I have a 98 Disco I purchased recently. Under the hood much of the front end is almost brand new; radiator, hoses, and expansion tank.The main radiator and exp even have their "Land Rover" replacement part stickers on them. From what I can tell the work was done recently in miles (not years though), and may have been by the local Rover dealer, although they have stopped working on the older trucks and referring out to secondary shops. The work was completed in 2017, but the truck sat for most of 2018 until my recent purchase.

What looks really strange though, is the coolant. It is a greenish yellow, and appears it could be old school IAT, or more likely Euro Coolant, maybe Zerex G05. Based on what I am reading this should be orange, DEX-Cool, coolant. So that leads to me the question of what is everyone else running? I find it hard to believe the dealer or even a shop would put the wrong coolant in if they went to the trouble of using factory parts, but I would had to find out in another 25k miles that it should indeed be orange.

I've tried two local auto stores and even they have conflicting info, they too are saying it could be either HOAT or OAT (yellowish vs orange). Very interested to see what everything thinks.





Thank you

 

87-99 RRC & D1 = green coolant no doubt about it! Dexcool/hoat was only introduced on the D2/P38 with a Bosch config.

 

So just classic IAT? That's good to hear. Prestone had that as the recommended for my year, but as I was getting some many different answers, I figured it would be best to as those that are already doing this.

 

most of us with D2s switch to the green coolant anyway. too many potential issues with air getting into the system and messing with the Dexcool.

 

Go green!
Get the orange out of the truck.

 

I run Nissan long life Blue coolant in mine, but only because I'm a nissan tech and i get it cheap at work.

 

Suit yourself with whatever color you like, but Dexcool and other OAT coolants without silicates or phosphates will work fine in any Disco. It's what Land Rover used from '99 on and GM, Honda, and Toyota all use them. Land Rover V8's did not ever have incompatible gaskets.

By far the thing that will kill your Disco engine is not OAT coolant but low coolant level and overheating. Low coolant level is commonly caused by cracked cylinder walls (super common on Land Rover V8's, but you have more favorable odds with a '98 NAS Disco 1 than with other models (P38 and Disco 2)). The crack will cause the headgasket to erode and then coolant will be lost out the exhaust manifold and down the exhaust pipe. A simple blown head gasket without a block crack can also cause coolant loss into the oil or into the exhaust. Almost all Discos with Rover V8's need the headgaskets replaced sometime after 100,000 miles. Another cause of coolant loss can be a pressure cap that is stuck open.

Common causes of overheating on Disco 1, and I mean very common, are radiators that are clogged with rust, sediment and minerals because the brass radiators also have solder bloom that contributes to restricting the orifices in the core. There's nothing than can be done about the build up of solder bloom over the years except to rod-out, recore or replace the radiator, but if you get it clear of removable debris, it should flow well enough. It's worthwhile to flush it with a citric or phosphoric acid and use distilled or DI water for the 50% fill. Since you appear to have identified a replacement radiator, that part should be in good shape.

Bad water pumps are common past 100,000 miles. If you're keeping the Disco long term and not just going to flip it when you find out it starts to cost you more than four times what you had in mind, replace it with one with a cast bronze impeller, not just the cheaper stamped steel impeller.

Bad fan clutches are also common. You can test the fan clutch and replace it with the water pump at the same time if needed.

Some people use a 180 deg thermostat. The shop I bought mine from put one in mine. I think the standard 190 F is fine. If the cooling system is broken, getting it flowing a little sooner will only help for a few minutes before you get into trouble anyway.

Don't think because you see a bunch of new parts that you're golden. The new parts are there for a reason. Expect more to come.

Be sure to have a OBDII water temperature gauge attached and displaying at all times while operating. The factory temp gauge is totally worthless. I use an Ultra-gauge but it's been going for about 9 years now and there's probably better ones but I don't know about them.