T stat number
Post Fiend
Joined: Apr 2002
Posts: 19,311
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From: Waterloo, Iowa
Yep, the el-cheapos from the drug store and once good aftermarket names have been causing lots of problems since outsourcing everything overseas in recent years. Buy a Motorcraft. Just about everything hanging on a rack these days or that comes in a blister pack, battery cables, vacuum caps, bulbs, you name it - is just trash. Not a bad plan to test it in a pot of boiling water before installation.
Logistics Pro
Joined: Nov 2011
Posts: 4,685
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From: Northville, MI
Just curious but why do you want to change your thermostat? You might want to test it in boiling water first. Many thermostats that are replaced are really OK and overheating problems lie elsewhere. Just a suggestion.
Fleet Owner
Joined: Jul 2004
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From: NM
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Senior User
Joined: Aug 2011
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From: tinley park
The stat was all rusted and so was the housing.. took off intake and cleaned it out to will be putting it back on next day or so..than I can hook up radiator..
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More Turbo
Joined: Aug 2009
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Sorry I don't have the MotorCraft number handy, but any Ford dealer should have them on the shelf
Logistics Pro
Joined: Nov 2011
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From: Northville, MI
They are usually brass so if it is rusted it is cooling system residue and should clean up. I would still test it.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
The second you mention the year, most of these parts clucks say OBSOLETE whether the part is or not, because they don't want to bother, just "shine you on."
1965: Ford changed the thermostat sizes on most vehicles, what they didn't change in 1965, they did by mid-year 1966.
Originally the flange diameter was 2 1/2" .. but after Ford changed 'em, the flange diameter: 2 1/8."
NAPA has the 2 1/2" flange diameter Y block thermostats (same as 1958/65, some 1966 FE engines), but are not listed in their computers.
So you have to get the parts clucks to look in their paper parts catalogs, usually stashed under the counter.
Ford: A8AZ-8575-D .. 160 degree T/Stat (Motorcraft RT-16) / Obsolete ~ GREEN SALES has 36 // A8AZ-8575-E .. 180 degree T/Stat (Motorcraft RT-18) / Obsolete ~ GREEN SALES has 64.
Lead Driver
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From: Wentzville, MO
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Did Y blocks use the same flange size from 53 to 64, including the Lincoln variants?
Napa #6 will work, there's a thread over at the Ford Barn discussing this. A big block chrysler or Mopar 440 uses the same size, Mr Gasket 4367 - 180°, brass, made by Robert Shaw. Good choice.
160° stats were spec'd before "permanent" antifreeze came into wide use, when methanol and water was used. I believe they are too cold for efficient operation and especially, burning off sludge and condensation. One thing Y blocks had a problem with before detergent motor oils was sludge buildup and oiling to the valvetrain. I would use a 180° thermostat at minimum, but only a 195° in the wintertime, as it is noticeably hotter for good heater output. Engine wear and sludge buildup is reduced by quite a lot with proper engine running temperature. Y block cylinders have lots of meat on them as a class they are known to have some problems but running hot is not one of them.
Napa #6 will work, there's a thread over at the Ford Barn discussing this. A big block chrysler or Mopar 440 uses the same size, Mr Gasket 4367 - 180°, brass, made by Robert Shaw. Good choice.
160° stats were spec'd before "permanent" antifreeze came into wide use, when methanol and water was used. I believe they are too cold for efficient operation and especially, burning off sludge and condensation. One thing Y blocks had a problem with before detergent motor oils was sludge buildup and oiling to the valvetrain. I would use a 180° thermostat at minimum, but only a 195° in the wintertime, as it is noticeably hotter for good heater output. Engine wear and sludge buildup is reduced by quite a lot with proper engine running temperature. Y block cylinders have lots of meat on them as a class they are known to have some problems but running hot is not one of them.
Fleet Owner
Joined: Dec 2000
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From: Central PA
This is what I found out about thermostats this spring when I was deciding which T-stat to use.
The Stant tech called me back. Here's the details about their T-stats:
The 160° T-stat starts to open at 160° and is full open at 180°.
The 180° T-stat starts to open at 180° and is full open at 200°.
The 1954 shop manual has two listings in the spec section.
STANDARD: opens at 152 -157°, full open at 177°.
HIGH TEMP: opens at 167-172, full open at 192°.
So I put my old 160 degree T-stat back in as it is closer to the shop manual spec. The 180 T-stat is not fully open until 200 degrees and that is 8* higher than the book calls for with the high temp T-stat.
My Temp gauge points between half and Hot when warmed up.
The Stant tech called me back. Here's the details about their T-stats:
The 160° T-stat starts to open at 160° and is full open at 180°.
The 180° T-stat starts to open at 180° and is full open at 200°.
The 1954 shop manual has two listings in the spec section.
STANDARD: opens at 152 -157°, full open at 177°.
HIGH TEMP: opens at 167-172, full open at 192°.
So I put my old 160 degree T-stat back in as it is closer to the shop manual spec. The 180 T-stat is not fully open until 200 degrees and that is 8* higher than the book calls for with the high temp T-stat.
My Temp gauge points between half and Hot when warmed up.