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Where's the coolant going?

The coolant in our Ford Windstar 1995 van was very low so we filled it. The next day it was low again and there doesn’t seem to be any evidence of a leak showing under the car after parking it. So, my question is where does all this coolant go? We’ve filled the radiator and the reserve tank and can’t figure out why it is drinking up so much. Any ideas? We replaced the radiator cap since it was worn and this still persists.

This Can’t Continue.

Any indication of a too low engine temperature or overheating ?

Why did you decide to check the coolant and start adding some ?

Should this continue you could damage the engine. I’d have the cooling system pressure tested if no leaks are obvious. If you don’t have a head gasket leaking and allowing the engine to consume coolant at this time, you will have if it operates low on coolant.


As I see it, there are three possibilities:

There is an external leak from a hose or a gasket, but it only appears when the engine is running, and not when it is parked. This should show up if you do a pressure test of the cooling system-especially if a dye is used to reveal the leak.

The heater core is leaking. Do you smell a sweet smell inside the car when the HVAC system is in operation? Do you have an oily coating on the inside of the glass?

There is a head gasket problem, and the engine is consuming coolant. This may require a compression test and a leak-down test to diagnose properly. In the meantime, take a look to see if there is evidence of coolant in the motor oil. If there is, the oil will look like a chocolate milkshake. I hope that you don’t have a breached head gasket because the repairs will exceed the book value of the vehicle.

While driving home for about 3 hours on a very hot day, the temp gauge started fluctuating between low and high. When we stopped and looked at the reserve tank, it seemd full. A few days later after a very short trip, the “check engine” light came on. So, we called our mechanic. He said that cylinder 4 was misfiring but he alos looked in the radiator and saw the coolant was low so he filled it as well as the reserve. All seemed fine. Then, the next day it was low again so we filled it again per our mechanic’s advice.
A bit of history, for the past several months, we have had the “tappits” when starting up the car. We had the oil and filter changed but it was still making the clanking moise when starting. Not sure if this is related. Thanks for your help.

Early Windstars were known for head gasket problems with the 3.8 V6 engine. The 3.0 Vulcan did not have this problem. I think the head gasket was redesigned for the late 97 models. My wife had a 98 Windstar.

Has the mechanic checked for an intake manifold gasket leak? Has the oil been checked for the presence of coolant?

Ed B.

We talked to the mechanic last night who said to keep checking the coolant levels. I don’t know the status of the coolant today. BTW, I’m blind so I rely on my wife to do all this checking. I suspect the mechanic will need to do some more searching for this “leak”.

It’s interesting that I came across your post, because just last weekend, I solved the same problem with disappearing antifreeze that I’ve been trying to figure out for the past year with my 1995 Windstar with 3.8 motor. I smelled antifreeze on hot days, but never saw any external leak. I poked my head all around the motor and never saw any leak on over a half dozen occasions. I figured eventually it would show itself, and sure enough it did. When you’re standing in front of the car with the hood up, looking at the motor, going from right behind the thermostat housing, across and under the intake manifold (to the left) is a heater hose. It goes down into a Y-pipe which attaches to the water pump or just behind the water pump. The other side of the Y-pipe goes somewhere towards the rear of the motor? maybe to the heater inlet line at the firewall. I believe this whole assembly, the Y-pipe with the two hoses connected to it, is a dealer only part. So what happened was that I took my flashlight and looked from the hose that attaches to behind the thermostat housing and followed the rubber hose under the intake manifold. When the car was running, I saw a tiny stream of fluid shooting out of a pin hole and hitting the manifold and evaporating on the spot. Soon as I shut the car off and the pressure relieved itself, the stream stopped. Without my flashlight, I would have never seen this steam, as it was in a dark area under the manifold. I bought a piece of heater hose and used a 3/4 brass union that I had laying around from a plumbing PEX job I did in my house earlier. BTW, the original configuration has the two hoses swedged onto the Y-Pipe, so I couldn’t remove it at that point, which was my first wish. It’s been driven on several hot days now and seems to be holding up just fine. I changed my ignition switch two weeks prior on the windstar for another problem, I can enlighten you if you’d care to email me. That’s another problem you can look forward to in the future.

Wow, that is quite interesting. Thanks for sharing. The Mrs. checked the coolant while I was home for lunch and the levels seemed ok. As a matter of fact, when she opened up the radiator cap, a bit came out. She also noticed a gurgling noise when she opened up the radiator and/or the reserve tank.

OK, here’s a new twist to this problem.
It doesn’t seem like we’re loosing much coolant but it seems like the coolant is running low in the radiator itself but the overflow reserve tank is running very high. So, does the radiator always need to be full? My wife saw that the radiator was low so she put more coolant in it (around 16 oz.). When we looked the following day, the radiator was low but the reserve tank was very high. I guess another question is that is this “normal”? Or, should the radiator always be full or near full? Is there any danger in this “imbalance” in the coolant?

If you have a breached head gasket, that will increase pressure in the cooling system, and that might force coolant from the radiator to the overflow reservoir. If there is a dark, oily line at the upper level of the overflow reservoir, that would be pretty good evidence of a leaking head gasket. If you find this, prompt action is important in order to save the engine.