Code P0303 cylinder 3 misfire
 

Help Please 99 DiscoII
Code P0303 cylinder 3 misfire, and coolant leaking above and just behind the drive side o2 sensor. Cant see where it's coming from.
Could it be the head gasket? I looked at the owners manual and it was right there on the front page It said Land Rover . :eek: So I am going to say it probably is.
But how do I know for sure? Its missing badly so I don't want to drive it very far. Plenty spark on the #3 spark plug wire.

I am going to look at the rave about repairing myself. But I didn't see a sticky about it. If it's really complicated maybe I will take it somewhere. Looks like it would be a big deal I am fairly handy but the hardest task I have done is high mileage service and a brake job.
I have lots of time now that I have a spare. Should I do both heads? should I take them to a shop and have them shaved or anything like that?
As always thanks for the help.

You can do the head gaskets, but follow the RAVE steps. Will need a variety of basic tools, cheater bar, and plan on sending heads to machine shop to be re-finished and new valve seals installed (comes in the HG kit). Takes average guy two weekends with machine shop inbetween. So even if double, still not so bad. $2000 indy shop and up vs $300 for parts and whatever machine shop charges. May want to consider ARP studs rather than new stretch bolts.

Yes, you do both heads.

It would be practical to rent a coolant pressure tester and pump up system to 15 psi and wait 30 minutes to see where leak is from. first.

Bad thing about misfires on inboard cylinders is that they are not near the coolant channel of the gasket. Could be a cracked block.

If you are leaking coolant and are not sure where, do a coolant pressure test to verify the location of the leak first just to make sure.

x2 on the cooling system preasure test

It's leaking on the same side as the cylinder misfire. I hope it's not a cracked block off to the junkyard if it is.
Im guessing Advance auto or somewhere like that will rent the tester.
I will probably start on it this week or weekend. The misfire started all at once while I was driving it . I got on it a little and it started missing. Wasn't hot or anything like that Pleas be a headgasket (never thought I would be saying that. :()

Did you have an overheating event in the past??

#3 cylinder is not near a water passage.
Only way water is getting in there is the head is cracked (rare)
or you have a cracked block and a liner is slipped down and water is arriving that way.

Pull out the spark plug - probably is steam cleaned.

Overheat
 

Last fall it started getting hot going to work. I left the cap off the reservoir when I checked it the day before. Shut it down and let it cool for awhile then added some water while running. It burped a bunch out but was later able to get to a place and flush all the air out without it overheating again.

Spark plug looked normal not steamed. I will pull a couple more to see. This is starting to sound bad

Yeah a middle cylinder misfire is no joke.

Also, the plug may not be cleaned if you didn't run it much. My #5 plug looked normal too.

check the spark plug boot.
It may have been heated and is cracked and is arcing.
Maybe just replace that wire, clear the codes.
Maybe that's all it is.

Yeah sorry, I shouldn't have made it sound so immediately dire!