OK before I start I just want everyone to know I have already replaced the lower and upper intake gaskets about a year and a half ago. Now my wife tells me today that again the Disco is leaking anti-freeze. So today I slide underneath with the car on and I can see it leaking and trickling down the passenger side of the trans. I stuck my hand up every gap that it could fit in and could not see or feel where the leak was coming from. But now the funny part...... I decided to take the truck for a ride and after 15 min. of driving the temp started to go up. By the time I got back to the house it was getting close to red so I parked it. The truck was at a slight angle going down towards the passenger side and when I looked underneath, the coolant was leaking as if I was pouring it from the bottle to the floor! That lasted about 1 min or so. I waited about 5 min. to let it cool down and to add more coolant. Now this is where it gets good..... I look at the resovior and it was pretty much empty....so I thought. As soon as I opened it the coolant came rushing up to about a little more than a 1/4 full. Why is this happening? My first thought of course is the thermostat going bad but this does not happen on a daily basis. I know it is leaking from somewere but I can't figure out where. If any of you have had an experience like this your help is greatly appreciated and thank you in advance.

Alex

 

The coolant reservoir on the Discovery is pressurized when the engine is warm, which raises the boiling point of the coolant. The pressure is held in by the cap on the reservoir. When the cap is removed, the pressure is reduced and the coolant is no longer under pressure which reduces its boiling point. If the engine is hot, this will cause it to boil in the hot areas of the engine and rush into the reservoir. It's a pretty dangerous situation, and you couldbe scalded if the engine is really hot, just as removing a hot radiator cap is dangerous on a conventional setup.

The leak could be the same gaskets leaking again or the cylinder heads. It could also be a leaking heater hose or bypass hose. Whatever you do, stop driving it and get the problem corrected. If you get that engine hot, you're going to absolutely do permanent damage in short order.

Dave

 

Step number 1

When it gets hot DO NOT SHUT THE MOTOR OFF.....

A full alloy engine should cool itself down (even if leaking)

You could crack the motor if you let it sit and be hot ....

Step number 2

Get a pressure test, you could have an external leaking headgasket ... 16-18 lbs of pressure at no less than 15 mins, it's free at any shop or Meineke. during those 15 minutes watch all hoses, especially that place behind the motor you noticed.

Crawl up on top of the motor and take a peak back there, it's leaking from the top, not the bottom, so underneath peeking doesn't do as much good.


Don't drive it again - We're not kidding ... I have made that mistake FIRST HAND and am currently replacing the motor because of it ...

Please let us know if it's a Disco 1 or 2 ....

 

Very bad advice, IMHO and an old wives tale.Whenthe engine is low on coolant, the combustion in the cylinders is continuing to add heat into the (now empty) water jacket at a high rate, even at idle. And there is no coolant circulating to dissipate the additional heat. Shutting off the engine stops the addition of new heat to the equation and all that's left is to dissipate the heat that's already there.

The laws of physics are everywhere the same.

Cheers,
Dave

 

Everytime my motor overheated, I pulled over and let it idle, in less than a few seconds it cooled down because there was LESS heat being generated (but yes still heat) but it balanced the equation between heat and coolant ...

If he is 'completely' out of coolant, which I doubt he is, unless he's just completely neglecting it and never adding water.... then yes by all means shut it off .

My alloy motor would cool faster if I left idling, than if I just shut it off. (verified by digital temp gun, on block/exhaust/intake/waterpump/both sides of radiator/ and hoses ....) My motor would maintain the temp between 220-200 degrees even with hood open and shut off, for almost 5 minutes ..

 

Thanks for the quick response guys. It is Disco 2 and I already told my wife to go to the nearest Budget to rent an alternate vehicle until we get the issue resolved. I am still paying for this truck and I don't want to cause any more problems by just letting go so I am going to have towed to the dealer tomorrow. Thanks again

 

They are going to tell you both head gaskets are blown and it will be around $4000 ....

Prepare to be scammed, good luck.

 

Yeah I am sure. It was amazing to me when they told me 1400 to do the intake gaskets. Thank god I know how to work on cars cause I saved atleast $900 by doing it myself

 

Quick question if it is the head gaskets that means that I will find coolant mixed with the oil correct?

 

Yes, this would make sense if there is still sufficient coolant to circulate, the thermostat isn't stuck, and the radiator (or even the heater core) are doing their jobs. Under load, the engine will produce more heat than at idle so as you say it's possible to tip the balance the other way.

It's a very different situation if the overheating is caused by low coolant level, a stuck thermostat or other circulation blockage. Hot spots will develop and get really hot with the engine running, even at idle. Since his leak is causing a low coolant level, I wanted to point this out.

Dave