Question: Could a loose clamp (replaced spring-type with worm-type during a past service) on the lower radiator hose create a coolant flow issue that would result in both the "waterfall sound" and an overheat while trying to troubleshoot and resolve the issue?

History: Out of country for a year with '02 Disco in storage at dad's. He runs it once a week. Gives report of coolant level dropping after being driven and dropping a quantity (enough worth mentioning, not sure exactly how much, seemingly less than a gallon based on the bottle he showed me) of coolant onto the garage floor while/after running. The losing coolant while running can be explained because the expansion tank had a crack at the fill line that I could tell was leaking, but not enough to spray the engine or cause a puddle. It had run fine with this crack for a year (or longer). I use an UltraGauge and oil pressure sensor and monitor the engine vitals religiously. New 180º thermostat (preventive) and water pump (failed) within the past 18 months.

First Attempt : I replaced the expansion tank and bled the system exactly as I had successfully done twice in the past (thermostat and water pump services), and drove it home 15 mi., but I noticed the waterfall sound in the dash and observed loss of coolant on the tank and dripping near the front. I tightened some clamps and tried various methods posted here to bleed it, and took it on several normal test runs at operating temps to observe whether the waterfall sound persisted. Note: Even throughout this process I've always had good, strong heat in the cabin.

The waterfall sound did persist. And I was still observing coolant collected on the passenger side of the frame before the engine and dripping from the steering rod, damper, etc. Also, coolant was coming out of the expansion tank cap, which I mostly attributed to Disco Mike's overfill bleeding method—hey, I was desperate and giving it a shot. Originally, I thought the tank overflow was just working its way down to the lower location, but read on...

Current: On the last test run, it began to overheat (temps > 215º on UltraGauge), so I turned off the engine and hit the side of the road (level ground) as fast as possible. Same situation: coolant escaping from near lower radiator outlet and expansion tank cap. While letting it cool, I cracked the bleed screw about half way and got several seconds worth of steam before any coolant came out. I wondered whether maybe it was simply vapor locked as air throughout the system finally came together and got trapped in that area. So I let it cool down to a cool-to-touch temp, topped off the system and tried again with the same result.

I towed it home and my first order of business was to make sure the system was indeed cooling the coolant, so I pulled the thermostat to test it (it seems to open fully in water > 190º). In the process of removing it (but after I had already drained the system) I discovered that the worm clamp on the lower radiator hose was only finger tight—I had checked the other clamps but neglected this one—doh! This definitely explains all the coolant on the lower engine that only happens as pressure in the system builds.

BUT does it explain anything more than that? I realize the waterfall is indicative of an ongoing air leak into the system, and that is usually being introduced through a bad head gasket. But having had no evidence of that prior to this point, I'm trying to rule out a mistake in the cooling system repair on my part before going there. Which leads to more questions as I try to troubleshoot anything I can before throwing in the towel and taking it to my indy:

- How does one test the proper flow rate of the cooling system?
- Is the water pump doing it's job? (God forbid my dad ran it while dry—there's just no way for me to know other than he said he only had to add a half-gallon of coolant ever.)
- How can I tell if the radiator is obstructed? If so, how can I tell by how much? (It doesn't seems too obstructed as I could easily blow coolant through it while draining.)
- What else am I not thinking of?
- What should I try next?

Thanks and apologies to anyone who read this whole thing My searches here usually fix all my problems, so you've all made owning my old Disco a lot of fun.

 

Simple fixes first, b4 any conclusions, fix the clamp, bleed system, check oil for water contamination, and see if it's better,,
Having a loose clamp can cause air in system, but you don't know for sure until you try step by step troubleshooting first,

 

A follow-on question would be: is there anything I can try/test while the system is empty and open/apart before I button it all up and refill it? I have a few days before the new expansion tank cap that I ordered arrives. Thanks!

 

The system is pressurized. If theres a crack on the tank that can cause the drain or loose clamp. Fill while engine is cold. Then fill again when cold. Waterfall usually disappears.

 

It can take more than two times to get all the air out of the heater core. I am on my third fill/ bleed. It gets better each time I do it. Hoping number four in the AM will be the last.

 

"Don't go chasing waterfalls"

Sorry, couldn't resist...lol.

But seriously...fix known problems before looking for more. If problem presist afterwards...then continue your search. But, for now...let's just pursue the leaks and bleeding method.

Brian.