Ok, compression test was OK. 120-130 psi on all cylinders. I also did a spark test on #7 (which was good) after which I put it back together and fired it up. It seemed to idle a little rough, but not quite a misfire. After lap two around the block I noticed drips from a coolant leak and temps spiked again. I found that the upper radiator hose had a bad seal (reused the spring clamp) on the larger pipe running straight forward out of the intake manifold. When I pushed sideways on the hose it would get worse. I installed a fresh clamp and fired it back up, but my #5 misfire returned. I parked it back under it's shade tree to try again another day. My brother is coming down for some mountain biking, so I don't know if I'll get to it this weekend or not.

 

Now would be a good time to pull # 5 and inspect for coolant in the cylinder. Either rule out or confirm the block.

 

I pulled the plug. It was wet, not a surprise, but it didn’t smell or taste like coolant.

The miss has been a bit of a moving target. It was 5 and 7 first, cleared it then 7 only. Today it was 5 only. I’m getting some O2 sensor errors too which may, or may not be related. I’ll add a screen shot from a generic OBDII reader in case it is informative. I REALLY wish I could use my GAP Diagnostics tool from my 3!

 

This may sound obvious, but with all the fussing around, you may have loose connections at the ignition coils. I know that when I replaced my coils a few years back two of the boots were not fully seated. Car ran rough on start up, but smoothed out for a while then popped spark plug codes. Went bac and made sure the plugs were all properly seated at the coil and the spark plug. I had two not fully seated at the coil.

 

That’s very possible and that thought entered my mind as I was putting the wires back on the plugs. Some of them were difficult to get clip on the plug due to weird angles and the SAI piping. I did check #7 at the same time because it was previously the problem child. I’ll go back and check next time I’m out there.

 

whenever there is a 'misfire' on these engines, my first though is coolant in the cylinder....

but many other things do it:
leaky/sticky injector
intake air leak
crossed/bad spark plug wires
bad coil
fouled plugs
crank/cam sensors
bad wiring harness connection
sticky valve/valve seat issue

 

Well, I seemed to have tracked down all the leaks and installed a new coolant reservoir cap after carefully bleeding the air out of the system. I still get a miss on #5, which has good spark. Today temps slowly rose to about 170 about half way around the block and then spiked like mad and was accompanied by coolant blowing out the top of the reservoir. To me it seems I'm getting combustion gas in the coolant which is causing me to heat up and blow out after whatever flaw I've got is heating up and expanding open.

 

I thought I had answered some of these concerns, but upon review I did not. I have all new coils, plugs and wires. I've triple checked the wire placement and have put a spark tester on cylinders 5 and 7 which were the only 2 I got codes on. It has since changed to only 5 that has a miss. It's hard for me to tell (not so good sniffer) but my brother says there's definitely coolant on the plug when pulled from #5. The heads were resurfaced and vacuum checked for leaks by a cylinder head shop who was the shop used by the Land Rover dealer back when these D2's were new.

 

I'm going to make a few calls, but I think it may be time to pass it on to someone else, full disclosure of course. I'm going to LS swap one of these one day, but I don't think this one is the one for that undertaking.

 

So I got back to this project finally. I found a youtube video of a guy who had pinhole leaks in the aluminum in the cylinder walls, which then creeped up into the cylinder. I was convinced this was my issue, he had the same symptoms. I bought a junkyard engine for $300. My plan was to use the short block off the junkyard engine and put on everything else off my old engine. As I'm tearing things apart I found water under the valve covers and a rather significant build up of a waxy substance on the intake of #5, the one with the miss, and now I'm second guessing myself. Do I attempt a new intake gasket, or keep with my plan to swap out the short block? What would cause that build up? The vehicle ran very little, so it built up quick.