Going back to your no leak under pressure test, I had one that would not leak for any reason when pressure tested at ambient temps.

Finally gave up chasing my tail and removed the sleeve from the offending cylinder to find a crack behind the liner that was causing the leak once it got up to operating temps.

 

True. Most of the test i saw even in some larger engines the liner was still on and the leak was visible around the top when soapy water was sprayed at only 55 psi. The other was the liner was completly removed, then the actual pin holes can be seen leaking with soapy mix. I thought the test would be possible with 3x the amount of pressure used. I wont go that far removing the liner. Lol. Anyway, lesson learned. I thought it was possible Cheers

 

so just want to follow up with the results. As of this time, Im still rebuilding the p38/4.6 engine that came from a range rover slowly since its very hard to work with winter temperatures in the teens most of the time. While still in progress, the old engine with a band aid fix passed over 2100 miles and still going strong. All seems to be normal and no codes since then.

 

woohoo!

 

Nice. I may have to do this

 

Sick, I saw your post with some sort of similarity with my problem. as mentioned by Southern he did the pressure test as well and failed. In youtube there I have seen pressure test that worked with the sleeves still on and some, really had to remove the sleeves to see the crack when pressure is applied. I did well over the desired pressure the plug can handle and I think I almost reached 3 times the air pressure but bubble test did not work. After installing the complete engine back, the cylinder was taking in more coolant depending on the position of the piston. The worst part was, I cant get the truck not to overheat. It kept bursting old hoses, water pump etc and I can see coolant flowing out of the reservoir because of the pressure.
The fix was meant to be temporary coz I have another engine to swap so I can move the truck out of the driveway to get all the cars out behind where it was parked.
It will be better if your system is not overheating yet and it will be faster to cure any liquid fix if you decide to go this direction. At this point, the disco runs normal as it should. I am driving the truck more aggressively everywhere even flooring it when driving uphill just to see if the patch will stay. I have driven lots of miles since then and still going strong. I also thought of clogging the cooling system, but so far temperature stays around 188.6 to 94 degrees all day long.
The only thing I'm worried about is how long? But now I just consider this like another HG that could also fail in time.
If yours is overheating already, use regular tap when adding the fix and bypass the heater core. I drove the truck for a while until I re connected the heater core then add pure coolant not 50/50 after I got comfortable with the fix.
Cheers

 

Yeah I'm not overheating yet and truck still runs fantastic. Just rough idle. I'm not loosing coolant from what I can tell since 2 months ago I pored in some head gasket fix.