My DiscoII has started running rough, particularly at idle. I hooked it up to my ODB reader, but don't see any fault codes. The O2 sensor voltages seem to fluctuate from 0.785 to 0.2ish on occasion, but I'm not sure if this is normal.

The truck does have a cylinder head water leak, but its had this for a while. Not sure if this is causing it.

Plugs and wires are new, but MPG is moving to the low side (12-14MPG on highway average).

Any ideas where to look for some hints on what is wrong?

 

Do a coolant pressure test, conirm if your head gasket is leaking and replace them before you toast your engine.

 

Coolant is definitely leaking, but why would this 'toast' my engine?

This is my wife's truck and I'm about to go away on business. Can I put in one of those 'sealers' (one that works with antifreeze) to keep it for a while?

 

Okay I've read up on this and she 'hydrolock' and other problems.

Looks like I'm in need of a head gasket job then. Thanks.

 

If you run around with a low coolant issue, the air trapped in the engine will get super hot when the engine is turned of and warp or crap a head or the block.
Your are not hydro locked, if you were the engine won't start and you haven't pushed a piston the side of the block yet.
Quit guessing/driving and get it repaired before the engine does turn to junk.

 

Thanks DiscoMike. Much appreciated.

I've looked around and see people talking about $1500-$1800 for a head gasket change. Does that sounds about right? The LR service manual says 9 hours for a LEV vehicle (I'm in california so assume LEV) (7.2 for not). Even at $100 an hour 9 hours isn't gonna make $1500. Where does the rest of the cost come from?

Any suggestions for how to reduce the air in the coolant system while I take it to the shop (a few miles away). I've seem your suggestion of leaving the truck on a slope over night with the coolant topped up. Would that work best?

 

What year is your truck, how many miles on it and do you have secondary air, an emission control devise?

 

2000 with 97000 miles.

No second air. Not sure what an emission control devise is.. It has Catalytic converters.