Wild temp gauge....
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New User
Joined: Dec 2012
Posts: 4
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From: Surrey
Wild temp gauge....
Hi there.
i am new to the Bronco II (pretty much a newbie full stop really).
i recently bought mine off a guy on the south coast of England.
it's an ' 87 (i believe), shipped into the UK at the beginning of the '90s.
i am slowly working thru a list of faults i want to fix.
i just had some core plugs replaced in the cooling system as i had a leak.
seems to be holding coolant fine now...finger x'd,
however....for at least 10 minutes (until getting properly warmed up), the truck's temp gauge seems to creep back and forth between a third and two thirds within the 'normal' field.
why do you think this is?
dodgy temperature sensor/sender? thermostat?
any help greatly appreciated.
i'm sure i will be here quite a bit over the coming months as i roll out my list of things-to-do.
hope to hear from someone soon...
Mills.
i am new to the Bronco II (pretty much a newbie full stop really).
i recently bought mine off a guy on the south coast of England.
it's an ' 87 (i believe), shipped into the UK at the beginning of the '90s.
i am slowly working thru a list of faults i want to fix.
i just had some core plugs replaced in the cooling system as i had a leak.
seems to be holding coolant fine now...finger x'd,
however....for at least 10 minutes (until getting properly warmed up), the truck's temp gauge seems to creep back and forth between a third and two thirds within the 'normal' field.
why do you think this is?
dodgy temperature sensor/sender? thermostat?
any help greatly appreciated.
i'm sure i will be here quite a bit over the coming months as i roll out my list of things-to-do.
hope to hear from someone soon...
Mills.
More Turbo
Joined: Mar 2006
Posts: 687
Likes: 1
The cooling system is sometimes difficult to get full. It is best to remove one heater hose at the engine end and fill the heater core and reconnect the hose and insure the radiator is full within 1 to 2 inches from the mouth. Fill the overflow reservoir to between 1/3 to 1/2 full, then with the radiator cap off, run the engine to warm and replace the cap and let fully cool. Check your overflow reservoir and fill to half full if it has emptied any. The vacuum in your cooling system will complete filling the system. Normally the gauge will rise when the thermostat opens, drop some and rise again in response to the thermostat. If it drops out all the way it is likely not touching coolant.
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New User
Joined: Dec 2012
Posts: 4
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From: Surrey
thanks fl1a.
the gauge never drops below a third....mainly hangs around there or just above...usually settles there after about 15 mins of driving. that first 15 mins sees all the activity.
Gonna replace the 'stat and sender this week hopefully....will post my results.
cheers again
the gauge never drops below a third....mainly hangs around there or just above...usually settles there after about 15 mins of driving. that first 15 mins sees all the activity.
Gonna replace the 'stat and sender this week hopefully....will post my results.
cheers again
Thread Starter
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New User
Joined: Dec 2012
Posts: 4
Likes: 0
From: Surrey
So.
Replaced the thermostat and the Temperature Sender.
Hasn't really done that much to remedy the situation.
10 minutes of temperature gauge fluctuation, and now settles at just over the half way mark occasionally rising up to two-thirds and falling to just over half again.
very frustrating.
any more suggestions from anyone?
Replaced the thermostat and the Temperature Sender.
Hasn't really done that much to remedy the situation.
10 minutes of temperature gauge fluctuation, and now settles at just over the half way mark occasionally rising up to two-thirds and falling to just over half again.
very frustrating.
any more suggestions from anyone?
Postmaster
Joined: Nov 2011
Posts: 3,533
Likes: 17
From: SW Florida
When I bleed a cooling system I always fill it up, let it warm at idle with the cap off until the thermostat opens, then give it some RPM and let the pump draw the level down more. While holding the RPM steady, fill the radiator up and put the cap on, then let the engine return to idle. Let it cool down, check it again when cold, add more to the radiator, cap it and drive it. Check again when cool and fill again if needed.
Always worked for me on everything I've owned, but I don't remember ever working on the cooling system in the short time that I owned my BII so it might be different.
Always worked for me on everything I've owned, but I don't remember ever working on the cooling system in the short time that I owned my BII so it might be different.
Elder User
Joined: Feb 2006
Posts: 681
Likes: 0
From: SE Michigan
Mills, welcome to the forum. You'll find a lot of good advise here.
The filling of your cooling system as "dixie460" has suggested should work pretty well for you and help minimize the trapped air in the system. Keeping it full is part of the key to getting the most air out. The rising and falling of your temp gauge indication should be indicating when your thermostat is opening. It will be at the highest indication point, just before it opens. Then the needle starts to go toward the cool side as colder coolant will be coming in. It will go to a low point until it starts to detect warmer coolant coming in again. Once you drive it a few kilometers this large amount of needle movement should become less because the overall temperature evens out at a higher amount since the engine will be working more. Sometimes an older thermostat will not act very well when operating and will make this large temperature swing occur all the time. But a new thermostat of good quality won't do that. I hope you have quality parts available where you are. Let us know how it goes.
The filling of your cooling system as "dixie460" has suggested should work pretty well for you and help minimize the trapped air in the system. Keeping it full is part of the key to getting the most air out. The rising and falling of your temp gauge indication should be indicating when your thermostat is opening. It will be at the highest indication point, just before it opens. Then the needle starts to go toward the cool side as colder coolant will be coming in. It will go to a low point until it starts to detect warmer coolant coming in again. Once you drive it a few kilometers this large amount of needle movement should become less because the overall temperature evens out at a higher amount since the engine will be working more. Sometimes an older thermostat will not act very well when operating and will make this large temperature swing occur all the time. But a new thermostat of good quality won't do that. I hope you have quality parts available where you are. Let us know how it goes.
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Laughing Gas
Joined: Feb 2007
Posts: 821
Likes: 0
From: hohenwald, tn
Is the temp the only gauge to do this? I put a motorsport 140 mph speedo in and then started noticing my gauges would fluctuate (fuel and temp). I added another ground wire to the cluster regulator. I put a couple miles on it yeaterday and believe it is working.
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