For what it's worth, OP, I think Extinct is correct. It sounds like you have a thermostat issue and now is the time to switch to the Inline Mod.

Even if you do end up having a HG issue after you do the Inline Mod at least you'll have a better, simpler thermostat set up with less to worry about down the road.

 

Thank you for the offer! I'm going to take your advice though. I just ordered the inline kit. Once installed, I'll update the thread.

 

this site is helpful:
https://discoii.wordpress.com/2012/0...-temperatures/

I think that if you replace the T stat with another new unit like you said you were going to do, and the water pump is new, then if that still does not work, then you probably need to investigate the HGs further (due to hard hot hoses...exactly what I had with my 2 HG failures)... you can pull the plugs and look into the cylinders with a small scope like:

I have one of these and it works great. Although many people have done the T-stat mod, I have not. I have a working OEM cooling circuit which functions fine (according to temps provided by my ultragauge) in summer up and down the west side of the Appalachian mountains. But I was not towing a trailer or overloaded.

You do mention a 'cool' lower radiator hose (t-stat or water pump not working, or a blockage..which would be unusual).....are all your hoses correctly placed? some of the small hoses can be routed incorrectly....I had this on a disco I purchased. If there is excessive pressure in your cooling system, you can cause a leak in the cabin heater connections.

 

Thank you for your suggestion! I went ahead and got the inline kit with the 180° thermostat and voila... just took it out for a test drive. Hot today also. Never got up to 200.... bounced around between 174 and 196... only did 5 miles but I'm thinking A-ok... before it was getting to the 250s within 2 miles.

The fix wasn't without its challenges though. The housing that came with the kit had a almost invisible crack in it. I saw a leak and couldn't identify where it was coming from so I stopped the engine and dried everything off and there it was, a tiny crack. Followed up with the company and attached pictures and they sent me another one no questions asked! Until I get it in, I went ahead and smeared high heat JB weld and that worked like a charm. I also had to do some trimming on my hoses to make the housing fit. It may still be touching the underside of my hood but I'll check the clearance later. There are also tiny leaks around the bolt holes. I opted for the reusable gasket for the housing and there wasn't any indication of I should use RTV sealant so I didn't. I have since disassembled the housing and added RTV around the gasket on both sides and around the bolt holes. We'll see.

But who cares about a few drops here and there... the Rover is purring like a young kitten again 😆

 

Yep, replacement on the way. If you run your coolant tank cap one full turn loosened from full tight it will not leak while you are waiting for the new one. BTW, I run mine like that all the time.

 

I did that since I read your last post and it seems to work well. Are you the one who makes the inline kit? Thank you for the excellent service and the suggestions!

 

Yep, thats me.

 

Awesome! Brilliant idea! It's amazing how it fixed my problem immediately. I wish I had started there but at least I have a brand new everything so I won't be doing any fixing to my cooling system any time soon.
thanks again for an awesome product!