I'm new to my 2004 Disco II SE and this forum and felt like I did due dilegence on my research before I bought it. But god help me I love it! When I bought it, the "service engine soon" light was on and idled a little rough upon start up w/rpm at 1000, but after 20 seconds would drop back down to 500 rpms and smooth out. Was told it needed new coil packs which dealer supplied and I had installed(at his cost). Did not solve problem. As I've been driving it I've noticed loss of coolant(no visible leaks - am using Dexcool)and fairly strong coolant odor when hot. Had my mech. check codes and got 306 (misfire in #6). That would account for rough idle at start up. Has new plugs, wires, and coils. Mech. suspects slipped sleeve - I'm trying to be more optimistic. I suspect, based on what I've read here, is the HG's( I also have been noticing the running water sound behind the dash). Is there a good place to start digging, starting from least expensive to marriage killer? Oh, and at highway speeds its very smooth and has lots of power. Any help out there?

 

There is an exhaust gas in coolant test (around $50 from parts store) that will confirm that those bubbles under the dash are exhaust. That lets SWMBO know that you are on the ball. Assume it is that problem, then you are looking at $300 parts plus maybe $200-$300 machine shop (to level the heads) and 12 hours for an experienced tech with plenty of tools you may not have. Market indy rate is $1700- $2400. Slipped sleeve would could have a tick, but some say interior cylinders leaking is cracked block, however a head gasket can pretty well leak when and where it wants to.

Pix of typical "end cylinder" leak.

If you are on the fence of having this done, or have to wait for the quarterly bonus check (they still award those?) you can put in a container of KSeal, which is a type of stop leak. Might help, maybe even for a few months. Depends on the how much allowance SWMBO allows (honey, we will just skip your hair appointments for a year...)