Hi All...

Having another problem with my windstar, and you guys have always been tremendous help...

I'm having a somewhat-overheating issue & seem to be using a lot of antifreeze.

While driving to work, I noticed my temperature guage keeps increasing, it does not max out on hot, goes about 85% of the way up, then comes back down. I find if I take my foot off the accelerator, it makes it come back down. Also turning the heater on makes the guage go up, turning it back of makes it go back to normal.

I have little to no heat coming through the vents when I turn the heat on.

My hubby checked the coolant last Wed when this first occured, and it was empty. He put in 4L of coolant Wed evening. Today, this problem occured again, and when checking the coolant.. the reservoir was empty again. He put another 4L in.

Also checked the oil, the oil looks normal, but there is a gunky substance on the cap, that has been described to me to be condensation build up. No milky appearance to the oil.

Can anyone give me any ideas of what may be causing this problem?
Thanks so much!!
Lyndsay

don't want to sound alarmist but loosing 4L's of coolant twice now is a serious condition. If the coolant is entering the oil, that will ruin the motor. If the coolant is leaking onto the ground, this will cause the motor to run hot and will ruin the engine. If the coolant is entering the combustion chamber and is burning up with the gas and air, this is not good for the motor either.

Your heater is not blowing warm air because there is insufficient coolant in the engine to circulate through your cabin heat exchanger.

What year is the van and what cap do you say has a gunky buildup on it?

Hi,
It's a 99 Windstar, 170, 000 someodd kilometers on it.

No antifreeze in the oil... Not sure about the combustion chamber.. how would I check that?

There seems to be a puddle under the van quite often, we had thought it was from the truck... but going to investigate if it's got a leak.. hopefully tomorrow as it's been raining here all day today.

It's been running fine all along, no engine lights, and temp guage only goes up from time to time..

Question.... Is it possible that when it was low last week, the 4L would not have completely topped it up, and it needed more than that for this week? Could a stuck thermostat cause some of these problems?

that is good news that the oil looks fine, no contamination there. if it's being drawn into the combustion chamber, you should see white vapor coming out the tail pipe exhaust. It would appear to be wispy smoke but would not smell like smoke as it"s steam.

With the qty's of coolant leakage, it appears to be an external leak, that would be good news as long as you haven't ran the engine too long under low coolant levels. the temp. gauge will not read correctly if there is insufficient fluid, it can't read the true temp of the water if there is no water in the engine.

there are various hoses / tubes that could develop leaks as you describe. search this forum for coolant leak issues. It will help to check a dry engine and ground once it stops raining to pinpoint the source.

a stuck shut thermostat could cause these issues as the pressure buildup would cause the water to escape the system probably through the radiator cap / reservoir cap relief valve. Just make sure the engine is fully filled with coolant / water b4 driving any extended amounts.

The amount you mention points to some leak.
It could be a hose, etc.....or something more serious.
The 2 more common "serious" leaks are the lower intake manifold gaskets and the front cover (aka timing cover) gasket.

A "gunky" buildup on the oil fill cap could be an indication of coolant leaking into the crankcase (and thus the oil).
If the gunk is light in color.....then I would suspect this.
Summertime is not a normal time to find condensation in the crankcase.
It takes a LOT of coolant in the oil to make it look milky....and it can be causing serious damage to the bearings in the motor long before the oil takes on a milky color.
The best way to check for coolant in the oil is to take a sample and send it in to a lab for testing.
If you take a small sample from the drain plug after the vehicle has been left to sit overnight.....loosten the drain plug on the oil pan to drain a small amount of oil into a glass container...and then tighten it back up........let the glass sit.......and see if you can see coolant......you may see it then......as water is heavier than oil....so the coolant may settle to the bottom of the oil pan overnight.

I seem to remember seeing posts about the "crossover" tube leaking on the 1999 and newer windstars....this passes through the lower intake manifold....from the water pump side.....to the driver's side......and the heater hose connects to a fitting on the driver's side of this pipe.

Lack of heat is a sign of air in the system.....just a little bit of air can cause this....and high temperature.

High temperature can be caused by a sticking thermostat.....but the lack of heat has me thinking that it is air in the system.
A stuck thermostat on its own would not cause you to have no heat.......as the thermostat does not control coolant flow through the motor.....it ONLY controls coolant flow from the motor.....through the radiator.

How would air get into the system?.....if the radiator gets low enough on coolant.....but the other way is.....a leak in the system.....leaks coolant out under pressure, which is obvious....but on the cool cycle.....you can have a vaccum.......at which time AIR can leak INTO the system through the same spot.

First......carefully look for signs of coolant leakage......dried coolant leaves a white/yellowish (if G-05 or motorcraft GOLD coolant) stain, or greenish (if green coolant).
Inspect around all hoses, around all hose ends (clamps), around the radiator (drain, and where the side tanks are mounted to the fins.....and any fin surfaces you can see...as well as the bottom rail of the radiator mount).
Don't forget to inspect the heater and bypass hoses.....and look carefully around the water pump mounting.
The "front cover" is what the water pump and oil pump (oil filter is mounted to the oil pump) are mounted to.