on several vehicles that had the
> thermostat removed. Upon installing a good thermostat, the o/h problems
> went away.
>
> I have always had the belief that removal of the thermostat allowed
> coolant velocity to increase, causing the coolant to pass through the
> radiator too fast. This I figured would result in the coolant not being
> able to shed the heat due to reduced “dwell time” in the rad. With Matt’s
> comments, i now realize that velocity and dwell time in the engine is also
> a factor.
>
> I’m thinking that the test described by Bob may not be a reliable method
> under certain conditions. High flow water pumps, high ambient air temps,
> poor airflow through rad, etc. can all cause varied results.
>
> Les Burt
> Montreal
> '75 Eleganza 26'
>
>
> > On Jun 11, 2020, at 8:27 AM, Johnny Bridges via Gmclist <

> >
> > I can tell you it happens, if racing is real world. The Spridget we
> sponsored at Mac's (the inspector was the driver) would overheat with no
> 'stat.
> > Mac did some destructive testing and we used a washer a bit bigger than
> the 'stat opening. Worked fine.
> >
> > --johnny
> > --
> > Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
> > Braselton, Ga.
> > I forgive them all, save those who hurt the dogs. They must answer to
> me in hell
> >
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502
 
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