A litany of leaks and motor musing

Greg_M

Well-known member
Dec 27, 2021
177
78
Vancouver Island
I've been thinking lately how happy I am with this Discovery 1 (never do that!) but have been hearing something like an exhaust leak - only when cold ie. having sat overnight, and under a bit of load like out of a corner - so I went poking around to figure out what I'd need to do to take care of it and... found a coolant leak! HGs were done by PO so I thought I was safe but I've got a combustion gas test kit for the coolant coming tomorrow afternoon (oil looks fine). See the photo for the leak. Thought it could be one of the freeze plugs but convinced myself I saw some green higher on the block. Ruled out the faint possibility of it being one of the two long water pump bolts (both dry) so I degreased the driver's side of the block a bit and ran it up to temp. Now I can't find any sign of coolant, nothing. Bloody hell. This thing is female I swear. Anyway, I might have found the exhaust leak at the upstream DS O2 sensor bung. Will mess with that over the weekend and see what I get.
But I really do like this car, and my wife has taken a shine to it as well calling it our camping car, so I've started to think about building an engine to take me through the next decade. I wouldn't be looking for gobs of power and stratospheric rpm preferring smooth idle, torquey power, and long life (I tow a small trailer). I have a light foot now. So what would you build? Keep in mind I've only owned one modern LR engine - this one - and a couple of 2 1/4 petrols so I'm not up to speed on the desireable differences over the years/models. I'd be building this for a GEMS truck ('97 Disco 1). What's the engine to look for? Heads? Crank, pistons, etc.? What would you build? Share the recipe, I might just do it. And it's fun to think about regardless.

leaksm.png
 

terryjm1

Well-known member
Jan 23, 2011
1,509
388
I have been debating this very topic with myself. I have mostly decided what I will do. I have a good condition 1996 4.0 long block with about 125,000 miles that will serve as my base. My hope is with being an early block I won’t have much worry about a slipped liner and can avoid the cost of top hat liners. It’s uncommon to slip liners in the earlier blocks, although I have had one. But, I don’t know what that engine may have been put through as I purchased it with the bad engine from someone that didn’t know the owner that had the failure. Use heads that haven’t been skimmed previously and hopefully won’t need much skimming for reuse. I have a set of new heads I lucked into set aside for my build.

I also sourced a 4.6 crankshaft and pistons that measure well within standard spec. I haven’t taken apart the 4.0 to measure wear on the cylinders but in previous experiences they do pretty well with being within standard spec even with high miles. I am debating between an uprated camshaft or a standard Rover one. I also haven’t decided which pistons to use. I know the 4.0 pistons give a nice compression boost but I kind of like the idea of less stress on the engine. I’d like a little more power than the 4.0 but don’t want to spend a lot of money. Im now leaning toward an uprated camshaft from a high quality supplier. In my experience an uprated camshaft in these engines is the best bang for the buck and is worth the extra expense. I will likely call the wedge shop and buy whatever they recommend for what I am trying to accomplish. They are enthusiasts with decades of Rover V8 experience. I have been kicking this around for a few years as of all the issues my LRs have encountered since my last engine replacemen haven’t been engine problems. The “rebuilt“ 300tdi I purchased from someone else will probably be the one that has issues first. It burns and leaks a fair amount of oil at only 15,000 miles. As far as engine building goes, either do it yourself or pay the price to have an experienced machine shop with a good reputation do the work. Rover V8s are not complicated engines to build but sloppy is sloppy and my 300tdi was done sloppy.

Do your best to find a timing cover that doesnt have excessive wear in the oil pump. Those are becoming hen‘s teeth. Hopefully, someday, someone will start refurbishing them or start manufacturing new ones again. I have one removed from the aforementioned 4.0 that had the slipped liner. I also left it on the engine when I took it to the metal recycler assuming it was shot. At the last minute I decided to pull it off and take a look. Much to my surprise it was in like new condition. But, it was a low mileage engine (55,000) so I guess that makes sense. However, it looked way better than I would have expected even at 55,000. It seemed more like 5,000 miles. The flywheel and clutch looked like new as well. Who knows what happened with it before I purchased it. The liner slipped far enough down to strike the crankshaft and caused all kinds of damage. The rest of the engine was trashed.
 
Last edited:
  • Wow
Reactions: kris812

terryjm1

Well-known member
Jan 23, 2011
1,509
388
My understanding is all the 4.6 crank / pistons / connecting rods are the same. I hope so… as that was my assumption when I sourced one. As far as when the blocks started having issues, perhaps one of our long time rover mechanics can answer that question.
 

4Runner

Well-known member
May 24, 2007
677
115
Boise Idaho
The
My understanding is all the 4.6 crank / pistons / connecting rods are the same. I hope so… as that was my assumption when I sourced one. As far as when the blocks started having issues, perhaps one of our long time rover mechanics can answer that question.
The pistons are different. They will fit and work but make for two different compression ratios. 4.0 pistons in a 4.6 make a higher compression ratio.