Fluctuating Temp Guage

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Mar 3, 2009 | 11:09 PM

dkbrake

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Fluctuating Temp Guage

Hello all, I need some help. I have a 1993 Ranger with the 4.0L. I have recently had problems with the coolant playing the disappearing act with no obvious leaks. Also my temp guage flucuates.

Here is what I have done so far...

1. Oil looks fine and no smoke and no ping.
2. Changed thermostat.
3. Changed water pump.

I have burped the system. Heater works great with no thumping noises or unusual noises coming from the heater core. Usually the temp guage will consistently be on the "O". At random times the guage will move to the "L" and approximately 2-4 seconds it will rapidly drop past the "C".

I am totally confused. I have purged the cooling system multiple times thinking it was just air in the system but it does not help. Like I said I have coolant disappearing without any visible leaks.

At times after running the truck and parking it and shutting it off I get a brief smell of coolant. I will then pop the hood and look for any leaks and am unable to locate any.

Any help with this would be greatly appreciated.

Mar 4, 2009 | 02:52 AM

michigan66

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Joined: Mar 2005

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From: Dexter, MI

Welcome to FTE. You've come to the right place for good ideas and help.

Two possibilities come to mind. Sometimes new thermostats fail. As the temp. gauge fluctuates, feel the upper radiator hose. Does it seem to be the same temp? How is your radiator cap? When you shut off a got engine, the residual heat will heat the coolant and blow some of the coolant back to the overflow tank. If the cap "pops off," a smell of coolant can be released.

Last edited by michigan66; Mar 4, 2009 at 02:54 AM. Reason: Added comment

Mar 4, 2009 | 05:02 AM

wendell borror

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The coolant is going somewhere, it can't just disapear. We just have to find where. Are you sure it's not going in the oil? How much are you loosing?

Mar 4, 2009 | 07:50 AM

pawpaw

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Joined: Jan 2004

Posts: 13,851

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From: SW Va

Welcome to FTE.

You may have more than one problem.

I like the suspect list so far.

Are you getting the coolant smell inside the cab, or outside of the vehicle???? If outside, where are you standing????

If your geting it inside, check the pasenger side footwell floorboard carpet, to see if it's damp.

If so, suspect a heater core or heater hose, or connection problem.

The core may be leaking & draining out the A/C condensate tubing, so check the ground underneath it & check the rubber tubing underhood, where it exits the cabin, back next to the firewall, with your finger, for signs of coolant in it.

The description you've given of the fluctuating temp gauge, sure sounds like a faulty thermostat, thats intermittently sticking open, so do michigan66's upper radiator hose temp feel test when the temp gauge swings cold.

You might also put the single wire temp gauge temp sender, it's wire & connector & connecton on your check out suspect list.

Intake manafold gaskets on your 4.0L probably belong on your suspect list too.

I had a slow coolant disappearing act, on my then new 99 4.0L.
The Dealer/Factory finally traced it to head gaskets, three years later.

A bunch more thoughts thoughts for pondering, let us know what you find.

Mar 4, 2009 | 12:24 PM

dkbrake

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Coolant Disappearing/Fluctuating Temp Guage

I changed the thermostat last month, I checked all hoses and connections and no apparent leaks. I have also checked the passenger compartment floor board. DRY! I guess I will try another thermostat.

I just changed the oil last week and have been watching it closely. It is not milky and no smoke from the tailpipe.

The only thing I can think of is that the radiator is clogged and backing up in the overflow. The only sign of a leak is I sometimes have coolant standing on the cross-member but I can not trace down the origin of the leak.

The coolant smells outside of the vehicle. I can usually smell it as soon as I shut the truck off and open the door. I get no smell at all from inside the vehicle. And the coolant reservoir cap never pops off.

Also, the only time that the guage fluctuates is at interstate speeds that I have noticed. And it doesnt do it all of the time. Some days it will run like it is supposed to with no smells and other days I just want to roll it off a cliff.

Any help would be grateful.

Thanks

Mar 4, 2009 | 12:34 PM

Toehead

5th Wheeling

Joined: Aug 2008

Posts: 43

Likes: 2

The way you say it, with the rapidly moving gauge, sure sounds like an electrical problem with the sensor. I can't see anything else causing that.

Mar 4, 2009 | 12:48 PM

pawpaw

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Joined: Jan 2004

Posts: 13,851

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From: SW Va

If your smelling coolant only on the outside. on the drivers side & I'm assuming when you say you see coolant on the cross member, you mean the tranny cross member????

Anyway right now it seems your saying you smell & are seeing coolant outside, on the drivers side of the vehicle & is it the drivers side of the tranny cross member that you see the coolant on?????