So I have a Land Rover Discovery II 1999, I've been having some issues for around 2 weeks, I've been trying to get them resolved, but I'm running out of ideas on how to solve them. First, I've been having misfires on Cylinder 8 every 2 days or so... I first replaced the spark plug, still misfires, so I decided to replace the wires, and believe it or not! Another misfire. It is only cylinder 8 causing it, and it only happens when it starts, it doesn't do it too often, I've had many starts where it won't throw a code, but sometimes it does. Now, to my next problem, I've noticed my coolant disappears quite quickly in the overflow reservoir, when I got back this morning, I noticed that there was coolant spewing on the ground and boiling. I think this has to be from being low on coolant, but I'm not sure. I'm not sure if there might be a blown Headgasket here. Any help would be greatly appreciated!

 

it is quite possible that it is a failing head gasket, #8 is right next to the water passage. it could be possible that the coolant get splashed up on #8 during start up giving you the misfire code.
you could try a few checks, pressure test the coolant system a lot of times you can see #8 leaking in the back on the head, do CO2 test on your coolant to check for hydrocarbons, or simply pull the number 6 & 8 plugs see if there is a difference in color then re install them in the opposite hole that they came out of and see if the miss moves.

 

Thanks, I'll try what you said to do, and then see what happens, I'm going to also check for other leaks in the system, any hotspots that are known for leaks that I should check out? This cooling thing is causing some minor overheats, it's getting closer to the red on the temp gauge then I would like it to.

 

if its getting anywhere near the red it is probably is over heating, LR gauges sux.
the temp gauge reads cold and Chernobyl anything in between is BS.
i would say start with the preasure test and see how many small leaks you find,
hoses , throttle body heater are common leaks

 

I did some diagnostics on the rover, didn't find any leaks anywhere else (I double checked the throttle body heater), everything points to the head gasket, including a leak I just noticed earlier from the tailpipe. So to combat this problem without dropping a load of money, I went ahead and tried BlueDevil Head Gasket Sealer despite the mixed responses on this product. I followed the instructions as to turning on the heat to max and slowly pouring into cooling system, about 20 minutes into the process, the water leaking from the tailpipe stopped, and I continued for the full 50 minutes without overheating. I've started and ran it for a few minutes at a time about 5 times to ensure there's still no leakage from the tailpipe. I don't know if I've fixed it yet, but I've yet to have another misfire! Usually it would have happened within one of those starting tries. Also, there's no more crazy amount of pressure when I open the coolant reservoir.

Thanks for your help!

 

Well, I shouldn't have said anything, it seems I've jinxed myself. The problem seems to be worsening. No longer does it throw a misfire code on startup, but it instead throws one while I'm driving down the road. I just got back from another drive after the code had been cleared to see if it would come back, and while I'm driving at about 40 mph, I could feel it beginning to lug and have a loss of power, I gave it some gas and it pulled out, anything lower than about 35 MPH and it didn't lug. I'm not sure what to do next here. Any ideas?