It sounds like getting the heads off for further evaluation of them and the block is the right thing to do. Blocks do crack, and redlining the stock temp gauge means it was very hot, so hopefully you have good luck and the block passes a pressure test. I do not know if you can do that at home.

Here's a link to my tumblr with my list of steps, and what I used, and any advice I wanted to have in case I do them again.

https://thegeneralistblog.tumblr.com/post/180986242383/03-discovery-ii-hg-project-record-of-activity

https://thegeneralistblog.tumblr.com...artstools-list

 

Thank you!!!!!!

 

I don't know that the info will help, but it was my first time with anything this big so I kept detailed notes, bolts in labelled baggies, and man it made my life better.

 

Adding an oil cooler would be a good idea too. A few early 4.6 engines had them, but then Rover scrapped them. I measured temp differences between coolant and engine oil of at least 60 degrees Fahrenheit (190/250). This difference creates mechanical stress and then we get all those typical symptoms with the 03/04 D2s.

 

I put in a remote oil cooler after not being able to find good used oil cooler lines, but I would have preferred that. And the inline thermostat mod which I regret not doing.

 

I can say that our 4.6l P38 with an oil cooler and stock T-Stat runs around town at 179 and goes up to 184?at stop lights. So clearly oil coolers help.

 

Is the cooling system similar?

 

Oil coolers from summit racing are cheap and easy to install, I'll just do it, too cheap not to. $70 bucks or so plus some lines and fittings.

Today I'll begin the tear down. I cleared space in the garage last night for the head removal to occur. Tonight I'll begin removing components and see how far I get in removing the head.

 

I prefer the stock cooler, since the radiator does not take up additional space and just fits into existing brackets. The cooler lines are not available anymore and, from what I read, they are prone to leaking. I already got the radiator, still looking for the right fittings. For the ports on the front cover there are M20x1.5 to AN adapters available. I haven't found connectors for the radiator. Some people just clamp the hydraulic hose over the tube, but I prefer a more professional solution. Compression fittings would be perfect, but 14mm for aluminum tubing is hard to find. Any ideas?

 

New information!

I'm puzzled. I tore the head off, one bolt at the intake plenum side was HAND TIGHT. Cylinder 5 is full of water. Strangely, the gasket while it has some pitting, does NOT have pitting near the combustion chamber. It does not look like failed head gasket typically would, no area is blown out, no area seems to be a direct path to water. On that subject, how the hell is water getting into cylinder 5 and not cylinder 7 which would be right next to the water jacket. I see no way for water to be making it into cylinder 5 at all. Further puzzling subject is that the intake plenum path is VERY clean for only cylinder 5. The only place it has buildup is right at the intake port into the cylinder, the rest of the path up through the intake is polished clean and has bright green coolant. Cylinders 1-3-5-7 all look wonderful, factory crosshatch pattern and by feel and look don't seem to be slipped sleeves, looks brilliant. I wonder, could the bolt hole have cracked in the block, loosening that one head bolt and allowing water in that way perhaps? I'll try to pressure test that bolt hole using a syringe/plunger and see if it acts differently than the others. Still at this point in time I'm wondering if my inlet or intake manifold is cracked allowing water in and my problem was never a head gasket failure.

My hope is to make this experience useful to our forum here not to just myself but to all.

Let's recap some information:

-Head Gasket had been recently replaced by previous owner. (Composite gasket Victor Reinz brand w/head bolts)
-Engine always made light knocking sound (fellow Disco owners pointed to valve train noise and called it harmless)
-Failure was immediate, within a couple miles.
-Running the engine would show temps go from normal to extreme over-heat in ~15 seconds. (Likely reading temps from combustion gasses that were pressurizing the coolant system rather than actual block temps)
-Coolant was quickly consumed by the engine, constant flow of white smoke from the moment the motor is started.
-Coolant is found mixed with oil in the head, mostly on valve covers etc.

Upon tear down:
-Head bolt (front/intake side) near cylinder 5 found to be hand tight. (Possibly never tq'd properly, possibly stretched by hydro-lock cylinder etc.)
-Intake manifold track for only cylinder 5 is perfectly clean except right at port to combustion chamber. All other tracks have oil residue.
-Composite gasket does show pitting all around the area of the loose head bolt. However gasket does NOT show path of water into intake cylinder 5.
-Sleeves look flawless, do not appear to have dropped.
-Head does not appear by visual inspection to be cracked.

So as it sits. My first concern is not re-using failed culprit components. It MAY be a cracked intake manifold allowing water into only cylinder 5, but how....?
If that's not how water is making it then, then HOW is the water making it into cylinder 5, we are seeing overheating so we know that the gasses are making it into the coolant system too, which would not support the theory that just the intake manifold was cracked. If it was, I'd be consuming coolant but not overheating. Since it is an overheating situation, I immediately would expect combustion chamber seal failure but without a path to the coolant system, I can't see how that's possible. One possibility would be that while the sleeve is fine, the block behind it has a hole, this would allow for water (perhaps) to make it into the cylinder and back into the water jacket describing the situation found. Without pulling the motor down it would be near impossible to pressure test this block and a lot of time and money. I would need to remove the sleeves to find the hole potentially. I'm told the 04 motor sleeves don't drop as other years do, due to a design change where the base of the sleeves sit on the block. I would suspect there's no easy way to remove the sleeve from this block for inspection without damaging it...

Thoughts?