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Discussion Starter · #1 ·
Is it possible that air in the cooling system could cause over heating after about 1000 miles of driving. Recently replaced the leaking water pump. Topped off the coolant and didn't bleed the system because it was cooling just fine.
Drove around locally with no problem then on a 900 mile trip after 780 miles the engine over heated. Went to full hot. This was after negotiating Raton pass 7800ft. with no problem. Don't know if this had any effect on the heating problem. Let the Rover sit over night and then remove the thermostat. Initially coolant temp resumed to normal after start up, it over heated again when I started driving.
Removed the water pump thinking it might have failed, it's just fine. I've, flushed the Radiator and the Engine block. Can't find any blockage.
Anyone have any Ideas?
Thanks, Ron
 

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disco biscuit
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No I don't think air would wait 1000 miles before having some affect on your cooling system. So how long did you drive it before the long trip? Why did you changed the water pump? Did it overheat then?

Also you said you removed the thermostat, I'm guessing you meant changed it? That overheat sounds like air or sticky thermo after you changed it. Describe it a little bit better and we might get closer. Overheating very hard to give advice on a forum cause I'm sure you're well aware there could be a whole lot of things causing it and symptoms for these root causes are all the same...it overheated.
 

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Discussion Starter · #3 ·
I replaced the water pump because it was leaking. No overheating occurred with that problem.
When the overheating occurred we were close to a rest area so we spent the night.
Next morning I removed the thermostat, suspecting it was the culprit. Topped off the coolant tank, started up, the engine came up to normal temp. Drove away and as I accelerated on the freeway the temp went full hot again. Shut down and called a wrecker and was hauled the remaining 120 miles to our Colorado home. Removed and inspected the water pump, looked perfect. Even heated the water pump up in boiling water on the stove top to be sure the impeller was not slipping on the shaft. Flushed the rad and the block. No obvious problem was found?
 

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Did you replace thermostat ? I'd do that them fill with correct coolant plus water wetter and bleed system. If you ran too hot for too long you could damage head gasket - any sign of smoke from exhaust or water in the oil ( look at oil cap for milky mess)
 

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Discussion Starter · #8 ·
Yes, this is an '05 LR-3. I'm using Zerex G5 coolant.
Have it back together now. Got what I thought was a small quantity of "material" (gray in color sort of chunky). Apparently this was something that was added to the cooling system? Not sure but, the engine hasn't overheated since I removed/inspected and reinstalled the water pump and flushed/refilled the system with coolant. Think I will pull the lower coolant hose and see if any more "material" flushes out.
 

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If the wrong types of coolant are mixed - they can gel - not sure if that is the " lumpy" material you are seeing. This is 4.4 v8?
I'd use oem coolant or Pentosin Sf only ...need to flush old stuff out completely including from heater core
 

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Discussion Starter · #10 ·
Now I'm thinking I have a head gasket problem. Pressurizing the cooling system.
I've replaced the thermostat, check the almost new water pump, and still having cooling problems. Temp will be fine for 40 or so miles and then it will go to hot. Sometimes the temp will come down for a while then go back up. Just fluctuates. What a pain. Getting to be that I can't rely on the Rover.....If I can't get this sorted soon I will give up on the Rover. I'm regretting selling my Disco 2 for the LR-3 !
 

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Interesting, keep us posted. Is it possible the thermostat was fitted backwards? I definitely would also think the bleeding and correct coolant would be important. If you have gunk, perhaps also the radiator should be checked for cool spots (blockages) and the fan should be checked.
 

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Unheard of in an LR3 V8
 
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