Thermostats

[Blu Dice]

What's the deal with thermostats today - second set installed and again one or both delay in opening (180) - pegs to hot - then opens. Once open they operate normal. This is only happening during the first trip out after sitting overnite. should I install fail safes?

[JSeery]

When you say "pegs to hot" any idea how hot it is actually getting? If it is not boiling over is it really an issue?

[ford38v8]

I think that may be the nature of your dual electric sending units. The driver side sending a normal signal, and passenger side overrides that signal and pegs to hot. ...So, once the mechanical valve opens, the passenger side opens and the gauge will again read only the driver side signal. Mine being an early model, I have a liquid filled sender and gauge, so I'm just blowing off some steam here...

[Blu Dice]

FYI I'm still running stock gauges. Has new belts, new hoses, '52 FH V8 with 37,000 actual original miles. I'm planning to install twin mechanical gauges very soon, but since the interior is still stock and in near perfect condition - being very picky of what and how I'm going to do it.

[Blu Dice]

BTW how does the water flow / thermostats operate in series - driver side first in line or passenger side first?

[34PKUP]

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Originally Posted by Blu Dice

BTW how does the water flow / thermostats operate in series - driver side first in line or passenger side first?

Never heard of thermostats running in series

[JSeery]

Flatheads use two separate cooling systems, one for each side of the engine, the only place they come together is in the radiator. In #3, ford38v8 was referring to the sending units, on one side there is a temperature sensing sender and on the other side an on/off switch.

[Blu Dice]

Well I guess maybe they aren't - ford38v8 comments made me think about that left & right thing, but since the two electric sending units are connected to one gauge - how do you know if a thermostat is acting up or a sending unit - and since there's two how do you determine which side is bad??

[JSeery]

A shop manual will give you the testing procedures, but the temp gauge and system is just a rough indication, if you want the actual temps you would need to install two separate quality gauges.

[Blu Dice]

Re diagram
Sending unit opens at 206 and gauge is showing hot - so I have nothing to be concerned about right - as long as the gauge drops down to mid range.

[JSeery]

Engine heat is not the issue, you don't want the water to boil. As long as it is not boiling or consistently running hot or spewing water out the overflow it is fine.

[Blu Dice]

None of that's happening so I guess I'm go to go huh? Thanks a bunch.

[Old Henry]

Originally Posted by Blu Dice

What's the deal with thermostats today - second set installed and again one or both delay in opening (180) - pegs to hot - then opens. Once open they operate normal. This is only happening during the first trip out after sitting overnite. should I install fail safes?

I just had a PM conversation with another barner whose stock temperature gauge does the same thing - pegs to hot then back down to normal operation. He just bought new thermostats and tested them before installing, and he has a mechanical gauge on the left side that shows normal operation. I've heard of that from others too. I don't think it has anything to do with the real temperature of the right side. I think your cooling system is working fine - just a little quirk in your stock gauge system.

[Old Henry]

Originally Posted by Blu Dice

FYI I'm still running stock gauges. Has new belts, new hoses, '52 FH V8 with 37,000 actual original miles. I'm planning to install twin mechanical gauges very soon, but since the interior is still stock and in near perfect condition - being very picky of what and how I'm going to do it.

Install your mechanical gauges in the glove box to take a peak at when you doubt your stock dashboard gauges or just want more accurate detail.

[Blu Dice]

Thanks Old Henry

[Drbrown]

Same long-term problem but culprit identified. I had 180 deg stats before. Testing found one opened at 190 deg other at 200 deg. Now have pair new 170 deg Stant thermostats that out of the box tested fine. Aftermarket mechanical gauge on left bank no longer spikes and gauge now rides between 160-170 deg. However, crazy stock sensor and stock gauge that serves right bank still spikes to "H" and back quickly to about 170 deg. Coolant in top radiator tank reads between 130 and 140 deg at idle. Even before new stats the system never overheated. Have new radiator, pumps, clean system, 50-50 Extended Life Preston. Either the stock sensor and/or the stock gauge are malfunctioning (I by-passed the stock two post sensor previously). Have spare used stock gauge - will see what that does !

[JSeery]

IMO your running your engine to cool, this decreases efficiency, increases sludge build up and increases engine wear.

[G.M.]

All thermostats are not created equally. I think Robertshaw 330-180
were the best ones made. They open and close between 178 and 182
on all the old Fords I have them in. They have a larger flow opening
then most other stats. Bob Shewman, [email protected] supplies them
for in the hose style for 32 to 48 years and the gooseneck mounted type
for 49 to 53 years. G.M.

[Old Henry]

Originally Posted by JSeery

IMO your running your engine to cool, this decreases efficiency, increases sludge build up and increases engine wear.

On the other hand, Mr. Ford thought 160° was right since that's what he put in the operator's manual. The Stant stats don't come in 160° but 170°. I still think that's cool enough. (And hot enough too.) Opinions do definitely vary.

[Old Henry]

Originally Posted by G.M.

All thermostats are not created equally. I think Robertshaw 330-180
were the best ones made. They open and close between 178 and 182
on all the old Fords I have them in. They have a larger flow opening
then most other stats. Bob Shewman, [email protected] supplies them
for in the hose style for 32 to 48 years and the gooseneck mounted type
for 49 to 53 years. G.M.

Before considering Shewman's stats review this real life controlled test of them vs. the Stants: https://www.fordbarn.com/forum/showthread.php?t=143576