Mystery coolant leak

[99RangerKrazy]

Hey all,

Truck is 94 Mazda B4000, 4.0L, 2WD, 5 speed.

I've got some sort of a coolant leak. I replaced one of the hoses that appeared to be leaking a little bit. It was one of the hoses that connect to the heater core to the underside of the front of the engine.

I replaced that hose, drove it around, the truck cools down fine. I got home, popped the hood, and I could hear a slight hissing sound from the driver side of the engine. I looked down near the valve cover/where the headers bolt up and there was an occasional small puff of smoke. Seems like this is where the leak is coming from. However, I don't know what would be leaking on that side. I just went out after letting it sit for an hour and a half or so, and there is a little puddle of coolant, roughly the size of half a dollar bill, under the driver's side of the engine.

I got up under there, I couldn't really pinpoint where exactly the leak is coming from. I'll look again in the morning when it's light out.

My biggest fear has been head gasket; however, the oil looks great, no overheating/warming up too much issues, any of that. Just wondering what y'all though.

Thanks, much appreciated.

 

[crusin93]

Freeze plug, backside of the head. Possibly the intake manifold. Be sure all the intake manifold bolts are torqued to spec.

 

[Clay Lorance]

You might check your Thermostat housing, from what I've heard from my buddy Jesse at JN Wrecker, the 4.0s are infamous for the plastic thermostat houses cracking. The parts manager at the dealership in Sherman alerted him of it when we had a similar problem on my 4.0. Just my $.02.