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doesnt overheat but temperature fluctuates radically

02-08-2008, 01:27 PM
96 windstar GL
with tow package
77,000 miles

I first noticed problems when my interior front heater was changing back and forth form cold to hot and back to cold again then hot etc, Im guessing there is a coolant flow restriction or insufficient coolant levels. also the engine temperature gauge moves radiacally from cold to normal and back to cold and back again. though it never really overheats, the temp gauge never seems to go past the halfway mark just moves from cool to hot radically and then back down again and it seems you can feel that fluxation from the front interior heater.

Im guessing I will focus on the thermostat and flush the coolant system as well and do a backflush,remove the old thermostat and run engine without thermostat and flush system as well and then install new thermostat, the coolant overflow tank is brown and grungy looking oh shoot Im trying to sell myself...sorry bout that! LOL, so was the radiator cap and stem, a greasy oily residue and I suspect this has plugged up the coolant system, the coolant looks sludgy and brown more than the normal green, I checked the dip stick and oil seems to look like there is not water intrusion, Im praying I dont have the dreaded head gasket or lower mainfold gasket problem. seems like I have the opposite problem of oil in the coolant system instead of water in the oil system

everyone seems to mention a rear heater, Im sure its obvious if I had one ..right? because I dont see any evidence of a rear heater, how would I verify this?

forum mentions the blackhawk oil evaluation for for water intrusion but it takes two to three weeks to get the sample kit and add more time to ship it and get it analyzed, any suggestions for a faster test?


questions I need answered.

1. how to properly backflush my 96 windstar
2. what type of Bars stop leak should I use? or in fact use at all?
3. how to properly remove the sludge in the coolant system.
4. why does my temperature fluxuate so radically and the same case with my heater, goes cold to hot hot to cold etc etc
5. what is best way to burb out the air in the coolant system, seems to be a big problem of adding coolant because of air traps. YEs I have checked my coolant level and the overflow tank level doesnt seem to move, I feel the overflow tank is not doing its job. cant seem to add no more than a few ounce of coolant after a long drive and check when cold.
6. the CEL is on, once it flashed during a cold start up and then stopped and change to a steady on, I will get an OBD II reader and see what its telling me but only flasshed once now its staying steady on

7. Im wondering if Im getting oil into coolant system through the tranny cooling lines into radiator or maybe the oil cooler (tow package)?

02-09-2008, 03:38 AM
A lot of what you want can be hunted done in this and other Ford forums, Taurus is a good one or just search al of ford. Your fluctuating temperature sure sounds like your thermostat is bad, but it also sounds like your radiator cap is bad too as it isn't circulating coolant back and forth as you seem to observe. The brown sludge does not sound at all like an oil problem, as you would get a milky white to brown milkshake looking stuff in you radiator and overflow tank. Insteac, you have what sounds like a problem described here that involves the water pump and no grounding of the heater coil, something you should definitely research here in the windstar forum to see if your year van historically has this problem. Unfortuanely, the water pump blades will literally desolve away, creating the sludge you are observing. I hope I'm wrong, but this could also contribute to all of you other problems of fluctuating temp, rad cap not right, blockage of heater core. Make sure your temp guage and heater temp fluctuate together. They may not fluctuate exactly the same time, but one should follow the other. If your gauge alone fluctuated, I would have said you have a bad temp sender, which is mounted right next to the thermostat.

02-09-2008, 07:22 AM
I have pictures that show information on the thermostat and temperature sensors that you can get to by clicking on the link in my signature.

I would recommend a coolant flush, new thermostat, and new radiator cap.
Personaly, I would not go for a chemical cleaning, just a flush and new coolant.
I would also ONLY use traditional green, or G-05 type coolant.
The most common out there is OAT type coolant, which includes "Dexcool" and other non-sylicate coolant.
Our '96 windstars came with traditional green, I have converted mine to G-05.
Don't rely on the auto part store clerks to sell you the correct stuff.
G-05 is sold at auto part stores under the Zerex brand name....available at AutoZone, Carquest, and maybe some Napa stores.....also sold at dealerships under the Motorcraft "Gold" name.
Visit the Zerex and/or Peak websites to learn which of their coolants are traditional green, if you want to get that.
This way, you will be able to recognize them on the shelf.

What you are having happen sounds very much like you have air in the system.
The heater issue is what points me to that.

I would also verify radiator fan operation.
With the A/C on (including defrost setting) the radiator fans should come on, and stay on at low speed.
The radiator fan low speed dropping resistor is a likely failure item......located on the metal bumper behind the passenger side headlight..

I would recommend the Bar's Stop leak in the tablet form, sold at Napa.
It is very good at catching leaks at the "seepage" stage.
It solved the front cover leak for me.....but not the lower intake manifold gasket leak.
Lower intake manifold gasket job should cost $400-$500 to have done....including a coolant flush and oil change.

A VERY good inspection of the radiator, heater, and bypass hoses is in order.

If you are having to add coolant, it is going someplace.
Common leaks are the front cover, aka timing cover, gasket and the lower intake manifold gaskets.
Head gasket is not a common failure on the 1996 and newer 3.8L windstars, and not a common failure on the 3.0L windstars for all years.

The rear heat and A/C is a OPTIONAL item.
You will have controls for this on the console if you have it.
I do not have one......and it does not sound like you do.

02-09-2008, 06:08 PM
well it turned out to be a faulty thermostat. I also did a flush, also observed alot of oil coming from crankcase ventalation line into the mass air flow rubber boot, any insight on that? thanks guys for your feedback, I also retrieved the CEL codes and it said cyl #5 misfire so I will see what the forum says about that solution. thanks again

02-09-2008, 08:05 PM
The oil into the big flex line that goes from the throttle body to the MAF/air filter unit is common, at least on the '96 3.8L.
Additionally, there is MUCH more vapor in cold weather than in the summer.
The issue can be worstened by some aftermarket PCV valves that do not meter the airflow correctly.
I used to think that a PCV valve was just a check valve, that permitted airflow in only one direction.
It is actually far more than that.
There is a spring inside that will restrict the airflow as the vaccum increases.
This keeps the actual airflow somewhat constant under varying vaccum conditions.
I installed a catch can on mine, shown in my pictures.
I have found that I get a LOT of liquid in cold weather......and very little in the summer.
My reason for installing the catch can is to try to keep the stuff in the intake cleaner.....EGR ports, Fuel injectors and the IMRC "butterflies".
It is very important for the PCV to provide a healthy flow from the crankcase to draw out the moisture (winter) and the impurities that would break down the oil....and also cause sludge buidup, if not removed.

Misfire on cylinder #5 could be caused by a variety of issues.
First would be the normal "tuneup" items, spark wires, fuel system cleaner (Berryman's B-12 Chemtool is great).
Also common, but more work would be clogged EGR ports.....although I am leaning away from that for this as that would be more a misfire on Cylinder(s) 3 and/or 4.
The coil pack is getting a number of posts lately for causing misfire.
They seem to fail by developing a crack in the epoxy body.....which also serves as a electrical you end up with arcing at that point.

The windstar is super prone to dirty spray ends on the fuel injectors.
Dirt builds up inside the end cap....that is over the spray end of the injector.
I have tried MANY cleaners, and the only cleaner that I have found that works for this particular deposit is the Berryman's B-12 Chemtool.
I have been told that the deposit is caused by the combination of the oil vapors from the PCV system and the combustion byproducts from the EGR system.
It might be worth running 2 or 3 tanks of fuel.....each treated with a can of the Berryman's.
It is about the cheapest maintenance thing that you can do.......excluding the cost of the gasoline.....which you have to buy anyhow.

I would also advise you to get the fuel filter changed, if it has not been done lately.
When they start to will increase the pressure that the fuel pump feels....causing it to work harder.

02-10-2008, 11:29 AM
I have viewed your posted photos several times and dont recall this "catchcan" but I will look again or Im I looking in the wrong area? The "catchcan" was an Idea I had going on in my head as well. I only have one PCV valve on rear valve cover plumbed into BEFORE the Throttle Body and one line without PCV on front valve cover plumbed into manifold after Throttle Body, is this correct, it looks factory stock to me? so I guess your saying to make sure I have a OEM PCV valve?

as far as the beeryman b-12 your saying only add it to the fuel tank, at this point dont take out the injectors and clean them manually? considering our discussion of observing alot of oil getting into the combustion chamber from the crankcase ventalation lines would make sense that the spark plugs and injectors are dirty from all this oil and would cause a cylinder misfire code.
I wanted also to add that I was adding a fuel additive from Lucas, it seems to be a cylinder lubricant more than a fuel cleaner, it could be a suspect to my cylinder misfire? its called Lucas upper cylinder lubricant, now that I think about it this could of been the culprit. I will switch over to berryman, Im sure a good thing to do is physically remove injectors and clean them BUT if Ican get away with just adding to fuel tank Id be more happy. I will also change the fuel filter.

your advise is awesome and to the point, your very sharp when it comes to windstars, I will do all the procedures you suggested and thanks for your valuable time.

02-11-2008, 12:25 AM
I would keep using the Lucas, it is highly respected.
I use Schaeffer's Soy Ultra, aka 131c.
However, the Berryman's is good for a periodic clean up.
I would NOT use the Berryman's as a add to each tank.....just a couple times a year.

Removing the fuel injectors requires removal of the upper intake manifold.....and the fuel rail.
I would not do that at this time.....the Berryman's should clean the injectors up just fine.
Of course, NO fuel additive will clean the EGR ports.....they require a removal of the upper intake manifold to clean.

The line to the FRONT valve cover is the breather......air travels INTO the crankcase through that line, to replace the air that is drawn out the PCV valve in the REAR valve cover......that is how they are up through 1998.
In 1999, they switched.....and put the PCV line into the front valve cover, and the breather in the rear valve cover.

I put my catch can in between the radiator overflow bottle and the windshield washer fluid add neck.....and ran a line from the PCV valve to the catch can, and another line from the catch can to the place that the original PCV line connected to.
I ran the lines under the "cowl" behind the upper intake manifold...and down along the A/C lines to the catch can.
I used a Greddy catch can.......I considered a home made one but wanted the big capacity.
A small one would fill up quickly in the cold winters we have in Wisconsin.

02-11-2008, 03:35 AM
Wiswind, I have in-laws in Sparta.
Where can you get a Greddy catch can and what do they cost?
How big is yours? I may make my own.
What kind of hoses/lines can be used to connect everything?
Just how much oil are you catching?
Why is it important to have it?

02-11-2008, 09:42 PM
wiswind, do you have any photos of this catch can device? I didnt realize that the weep hole on thermostat needs to be aligned to the top, why is this? I palced my thermostat at random, is it that critical that I should reclock it?

02-12-2008, 08:52 PM
well the new thermostat did not solve my heat flux problem in fact it overheated just once which it have never done before, remember my original probelm was not overheating but a rapid heat change from cold to warm back to cold again etc etc, and the interior heater would do the same as well, I think I have a flow restriction somewhere, either the heater core or my oil cooler.....if you remember I have the tow package and it comes with an oil cooler that is plumbed in line from the heater core ouput and the water pump, so Im going to purchase a motorcraft thermostat instead of the napa one and by pass the oil cooler and maybe bypass the heater core and do back flush and even a chemical clean for I am desparate.
any suggestions? is there any thing else that controls the temperature besides the thermostat, bottom line is I either have a temp control issue or a flow restriction issue somewhere? this problem only seems to happen from a cold start up to normal operating temps ,once its reached that point the fluxuation seems to stop.

02-12-2008, 09:41 PM
As far as the catch can.
I bought mine on Cardomain....about $80.
You can get "Greddy style" on ebay for MUCH cheaper.
I have found that the level indicator tube sometimes gets clogged......and fails to indicate the correct level.
I get a LOT of fluid in the cold winter....and it can fill up quickly......within a few weeks (depends on how much you drive....and the weather).
In the summer, it does not catch much at all....but what I DO catch is a thick tar that barely runs out when I tip the can on its side to drain it.
I have seen pictures of the catch cans that people make out of the air driers for air compressors.....however the ones with a visible bowl, are made of plastic that is not rated for the underhood temperatures.......and the capacity of the bowl is way small.
The idea of the catch can is to provide a dead air space......which causes the vapors to drop out of the air.
Which is what happens in the intake manifold......the PCV air is moving very slowly compared to in the hose.
The reason that I have it? is an attempt to keep the tar build up on the fuel injector spray ends and IMRC plates to a minimum.
I STILL add the Berryman's a couple times a year.
I think that Catch cans are normally installed on turbocharged / super charged vehicles......which seem to draw more junk in due to the application.

My catch can pictures are toward the end of my windstar pictures.
I just brought them up......and they are on page 9 of 10.

Thermostat weap hole.
One of our more experienced members may be able to add more....
The main reason that I can think of for the weep hole in the thermostat to be up is to help the air "burp" out of the cooling system.
One reason for your overheating could be from air in the system.
EVEN with my thermostat weep hole engine temperature shot up the first few times after I had drained and re-filled my coolant.
When this happens, I shut the engine OFF (before it gets real hot) and let it cool.
Then I squeeze the upper radiator hose (you can tell if it has fluid in it.....or air) and if it has air in it......AFTER THE MOTOR IS COOL, and you can feel that there is no pressure (by the feel of the upper radiator hose), I remove the radiator cap....and top off with a 50/50 mix of coolant.
If there is a large amount of air in the system (which there will be if you did a drain and re-fill) then you could have a large air pocket at the top of the radiator, which the add directly into the radiator will cure.

The tauras had issues with the water pump blades being eaten off by the coolant, if the coolant was not changed in time.
The coolant becomes more acidic as it gets old.......and can cause damage, such as this.
However, I have not seen any posts about this happening on the windstar.
Perhaps the windstar has the water pump impeller blades made of a different material......some are plastic and some are metal.....and I don't know which the windstar ones are.

I would not try to bypass anything at this time......

I am not personally familiar with the factory oil cooler.
I have read about is a heat exchanger that is mounted at the base of the oil filter......the oil filter mounts to the oil cooler.
Coolant flows through passages in it.....and your motor oil flows through different passages......being cooled by the coolant.
The 2 fluids do not mix.......unless you have a leak.
If you develop a leak (you will know by having to add coolant or motor oil), the repair process is to replace the oil cooler unit.
As the coolant flows through the oil cooler and the heater core ALL THE TIME, they are not as prone to clog as in the old times, when your heater temperature adjust was adjusting a valve that controlled coolant flow through the heater core......causing you to have coolant just sitting in the heater core over the summer.....allowing a good chance for deposits to build up.

As there are not so many windstars with the oil cooler......VERY little mention of it on any forums that I have been on......not much data.
I would guess that many people who have the oil cooler are not aware of it.....unless something goes wrong with it.
This is why I have ranted on about it.....some repair guides don't even mention have to look for it in the ALLDATADIY......but it is there. should be on all windstars that have the FACTORY towing package.

02-12-2008, 11:01 PM
Why did you originally think the new thermostat worked? When you opened it up at the tstat, was there any kind of junk behind it? When you take off the Napa tstat, see if there is any junk. I would try running your van without the tstat and see if your fluctuations stop. If not then your problem is elsewhere and you will have to tear the entire cooing sytem apart. Hopefully you won't need to pull the pump so I'd leave that as a last resort. Visually inspect everything. run compressed air, good pressure garden hose, or maybe a power washer on a low setting, like an electric model, through everything to push out any loose material and obstructions. Have you ever put any kind of stop leak product in it? My last resort thoughts are I think your heater core has buildup or crud in it, but I would also be suspicious of your radiator experiencing that too. Would you say you can't get as much heat out of your heater? Did it run hotter on the dash guage this summer than last summer? Have you drained the radiator yet and get any crud out? If not, drain it by the lower hose to get it out faster to help get any crud out. See if you get any crud and what it looks like. Another thought, when you start up the van from cold, the heater hoses should slowly warm up and get hot on both sides. A noticeable temperature difference between the hoses or they really don't heat up means you have a heater core blockage. i'd also compare hose temps with the bypass line that goes under the intake manifold.

02-13-2008, 10:53 AM
I found the photos of the catch can on your photo album thanks, so you only have a catch can on the rear valve cover that has the PCV valve? is your PCV valve on the rear vasvle cover still in conjunction with the catch can mounted on the side engine compartment?, what do you do about the crankcase (no PCV valve there) line on the front valve cover that runs to the flex tube on air filter intake? that one for me also seems to dump alot oil into intake before throttle body and throttle body is getting oil deposited in it. and then ford post a sticker "do not clean throttle body because of a special coating" and yet I have oil depositis all over it that I feel should be cleaned somehow?

my cooling system definately acts like a flow restriction or air pocket somewhere as you accelerate and increase RPM's you can feel the heater core get warmer.
I only seem to have the heat flux problem from a cold start, once I reach a good heat soak everything seems to stablize.

And yes I do have traces of gunk in cooling system, after I removed my new thermostat after one or two days of use so that I could reclock the weap hole I did see brown sludge residue, I truly feel this brown sludge residue is my problem, I feel its clogged the cooling system somewhere so I desparatley want to do a chemical clean but everyone tells me otherwise?

02-14-2008, 05:48 PM
On the 3.8L windstars up through 1998, the line to the front valve cover is the crankcase breather line, air flows FROM the flex hose INTO the motor.
On my '96, if I spray some SeaFoam (or other stuff) into the PCV line with the motor running, I get a fair amount that flows out of the throttle body into the flex hose.
This leads me to believe that the oil that I used to see in the flex hose came from the PCV line, not the breather line.
I have sprayed cleaner onto the inner parts of the throttle body.

I try to steer clear of chemical cleaners in the cooling system as the 3.8L windstar engine is prone to develop leaks at the front cover (aka timing cover) gasket and at the lower intake manifold gasket.
The front cover gasket is a major job....and expensive to have done.
If you have deposits in there that will not come out with a good flushing, you may not have another choice.
Prestone sells a flush kit, that is a "T" that you put in a heater hose and connect a garden hose to......this might be a good way to go.
I would follow this type of flush up with a good rinsing with steam distilled water (can be bought a the grocery store, and many other places in gallon jugs).
Many tap water sources will give you a LOT of scales, calcium buildups if left in there over time.
The distilled water will not have this problem.....and flushing as much of the tap water out as possible will prevent this problem.
Then, what I do, drain as much as you can, add 100% coolant (not the pre-mixed) to the system in an amount equal to 1/2 of the total capacity of the cooling system (6 quarts (1.5 gallons) to a 12 quart system) to get a 50/50 mix.

Again, it will take some time to burp the water pockets out of the if the temperature shoots up, shut the engine OFF, and let it cool.......then add 50/50 mix of coolant as needed and run the engine again.

02-14-2008, 06:16 PM
I removed the thermostat and also added "Zerex Super Clean" to the cooling system and will run for several hours then neutralize the system with baking soda to reduce potential harm from acidic breakdown, what do you think?

With the thermostat removed the heat flux has stopped and the heater temperatue is constant and it runs rather cool almost too cool so I feel there is no issue with water pump or major restrictions or clogs and raditor is fine, could be like you said that these darn deathstars need to be burbed like babys and the air pockets dont beeld out on there own like most other vehicles, if it was a Japanese vehilce they provide a pipe plug at a high spot to remove air during coolant fill or a design that will bleed the air properly but were dealing with Ford here KING OF THE SHORTCUTS and brain farts.

02-14-2008, 06:28 PM
I have run across the issue with burping air with my Chrysler products that I used to have.....
When you don't have a spot to bleed air out at a high spot on the motor......this is a common issue.
I would be pretty certain that the need to burp the air out was a issue for your situation if you fully drained the radiator.
I would spend a lot of time rinsing out your cooling system to get all the chemical that you don't have it in there to compete with the additive package in the coolant that you are putting in there.
DON'T leave just water in there overnight if it is cold in your area (I'm in Wisconsin.....and it has been COLD lately).
Use steam distilled water at the end of the flushing routine to have in there for when you add the will NOT be able to drain all the water out......maybe 1/2 of what is in there (6 quarts or so).
Then follow the steps that I listed above to burp the air out.......I have had to do it a few times to get it all out.
After may need to add some coolant to the overflow bottle 1 or 2 times.
Of course, after that.....if you need to add coolant.....even a quart or so every will need to address that as a coolant consumption/ leakage issue.

Let me add to this...that I ran a LOT of the Bar's brand of Stop Leak......I had the silver stuff......and I did NOT have any sludge.....when I removed my upper intake manifold......the water passeges were very clean.
The stop leak was like particles....not the coolant.
When I flushed it out and put in new coolant....I had the old coolant in my old distilled water jugs....and you could see that the stop leak was particles mainly floating on the top......or suspended in the coolant.
If it were me.....I would add some of the stop leak preventative maintenance......
If you develop a slight seepage (the early stages of a real leak) the stop leak will help to seal it up.
It has, so far, taken care of my front cover gasket leak that developed over 5 years ago.

02-14-2008, 07:08 PM
no the original problem of heat fluxuation and the problem of the interior heater surging from hot to cold to hot again was NOT from me draining the radiator, it just starting doing it one morning on its own without me touching anything, I didnt drain the radiator until after the problem had started. diagnosis is 9/10 of the law, its easier to fix a problem than to diagnos a problem...LOL I will be glad when this is behind me, I will be glad when I have a second vehicle so I dont have to rely on a Ford...LOL

I have two classic 65 mustangs, a convertible and a fastback that are in restoration process but they wont be available for sometime and I need this deathstar to live at least one more year....LOL

I will say I like the comfort and the handling and the versatility of the windstar but my GOD the trannys and the head gasket issues and intake gasket issues are terrible!
thanks for all your valuable time MR. wiswind.... and the rest of the gang

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