Disco 2 Top End Re-Build
 

Here we go ...
First time posting but have utilized the wealth of knowledge here for a while.
In the process of an 01 Disco 2 w/ 225K miles top end rebuild.
Have had over heating issues off and on for a while now. Heads gaskets/heads replaced twice. Small leaks in too many coolant reservoirs to remember (I assume partly from bad plastics and partly from too much pressure in system). Couple years ago I let mechanic put ceramic liner stop leak product because nothing else was working. I KNOW I KNOW .... THIS WAS A BAD DECISION.
Have replaced radiator and thermostat since then.
Recently got to where can not pass emissions and good bit of white smoke in exhaust with rough idle.
Replaced coils and wires to no avail so I dove in for the DIY head gasket replacement.
Heads off last night and taking them to machine shop today to get checked.
Below are pics of last codes and of the heads.
This is where my technical skills stop. I know a visual inspection of the heads and cylinders can tell me something .... just don't know what. I am wondering:
Should I drop the pan and clean the block out while heads are off?
Should I replace O2 sensors? Or get it back together with new head gaskets and re-read codes before?
What does all the carbon build up tell me?
Is the shiny piston head tell tell sign of coolant leak?
Thanks for any help that is out there.

Looks to me like your #5 is pretty well steam-cleaned, indicating the location of the head gasket breach. The carbon buildup is standard and not excessive, so you probably don't have any other significant issues. Nothing looks too oily so your evaporative systems should be mostly okay along with the piston rings.
I would wait until after reassembly before you mess with the O2s. You may not have to worry about them, and they can be tackled with everything else in place anyway.
Similar with the oil pan. I don't think that having the head off is really any advantage there unless you're overly concerned about large amounts of gunk dropping down into the valley.

Thanks for the great feedback.
Update .... Attached are pictures of the heads and gaskets removed from the heads.
Also, the machine shop called today, pressure test on heads good, pressure test on valves good. They stated that the heads needed to be machined down to flat.
So my conundrum ... is there enough evidence on the block, heads and gasket of a gasket failure? Or is there potentially slipped liner or cracked block?
https://cimg4.ibsrv.net/gimg/landrov...c1f66b89c1.jpg

https://cimg5.ibsrv.net/gimg/landrov...ff51c01d53.jpg

https://cimg6.ibsrv.net/gimg/landrov...26b372ce1d.jpg

https://cimg7.ibsrv.net/gimg/landrov...535b3b102d.jpg

Disco 2 Top End Re-Build
 

Thanks for the great feedback.
Update ...... Talked with the machine shop yesterday. Pressure test on heads (including valves) came back ok. They said the heads needed to be machined down but did not look bad.
Attached are pictures of heads and gaskets. To my uneducated eye there does not look like big problems.
Now I wonder, am i fixing my problems or should I go further and test for cracked block or slipped sleeve?

I would be concerned that the steam cleaned piston was an indication of a crack in the block behind the liner.

do you have the gaskets to confirm it failed on the steam cleaned piston? Being that it's a middle cylinder is more alarming than at the back where you have coolant passages.


You say HGs were replaced twice, was that recently or during the span of the 225k miles?

edit: check those gaskets for the breach. If one does not correspond with the steam cleaned piston, might be a crack.

I don'r really see evidence that the gaskets failed. However, there is no doubt that coolant is in the system due to the steam cleaned piston. Also, seeing that piston #5 is the main culprit the it leads me to believe I have a block issue.
I have read that its not uncommon that these blocks develop stress cracks around the cylinder walls near the head bolts. My oil has never seemed milky and a crack between block and liner would push fluid both to the combustion chamber and inside block correct?
One thing that is puzzling is the head bolt hole between #5 & #7. Seems to show signs of burnt fluid, however the gasket itself does not look like it failed.
Is it possible that there is a crack in the block between the head bolt hole and water jacket around the piston wall? And the fluid migrates up the threads of the head bolt?
If so, would that also explain the pressure in the coolant system?
Oh the calamity of it all ...... heads are being milled, as stated above, valves are seating well and everything there pressure tested ok.
Now i am trying to decide, do i pull the engine? Should I invest in the kit that will let me test the block in the vehicle. Or do I expect a problem with the block and get a new/use one and quit trying to figure it out?

I would go with cracked block.

As far as the block test, it’s very hard to replicate running temps and other factors while bench testing a block.

i have gotten a motor up to temp, then removed all the spark plugs and administered a leak down test with results being negative for cracked block/blown head gasket. Although it was clear that #5 was steam cleaned and the system was over pressurized.

http://qande.com/site/