Thermostat troubles
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From: Perry Georgia
Thermostat troubles
I am on my second thermostat in 2 weeks. My truck is a 1987 F250 with a non-turbo 6.9. I can't tell the exact temprature since I'm using the original Ford temp gage. Anyway, after putting the brand new FORD thermostat in the temp gage stayed between the "n" and the "o" (normal) and doesn't vary till I shut it down. It also warmed up within 3 to 5 miles. When i'd restart it the temp was still about the same as when I shut it down if I wasn't gone long, an hour or less. After about 2 or 3 days. It takes it takes about 10 miles to warmup. The needle only gets up to the "N" and will vary all the back down to the cold line for up to 10+miles on the temp gage going down the road. When i stop to go into a store for just a couple of minuets the temp gage will be all the way down to the cold line and another 10 min warmup. It's like the thermostat is sticking open but on a new thermostat? The thermostat I took out about 3 weeks ago was in the truck for about a year when it started going crazy. Could there be trash in the coolant stopping up the thermostat? Right now I'm looking for a coolant filter setup.
Senior User
Joined: Jun 2004
Posts: 477
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From: florida
only buy a motorcraft thermostat. after market all blow up. 2 aftermarkets in 3 months, bought motorcraft 2 years ago, no worries.
my bad, you said you had a ford thermostat. you have the best already.
my bad, you said you had a ford thermostat. you have the best already.
Lead Driver
Joined: Nov 2003
Posts: 6,900
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From: Campbell River, B.C.
There is a check ball in ther theremostat housing, sometimes they can fall out when servicing the thermostat, might be worth checking. Also do you have any other way of checking if the temp gauge is in fact reading accurate?
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Joined: Mar 2005
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From: KY
Ford dashes back then were not very accurate. My 83 and 86 dashes would eat voltage regulators which would allow the dash to go stupid.
Let me back up. Dashes like these have voltage regulators in them. Plug like a 9 volt battery on the back side of the dash. They have to have them to keep a constant voltage to the cluster so the signal voltage to your senders won't vary. As your truck runs and you do different things, lights ect. the charging voltage will vary some and if you didn't regulate the voltage to your senders they will go up and down will the alternator. A tenth of a volt matters.
My 83 would last about 6 months and would go out. I would try a mechanical gauge to varify your coolant temp.
Let me back up. Dashes like these have voltage regulators in them. Plug like a 9 volt battery on the back side of the dash. They have to have them to keep a constant voltage to the cluster so the signal voltage to your senders won't vary. As your truck runs and you do different things, lights ect. the charging voltage will vary some and if you didn't regulate the voltage to your senders they will go up and down will the alternator. A tenth of a volt matters.
My 83 would last about 6 months and would go out. I would try a mechanical gauge to varify your coolant temp.
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From: Perry Georgia
catfis101: Where do you plug in the 9 volt battery? Is there a plug on the back of the dash? I've had the dash loose but not out because the dash felt like it was pulling the wires loose and i'm not looking to play guess which wire goes where! I looked under the dash and needless to say, air has a hard time getting thru the mess under the dash. Why can't they make the underside of the dash easy to get thru? Oh yea, the dealer has to have somthing to work on.
As far as the ball in the bypass, I've already placed the copper/brass fitting in the thermostat housing last year when I had the housing off to replace the thermostat.
I know what you mean Harleyjohn about the thermostat blowing up. I replaced 2 from advance auto before I read the post about only using FORD Thermostat. One literally broke apart, the other one was worthless as it didn't keep a steady temp. It was more like a bungy cord, Up then down then back up. Kind of like what mine is doing right now.
As far as the ball in the bypass, I've already placed the copper/brass fitting in the thermostat housing last year when I had the housing off to replace the thermostat.
I know what you mean Harleyjohn about the thermostat blowing up. I replaced 2 from advance auto before I read the post about only using FORD Thermostat. One literally broke apart, the other one was worthless as it didn't keep a steady temp. It was more like a bungy cord, Up then down then back up. Kind of like what mine is doing right now.
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From: KY
It isn't a 9 volt but it reminds me of a 9 volt type plug. On the 83 dash it is above the speedo head. It screws to the dash cluster and the printed circuit plugs into it. It looks like an older circuit breaker and it is about that size. I don't know about the 87 dash. It may be the same. Somebody on here may know.
Pull the dash out a little bit and feel on the top side of the dash over the speedo and see if you can feel it.
Pull the dash out a little bit and feel on the top side of the dash over the speedo and see if you can feel it.
Last edited by catfish101; Feb 5, 2008 at 04:08 PM.
Postmaster
Joined: Dec 2002
Posts: 3,594
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From: Southern Oregon USA
I put a Stant T-stat in mine about 4 years ago. I haven't had an issue with it.
I would definetely look into a gauge issue. Like everyone has said, Ford is notorious for having inaccurate gauges in these years. When you shut the truck off warm and then restart after the 10 minutes, does your heater blow warm air when the gauge says it's cold?
Jason
I would definetely look into a gauge issue. Like everyone has said, Ford is notorious for having inaccurate gauges in these years. When you shut the truck off warm and then restart after the 10 minutes, does your heater blow warm air when the gauge says it's cold?
Jason
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Post Fiend
Joined: Nov 2004
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From: Manitoba
The item your looking for is an IVR... instrument voltage regulator.... any AP store or Ford dealer will have them...... they are a little silver box on the rear of the cluster.....
Was the Tstat you installed a short stubby one or a long one.......
Was the Tstat you installed a short stubby one or a long one.......
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Cargo Master
Joined: Nov 2003
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From: Duluth, Mn.
More than likely, it's the temp sender. After all the coolant draining, there might be an air pocket around the base of the sender. Or it could be shot.Try running the truck to temp, then sloooolwy unscrewing the sender, just untill you get some coolant to seep around the sender. Then tighten it back down.
Don't trust the guage. Ford guages are jsut glorified idiot lights. As long as you get heat, and your not over eating the thermostat is prolly doing it's job, just as designed.
After reading your post again. It sounds like you've got air in your cooling system.
Are the radiator, and expansion bottle properly filled. Are you losing coolant?
Don't trust the guage. Ford guages are jsut glorified idiot lights. As long as you get heat, and your not over eating the thermostat is prolly doing it's job, just as designed.
After reading your post again. It sounds like you've got air in your cooling system.
Are the radiator, and expansion bottle properly filled. Are you losing coolant?
Last edited by fonefiddy; Feb 6, 2008 at 04:53 AM.
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From: Perry Georgia
Ok, I drained the coolant system completely including blowing any coolant in the heater circuit out with an air compressor. Refiled the coolant and keep topping it off in the radiator and overflo tank . I'm still using the original temp gage but also have an IR thermometer with the red laser dot to compare temps. I just got home from a round trip of 20 miles and the highest temp at the thermostat housing was 174. Checking temps around the engine showed that was the highest temp other than the exhaust. Also the fan clutch was replaced within the last 6 months and you can hear the fan disengage around 45/50 mph.
Last edited by dyoungen; Feb 7, 2008 at 04:44 PM.
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From: Perry Georgia
Well, after blocking the radiator with a piece of cardboard, going 15 miles and the temp gage reading in the cold zone, I'm going to replace the Ford temp gage with an aftermarket gage. I was checking for a 212 degree thermostat and coundn't find one. Are there any 212 degree thermostats ?
Cargo Master
Joined: Nov 2003
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From: Duluth, Mn.
Depending on where you live, 20 miles might not warm the engine to operating temp.
No 212 thermo's. Stick with the stock Ford/IH. Any others will not work properly.
Theres an Ohm scale in the FSM, to trouble shoot the sending unit. I believe the last one I replaced was under $20 from Ford.
No 212 thermo's. Stick with the stock Ford/IH. Any others will not work properly.
Theres an Ohm scale in the FSM, to trouble shoot the sending unit. I believe the last one I replaced was under $20 from Ford.
Last edited by fonefiddy; Feb 9, 2008 at 04:19 PM.