Flaky temp readings before it settle down
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Junior User
Joined: Jul 2004
Posts: 86
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From: NE Kansas
Flaky temp readings before it settle down
I can't remember how long this has been going on, but probably six months or better.
On any given day, when warming up for the first time, the temp gauge reads like the t-stat is stuck closed as the gauge rises up about 5-15% above where it normally sits before coming back down to get settled. I thought I had a flaky t-stat and so I had Ford replace it during a recent cooling system flush (ouch/$$$). Anyway, it is still doing the same thing. If I back off the throttle it seems to help it settle down quicker and if I keep my foot out of the throttle all together, it seems to settle down even more quickly. The more throttle I give it, the higher the needle goes before settling down.
Needle runs at left leg of N during normal conditions. When it misbehaves, it usually goes up to the M before coming back down to the N.
water pump is about one year old. t-stat neck/connector is about 6 months old (dieselsite). Heater core is one week old.
On any given day, when warming up for the first time, the temp gauge reads like the t-stat is stuck closed as the gauge rises up about 5-15% above where it normally sits before coming back down to get settled. I thought I had a flaky t-stat and so I had Ford replace it during a recent cooling system flush (ouch/$$$). Anyway, it is still doing the same thing. If I back off the throttle it seems to help it settle down quicker and if I keep my foot out of the throttle all together, it seems to settle down even more quickly. The more throttle I give it, the higher the needle goes before settling down.
Needle runs at left leg of N during normal conditions. When it misbehaves, it usually goes up to the M before coming back down to the N.
water pump is about one year old. t-stat neck/connector is about 6 months old (dieselsite). Heater core is one week old.
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Junior User
Joined: Jul 2004
Posts: 86
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From: NE Kansas
I'll check everything you listed, but the fluid is only a few days old (changed by Ford), and it only happens once a day (from a cold start). It's as if there isn't enough system pressure to open the thermostat. After it has warmed up once, I can run it as hard as I like without issue.
Hotshot
Joined: Jul 2008
Posts: 11,231
Likes: 130
From: Thomasville, GA
I think that's pretty normal. Mine does that when it's first warming up. Goes up a tiny bit more than normal then settles at it's normal operating temp.
Do you have a EGT gauge? If not I'd get one. As long as you keep the EGT's under 1200* you should be ok.
Do you have a EGT gauge? If not I'd get one. As long as you keep the EGT's under 1200* you should be ok.
Elder User
Joined: Oct 2004
Posts: 782
Likes: 1
From: Olympia, WA
Check the coolant temp sensor connection at the top of the water pump. If the heater core is only a week old, any chance you have air in it still? Have you had it hot with the climate controls on hot?
FOREIGN GURU
Joined: Jul 2006
Posts: 7,655
Likes: 7
From: Celaya, Gto. MX
I can't remember how long this has been going on, but probably six months or better.
On any given day, when warming up for the first time, the temp gauge reads like the t-stat is stuck closed as the gauge rises up about 5-15% above where it normally sits before coming back down to get settled. I thought I had a flaky t-stat and so I had Ford replace it during a recent cooling system flush (ouch/$$$). Anyway, it is still doing the same thing. If I back off the throttle it seems to help it settle down quicker and if I keep my foot out of the throttle all together, it seems to settle down even more quickly. The more throttle I give it, the higher the needle goes before settling down.
Needle runs at left leg of N during normal conditions. When it misbehaves, it usually goes up to the M before coming back down to the N.
water pump is about one year old. t-stat neck/connector is about 6 months old (dieselsite). Heater core is one week old.
On any given day, when warming up for the first time, the temp gauge reads like the t-stat is stuck closed as the gauge rises up about 5-15% above where it normally sits before coming back down to get settled. I thought I had a flaky t-stat and so I had Ford replace it during a recent cooling system flush (ouch/$$$). Anyway, it is still doing the same thing. If I back off the throttle it seems to help it settle down quicker and if I keep my foot out of the throttle all together, it seems to settle down even more quickly. The more throttle I give it, the higher the needle goes before settling down.
Needle runs at left leg of N during normal conditions. When it misbehaves, it usually goes up to the M before coming back down to the N.
water pump is about one year old. t-stat neck/connector is about 6 months old (dieselsite). Heater core is one week old.
Thread Starter
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Junior User
Joined: Jul 2004
Posts: 86
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From: NE Kansas
Someone said it might be the EPBV so I unplugged that this morning and the problem didn't manifest itself (my jaw literally dropped). The wife is picking up the truck from me this afternoon, so I'll have to wait until tomorrow to verify.
Everything else should be bueno.
1. t-stat (happened with more than one t-stat. one I installed myself and know it was correct)
2. I changed the fluid when I changed the heater core and then had Ford do a flush and fill a few days later. Coolant must be good. Plus, the heater core always circulates fluid. The heater control switch only opens or closes the air path. I'm pretty sure there are no bubbles too.
3. New water pump installed last November
4. Fan clutch is very tight.
I have a set of gauges, but haven't installed them yet. It was too cold over the winter and I have been extra busy this Spring. Guess I need to make time.
Everything else should be bueno.
1. t-stat (happened with more than one t-stat. one I installed myself and know it was correct)
2. I changed the fluid when I changed the heater core and then had Ford do a flush and fill a few days later. Coolant must be good. Plus, the heater core always circulates fluid. The heater control switch only opens or closes the air path. I'm pretty sure there are no bubbles too.
3. New water pump installed last November
4. Fan clutch is very tight.
I have a set of gauges, but haven't installed them yet. It was too cold over the winter and I have been extra busy this Spring. Guess I need to make time.
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FOREIGN GURU
Joined: Jul 2006
Posts: 7,655
Likes: 7
From: Celaya, Gto. MX
Glad its fixed. thanks for the update.
and the winner is: DRRXR
I tried to rep him but you know the story.