BIG coolant leak..

[svoeric]

I have a 98 4.0 SOHC explorer.
I'm starting to think the thermoststas on these trucks are disposeable, this is my 4th in 176k miles, Anyway..

I removed the upper intake to replace the thermostat (2-days ago), replaced the t-stat, stuck most everything back together.
It got late, and I wanted to flush the coolant system while I was at it, so I let it sit for a couple days. I finished plugging in hoses today, and started to flush the coolant system, and I have a HUGE coolant leak.

there's coolant running out onto the drivers side exhaust collector like there is a 1/4 inch open hose. if I fill the radiator, it runs out back there even without the truck running,

the thermostat housing looks to be dry, from what I can see of it (It could be leaking from the back, and I'd never know)

anyone got any idea where this might be coming from ? I can't find any loose hoses, and I can't even think of any coolant hoses running in that general area...

Thanks

 

[Anime]

The thermostats do seem to last only a short while, but the factory originals seem to last the longest, so...who knows? Best bet is replace with a Motorcraft 'stat or top-o-the-line aftermarket as soon as theres any funny business to avoid problems. A $10-20 'stat and replacement is a LOT better than fixing the damage from overheating.

Flushing the system AFTER a thermostat replacement can be a bad idea, since theres the possibility of loosening a bunch of gunk and getting it stuck in the new thermostat, blocking it and having the same performance as a nearly-stuck-closed one. The leaks might be from the back of the housing, since it can leak onto the top of the block and then go onto the exhaust manifold. The pressure from a blocked 'stat would cause the coolant to seek out an escape route. You might want to redo your previous work, using a gasket sealer on the thermostat housing (theres special Permatex sealant for this, works great), and flushing out the radiator top to bottom by just pouring water in.

 

[svoeric]

Flushing the system AFTER a thermostat replacement can be a bad idea,

if there's anything in there big enough to get stuck by the thermostat, I don't mind re-doing it...

I just popped the top intake off again, yep, that freaking thermostat housing is leaking like it's got a hole in it, and it's running down the back of the block.