I have waded through a lot of post and I haven't found one that quite fits yet with my overheating problems. But it is good to know that I'm not the only one out there.

01 disco II

I had a bad oveheat coming down off of mt Rainer and it pushed the head gasket over the edge and led to a tow home.

A couple months later and I have it put back together, low and behold the the initial condition must have stayed put. First test driveout and I got the temp going in the wrong direction. But it had no problems sitting and idling for an hour, temps held steady on a hot day. Measured with infrared, I don't trust the gauges until I git her running right.

What has been done or observed:
-Heads worked new gaskets from there up.
-Block checked out ok, no cracks or dropped sleeves
-new hoses
-new temp sensors, both of them
-new plugs/wires
-new plastic tank cap
-Water pump solid, no play, weep or leak.
-viscous in fan feels good
-Checked electric pusher, ok
-Everything is pretty clean should have no heat transfer problems.
-Pressure tested, held 13 for hours no problem.
-Did a flush and the effluent came out pretty clean. Nothing but OAC in it. The manifolds water areas were pretty clean.

Maybe the radiator? not really the same signs as my last one that I had to replace a radiator. I miss her RIP, the only problem I had with that one on over 70,000 miles.

Running out of things to replace.

 

1. The RAVE points this out for temp sensors, if not plugged in good.

temperature gauge will read cold and the high coolant temperature warning lamp will be illuminated.

We shall assume that by wrong direction you mean getting hotter, not going backwards.

2. The D2 uses the top of engine sensor to drive ECU, which computes a signal to make gauge display. So your OBDII port is best place to read temp. It should be logical when cold - like ambient, not -40F.

3. Here are two trucks. Note the Ultra Gauge temp shows different, but oem gauge is glued on 50%. Using the dash gauge to diagnose overheating is not the best way. It points at 50% from about 130 - 240F. You would like to be in the 180 - 200 range on the highway. You may be idling along at 227.

4. So if your gauge is showing an eyelash above 50%, my point is that you have been overheating. Even at 50% you don't know without an OBDII gauge.

5. Take your IR thermometer and measure the radiator fins, truck warmed up, engine off. Measure top to bottom in a vertical line. Should be under 10F difference, unless sludge has started to block off lower rows. If sludged, lower areas will be cooler. There is no reliable homebrew formula to remove it, other than replacement. Could be half full of dried sludge-crete and not show much of it on a flush.

6. The aftermarket (or Rover) 180F soft spring thermostat is a great device to lower temps across the board.

7. Check fan belt route again. Don't want pump running backwards.

8. At idle hold plastic bag against grille, it should suck toward grille and not be blown away. All fans (electric and viscous clutched) should send air thru radiator toward engine. If fan blades or electric wires reversed, the fans would subtract air during forward motion, and there would be a speed where air flow thru rad was in effect "zero".

9. Is the new condition also causing gurgle bubble sounds under the dash from bubbles in coolant? If you bleed and they keep coming back it may be exhaust gas. A $50ish chemical test will confirm/deny this and is a proof of performance for HG work.

10. If head gaskets were slapped on, without a machine shop inspection or re-surface of heads, could be a problem. Spec for flatness is 0.002 inch, or about 1/2 the thickness of a sheet of printer paper.

11. Viscous clutch, when warm, engine off, spin and release - should coast to a stop in under one revolution. Probably OK because your idle is not grossly overheated.

 

pressure test it again, it could hold at 13 psi for hours, yes. but you system is rated at 18 psi at 14-15-16 psi you could be pissing water out of every hose.

 

Buzz thanks for the feedback. I used my ir thermo to determine that I was getting over heat. I stopped every mile or so and shot temps on various cooling system parts (hose,radiator,etc) but I will reshoot the different spots in the radiator to see if I get a significant delta t. I don't think I have a single car where the temp gauge isn't much more then a go no go gauge.
Belt is right way, thats. Getting to be old hat with how many times she has come off and on lately. And the fan is sucking in the air.
No gurgle. System fully purged, another all to familiar task.
Heads are true as well as the block. Decked the heads checked block heigth for fairness.

I always keep a fresh bottle on the shelf for the exhaust test. It was clean. I never but the kit. Made my own. The chem alone is pretty cheap at my local parts store.

Idle is not overheated at all. In fact it cools off at idle. Temps are normal until highway speeds (50+). Since this was pre top side rebuild I'm thinking the radiator delta t you suggested might end up being very revealing. I will post the results.

 

Drowssap. Ill push it up again higher. Most everything else I have pops the cap at 12 so I didn't think about it. I am reasonable confident that the top end is tight and there are no external signs of leakage, so that is scary if it is, you know what that means then. Since it was also before the head job as well as after.....

 

Put in a new radiator and a new fan clutch.
Overheating DOWN mt Rainier is odd.

Looks like a plugged radiator.
and a bad fan clutch..

Also - I bet your AUX fan never comes on.
At 210 - 212 F your aux fan - same one as A/C has to come on to help cool it down.

I would say replace radiator..

Get one at Rockauto.com

$230 shipped to your door

A couple months later and I have it put back together, low and behold the the initial condition must have stayed put. First test driveout and I got the temp going in the wrong direction. But it had no problems sitting and idling for an hour, temps held steady on a hot day. Measured with infrared, I don't trust the gauges until I git her running right.

 

Also - put in a 189 degree soft spring thermostat.
This is a must.
even in Seattle.

 

correction
180 degree soft spring.
Put that one in.

Since I had put that soft spring into my 2001 - I never have the AUX fan come on
when in a parking lot.

I had this problem in Seattle - AUX fan came on from overheating.
and here in Southern CA - still OK with the 180 degree soft spring thermostat.

Of ALL the things replaced - temp related.
The soft spring made the BIGGEST difference.

My radiator was probably only 20% plugged - max.
My fan clutch was 40% dead.

 

As a result, I don't have a temp gauge on my rover all the time.
Never care about it now.
If I don't hear the aux fan in the parking lot - I know all is well.

 

Is the one you are mentioning similiar to the warm weather one from BritishAtlantic? that is the one I put in. If so good, if not I need to go shopping again it sounds like.