Cooling system heater core went out

LISA CROGHAN

MEMBER
1995 MERCURY COUGAR
V8
AUTOMATIC
250,000 MILES

The heater core in my car went out so I bypass the heater core until I can get it replaced. Since I have bypassing the car has been overheating and excessively short amounts of time and there is a large amount of water leaking from the front end of the car behind the pulley system. What is causing it to leak and what is the most frugal way that I could fix it?

1 Reply

CARADIODOC

MECHANIC
33,737 POSTS

You need a live person to look at it, but the common suspects are the water pump, the little bypass hose, and a loose radiator hose clamp. A leaking water pump typically starts out as a very small leak that grows larger over time. If you have a large leak that showed up suddenly, that is more typical of a ruptured hose.

We change antifreeze every two years because the water pump lubricant, corrosion inhibitors, and other additives wear out by that time. If the old coolant is left in there too long, the acids that normally build up in the system do not get neutralized, and that leads to corroded heater cores and radiators. If you suspect that may have caused your heater core problem, the acids may have attacked the water pump too leading to that leaking.

"Core plugs" also corrode through, but when those leak, you will usually find the puddle under one side of the engine, or the coolant will be dripping from between the rear of the engine and the front of the transmission.