2000 disco overheated! Plug popped out?

2000 Disco, 104K, ran beautifully up until yesterday! Driving on I95, 70 mph and noticed a one time slight miss. Looked at temp gauge and it was a tad higher than normal. Kept driving, traffic was heavy. A few miles later I noticed temp gauge higher but not in red. decided to get off at next exit. Approaching exit temp got higher and truck started to miss and lose power. Looped around exit and temp went to red and truck lost power and cut off. Coasted to stop, popped bonnet saw coolant all over back of engine, with steam everywhere. Let vehicle cool, added fresh OAT and noticed that everything I put in was pouring out on ground. Looked for hose break etc. BUT to my horror, coolant was pouring out of the rear of the passenger side cylinder head. I felt aound and put my finger in a perfectly round hole, around the size of a quarter. Is this a freeze plug or something? What could have caused this catastrophic failure? Is my engine toast? Headgaskets are original. BTW, I have a 2003 4.6 with 106K. Is this going to happen again?

I have a '99 DII, and are quite friendly with my local Land Rover dealer as well as the manager there who owns a '00 DII just like yours.
The advice he gave me was that as soon as that needle creeps above normal, pull over and shut off the engine to avoid catastrophic damage to the engine and radiator. My guess with your engine, since it cut off, is that it hit critical mass, which is not good by any stretch. Aluminum expands when hot, so the best thing you did was to let the engine cool, let the aluminum get to acceptable temp, and put coolant back in (make sure it is DexCool approved).
I am not familiar, unfortunately, with the area of the engine where that hole is, but I will look at mine later and ask my sources what that is.
From all that I know, the reason for the failure could be due to a seal on the plug for that space, age, pressure, any number of factors. I do not know if your engine will continue to work, but you need to go to a Land Rover specialist. There are a few around, but I95 is pretty long, so I would ask Rovers North if they could recommend someone close to you.
As far as the '03 4.6, the issue there is not coolant leak, but grenading of the oil pump. On page 2 of this Forum, under the heading of "Oil pump blown to pieces in 2004 Disco", you will find out all the information relating to this issue from a mechanic who worked on the '03-'04 Disco with that issue.
Hope everything turns out OK.
Hope this helps.

Thanks so much for your reply. Yes I should have pulled over immediately! If I would have had any inkling this could have happened I would have 'slammed' on the brakes. Anyway after I got the vehicle towed and engine had cooled significantly I pulled the coil wire just to see if the engine would turn. It did so I was encouraged that I might not have to replace the engine. Well I tried it again this morning with engine cold and now it appears that it is locked up!!! Sucks all the juice out of the battery and nothing happens. My God, I am so pissed at this turn of events. What is it with these Disco versions of the 4.0 engines? I had a 96 Range Rover 4.0 and it had 245,000 miles on it when I bought my 2003 Disco. Never had any problems with it except for oil leaks.

Sounds like head gasket to me. Pull the spark plugs out of that side, you will probably find the cylinder is full of coolant.

Sounds like it's probably buggered though. :(

Sorry to hear about the lock up of the engine. It is very hard to determine why it seized the next day, as the oil pump still worked after the coolant was replaced and it was cold outside. Whatever expanded due to thermal conditions should have been reduced at that time, so now I am at a complete loss other than additional part failures due to the coolant issue.
As far as the 4.0L '96 RR engine and '00 Disco II engine, other than displacement they are two different engines. The Disco II engine underwent a major overhaul in '99 for the Disco Series II launch that year as BMW owned the company then ('94-'00), and installed Bosch instead of Lucas for much of the hardware and parts for superior reliability. The RR engine, as far as I know, was still the mid 60's Buick design for the most part with 30+ years of manufacturing. That is all I can think of.
Interestingly, the best years to purchase the Disco II, in my opinion, are '99-'00. This is for three simple reasons. First, one trim level in '99 and only one modification (compass in the mirror) for '00. Second, those years the transfer case was still equipped with a center diff lock, but it was never connected. A kit is available from Rovers North to enable this feature. Third, BMW ownership ended in 2000. When Ford took over, trim levels multiplied, the transfer case center diff lock was completely eliminated until 2004, the dashboard and carpet became black no matter what interior color was ordered, and a vinyl interior was available. Oh, and some of the '03-'04 Discos with the RR 4.6L engine had grenading oil pumps and leaked oil from the factory.
I would call Rovers North as soon as possible and explain what happened to one of the sales representatives who, from my experience, know equal if not more than most mechanics I have spoken to. Perhaps it is not as bad as it looks.
I hope the situation becomes positive for you. Losing a Land Rover is never easy, as they are becoming much harder to locate from enthusiats who care.
My best to you and good luck.

It may be possible to get it un-seized, but I would bet that it is smoked from the overheat.

What was your coolant level before the incident on the Highway? Do you know? You may not know, however, the pressures can get extremely high in a coolant system, in an overheat. If it was low, the pressure may have gone sky-high. This may be why the freeze plug blew.

Recently, there has been an increased demand for these engines (imagine that!:mad:) I believe it will be difficult to procure a replacement, and of course this will drive the price up as well. I think these DII engines are a big problem for the Land Rover name.

oneohsix, Where are you located in the US?

Surely you could get a 4.6 short engine from over here and re-fit all the ancilary items. I'm not sure what engine is fitted over there. Is it the same as the P38 4.6 Thor engine?

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Originally Posted by Rineheitzgabot

It may be possible to get it un-seized, but I would bet that it is smoked from the overheat.

What was your coolant level before the incident on the Highway? Do you know? You may not know, however, the pressures can get extremely high in a coolant system, in an overheat. If it was low, the pressure may have gone sky-high. This may be why the freeze plug blew.

Recently, there has been an increased demand for these engines (imagine that!:mad:) I believe it will be difficult to procure a replacement, and of course this will drive the price up as well. I think these DII engines are a big problem for the Land Rover name.

oneohsix, Where are you located in the US?

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I had checked the coolant leval a few days before and all was well. Yes I am sure it will not be easy to find a 'good' replacement engine. I am checking Ebay but my biggest fear is that I will end up with an engine with similar problems. Can you recommend a way to check the engine out of the vehicle? O mean I am ready to fit the engine with a new set of head gaskets and head bolts but how can I check the lower end for compression, scoring etc. while it is out of the vehicle. I woul hate to buy an engine off of Ebay, get it shipped and have to disassemble it just to verify that it is a good engine that is worthy of head gaskets and cylinder head work.

In short, you can't. You could do a compression test by spinning it over on the starter, but without disecting it there isn't much more to do.

Did you try taking the plugs out of yours? It might be cheaper to get yours re-built. New liners, pistons, etc.

Where are you at?

Well, I spoke to my sources and it looks like what you described as being missing from the hole on the rear of the block was not a freeze plug (although there are 12 of them as it was explained to me: 2 rear, 2 front, 4 each side). There is one in the position you mentioned, but it is enclosed & covered under a metal shield. The only conclusion we could determine was perhaps it was an actual engine block bolt that failed, which is in that approximate position and is exposed to the elements.
As far as purchasing an engine on E-Bay, I would not. If you cannot see the condition, if you cannot confirm its mileage, that is bad enough. But remember, the vehicle may have been totaled and the engine might be all that was left. With no way to inspect it, I just would avoid it.
I agree with Spacemutt. Rebuilding it is the best option, especially since you know where the parts are coming from. That way, you have an upgraded engine with the history known.
Think of it this way, what I just stated is all you would have to do. If you bought a new engine on E-Bay, first you have to tear it down and then verify the condition of the parts. Then you have to rebuild it anyway. Skip the extra step and save the money, and go with peace of mind.

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Originally Posted by Rineheitzgabot

Where are you at?

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Hello again! I am located in Richmond, VA.

Oneho-

The reason I ask where you are from, is I highly recommend a guy around my neck of the woods by the name of PTSchram. I don't know what your plans are, but he would do a fine job with your repairs, if you are planning to repair it.

Good luck.

-Gary