Thermostats
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Junior User
Joined: Dec 2003
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Thermostats
What brand of thermostat do you guys recommend ?
I recently purchased a 91 F-250 4wd , it's a 4.9l zf 5spd. I replaced all the hoses , belt , belt tensioner , flushed the system , replaced the t-stat and housing , but I never get above the first "hash" mark on the temp gauge . The t-stat came from the "zone" , that may be the problem ....... lol !
Been slowly going thru the old girl , new exhaust , new shocks , complete tune up and all fluids and filters , {all Motorcraft} , clean codes from the ecm with the help of this site , she runs great now , just concerned about the engine getting up to proper operating temperature and fuel economy.
Thanks , Volks
I recently purchased a 91 F-250 4wd , it's a 4.9l zf 5spd. I replaced all the hoses , belt , belt tensioner , flushed the system , replaced the t-stat and housing , but I never get above the first "hash" mark on the temp gauge . The t-stat came from the "zone" , that may be the problem ....... lol !
Been slowly going thru the old girl , new exhaust , new shocks , complete tune up and all fluids and filters , {all Motorcraft} , clean codes from the ecm with the help of this site , she runs great now , just concerned about the engine getting up to proper operating temperature and fuel economy.
Thanks , Volks
Posting Guru
Joined: Nov 2009
Posts: 2,244
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uhm brand really isnt the issue nore where u baught it... it all depends really on what *F u got unless it was a made in japan china tiwan korea or vietnam then i would stay away from them but my truck is an f150 with the 5.0 and i stay on the N on normal the guages arent perfect in these trucks and may be off a little but if ur heater is blowing flames then ur in good shape lol
Lead Driver
Joined: Nov 2002
Posts: 9,557
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From: Concord, NC
I recommend Motorcraft for thermostats for the proper temperature rating and OEM function.
Sorry to sound like a sales pitch, but this is what was recommended to me by a trusted mechanic friend of mine.
Sorry to sound like a sales pitch, but this is what was recommended to me by a trusted mechanic friend of mine.
Posting Guru
Joined: Jun 2003
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From: southwest michigan
Do you remember what temp you bought? it should be 195°F. I bought my truck and the guy that had it before me had a 160°F in there.
I've heard that down that low they can cause problems.
I've heard that down that low they can cause problems.
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Junior User
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195'
I bought a 195 degree t-stat. I have been told Napa t-stats hold temperature better than the discount parts house brands.
Thanks for all the replies ! This site has been a BIG help getting the bugs worked out of the old truck !
Thanks for all the replies ! This site has been a BIG help getting the bugs worked out of the old truck !
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Elder User
Joined: Feb 2007
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From: Chicagoland
I hear horror stories about AutoZone t-stats but I've never had a problem. However, I always check my new t-stats before installing them. A 195F stat in a pot of water should START to open right before the water begins to boil. It should be fully open once the water hits a rolling boil. You should see it close pretty quickly when you pull it out of the water. *(disclaimer: use tongs, gloves, mits, pliers, old coathanger to handle the hot t-stat - DUH)
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Junior User
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From what I have read on this site , 180' seems to be the magic number between open and closed loop for the ecm. Does the ecm determine that from the temperature sending unit and if so , what reading should I see at the sending unit ?? Guessing it's a resistance based value .
Lead Driver
Joined: Nov 2002
Posts: 9,557
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From: Concord, NC
From what I have read on this site , 180' seems to be the magic number between open and closed loop for the ecm. Does the ecm determine that from the temperature sending unit and if so , what reading should I see at the sending unit ?? Guessing it's a resistance based value .
Posting Guru
Joined: Jun 2003
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From: southwest michigan
Somewhere near 180 is when the computer enables closed loop fuel control, yes. The computer has a coolant temperature sensor that is uses to scale the fuel and spark based on the current engine temperature. The sensor does vary resistance with temperature, but I do not know off the top of my head what the specific values should be. You could try checking at fordfuelinjection.com or look in a Haynes manual.
Lead Driver
Joined: Nov 2002
Posts: 9,557
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From: Concord, NC
Either always in open loop or not in closed loop as much as it would be fully up to temperature. This could cause poor fuel mileage, because the computer runs the engine progressively richer the colder the engine gets.