Leaking coolant from behind passenger wheel well

[motohobo]

My trusty 94 is leaking coolant from here:

That pick is looking up through the passenger wheel well. That black unit is wet at the low point from coolant. Anyone know what I'm looking at there?

Thanks...

 

[Turdle]

Heater core leak?

 

[motohobo]

That's what I'm thinking and hoping...it's a cheap easy fix. In fact, I seem to remember having this problem before and the fix was free...I can't remember. It was something below the passenger side dash. I'll look into it tomorrow.

 

[bwryan]

I'd be interested in hearing some thoughts on this, too. I had a slow coolant drip in about the same place, thought for sure it was the heater core, went ahead and replaced it even though when I got in there the old core showed no signs of leaking (I kept the old core, on principle). I don't have any obvious leakage now, but the coolant level still gradually goes down over the months. Fairly sure it's not a head gasket issue as I've never seen any signs of coolant getting into the oil. Are there any other common coolant-related failure points in the passenger wheel well area, or more broadly on the passenger side?

 

[motohobo]

This one isn't slow...or maybe it is and I just noticed it when I was replacing the starter. It was a steady drip when the engine was running, and when I moved the vehicle, little puddles of coolant appeared, as if the motion caused it to slop out of whatever it is contained in. So I think whatever it is, it's collecting somewhere. I'll check the heater core tomorrow. You might want to check behind your wheel well and see if you have the same black unit with a wet area at the low point...

 

[410Fortune]

Things that can leak in that area

Heater hoses
Heater control valve
(Those are the easy ones)

Lower intake
Freeze plug
Head gasket major failure
(Not so easy ones)

The heater core leak would show up inside the truck usually, wet under passenger carpet

Get a brite flashlight and follow the wetness up to its highest point… after you check to ensure it’s not the heater hoses or control
Valve

 

[Sniperdyer]

Heater core hoses?

 

[motohobo]

OK, just went out to do some diagnosticating, idled it for a few minutes but everything was bone dry. Floor under the heater core, heater core, hoses at the firewall, heater control valve, no drops anywhere on the floor under the vehice, all bone dry. Added about a quart of coolant at the radiator, it looks like that ran into the overflow. Ran the vehicle it for about 10 minutes at speed. No leak, all bone dry, at least for today.

There's only one thing that changed on this vehicle that corresponded to the coolant leak, and that was installing a defective starter that didn't shut down when the engine started running. That's when the coolant leak appeared, and as soon as I put the OEM starter back in, the leak went away. How is that possible?

 

[Turdle]

Did you run heater for a minute, check for warm hot air?

 

[motohobo]

Yeah, just drive about 10 miles with the heater on high. Works great...no leaks. Makes no sense. I swear it was pouring out of somewhere, but now that the original OEM starter is back in there, no leaks. Maybe that's just a coincidence but, well, I'd sure like to know wt* is going on.