So,
I decided to dig back in, and this time throw even new more new parts in the mix.
I removed the intake manifold again and valve cover, I replaced new Bosch Spark plugs with new Champions, replaced both ignition coils, put in new Air mass flow sensor, replaced O-rings and cleaned all injectors, assembled everything together again and still had the same misfire code on cylinder # 7 and the engine started overheating after about 15 minutes of running time.
So in short: I put in new head gaskets, rebuilt heads, new spark plugs, new ignition wires, new coils, new Air mass flow sensor, new O-rings for injectors, cleaned all injectors, new water pump, new t-stat, fresh oil change, seafomed the engine and I STILL HAVE THE MISFIRE on CYLINDER 7 and OVERHEATING PROBLEM by having too much pressure in my cooling system.

I think by now it's safe to assume that I have cracked block at 86k miles and there's no point in investing any more money in this thing.

 

Sooo,
by the time I finish fixing this POS Land Rover I will be an expert at this. After putting about 2k dollars in new parts I found out that i have cracked engine block, WTF? I purchased another low mileage block from a local salvage yard and i will be installing it soon.
So, considering that misfire and overheating is a standard issue on all land rovers; here' what I learned.
1. If you have a misfire and pressure build up in your cooling system causing overheating, and the engine is not mixing oil and water; you definitely have a cracked block or slipped liner. Before you throw any more money into your car, you might want to stop and rethink your strategy with this car.

2. To be absolutely sure; remove the spark plug on the cylinder that has misfire, and go in there with inspection camera (you can get one at harbor freight for $89) and take a closer look at your piston. If it looks cleaner than the other cylinders that are OK and not misfiring, then you have a coolant leaking in your combustion chamber that's flushing the top of the piston making it look clean.

3. At this point your options are the following:

1. Sell the car as parts car and say good bye.
2. Spend about $3-4 on a rebuilt engine knowing that you'll never see that money back, because the truck itself is worth maybe $5K at best.
3. Buy a used low mileage short block for about $500-700, and hope that you can get another couple of years out of it and then get rid of it.

IMHO, the best option is number 1, however in my case after spending tons of money on new cylinder heads, ignition parts, water pump, gaskets, belts, battery, etc... I decided that investing additional 500-700 is not too bad. Now I just have to wonder how easy it is to pull the block of the DII.

 

Quick question, I've been dealing with a cylinder 7 misfire, on and off for about 2 months. It does not run rough, or show any other typical signs of a misfire (I dealt with cylinder 3 before), there is no overheating as well. I've replaced wires and plugs (Bosch, and NJK wires) cleared the code, and it will come back in about 2-3 days. I recently took it to a shop here in MN which solved nothing (foreign car get up). I'm wondering what else I need to check, or what might cause this issue. Code P0307 no other codes. Thanks in advance guys.

 

You landed in a seriously old thread Telecom!

Does your truck start rough after sitting overnight?

 

I see that now lol, this misfire situation has just been bugging me... No rough start in the morning, and I guess the wires are NGK not NJK

 

Hey Charlie - my other 03 does start rough after sitting overnight. Actually not so much as rough as it throws a misfire code for cylinder 7, if I clear it will not come back the rest of the day as long as it does not sit for more than an hour or so.

What do you know?

 

Worst case scenario is that you have a cracked block or slipping cylinder liner. When the block is cracked or cylinder sleeve has moved, coolant gets burned out of the cylinder at cold-startup. This is only one scenario but I'm not yet well-versed with this issue. There is a way to rule out the more serious problems, but it costs the same as starting off by throwing money at the smaller, less insignificant parts like plugs/wires/gaskets. If you have old plugs and wires, you should go ahead and replace all of that along with the valve cover and plenum gasket, injector O-rings. If you plan on keeping your truck all of this needs to be upgraded if old or original anyway. If the problem still exists you would begin troubleshooting the coil pack on that bank. If all of this stuff is fairly new then you may want to proceed directly to a combustion gas test on the cooling system or scope out the misfiring cylinder such as the OP this thread did. If no gas in coolant and piston/cylinder is not steam-cleaned then compression test cylinders and compare numbers to the one possessing misfire for issue with piston/rings/valves.
If the plugs and/or wires or old, you could easily have a single cylinder misfire but the diagnosis becomes more grim as the cheapest parts are ruled-out. You should also be using an aftermarket gauge or software to monitor your operating temps. If you are referencing the factory instrument cluster then most likely you are running your engine too hot which has caused a serious fault on cylinder 7.

 

If it is only on 7 then exchange wires from another cylinder and see what happens.

 

I'm typing this on my phone so there will be typos. Please translate to English.

A rough start after sitting overnight is an indication of a small head gasket leak. The water jacking opening is just behind number 7.

Basically, if it is leaking, the coolant would slowly drip into the cylinder overnight and then get blown or burnt off on the first start. I've had that issue myself and it was the head gasket. If it happens consistently I'd say it is almost definitely a head gasket. I've replaced mine probably four times in the truck (and more time off, on other engines) over the years and except for one massive failure, that was always the symptom.

So, the rough starts after sitting and problem with number 7 (or number 8) makes me think it could well be the dreaded head gasket. That's not a sure thing, but a strong indicator. If it is a leak it is a small one for sure. The had news is that small leaks turn in big ones but the good news is that replacing them won't break the band and you can go a long time with a small leak. The major risks are that it gets bigger and that it fouls your driver side cat.

If you want to eliminate a HG as the cause, watch your coolant level very closely and get a test kit for hydrocarbons in the coolant. You can also oressurize the expansion tank and see if that induces a rough start. And keep some with you in case it gets low because an overheat would quickly follow if it gets low. If it is a leak, the number 7 spark plug and cylinder would probably be a little cleaner than the others, having been "steamed" clean. When I have opened my engine after a HG leak one cylinder looks very different than the others. Also, when it is not cold, you might notice a little white steam from the tailpipe at startup. When the engine is running, it may or may not put a little pressure in the coolant system, but when it is off, the flow reverses.

Oh I just realized chubbs said most of this already. Sorry, chubbs.

 

Ok so quick update, I pulled all the wires and re greased the wires, the code has cleared for now, so I'll keep an eye on it. The engine temp seems to hold steady around 199-200 degrees. I DO have a pretty typical leaky D2 and have just started using Rotella oil for the thickness of it. Good move or not?