I recently tried to repair my disco 2 (163k miles, 4.0 Bosch, new head gasket at 140k) which had a vac leak (causing misfire codes) that I had tracked down to being somewhere beneath the upper intake manifold. Took everything apart, replaced gaskets, fuel injector orings, and noticed during removal that the intake manifold had oil in it with a fair amount of char throughout. Put in a new valley gasket, intake plenum gasket and rocker cover gaskets.
But when returned to service it sounded ugly (very rough), and spewed white smoke out the exhaust. I assume this means I've had a seal around the intake fail and leak coolant (and maybe oil?) into the intake. After I quit crying, I went back to start tracking down the leak. However, the engine only turned over a few revs before "clunk". Now it doesn't turn over at all. I checked the oil and it was mysteriously very low. So my question is: What now? I'm taking it apart tonight, but am pretty sure I'm going to find that the engine is a goner. What kinds of damage should I be looking for?

And if I don't like your answer . . . How much does a non-running disco sell for these days?

 

Is the coolant tank low?
Indicating it's leaking coolant into the cylinders/head gasket(s).

Can you rotate the engine manually/breaker bar and socket on crank pulley?

 

If you do indeed new a new engine you have 3 choices
1- buy a cheap disco or engine and cross your fingers
2- get it rebuilt
3- buy a rebuilt engine

 

Sounds like maybe the valley gasket is leaking. That would account for the smoke, and could hydrolock a piston if enough coolant got in. First thing I would do is pull the plugs and see there is coolant inside.

 

This, and then turn engine over with wrench on crank pulley. Sounds like it is hydrolocked. You missed something, sorry to say.

 

Diesel..

 

If your engine seized due to a hydrolocked piston, you're going to be looking for a bent connecting rod. It's hard to tell without removing the piston, but assuming you can get your engine turning over with a breaker bar, the piston won't rise as high in the cylinder as the other ones.

If your engine seized due to lack of lubrication, you're going to be looking for destroyed bearings, scratched cylinder walls, wrecked piston rings... the list goes on and on.

 

Thanks for all the good info. I hadn't thought about hydrolocking, but that makes sense. I'm gonna go pull the plugs now. I got it stripped down to the heads (removed valley pan gasket) and tried to turn over with a breaker bar. It was difficult, and could hear pressure hissing from the cylinders. Hydrolocked cylinder would make sense. Wish me luck!

 

Well, there was a "little" coolant in a couple of the cylinders. Also a lot of burning. The burn is probably from having driven on it with a vacuum leak for too long.

But I'm still trying to understand what would lead to getting *that much* liquid in there. Maybe there was a coolant leak into the block (around the valley pan gasket?) and it somehow got slurped up via the oil separator?? But then why does that second cylinder not have coolant in it??

 

Well there was coolant in 3 cylinders on the passengers side and one cylinder on the driver's side. (!) I spent a lot of time thinking about what could have caused coolant to get into those places, and thought I narrowed it down to how I applied the silicone to the valley pan gasket, which I had done to the entire surface. It was quite cold so I thought that because it doesn't flow as well when cold and doesn't cure as quickly, perhaps I had a catastrophic failure in multiple locations at the surface between the lower intake and the head (valley pan gasket mating surfaces). I stripped everything down, cleaned all surfaces to the nth degree, went ahead and replaced the head gaskets while I was there, cleaned the valves which were pretty gummed up (and may have been responsible for the initial vac leak issue that started this whole mess), and put it all back together, this time only using silicone in the notches on the ends of the valley pan gasket seals, and not around the entire surface . . . And the same thing happened again! Rough running for a few seconds/minutes, then hydrolocked.
Now, the one piece I left out at the beginning is that when reassembling the lower intake (1st time), the back-most bolt hole on the driver's side cross threaded and stripped. However it took a lot of torque, so I just went with it and pushed ahead, knowing that I really should back up and retap the hole. So in this second round of tear-down I did just that . . . Re-tapped with an m12*1.75 bolt. But to no avail.
So now I'm kind of stuck. I need to find out where the coolant is leaking from but am not sure how to do that. A friend recommended a compression check in the cylinders, and I thought maybe a pressure test of the coolant system (though I already know it's leaking, just not where). And my bigger question is--how could I have gotten coolant in cylinders on BOTH sides of the engine?!
Any other thoughts/ideas??