@zski128 Even some 4.0's had that issue there is no guarantee. Generally blocks cracking are a combination of casting flaws and overheating often combined with vibration. So for us the later blocks had poorer castings in general than the early blocks, add in owners who let the trucks overheat or run too hot and possibly had misfires and you can get a cracked block.

It is in general even in Disco's unusual but unfortunately still too high a rate of occurrence.

 

Agreed on that point. As soon as Rover made the bore bigger for the 3.9 it made the walls too thin. My point is it seems the consensus is that installing top hats with o rings is the only way to run with a crack in the block in the coolant passage. Using ARP studs and ensuring both the block and head is flat will reduce the possibility of head gasket issues.

 

A couple of machine shops that do good work on buick v8 are Q&E Engine & Machine in California and D&D Fabrications Inc in Michigan. Recommend you price both options but since you are East coast I would give Mark at D&D Fabrications a call to discuss your build; he is a wealth of knowledge and my D&D refreshed block has been solid for the past 2 years. I wanted more power and better reliability so I went with liners, ARP head studs, Crower 229 cam, 4.6 crank/rods with my 4.0 pistons. IMHO, to avoid future cooling issues you should refresh the cooling system parts and get the CARRS4x4 Land Rover Discovery II V8 aluminum expansion coolant tank & bleeder T & 4-Way tube kit. Looks awesome and greatly reduces the chances that you will have a coolant leak due to a cracked plastic part.

 

Cracking in the block itself behind the liner isn't going to change just because you installed different liners in front.

 

The o-ring on the liners prevents the coolant from coming out of the block deck between the liner and block.
However, I do not understand how it cannot just leak out of the bottom of the liner into the oil pan.
I have heard things here that 03/04 4.6 blocks have a ridge cast into the bottom of the block and the liners can't shift down(which still wouldn't stop a coolant leak), and that 4.0's and earlier 4.6's don't have that casting ridge.
I can call bs on that.
Here is my 04 4.6 and my 2000 4.0 block side by side.
Notice any difference? No? That's because there isn't any, they are exactly the same.
I do belive in poorly cast 03/04 4.6 blocks from the end of the run, and poorly maintained molds. As well as LR's admitted A,B, and C quality ratings, A being a P38 for the RR, and B and C being leftovers for the D2.
Still, I see how an o-ring at the top of a top-hat sleeve keeps coolant from going up and past it; but, what stops it from going down and out the bottom??
Who knows.

 

Exactly.

The theory of the top hat liner is that it prevents a liner from slipping upward into the head or head gasket. That's good.

Doesn't stop coolant from a crack behind the liner from dripping down into the oil sump, though.

Top hat liners are good. I'm not knocking them, but also, they aren't magical. They solve 1 problem... but they don't solve every problem.


For the best Rover 4.6 rebuild, your options are fairly limited:
#1: quality, pressure-tested block and heads machined flat to book tolerance
#2: top hat cylinder liners or all-metal head gaskets
#3: new performance cam, bearings, pushrods, lifters, and rockers/springs
#4: lapped or new valves, valve stem seals, and springs
#5: port-matched heads and exhaust headers
#6: new or machined crank with appropriate new main bearings
#7: matched rod bearings
#8: blueprinted, new piston rings (gaps)
#9: cross-hatched cylinder liner interiors
10: new oil pump, timing chain, and clean oil tube pickup with new seal
11: Turbomaxx added to the new engine oil after the break-in is finished
12: flow-verified fuel injectors and new fuel pump
13: high-flow exhaust/cats
14: aggressive air/fuel timing map (but how?!)

 

The o ring in the top hat liner is at the bottom of the sleeve. It will effectively turn it into a wet liner if a crack develops, at least from what I read. The top is “sealed” by the 90 degree turn and tight fit of the hat rim plus the “gap” is now located under the head gasket not at the edge like with the OEM liners. There are top hat liners that do not have an o ring at the bottom. Completely agree on the casting issues on later blocks and that you should attempt to source a P38 block if possible. Check out the articles on JE Robinson’s blog for more details.

 

That makes sense with the o-ring at the bottom, but I wouldn't be able to put that much faith in a metal on metal seal for the top.
Even with an interference fit, 2 different types of metals expanding/contracting at different rates, over time, I would be concerned that coolant would still eventually find it's way through.
Of course that's just an opinion with no proof, but given the issues with these engines, spending money in them is no fun.
I am hopeful to have no issues with the 4.0 block I have now.

 

There are some misapprehensions in this thread..
A steel head gasket does not have the same effect as a flanged liner. The flanged liner puts the head gasket sealing surface on the liner, not the block. Therefore, as long as that holds, combustion gas can't pressurize the block
4.0 blocks are not trouble free. They were the original "slipped liner" motors back in the 90s
Many of the things that used to be true, when these trucks were younger, no longer are. We see worn out pistons very often now. Warped blocks are more common. Corrosion damage is more common
We are seeing more engines with flanged liners suffer other failures when overheated. For example, we are seeing fire rings blow on head gaskets. The initial cause is an overheat and that happens because everything else is old, so you have many more points of failure
I have written a lot about this and our company has probably done more of these rebuilds than most. Costs are high but you get what you pay for

 

All viable head gaskets prevent combustion gasses from pressurizing through the block+head gap... that's not what anyone else is discussing in this thread.

There's a group of people who want flanged liners to prevent liners from slipping (the dreaded slipped sleeve).
There's another group that mistakenly believe that flanged liners will allow a motor to work properly even if a crack develops behind the liner. While it is conceivable that a flanged liner can prevent coolant from flowing up through the block+head gap from a crack behind the liner, such coolant would still flow down through the lower sleeve block gap into the oil sump.

If you'll search this forum for pics of head gasket failure, cheap composite head gaskets get a circular wear pattern from where a slipped sleeve impacts the soft composite material. That problem is mitigated or minimized by using *either* flanged liners or all-metal head gaskets.