Question about 1996 Ford Explorer

1 Answer

Fluctuating Temp gauge - '96 Ford Explorer 4.0

I just recently replaced the head gaskets on my Explorer (4.0L V6). The engine is running fine; however, I am experiencing fluctuating temperatures ONLY when I have the heater on (just past middle to the ''C'' notch. With the heater off, the temp gauge stays in the normal operating range.
I hear a ''gurgling'' sound coming from the heater core especially on turns , which leads me to believe there is air in the system (in the heater core).
I cannot burp the cooling system with the radiator cap off and the heater on - it will shoot out coolant. With the heater off, the coolant will not shoot out and I can top it off with coolant.

I checked the pass. side floor board for any wetness, and I cannot detect any. However, I can smell a faint coolant smell when I first start it up but goes away after it warms up. 
I lose coolant with the heater on after a 50 mile drive but after a 50 mile drive without the heater on, the level stays the same. I cannot detect any leaks underneath the car.
I am unfamiliar with a leaking heater core cause air to be sucked in to the cooling system, but is that possible? BTW, the heater control valve is brand new.

Posted by on

  • 1 more comment 
  • coreweave Feb 17, 2009

    I don't have the pressure tester for the cooling system. I bought the explorer for cheap, and I would hate to spend unnecessary repairs if I can help it. I have done quite a bit of work as a "weekend mechanic", so I am fairly comfortable doing a lot of the repairs myself.

    I may go to the auto parts store and pick up one up if it's cheap enough.

    I was able to get a little air out of the system, which helped the temperature gauge. Instead of the needle going from "C" to "H", it now only goes from "C" to the middle.

    This is how I have been purging the system:

    Start the engine (COLD) with radiator cap on. 
    Hold the throttle @ approx. 2.5k - 3.0k rpms. 
    Remove radiator cap while holding throttle.
    Add coolant as the level goes down.
    Put on radiator cap.

    I only did this for a few minutes and wondering if I should be doing it longer? Also, I don't believe there is a bleed valve on the thermostat housing or heads.

  • coreweave Feb 20, 2009

    I really appreciate your help...this is beginning to get frustrating. I will call around and see if there is a parts store that loans a pressure tester. I cannot detect any leaks.

    I purged the system as you explained and I am still experience "air in the system" symptoms only when I have the heater turned on. 

    I started the engine (cold), removed the radiator cap, and let it warm up to operating temp. However, I believe it's not warming up enough to open the thermostat. The needle only goes past the "C" notch and doesn't move any further with the heat on. In result, the coolant slowly rises out of the funnel that I have in the radiator filler hole and eventually overflows. I slowly increase the rpms up to 3k and it will barely go down.

    The problem is when idling with the heater on, the needle doesn't fluctuate. Once I start moving even at slow speeds (10mph) and put load on the engine, that's when the need will slowly creep up to the middle, and then drop down to the "C" notch. It repeats this until I turn the heater off or come to a stop. It's only when the vehicle is moving is when I hear the "gurgling" sound coming from the heater core.

    Should I be looking at the heater core? The pass. floor board is completely dry and no signs of leaking. This heater core looks easy enough to change out on this Explorer.

  • Keith Hirsch
    Keith Hirsch Sep 23, 2012

    I am Having the same concern on my Daughters 96 Explorer with the 4.0 engine. Have the solution actualy been found for the concern?



1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • Master
  • 1,218 Answers

Have the system pressure checked. This is simple and quick. Puts the system under pressure and helps to locate leaks. Check cap too. System needs to maintain pressure.

Some engines have a "Bleed" valve in the head so you can force the air out of the system as you fill it with coolant. May want to chekc to see if yours has one.

\Fluxing gage indicates coolant sometime there and sometimes not. Low level. Sound says the same thing.

Good Luck

Posted on Feb 16, 2009

  • Dennis Boxerman Feb 19, 2009

    I do not recommend that you buy the pressure tester. You may only use it once. See if your local auto parts place has a "Loaner" program so you can borrow it. They may even do it for you. Be sure to look up the recommended pressure for your vehicle. Your system of adding coolant seems to be working but if there is a leak, you'll be doing it forever. Start engine cold. Remove cap. Let engine warm up so t'stat opens. Then try adding coolant as you raise the rpms.

    As a side note. I had a Yukon with a similar problem. Found the leak at the intake on the backside of the engine where it bolts to the head. Had to pull intake and reset gaskets. What a pain!

    Good luck.

  • Dennis Boxerman Feb 21, 2009

    I would still look at pressure testing the system. Very doubtful that the heater core is the problem. It's like a small radiator. A fan blows air through it. Not much can go bad with that.

    You may want to look at the clutch on the radiator fan if it has one. They can give you trouble off and on. Can be tough to catch. Outside chance that the water is going out the tailpipe and not noticed. That could spell real trouble. Good Luck again.



1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya Mechanic can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repair professionals here in the US.
click here to Talk to a Mechanic (only for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

Thermostat gasket is leaking can that be replaced

Yes I have an 04 explorer it is a little tricky to get to. You have to check it close, more than likely it is the plastic housing replace it and the thermostat now. It seems to be a common problem and like I said a little tight to get too. But I did mine in the carquest parking lot. Here is a youtube video I found.
Replacing Thermostat Housing in 02 Ford Explorer V6 4 0L upper and...

May 10, 2014 | 2005 Ford Explorer

1 Answer

I have a 99 Explorer 4.0 SOHV V6. I'm loosing radiator fluid but I cannot find a leak. It still runs fine, for a car with 312,000 miles. Could it be a head gasket? I would think it would run badly

a slow leak will not make the engine run poor, at least not a first. another spot hard to detect would be the heater core, behind the dash. when these leak you can sometimes smell it, kind of a sweet smell from the heater/ a/c dash vent area

Jun 10, 2012 | 1999 Ford Explorer

1 Answer

Radiator not getting fluid overheating bad 98 V6 mustang 3.8L

Head gasket failed due to overheating. Get it pressure tested.

Mar 29, 2017 | 1998 Ford Mustang

1 Answer

I have a 96 ford explorer v6 with a pushrod motor and after we replaced the pushrods, the head gaskets, the valve cover gaskets and the fuses, the car will not idle. what could be the problem?

Have you adjusted the pushrods properly? Pushrods generally need to be adjusted after installation.

Not sure how to do this on this model, although I own a 94 Ford Explorer with the V6 4.0 Liter motor.

Basically, when a gas engine doesn't run, you check 4 things, and narrow it down from there.

1. Gas (Is gas pressure good, is gas flow strong enough?)
2. Spark (are all spark plugs firing properly? Is spark strong enough)
3. Combustion at each cylinder (timing, pushrod adjustment)
4. Air Flow (MAF/MAP sensor working? Air Filter dirty?)

Appliance Repair Utah

Mar 25, 2012 | 1996 Ford Explorer

1 Answer

2002 dodge stratus temperature gauge is fluctuating

its possible that you have a head gasket starting to go bad and driving it at a higher speed the engine gets hotter and can force combustion chamber gasses into the cooling system causing a higher temp showing up on the can get a block test down that hopefully show it up depending how early in the stage the gasket has deteriated.sound this as a diagnostic sign back in the early 80`s.

Nov 12, 2011 | 2002 Dodge Stratus

1 Answer

My 2004 explorer's temp gauge is fluctuating. The thermostat seems fine so does the radiator, any idea what it could be?

make sure the stat is new
check for restriction
does the flow seem ok
no hot spot
worst case head gaskets

Mar 11, 2010 | 2004 Ford Explorer

1 Answer

Working on a 1999 Oldsmobile Silhouette with the 3.4L in it. Recently I did the lower intake gasket cause it was leaking. Vehicle has 182,000 on it. Came back in with overheating problem, found out the...

One guess is there is air in the cooling system. The air pockets will cause temporary overheating (fluctuating guage).

It sounds like a bad head gasket is creating these air pockets.

May 05, 2009 | 1999 Oldsmobile Silhouette

1 Answer

Temp gauge fluctuation on 95 explorer

it is possible it might have a cracked or blown gasket head! simple trick check the oil to see if its milky colored if it is then its your head or head gasket if not let me know thanks josh........

Dec 15, 2008 | 1995 Ford Explorer

Not finding what you are looking for?
1996 Ford Explorer Logo

2,488 people viewed this question

Ask a Question

Usually answered in minutes!

Top Ford Experts


Level 3 Expert

77169 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22265 Answers


Level 3 Expert

5575 Answers

Are you a Ford Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides