Coolant Loss ?

[tractorboy]

94 DODGE CARAVAN V6 3.0L

It is my sisters van, she refuses to look after the van so I have to take care of it. I always check the coolant level, it is ok till one day she says that there is no heat. I go over and the van is low on coolant. I fill it up, rad and resevoir. There are no leaks, no oil in the coolant and no coolant in the oil. There is no excessive steam from the exhaust and no coolant smell inside or outside of the van. It goes low again. I pour in a gallon and a half of 50/50 aprox coolant. I drive the vehicle and the temp gauge stays on or near the cool, except at light it almost goes to the middle. The air temp outside is about 40 degrees. The upper hose is hot, not much pressure, can pinch off with my hand. Can feel slight something running through the hose. Still no smel of coolant or leaks.
what do you think is wrong. ?

[Vats]

Originally Posted by tractorboy

94 DODGE CARAVAN V6 3.0L

It is my sisters van, she refuses to look after the van so I have to take care of it. I always check the coolant level, it is ok till one day she says that there is no heat. I go over and the van is low on coolant. I fill it up, rad and resevoir. There are no leaks, no oil in the coolant and no coolant in the oil. There is no excessive steam from the exhaust and no coolant smell inside or outside of the van. It goes low again. I pour in a gallon and a half of 50/50 aprox coolant. I drive the vehicle and the temp gauge stays on or near the cool, except at light it almost goes to the middle. The air temp outside is about 40 degrees. The upper hose is hot, not much pressure, can pinch off with my hand. Can feel slight something running through the hose. Still no smel of coolant or leaks.
what do you think is wrong. ?

does the Van have rear heat? The pipes that lead to the rear heater are bad for corrosion. Have you let it sit overnight and then checked for leaks?

[Stretch58]

Originally Posted by tractorboy

94 DODGE CARAVAN V6 3.0L

It is my sisters van, she refuses to look after the van so I have to take care of it. I always check the coolant level, it is ok till one day she says that there is no heat. I go over and the van is low on coolant. I fill it up, rad and resevoir. There are no leaks, no oil in the coolant and no coolant in the oil. There is no excessive steam from the exhaust and no coolant smell inside or outside of the van. It goes low again. I pour in a gallon and a half of 50/50 aprox coolant. I drive the vehicle and the temp gauge stays on or near the cool, except at light it almost goes to the middle. The air temp outside is about 40 degrees. The upper hose is hot, not much pressure, can pinch off with my hand. Can feel slight something running through the hose. Still no smel of coolant or leaks.
what do you think is wrong. ?

I would say just offhand look at the trannie fluid too and make sure no Antifreeze there either. I wonder if she has not boiled it almost dry recently, should not get that much temp swing at a light. Is the radiator fan working? Turn on A/C and see if it comes on. Should really do a pressure test too, hopefully no bad head gasket.

[tractorboy]

What would turning on the a/c have to do with this ? no nothing in the trans fluid, how would coolant get there ? I was thinking the head gasket also, it is an almost inescapable conclusion to the missing coolant. No as I have said no leaks, no coolant smell outside or inside.
What about the rad cap ?
also if the thermostat was hanging open would everything just take longer to warm up ? ... or what ?

[Stretch58]

Originally Posted by tractorboy

What would turning on the a/c have to do with this ? no nothing in the trans fluid, how would coolant get there ? I was thinking the head gasket also, it is an almost inescapable conclusion to the missing coolant. No as I have said no leaks, no coolant smell outside or inside.
What about the rad cap ?
also if the thermostat was hanging open would everything just take longer to warm up ? ... or what ?

Turning on the A/C will kick on the radiator fan motor and verify that is one thing that is still working. If you are concerned about the radiator cap, I would just buy one and put it on.
In cold weather, a stuck open thermostat will cause very slow warmup, and if moving, will run much colder than normal. When stopped of course, it will come up, but may never get up to the point where the fan kicks on, depending on outside air temp.
Time for a pressure test.