Discovery II Ultimate Bleed Coolant System technique
#11
I see now that in your original post you say you changed the head gaskets. I'd had a couple of drinks when I posted that.
If you've bled it thoroughly (takes probly 10-15 minutes with the valve open and I had good luck with gently tapping on the plastic bleed housing), and it's still overheating, I'd start with the thermostat. One thing I will say is that these radiators are supposedly not good for flushing. The story is that they have such small passages they don't flush very well. So people always just replace them. I haven't done this myself, but guys who have known Rovers for a a long time support the idea that flushing doesn't work. The way to test your radiator is with a laser thermometer. Take regular measurements of the entire face of the hot radiator while the truck is running. If there's more than a 5 degree change, the radiator isn't flowing like it should.
The symptom of a bad thermo is it isn't regulating the engine's temp correctly. Either the cooling system gets too hot because it isn't opening or stays too cold. You can test it by pulling it and heating it til the thermo open, I think the preferred method is dropping it in boiling water, then pulling it out to see if it opened (though I have never tried this, and don't scald yourself!).
However, if it hasn't been replaced in some time, you should probly just replace it and use the TD5 thermostat that opens at 180 instead of the stock thermo's open temp of ~205 degrees.
Here's a link to the thermo.
They are a bit expensive, but people have had pretty serious problems with the cheaper Motorad version.
If you keep having problems, start your own thread. It'll get more attention and you'll get more help.
Good luck
If you've bled it thoroughly (takes probly 10-15 minutes with the valve open and I had good luck with gently tapping on the plastic bleed housing), and it's still overheating, I'd start with the thermostat. One thing I will say is that these radiators are supposedly not good for flushing. The story is that they have such small passages they don't flush very well. So people always just replace them. I haven't done this myself, but guys who have known Rovers for a a long time support the idea that flushing doesn't work. The way to test your radiator is with a laser thermometer. Take regular measurements of the entire face of the hot radiator while the truck is running. If there's more than a 5 degree change, the radiator isn't flowing like it should.
The symptom of a bad thermo is it isn't regulating the engine's temp correctly. Either the cooling system gets too hot because it isn't opening or stays too cold. You can test it by pulling it and heating it til the thermo open, I think the preferred method is dropping it in boiling water, then pulling it out to see if it opened (though I have never tried this, and don't scald yourself!).
However, if it hasn't been replaced in some time, you should probly just replace it and use the TD5 thermostat that opens at 180 instead of the stock thermo's open temp of ~205 degrees.
Here's a link to the thermo.
They are a bit expensive, but people have had pretty serious problems with the cheaper Motorad version.
If you keep having problems, start your own thread. It'll get more attention and you'll get more help.
Good luck
#12
Wow, this old thread revived.
I still don't have any problem from my bleed technique which I did Jan 2013.
Have not had to do anything since then.
Head gaskets March 2012
New Radiator Jan 2013.
Bleed Jan 2013.
Nothing since.
I still absolutely hate that bloody bleed screw and will never use it.
I still don't have any problem from my bleed technique which I did Jan 2013.
Have not had to do anything since then.
Head gaskets March 2012
New Radiator Jan 2013.
Bleed Jan 2013.
Nothing since.
I still absolutely hate that bloody bleed screw and will never use it.
#13
If you've bled it thoroughly (takes probly 10-15 minutes with the valve open and I had good luck with gently tapping on the plastic bleed housing), and it's still overheating, I'd start with the thermostat.
I dont really understand what you meant by valve being opened and gently tapping on the plastic bleed housing. Please explain more on this and I am going to replace the thermostat and re bleed the system again.
Many thanks for the tips so far.
I dont really understand what you meant by valve being opened and gently tapping on the plastic bleed housing. Please explain more on this and I am going to replace the thermostat and re bleed the system again.
Many thanks for the tips so far.
#14
Well, I truly don't mean to be obnoxious, but have you read the procedure in the RAVE?
The bleeding procedure is on page 26-2-14.
(Steps 1-4 are putting hoses back together)
5. Release top hose from retaining lugs on the fan
cowl, leaving the hose to rest on the lugs.
6. Remove bleed screw from top hose.
7. Unclip the bleed hose from the battery box.
8. Remove expansion tank from its mounting
bracket. Slowly fill the expansion tank with
coolant, approx. 4 litres (7 pt).
9. Raise the expansion tank approx. 20 cm (8 in)
vertically, coolant will drain into the system.
10. Refill the coolant expansion tank until a steady
flow of coolant is emitted from the bleed hole.
11. Fit the bleed screw then, with the expansion
tank still raised, continue filling the system until
the coolant level reaches the base of the
expansion tank filler neck.
12. Fit expansion tank filler cap, fit the expansion
tank to its mountings and clip the bleed hose to
the battery box.
13. Refit the top hose into its lugs on the fan cowl.
14. Start and run engine until normal operating
temperature is reached, and check for leaks.
15. Switch off engine and allow to cool.
16. Check for leaks and top-up coolant to cold level
mark on expansion tank
Be careful with Step 9, as the hard plastic hoses to the expansion tank tend to break. Step 10 is where I'd take my time and tap on the housing help bubbles escape. There'a drawing of the bleeder housing on that same page in the RAVE, but it's a T connecting three hoses directly behind the fan. It has a removable bleed screw in it, but try to be gentle, they will break from time to time.
The bleeding procedure is on page 26-2-14.
(Steps 1-4 are putting hoses back together)
5. Release top hose from retaining lugs on the fan
cowl, leaving the hose to rest on the lugs.
6. Remove bleed screw from top hose.
7. Unclip the bleed hose from the battery box.
8. Remove expansion tank from its mounting
bracket. Slowly fill the expansion tank with
coolant, approx. 4 litres (7 pt).
9. Raise the expansion tank approx. 20 cm (8 in)
vertically, coolant will drain into the system.
10. Refill the coolant expansion tank until a steady
flow of coolant is emitted from the bleed hole.
11. Fit the bleed screw then, with the expansion
tank still raised, continue filling the system until
the coolant level reaches the base of the
expansion tank filler neck.
12. Fit expansion tank filler cap, fit the expansion
tank to its mountings and clip the bleed hose to
the battery box.
13. Refit the top hose into its lugs on the fan cowl.
14. Start and run engine until normal operating
temperature is reached, and check for leaks.
15. Switch off engine and allow to cool.
16. Check for leaks and top-up coolant to cold level
mark on expansion tank
Be careful with Step 9, as the hard plastic hoses to the expansion tank tend to break. Step 10 is where I'd take my time and tap on the housing help bubbles escape. There'a drawing of the bleeder housing on that same page in the RAVE, but it's a T connecting three hoses directly behind the fan. It has a removable bleed screw in it, but try to be gentle, they will break from time to time.
#15
#16
#17
You can add a picture here if you click "Go Advanced" below the post block and then "Manage Attachments".
That way you have more people helping.
It probly doesn't matter either way if you're replacing the thermo. If it's years old, it could easily be the problem. But there could be other problems, too, so don't get your hopes too high.
That way you have more people helping.
It probly doesn't matter either way if you're replacing the thermo. If it's years old, it could easily be the problem. But there could be other problems, too, so don't get your hopes too high.
#18