Hey guys,
I looked through the sticky for D1's and couldn't find a write up for putting new coolant in and a new thermostat. I'm going through the 60K service and want to make sure that I do this before winter arrives indefinitely. If it is anything like it was last winter in Virginia I will need the disco handy!
I think a coolant flush should be done, driven with for 3-4 hours and then the coolant should be swapped is that right? Thanks for any help!
Lev

 

Replacing the thermostat is dead simple.
That should be fine for the flush. If you want to be compulsive there are two block drains one under each exhaust manifold. If I recall correctly they are 3/8" square.

 

Heres how I do it...
Remove the t-stat and drain the cooling system by remove the lower radiator hose from the radiator.
Stick your garden hose into the top of the engine and run it until it comes out clean.
Stick it into the upper hose and run it through the radiator until it comes out clean.
Put the t-stat housing (no t-stat or gasket) back and put hoses back.
Fill with your garden hose.
Start your engine with the heater on HOT.
Idle for 15-20 mins with the radiator cap off and making sure the system stays full.
Shut engine off, go inside and eat lunch.
30 min or more later drain the system. (you just want the engine to cool before draining the system)
Install your new t-stat and gasket.
Replace lower hose.
Fill with any aluminum safe 50/50 pre-mixed engine coolant you want, you will need 3 gals.
Bleed the system.
Check coolant level the next morning after driving the truck and the engine is cold.

 

Sounds simple enough, just need to find all the components you're talking about. Thanks guys, hopefully I will do a write up for the whole procedure with pics and stuff to save people the hassle. Throw that on the sticky board

 

Spike,

How do you bleed the system? I've done a lot of repairs, but never really messed with a cooling system before. My LR needs this done as well.

 

1. Raise Hood.
2. Look slightly forward and down.
3. A. Radiator. B. Top Hose. C. Bottom Hose. D. Overflow Tank with cap.

Sorry I could not resist the above. Thermostat is at the end of the top hose where it attaches to the block.

Also, do you have the original black overflow tank? I have heard these tend to faail and leak and should be replaced with the clear or whitish one. I have seen the replacements on-line for about 50 bucks. I still have the old black one.

I will most likely change all my hoses, t-stat and overflow tank next.

 

Lol...

 

With the engine cold and the coolant reservoir full remove the radiator cap.
Remove the fill plug from the top of the radiator making sure that is also full.
Start the engine and turn the heater to full hot both sides and fan speed on "1".
Let the engine idle until nothing but hot coolant comes out of the radiator fill plug.
Replace plug. (leave engine running)
Make sure there is heat coming from the vents, I put the HVAC to the "dash" setting and roll down the drivers window so I can stick my hand in and feel for hot air.
Once no more air bubbles up through the coolant reservoir and the thermostat is open (upper hose will be to hot to touch) replace the radiator cap.
Then shut off the engine.
Drive it for a day and then after it has cooled overnight check the coolant level and top off if needed.

Now keep in mind that it is a closed cooling system, so if the cap is on the radiator then air cannot escape from the system because it has no place to go.

This is how I bleed the system and it works everytime.

 

Thank you, Spike! That should be pretty straightforward.

 

Haha thanks Danny Lee! Will have to check to see which overflow tank I have in my Disco when I head back to school. Yeah I figured my disco hasn't had its coolant changed in a while and it is very important to keeping things from not corroding.
Also, when is it necessary to bleed your coolant? After you change your coolant fluid out?