2000 Disco w/ 109k.

Got a new radiator and thermostat put in about 6 or 7 weeks ago. I believe there was air trapped in the system when I got it back. Anyway, on a short drive to drop our daughter off at school today, I noticed the temp. rise just a bit. Nowhere near "hot", maybe 10-15% past the dead halfway point that it normally sits at. It went back down, then back up to the same point, then back down. When I got home, I slowly took off the expansion tank cap, letting the pressure release. When I took it off completely, a pretty good amount of coolant belched out of it. Coolant wasn't boiling, and really didn't seem very hot. It seemed like it took a lot more coolant to fill it back up than it belched out. Did I just belch the air out of the system? Drove it for 30 minutes after, and it never got beyond the halfway point that it normally runs at. Let it sit and idle for another 10 minutes, and temp. was stable.

 

There could be more air in it. Have you a sound like water rushing thru pipes under the dash (bubbles in coolant)?

Would keep an eye on it each day for a week to see if any more change in coolant level. If coolant is being lost thru a hose clamp, etc., the loss could continue slowly.

Good job on the eagle eye on the temp gauge.

 

First, that will happen any time you take the cap off when the engine is warm, that is why I always tell people to open the system is cold.
As for air in your system, where is your bleeder screw located, molded into the upper hose or on a black plastic Tee. If on the hose, that hose has a high failure ratre and Rover replaced it with an up-dated model 8 years ago, so if you have the old sytly, order a new one before you do anything else.
In the mean time if you want some help with the over heat issue, send me your number and I'll call you back.

 

Hi,
I just went thru all this.
When my discovery II was around town and I open the expansion bottle -
out came tons of coolant.
I could not bleed out the air.
When I coasted on a street and foot off the gas, then applied the gas -
waterfall sound in the heater core.

I pulled apart the engine and found a head gasket with a hairline crack
on cylinder 1 into the coolant jacket.

The combustion gas only has to go about 6 to 8 mm from the combustion ring
to the coolant jacket. Once in there it will pressurize your coolant system.

I have a Discovery I which my wife drives. I can take the coolant cap off when the engine is hot and it never throws coolant on the ground.

So, I bet you have a bad head gasket.

In a few days I hope to have my Discovery II back together and I'll report how it reacts with the new head gaskets.

 

Taking a cap off a hot engine is a good way to get incinerated.

 

I had the head gaskets done 30K ago by The Rover Shoppe (an independent Rover shop) here in Houston. They also put in the new hose with the bleed screw located in the plastic T about 2 years ago. The thing is, I had a new radiator and thermostat put in by a different shop (hose broke at the joint where it attaches to the expansion tank, and the radiator broke when they tried to disconnect the hose from it). I'm guessing they didn't bleed the system properly after putting it in. I do still have a little sloshing under the dash, but not near as much as before the "belch". I suppose I could have a bad head gasket, but I would be surprised it would be bad after 30K since it was done by a extremely reputable shop and was sent out for machining as well. Haven't had any further temperature issues either.

Here's what I have had done to the Rover:

Within last 2 months:
New radiator
New thermostat
New plugs and wires
Deep cleaning of throttle body - it was pretty nasty
New air filter
New oil cooler line

Within last 30K
Head Gaskets
Drive Shaft

 

Keep bleeding to get out the last of the air. If you are having HG issues the bubble will return.

 

Thanks. The sloshing didn't appear until right after I got the new radiator put in. That, combined with the fact that I had the HG done 30K ago leads me to believe that it's not the HG - fingers crossed.

I have read how to bleed the system by opening the bleed screw and pouring in coolant until it comes out of there, but I have perhaps a dumb question. I understand you're suppose to get the reservoir above the bleed screw - how in the world do I do that?

 

Unbolt and lift it up. And keep it up until all the bubbles stop coming out, not just there first 2 or 3 you see. Would be a better system if this bleeder went to a hose, into a bucket, which would caputer the coolant and bubbles. Then the de-bubbled coolant could be poured back in.

 

Gotcha, that makes sense. How long would you figure it will take to get all the air out of there? I just don't want to think they're all gone and stop prematurely.

And yes, it would be a better system if it went to a hose.