My 2003 Discovery 2 recently counted a strange overheating problem. It was running perfectly after a recent 2500 miles trip. But then one morning I found the heater was not working properly, sometimes hot but sometimes barely warm if not cold. And then yesterday morning the coolant temperature gauge suddenly shot to the red zone. So I pulled over and noticed the reservoir was very full and the coolant was dripping from the vent hose. I waited a while till the engine cooled down a bit and slight loose the reservoir cap, there were some steam air came out and it sucked in all the coolant from the reservoir. So I added about half gallon water to the reservoir till it's about full and purged the air out the bleeding screw and then drove the truck home, no problem at all on the way (about 10 miles). Then this morning I checked the vehicle around and found no coolant or water leaking, but the coolant hoses connect to the T where the bleeding nut is are all sucked (please see the photos I attached). Only when I uncap the reservoir or untight the bleeding nut, these hoses came back to normal with lots of air out from the bleeding nut and coolant sucked in from the reservoir ( I had to add about another liter water in to top the reservoir). I then started the truck and let it idled for about 20 minutes, occasionally peddled some gas, all looked fine. The temperature gauge was at about halfway and the heater worked fine blowing hot air. So I decided to drive the truck out around the town. The coolant temperature started to raise after about 5 miles driving so I decided to go back. After I reached home, the temperature gauge was already near the red zone (not in red yet), the heater was no longer hot (just a bit warm comparing to outside air). The coolant reservoir was full to the top with some coolant/water dripping out the vent pipe. So I stopped the truck and park it for about 1 hour and then I found the samething, those hoses from the T sucked in again. It seemed to me somewhere there was a blockage that stop the coolant circulating but I have no clue what caused it and where to find it out.

The truck has a newly renewed water pump so I doubt it's the problem cause. When the water pump was replaced, I also flushed the entire coolant system. At the time it seemed the water flows fine through the radiator, the heater core, and from the reservoir to the outlet on top front of the engine.

Any help is very much appreciated!

 

You need a shroud on that radiator too.

 

Park it on a hill, let it run, open the bleeder. Do this multiple times. I turn on the heat too but that's just me.

The reason you don't have heat is because there's no coolant flowing into the heater.

I like to raise the front of my rover so the bleeder becomes a highest spot with the horizontal hoses all pointing upwards.

 

Do you think I have clogged radiator that caused those hoses sucked in? What else could cause this kind of problem? Thanks,

 

Sucked up hoses are caused by faulty radiator cap usually.

Also. The gold color. What's that?

 

I repainted those in gold, just for fun.

Why would a failed reservoir cap cause those hoses sucked up?

Thanks,

 

Borrow a pressure testing tool from one of the auto parts store, pressurized the system and look for the leak. My guess is you have a blown hg and the cylinder is sucking in, then steam is repressurizing the system..

 

Change reservior cap and check return hose that runs along top of radiator for blockage. Bad reservior cap can cause this, system goes into vacuum, if cap is not maintaining pressure correctly, or there is a blockage in the system (small return hose along top of rad).

​​​​​​​ Brian.

 

Sounds cool. I painted one of mine British Racing Green . Hoped it would go faster. Alas.

A radiator cap controls pressure on the cooling system. Under pressure, a fluids boiling point is raised up. So depending on cooling needs, the pressure varries.

The spring and gaskets fail over time on a radiator cap .They are cheap and easy to replace. Good place to start before rebuilding an engine.

 

And x2 on that small hose. Had this happen awhile ago. Chunk of RTV found its way in there. So annoying.