Last year I replace the lifters, thermostat, plug wires and head gaskets on my 2000 Discovery II. It is a 4.0 with 120,000 miles. Last week a hose split running from the overflow tank to the intake. The split was next to the intake. The temp gauge did not ever indicate the engine was getting hot. The engine began to knock and sputter and the engine light came on. I immediately pulled over and shut off the engine. I was able to temp repair the hose after it cooled off and filled to coolant with water. It cranked up with no issues and I drove the 3 miles home and parked it. The following day I correctly repaired the hose that had split. I checked the thermostat and it was trashed and looked to be clogged with some sort of black plastic that I think came from the thermostat. after filling with water, I cranked it up and ran for about 15 min at idle and there was no rise past "normal" operating temps. I decided to test drive and went 1/4 mile and the temp gauge shot to the top and the light came on. I have now replaced the radiator, installed a new overflow cap, and a 180 thermostat ( I live in GA). After installing the new parts, I once again cranked the engine and let it idle for 15 min we no issues. I took the vehicle for a test drive and all was well. I drove home and parked the Discovery. The wife and I decide to make a run to the Sam's Club which was about 10 miles away and was uneventful. On the way back home the gauge began to go up. As I arrived home it had pegged out hot again. I popped the hood and the steam was coming out of the overflow tube. There are no noticeable coolant leaks, no oil in the coolant, no coolant in the oil, and no white smoke from the exhaust but, it was low on coolant approximately 1.5 - 2 gallons . Do you think I have blown another head gasket and that there is a small amount of water leaking in to the combustion chamber? Suggestions?

 

You may want to invest in an Ultra Gauge. That shows the actual temp of the coolant, from what I understand the factory in dash gauge shows the middle 50% reading at temps anywhere from 140 to 240 (!)

 

I replied to your PM. That much coolant loss has to go somewhere. It would be smoke out the back that could not be ignored, or oil overfilled and milkshaked; leaking out on garage floor, or maybe just venting like mad from coolant bottle, cap is venting under 18 PSI, or perhaps steam is making hoses rock hard and venting is supposed to happen , coolant is lost while driving and not noticed. Should be making a lot of gurgling sounds under dash from bubbles in coolant going thru heater core.

 

I also replied to your PM, don't drive it any more till the problem is found and fixed.

 

Thanks for the PM reply as well as your feedback. The upper hose on the radiator would get very hot and the hard when at running temps. Before I changed out the caps there was a constant drip from the overflow tube. It no longer drips. before I put in the new radiator and cap I heard the gurgling on the time. I have not driven it enough to tell if the "gurgle" is still there.

 

I will call you shortly

 

If the Water Pump was going bad, you should be able to notive that via weep hole. I'm thinking bottom 1/2 of your radiator is sludge, causing the rest of the system to cook. Only reason I bring that up is it's easy to test. When the top hose is hot, is the bottom one cold?

 

Mr. Alan,

Without an OBDII scanner of some type, you would be depending on the Rover factory gauge. Note these two pictures, by different members. Different OBDII temps, yet factory gauge is "dead center" in both trucks. This "undocumented feature" or "bug" in the ECU program makes both owners see same display, while they are 38F apart.

If you don't have a better gauge, running while it does not show overheat may be a like SWMBO saying she can't be overdrawn because she has checks left. When testing, no need to sail past 195-205, you don't need to go to 227 to "prove" you are overheating. Running on the high edge just helps warp heads, make sleeves slip, cooks oil to worthless dribble.

IMHO most Rover owners are riding along in blissful ignorance, if they saw the real temps, being the men of action, repairs would have started long ago. No one wants to be a fool and drive a truck that is overheating. But Rover drivers are just fooled by the instruments.

 

Prior to my original post the entire radiator was trashed and I installed a new one as well as a low temp thermostat and new overflow tank cap. No leaking from the weep hole but......if the pump was going or gone would there not be a lot of noise?

 

The pumps normally "wobble" the pulley as the bearing wears out, then leaking from the nose begins. Inside looks like this. The wobble allows it to eat aluminum. Sometime the impeller slips on the shaft, but in many trucks there is enough corrosion where this is not the issue. The loss of 33-65% of the total coolant has to show up somewhere, it did not just evaporate. You can rent/borrow a coolant pressure tester and pump up to 15 PSI and wait 30 minutes for leaks to show up.

10 miles per gallon of coolant is an mpg figure no one wants.

Also, double check your serpantine belt route. If wrong route, pump can run bass ackwards.