2001 Discovery II overheating 160k gas engine
 

Hello, I have read a lot of forums on here seeing many people have overheating issues but I can not find a working solution. It will over heat sometimes only a little bit and sometimes to the red. It will do it while driving and while idling. Sometimes after 10 mins at 5 in the morning and sometimes after an hour in the afternoon. So far I have flushed the radiatior, replaced thermostat, water pump, and fan clutch with the same results each time. From what I can see there is no milky substance in the oil and nothing is leaking. It will leak but only when the system boils over. Any help or suggestions would be greatly appreciated not sure what to do at this point I hate to keep guessing and buying parts. Thanks

have you checked the over flow cap, it like a $20.00 item.
How long has it been going on?
how many time has it over heated?
What year?
when did it start?
before of after you started replacing items?
need a little more imformation to work with.

1. You have done many good things, but what could be left behind is more expensive.

2. Could be head gaskets, which will usually cause a loss of coolant as well, either in the oil, on the ground, or out the tail pipe. Do you have loss of coolant? Any noise like rushing water behind the dash (bubbles in heater pipes)?

3. Could be cracked block or head, where metal opens up once a certain temp is reached, and very hot gas enters coolant system.

4. There is a $50 chemical test you can buy at parts store, it will tell you if there is combustion gas in the coolant. It will do maybe 15 tests, so it can be used to check other cars or verify repairs of this truck.

5. The radiator couild be clogged, reducing the level of heat that can be dealt with by all the other new parts. This will show by rad being cooler at the bottom than the top, by say more than 20 degrees.

6. The thermostat, if not a Land Rover OEM, may be suspect. There have been reports posted of new ones not opening at the right time, etc.

7. Testing this way, by waiting for the gauge to build above 9:00, is not good for the motor. The gauge will show 9:00 until overheating begins. If you have access to a scanner/code reader that will read live data, or an Ultra Gauge, you can see the temp in digital form. That way, if what you try does not work, you can see it going by 212 F, where the electric fan should cut on, and there is no need to get to 235 - 240F.

8. The short time in the morning makes me think defective thermostat. If work on the truck was done after stat change, possible some gunk found its way to the sensing holes on the top leg of the stat. They can't be blocked.

Pix attached of sludged lower rad, thermostat holes,
and an ultra gauge.

Thank you for the replys, I have only had the vehicle for 6 months, it was advertised to have no problem when I purchased it but within a few days of easy driving it overheated and the water pump failed. Thats when I started this process. Its a 2001 with a 160k miles and doesn't seem to have any other problems engine runs strong, somethings that stand out is I do hear rushing water sometimes when giving it gas it sounds like it comes from behind the passenger side dash. There does not seem to be antifreeze in the oil or vis versa. Two things that stand out right before it overheats is a squeaking starts around 2,000 RPM's that isnt there a lower temperatures (not sure if its related), and the pressure in the system seems to get really high, all the hoses are very firm to the touch. It is hard to tell if I am loosing coolant or if it just boils over. If I let it idle it will not over heat until pressure starts to build up then it will bubble out of the reservoir. It has started to overheat probably 6-8 times. It has only gone to the red once I always shut it off as soon as it started to climb. Is the best way to check the radiator cap just to buy a new one? Is it worth to try a had gasket sealer in the system just to see if it help before taking it to a shop to do the head gasket? I did re look into the thermostat I purchased it new from a land rover parts dealer online and it appeared to be an oem one the same as the previous, I checked the thermostat and all the wholes and housing were clean, I also flushed it out looking for debris and could not see anything. One other thing I figured worth mentioning is I have been using a premixed 50/50 solution, could that cause as big of issues compared to using drexcool?
Thanks everyone for your help Ive fallen in love with this vehicle and refuse to give up on it:)

I found a radiator cap locally for 14.99 at that price I am going to try it, I will update a post when I get back and get it on. thanks

You should stop diving the truck until you get you problem straighten out, it WILL cost you a motor.
the sound of rushing water behind the dash is a sure sign that you have a leak / low on coolent.
After you fill and bleed the system you should preasure test the coolent system to try and find your leak, it could be dripping on something hot and boiling off before you see it.
It is quite possible that you need the head gaskets replaced, there is a test kit you can buy to check for CO2 in your coolent.
But I would rent/borrow a preasure tester from advanced/ autozone or whomever you buy your parts from and try that route first.
while your there pick up a new cap for $15.00

Ok thanks Drowssap, I have the parked the LR for now and Im on my way to autozone will update soon.

I strongly second the recommendation that you stop driving the truck. You will cause more problems and can very easily toast your engine. You need to get the cooling system properly bled before you do anything more. The "waterfall" sound behind the passenger dash is a sure sign that there is air/gas in the cooling system. Check the forum for the proper way to bleed they system. There are a couple of ways to do it. I found that the way that worked best for me was to:

1. start with a cold engine (I did it in the morning after letting the truck sit over night)

2. open the bleed screw on the radiator hose,

3. open the coolant tank on the passenger side of the engine bay (remove cap) the tank is held in place by some runner clips, you can pull up on the back of the tank and then slide it back, there is a tab the holds the tank in place on the front.

4. Lift the tank higher than the bleed hole on the radiator hose. BE CAREFUL with the plastic lines that run to the throttle body heater, they are prone to break, they get very brittle. You may have to unclip one from the side of the coolant tank. If you break the lines, it will add to your frustration and take additional time to replace! Be Careful.

5. Once the tank is higher than the bleed screw, and with the screw removed, fill the tank with distilled water until the fluid starts to come out of the bleed hole. (I have also left the tank in place, filled the bleeder hole using a small funnel squeezing the associated hoses as you go to try to work the air out. When the fluid starts coming out of the hole, top off the coolant tank, trying all the while to make sure that fluid continues to come out of the bleeder hole, refit the bleeder screw, top off the tank and refit the tank cap)

6. While the tank is still elevated, replace the bleed screw and gently tighten it, not too much or you will break the screw or the t-fitting.

7. refit the tank and top off with distilled water.

8. Start the engine check for leaks. Check to see if air bubbles are making their way into the tank.

9. If no leaks drive around and listen for the waterfall sound. If it is still there (it probably will be, don't be alarmed), take the truck home, park it and after it is completely cold, ie the next day, repeat.

It usually took me three attempts/days to get all of the air out of the system. I have done this many times, too many to count. There are other methods described on the forum, I have tried them all. I have found that this method worked the best for me.

Note that at idle, the cooling system mainly circulates the coolant through the heater core rather than the radiator. Once the rpms are above idle, the pressure of the water pump opens a pressure valve in the thermostat. Parking on an incline or lifting the front of the truck to allow air to make its way to the highest point, ie the bleed screw, is recommended. It is a pain, but once you get the air out, you can them properly diagnose how it is getting into the system. good luck, do not rush the process, it takes time. Also, get the dexcool out of the system, it will eat up gaskets. Depending on where you are located, ie an area where the temperature doesn't get below freezing, I would use distilled water to fill and bleed your system, it is cheaper and cleaner. good luck, Phil

Currently, Disco Free

Where are you located?

im in the very south new mexico not far from arizona border, thanks everyone for all the replies I have the new cap in and im getting ready to start bleeding the system.