We are replacing a leaking radiator in a 2001 Discovery Series II. The existing coolant was put in 500 miles ago and so is OK to reuse. Two questions: (1) Do we need to drain the coolant in the block to change the radiator or just drain the coolant from the radiator itself. (2) Where are the 2 drain plugs in the block? The shop manuals says there are 2 and shows where they are supposed to be but we can't actually locate them in the block because we can't determine exactly where on the engine the pictures are from. Thanks. Tom.

 

Yes you need to drain the block, the left plug if fairly obvious the right one is INSIDE the engine mount so a bit harder to find. Took us about 10 minutes of looking. There's a whole lot in the block too. Once I had it fully flushed and drained I took the chance to switch to a non-toxic PG based coolant and it's been working great, I have it mixed 70/30 because I'll be seeing -50C on some days.

 

If you're going to use the same coolant, then I don't see the need to drain the block to change the radiator. Once you pull the hoses from the radiator and remove it, just keep the catch basin under the lower radiator hose to catch any additional drainage.

When refilling, be sure to remove the plug in the top radiator hose to get all the air out of the system.

Dave

 

Don't reuse the same coolant, no since if getting any of the old calcium out of the radiator and reusing it. Also, replace the hoses, all of them if they haven't been done as well as the t/stat. Make sure to refil using DexCool coolant only.

 

Thanks for the reply. I must be blind. I can't find the left plug. Roughly where on the left side is it or what is it close to?

The cooling system was flushed thoroughly and replaced with Dexcool only 500 miles ago and so I don't think I need to replace the coolant. Why do I need to drain the block to replace the radiator?

Thanks. Tom.

 

Thanks for the reply.

The cooling system was thoroughly flushed and refilled with Dexcool 500 miles ago. Why couldn't I reuse it?

The hoses all look fine with no significant signs of deterioration so I was not going to replace them. The vehicle has had light use and moderate California weather its whole life so it has not been stressed. Of course once I have the radiator out of the vehicle, it will be easier to take a closer look at the hoses. What's on my mind is the water pump. I don't know of any way to determine the state of its seal and, with the radiator out, that would be the time to replace it. On the other hand, if I take that position, I could just replace theradiator, hoses, pump, thermostats, belts, viscous fan, etc. etc.and make this a much bigger job than originally planned. It's not obvious to know where to stop.

 

Thanks for the reply. It seemed to me that you're right that I shouldn't need to drain the block. I was looking for some support on that position before starting the job. Why hunt for the 2 plugs and drain the block if the coolant in the block will happily stay there while the radiator is pulled, if it will really stay there?

 

How many miles on your engine? You don't need to drain the block just to replace the radiator, but depending on your mileage, the t/stat and hoses should be looked at seriously. While in there, also look at your power steering hoses and the tranny cooling lines, they are pretty easy to check and or replace while the radiator is out.

 

50,000.

I will check the coolant hoses, power steering hoses and tranny coolant lines when I pull the radiator. Thanks for the advice. Any advice on the water pump?Also being a BMW owner, I'm always thinking the water pump seal is about to go but I don't know if Discoverys have the same problems as BMW water pumps.

 

Water pump should be OK, do you have the old style upper radiator hose that has a bleed valve built into the hose or the new style with a black plastic tee?
With that low a mileage, the other hoses should be fine.
Have you read and replaced the 2 rear u-joints on your front drive shaft where they hook to the t/case? Check and see if they have grease fittings, if they don't, that should be your next project.
Back to your radiator, make sure to use DexCool coolant and have you considered using a bottle of Royal Purples Purple Ice to help maintain lower temp?
Last thought, do you know how to bleed all the air from the engine when you are done?