the hoses leading to and from your radiator might be clogged. If you had a rusty radiator, the rust may have clogged the hoses that carry the coolant. you should check all your hoses and even flush them out.
To disconnect the coolant hoses from the heater core supply line on a Saturn, first, ensure the engine is cool and the vehicle is parked on a level surface. Locate the heater core hoses, which are typically found on the passenger side of the engine bay. Use pliers to loosen the hose clamps, then gently twist and pull the hoses off the heater core fittings. Be prepared for some coolant spillage, so have a container ready to catch any fluid that may leak out.
Radiator hoses and heater hoses should be inspected yearly and replaced when neccessary.
Low coolant? System air bound? Hoses collapsing under pressure? Water pump not circulating coolant?
Heating hoses are exposed and need to be replaced. The heater core is leaking coolant.
If your van has rear heating it will have hoses and a heater core back there, that is most likely the source of the leak.
The water pump on a Mercedes ML320 is replaced by draining the coolant, removing the radiator hoses, and unbolting the pump. The gasket can then be replaced and a new pump put in place.
It is worn and needs to be replaced. It is collapsing when the water pump draws coolant.
The heater hoses.
remove hoses from firewall and make sure there is no rust or buildup on tubes. reinstall hoses and make sure hose clamps are really tight. If this doesn't work, your heater core needs to be replaced.
Radiator hoses,Heater hoses,Power Steering hoses,Air Conditioning hoses,Vacuum hoses,
You just have to see where it is leaking. There are numberous gaskets and hoses it can be coming from. Have it preasurized and it will be easier to find.