Just picked up a 2000 Discovery II under the assumption that it had bad head gaskets. Tore the whole thing down and reassembled with a Beck/Arnley head gasket kit, head bolts, and all the other maintenance items. Have the truck running up and down the street no problem, but the cooling system isn't circulating through the radiator. Will come up to temp, but the thermostat never opens. As it continues to get hotter, the upper radiator hoses start to bulge and get hard.

I'll list off the basics I've done that everyone would suggest for a situation like this:
-New radiator
-Tested old thermostat in boiling water and confirmed it opened at 212 degrees
-New thermostat, installed properly with the bypass going to the heater core
-Bled coolant system properly according to the service manual, with DexCool
-Verified serpentine belt is routed correctly, and water pump is moving fluid
-Hooked up a garden hose to the heater core hose and pushed about 20 gallons of water through the entire system, all clear by the end and good flow
-Rented the chemical block tester from Auto Zone and tested twice for exhaust gases in the coolant, once cold and once fully warmed up and both were negative

At this point, most posts on the forum lead to a dead end and no one ever updates with the solution to their issues.
Others have had issues with the sleeves slipping or leaking, but I have no mixing of coolant in the oil, and don't have boiling in the expansion tank

Anyone else experience issues like this and came up with a solution?

 

Did you replace the recovery/expansion tank and cap? It looks like the only part you haven't done. Have you flushed the system, disconnected upper hose from rad and feed water from a garden hose into upper radiator inlet with engine running and watch water run out from disconnected upper hose? Could it be corrosion flakes blocking water passages? I am going to do this flush before I do my head gaskets. Check the fan clutch and elec. fan also. Oh, and everyone says don't use Dexcool, use green coolant, don't know why. Keep us posted, very important issue.

 

Maybe your new thermostat is faulty...wouldn't be the first time. Pull it off and check it. Or put old one back on and see if you find any differences.

Brian.

 

Sounds to me like the prop broke off your water pump, unless I missed where you replaced it. Pull it and see.

Also, 212 is too hot on the thermostat. Replace it with an OEM 180 degree or switch to an in-line thermostat. The second option is the better one IMO.

 

x2 on water pump not doing it's thing, check belt for proper routing.
Valley pan gasket blocking water flow?

To check flow, take off cap to overflow tank, yes you may loose some coolant but you should see a small stream of coolant "peeing" into the expansion tank from the long skinny hose that runs from the top drivers side of the radiator.

When engine is hot and coolant is to temp the lower hose from the passenger side radiator to the tstat should be hot, if the tstat isn't opening it wont get hot.

 

Thanks for all the tips so far. Today I went and picked up a third thermostat and a new expansion tank cap. My old cap had some of the threads broken off and was always hard to screw on, while the new one threads on much smoother. Swapped both of those on, bled it and went for a drive. I used my obd scanner to watch the temps and they stayed between 195 and 200 degrees the whole time, which leads me to believe its not overheating. However, all of the hoses are extremely pressurized and look like they're on the verge of blowing off. I've worked on many cars in my life and this definitely does not look normal.


Compared to a dry hose.


Also the bottom hose of the radiator became a bit warm, but the center of the radiator was still cold to the touch after a 20 min drive.
Water pump is working properly, stream of coolant is being pushed from the rad to the tank. Both hoses on top of the thermostat are definitely up to temp and hot to the touch, but the tstat never seems to open.
Valley pan gasket is an interesting thought, although everything was lined up when I assembled the manifold.

 

You definitely need to replace that hose before it bursts. The cooling system is supposed to be pressurized. That's a sure sign your hose is failing. If it were me I'd replace all of them at the same time. You can get all the upper hoses on Amazon for like $35.

I know that's. It your immediate issue, but it's going to be soon.

I still say you need to replace your thermostat, too. Even if you've already replace it, they can be bad out of the box.

 

^^^^I believe he mentions getting another thermostat and having somewhat better temps.

I'd bleed the system again, maybe a couple times...since it has been opened up a few times now. The bulging hoses are a concern and may need replaced, but I'd make sure all air is out of system first. Take a few more test drives and bleeds...and see if you notice any change.

Brian.

 

My cooling system will still hold pressure 2 days of sitting stone cold. That said, your hose scares the hell out of me!!

 

Really the 180 degree stats available from Rover retailers fail frequently, I shudder to think of how the Autozone ones stack up. The two white OEM 180 degree ones available from AB run around 200, the grey OEM one from Lucky 8 runs 188 - 194.

And agreeing with above, That hose looks like trouble waiting to happen. The clamp doesn't look much better. Replace the clamps too!

Also a quick way to check your bleed is to open the bleed screw first thing in the morning before you start the engine, stone cold. If you can fit any more coolant in there, you found an air pocket. If it is full, you have bleed correctly. If it is low, top it off through the bleed hole with a small funnel. You may need to repeat this over a few days.

However in reality, you may as well replace those hoses and clamps before you go and get it bled all perfect with the right stat because you'll need to do it all over again soon.