I'm losing water. I bought a pressure test kit. Finding all sorts of fun.

First, the question: If my heater core leaked where would I find the water? In my BMWs they would drain onto the transmission, and in my toyota I would find it in the cab on the floor.

Now, the story.

I got the car, oil cooler was leaking, changed the gaskets and used $4 uro parts hoses because I wasn't sure more oil was going to come out before I installed $50 volvo hoses. Pressure tester found them leaking from the inside after about 30,000 miles. Not bad for $4.

When I bought those oil cooler hoses I bought the whole set, being cheap they will come in handy as spares. 10k or so ago the upper radiator hose started leaking and I put a uro hose on it. Started leaking rather quickly.

Bought dealer radiator and oil cooler hoses. They don't leak anymore. The car still loses water.

I started losing water when I changed the rear cam seal. I figure I pushed the heater hose out of the way and hurt it, or accidentally put my body weight on the radiator.

Well lo and behold after fixing the obvious leaks I find the heater hose (the one with the water valve) weeping from the engine end. It's just barely wet, not even dripping. And found another leak at the small hose on top of the radiator. But I think the pressure test pushed out a lot more water than I found, so that's what makes me wonder about the heater core.

 

I'm not sure of the year or model of your car but in the 240 the heater core is under the dash in the middle. I'd feel the carpet on the hump and both sides for water.

 

I had a constant water loss for years. It became progressively worse. Finally a pouring out as fast as it could. Turned out it was now obvious that it was the heater valve on the firewall. Cheap part and easy fix. It had suffered from old age and internal corrosion. Might check around the coolant surplus tank, but that would seem obvious to see.

 

I'm wondering if coolant would stay in the heater box, leak on to the carpet, or leak down into the ducts for the rear floor that go under the seat.

It is tough to tell where the water would go by looking at the drawings of the heater box.

 

I dealt with this and the plastic volvo valve was leaking so badly it was dripping when not under pressure. I replaced it with one from a 70s ford van since it was made of metal (new Motorcraft part). No problems with it yet even though the ford pressure cap is 15 psi and the volvo is 25 psi.