Learned , most positively , that I have gasket failure at number two cylinder , Leaking externally . Just random failure . Why ?? Turner engine . Runs smooth . Never , not once , overheated . They say it happens . Always number two . Can any mechanic explain why this is so ? Is it quality of head gaskets ?? I would really like to know . Please .

 

Are any of your head bolts loose? Possible error on install?

I had one blow out externally but I knew it was a ticking time bomb. Needed rig back on the road over a Christmas break, trued up heads as well as I could between a large smooth concert block and fine sand paper on a glass plate. Got a lot a year out of it. Installed head studs so they were reusable in the future.

 

The heads have been polished and ported . In February , when I'm scheduled to have the work done , I'll know the answer , whether its poor skills or ****ty gasket . I have had two techs tell me this happens in that particular area . And I would like to know .

 

This is why I like arp studs vs tty, less margin of error during install.

There's always the possibility of block threads giving out which would be no ones fault other than Rover for not using steel inserts in block.

 

Likely incorrect tightening procedure. As I explained here: https://landroverforums.com/forum/di...92/#post786998 LR head bolts are not TTY, they are torque to angle to achieve a prescribed amount of gasket compression and thereby compression strength.

 

But why failure at number 2 ?? A few techs say this is common for this area . I just want to know why .....this .......particular ......area .

 

I've seen more externally blown HG's at #5 or #6 in all my years of messing with Rover V8's. I've seen it caused from incorrect torque sequences, and surfaces not being clean before installation.

 

I've had 25 plus d2s and I've probably been at least a dozen head gasket jobs. I think in all of those I've had two head gaskets blow in the center cylinders to the external and most of the rest blew at the rear of the block, maybe one or two leaking up front on the number two cylinder. I wouldn't say it's common but it's likely that it was related to Something in the assembly process that wasn't ideal. I'm not one that says you have to play in the heads if they check flat, but I chased my threads 100% every single time, and take extreme Care on getting the 90 and 90 torque sequence. It's about gasket compression not about torque.

 

I've had 25 plus d2s and I've probably done at least a dozen head gasket jobs. I think in all of those I've had two head gaskets blow in the center cylinders to the external and most of the rest blew at the rear of the block, maybe one or two leaking up front on the number two cylinder. I wouldn't say it's common but it's likely that it was related to Something in the assembly process that wasn't ideal. I'm not one that says you have to play in the heads if they check flat, but I chased my threads 100% every single time, and take extreme Care on getting the 90 and 90 torque sequence. It's about gasket compression not about torque.

 

Chinese bolts? Head gasket with unnoticed damage? Tech was paying more attention to Facebook posts than his angle gauge? Machine shop didn't properly true the heads?

The world may never know.

I'd make a guesstimate that we see more heads blown out on the outside vs the inside as the outside is the exhaust side and would have much more heat. Heat expansion rates on steel head bolts vs aluminum block/heads differ enough that the bolts can come loose during an overheat. The disco 4.0/4.6 is an antiquated design pushed to the max in a very heavy rig with a sub par cooling system for American roads and climate. This greatly reduces any margin of error for some very small head gaskets. Briggs and Stratton 17.5 head gaskets have more meat from outside edges to cylinder... although they do run much much hotter being air cooled.