Strange auto cooling problem

[rogerwa]

I have a strange problem with my 97 Ford Expedition. Maybe someone out there can give me some leads.

Here are the symptoms. Up to this past winter, the engine would heat up normally. A gradual movement of the guage and likewise a gradual warming of the air temp.

This season, I noticed that the temp would not warm up as quickly, the temp guage would fluctuate during the warmup to full operating temp and when at idle the warm air from the vents would cool.

I figured that my Water pump had started to fail ( had not replaced it since I bought the car - it has 176,000) and replaced the WP and thermostat on the first warm day (it was 16 that day).

Well it didn't help the symptoms and it introduced an additonal symptom. When it is cold out, it will warm up slow, I will get some heat and then soemtimes the heat goes ice cold and teh temp guage pegs all the way to hot. After a minute and with the engine revving it will poip back to normal temp and I will have heat.

The air will cool when at idle as it did before.

any ideas from the Ford owners out there??

 

[Bondo]

Re: Strange auto cooling problem

Ayuh,...

I'd Guess the coolant level is Low, or the system is Air-bound....

Did you change the T-Stat when you did the pump,..??

 

[BaileysBoat]

Re: Strange auto cooling problem

I'm with Bond-O.

I would put in a Ford stat.

 

[Bob_VT]

Re: Strange auto cooling problem

Well you said you replaced both the thermostat and the water pump.

I few things could be going on. First you might have a bad thermostat (which has happened), did you purge (bleed) all the air from the system... the newer engines are more prone to air locks.... How is the blend door and heater control system working? Is it fully opening the valves? Have you felt the return line from the heater core.....

I would almost be willing to bet that the problem is in and under the dash.

 

[SS MAYFLOAT]

Re: Strange auto cooling problem

Sounds like air in the system. I had a similar problem on a Dodge Intrepid. There was a bleeder screw on the Tstat housing. I would open it up and bleed the air off. However, I failed to know that one needed to put a length of hose on it and stick into a container of coolant sitting on the ground. Very similar to bleeding brakes. Once I did that, I had no problems after that. My ignorance cost me over $600 as I went as far as pulling the heads off thinking it was a bad head gasket or warped head.

You may want to take it to a radiator shop and have a test done to see if there is CO in the system. If so, that indicates combustion gases are getting into the cooling system. Then a compression check would be in order. Good Luck cause I know these things can drive a person nuts...........SS

 

[Gary H NC]

Re: Strange auto cooling problem

The heater core is the first thing to act crazy with air in the system,no heat then engine temp jumping around.
Look for a coolant bleeder like SS said.If it does not have one remove the radiator cap with the motor cold,start it up and let it run up to operating temp.It should burp the air out along with a little coolant. Top it off and put the cap on,take it for a test drive.

 

[chiefalen]

Re: Strange auto cooling problem

Thats ole style and should work Gary. Thats what i do when i change the anti freeze. If that don't fix it might be the heater core going all rusted up.

One question though some t-stats are designed for a one car, They have baffles or something built into it to prevent a air build up.

Fix
Or
Replace
Daily

 

[NoKlu]

Re: Strange auto cooling problem

I have been told some of the new engines need the heater turned on while you warm the engine up with the rad cap off to bleed the air out of the heater core.

 

[luv2b0at]

Re: Strange auto cooling problem

If there is a coolant overflow container, make sure it has fluid up to the proper line.

 

[Gary H NC]

Re: Strange auto cooling problem

I have been told some of the new engines need the heater turned on while you warm the engine up with the rad cap off to bleed the air out of the heater core.

I do that on all engines when filling the anti-freeze. Heater control set to the hottest setting....you can leave the fan on low.

 

[puddle jumper]

Re: Strange auto cooling problem

I hate to say this but it sounds like the start of a head gasket problem. Go to a shop that can test for exhaust gasses in the cooling system like SS Mayfloat suggested. Something you can try is taste the water from the exhaust for sweetness (just a dab on your finger).

 

[Pascal]

Re: Strange auto cooling problem

I have a strange problem with my 97 Ford Expedition. Maybe someone out there can give me some leads.

Here are the symptoms. Up to this past winter, the engine would heat up normally. A gradual movement of the guage and likewise a gradual warming of the air temp.

This season, I noticed that the temp would not warm up as quickly, the temp guage would fluctuate during the warmup to full operating temp and when at idle the warm air from the vents would cool.

I figured that my Water pump had started to fail ( had not replaced it since I bought the car - it has 176,000) and replaced the WP and thermostat on the first warm day (it was 16 that day).

Well it didn't help the symptoms and it introduced an additonal symptom. When it is cold out, it will warm up slow, I will get some heat and then soemtimes the heat goes ice cold and teh temp guage pegs all the way to hot. After a minute and with the engine revving it will poip back to normal temp and I will have heat.

The air will cool when at idle as it did before.

any ideas from the Ford owners out there??

Some tstats from the factory have a bleed hole in them with a little wobble poppet that restricts the flow at the right times.... these will allow some air to escape thru and back to the rad/overflow after the initial fill.

I've seen where guys have drilled 1/16" or smaller holes in the stat to do the same thing. you may require other more elaborate methods to solve your problem though.

 

[freddyray21]

Re: Strange auto cooling problem

had same problem on two different Fords. air in the system on both.

 

[SS MAYFLOAT]

Re: Strange auto cooling problem

Make sure your radiator cap makes a full seat. When your engine cools, so does the coolant drawing in coolant from the reservoir. If the cap has a leak, the vacuum that is created during cool down will suck air thru the bad cap instead of drawing in the coolant from the reservoir thus putting air back into the system.

 

[rogerwa]

Re: Strange auto cooling problem

I think I may have a combination of these problems.. I have heard bubbling coming from under the dash and had a problem in the fall where i smelled antifreeze and it put a haze on the inside of the windshield - read leaky heater core. It stinks that it costs over $800 to have a $40 part replaced.

 

[Bob_VT]

Re: Strange auto cooling problem

If you have a leaking heater core and you don't want to spend the cash.... bite the bullet and get imtimate with removing the dash and center console. It is alot of work but if you consider the savings it is worth every penny.

The older Fords were notorious for having the AC lines rust through too. If it was my vehicle and I intended to keep it I would replace everything that it needs and still be ahead of the dealer charges.

 

[rogerwa]

Re: Strange auto cooling problem

I pulled out my trusty manual and checked out the procedure and I cannot beleive what has to be done to get that POS out. I just don't have the time to do this. If I were an auto designer I would fire myself for that design.

I also did some internet research and found thAt this is a common problem, something to do with stray electrical current causing a chemical change in the Antifreeze which cause it to be corrosive. Or something like that.

I was hoping to make 200K without having to sink a bunch of money into it.

Its a 4.6l v-8..

 

[Bob_VT]

Re: Strange auto cooling problem

Consider this..... if you do not make the repair and lose the entire rig you gain nothing. If you can not afford the time and can not afford to lose the truck for good then have a local repair facility or dealer do it.

 

[Shizzy]

Re: Strange auto cooling problem

I have had more then one NEW thermostat bad right out of the box. You also mentioned a "new" symptom upon doing the repairs. One thing I have learned when fixing things is if a new problem pops up you need to stop and look at what YOU just touched. 99% of the time I have found it was something I did. How fast does the temp gauge swing? A snapping or swinging temp needle has always been sticking thermostat as far as I have seen. You also mentioned if you rev the engine, the temp swings back down. I had a car do the same thing. If you think about it, the thermostat is sticking, you rev the engine, the waterpump spins faster pumping harder on the coolent and forcing the thermostat to open.

Although it sounds like you need a new heater core also, before you start ripping in to the dash I would toss in a new Ford thermostat and do your best to bleed the air out of the system. $20 and a hour or so of your time might get you by for a while.