So, my year and two month experience with my D2 has by almost every measure been great. I have had numerous preventative fixes, all enjoyable wrenching and successful in allowing the D2 to become a reliable daily driver. But I think I may be heading down the head gasket hole. Here is what I found. Crawling under the truck last weekend doing normal inspection to see what might be weird I noticed on the back corner of the drivers side head, right where it meets the block what looked like dried coolant. Dang it! I wiped it away and rechecked daily in the morning and evening and again last night. Until last night nothing then a slight wetting right at the junction of the head/block. Very slight like barely even enough to get a paper towel to soak it up, talking a 10mm ribbon 1mm wide no drips or runs. Daily the truck does not get driven far. Yesterday was the office commute and then a kids cc event so that ended up being about 75+ miles explaining the slight weeping. Guessing the highway run added to the workload causing the weep. See below for the corner I am talking about. My truck does not run hot (180 deg with Extinct mod) and doesn't even use coolant, reservoir will stay topped off for days, weeks and months. So this is a very slight leak.....so far. All that said what would the experts say? I have deduced the below.

• Leak is from the coolant passage to the outside. So not mixing with combustion. A good thing for a bad thing.
• Could be from another source but I don't think it is. I will check. I read where if the throttle body heater leaks it runs along the manifold to this spot. Anything else back there?
• Can It be sealed from the outside? I know not a real fix but maybe a time saving band-aid. JBWeld? I am in no position to do this job now so anything that gets me down the road.
• Drive and monitor? I am being optimistic thinking a pin hole that only opens when under longer operating load. How much time do I have doc? 3 weeks? 6 months?
• Loosened the reservoir cap a 1/4 turn like Extinct does to relieve pressure. Might help?

I don't have a tight service history but do know according to carfax the HG's were done at 168k. I am at 180k now.

 

Throttle body is the best case scenario and easy to check. Hard to say on timing. I drove one of mine with an external leak on the pass side for a few months (no major highway trips with most trips being under 30-40min) and just monitored it. Truck ran fine and other than the coolant causeway down the block no issues. I did have the cap loose which helped stem the coolant loss, however this was in the dead of winter. I am unable to run my cap loose in the summer (ambient temps over 90-95) here as it will boil over if I turn the truck off abruptly after a hill or climb, the elevation hurts me in this instance.

 

Check the top of your valve cover after a trip, also use an inspection camera to check the back and front edges of the lower intake gaskets, they can leak too. I have found the dye and black light are invaluable in these cases and cheap.

 

As Richard said, the intake manifold to head can leak coolant at the back (or front). I’m just in the middle of replacing the HG’s on my P38 for a very similar leak. As I’ve torn into it I’m pretty sure the leak was the intake to head, not head to block.
JB weld will not work, as it’s from the outside. I will make a confession to the forum. I used Rislone Block Seal Head Gasket Fix about 3 years ago. I’d had the P38 for a year and a half at that point and all I ever did with it was work on it. Every time I fixed something another thing would break, so I had no patience left for a HG job at that point. The leak never returned and actually the P38 has been very reliable since that time. This is not a recommended fix for a vehicle you want to keep but it got me through.
I finally had the time now to fix it properly, and at the same time I’m replacing the gaskets and seals on the timing cover as there was a lot of oil leaking from the front of the engine.

 

Get UV dye and UV flashlight. Combined 15 bucks on Amazon and you’ll know for sure where the leak is or at least have an extremely likely suspect that point

 

You need to loosen the cap 1 full turn. Keep driving it, can probably drive it like that 2+ years

 

Now that's what I want to hear! I will do the dye in the coolant and monitor it. Going into winter and cooler temps might help I would think. Maybe a spring project if it makes it that long. I actually have a complete short block to get rebuilt if I can ever find the time to get around to it. Then I could swap the entire motor.

 

if you have a 4.0 then swap crank and rods from a 4.6 and put a cam in it and maybe just maybe it will get out of it's own way a little better

 

Has anyone tried putting an LS motor in a Disco II. Does anyone make an adaptor plate for the transmission?

 

https://landroverforums.com/forum/engine-swaps-63/