Electrical Problem or Blown Head Gasket?

[ieatcivics4breakfast]

Recently my 93 240sx gave out on me. just cruising down the road i began losing compression signified by loss in rpm's. power decreased rapidly in increments and as my rpm's kicked down i noticed some smoke, but not much, rising from the engine bay....to make matters worse, 3 of 4 ignition wires melted....i suspected electrical failure but i just replaced the charging system [alternator, battery, ignition wires] less than a month ago but am not ruling it out as a possibility. my other suspicion lies in the cylinder head gasket...yet the temp gauge didn't surge like it normally would, a mushroom cloud didn't sputter out of my exhaust and i drained the oil looking for water but the oil is fairly new so i can't really tell.....my coolant level checks out so i don't think it's leaking into the head......then again i don't really know for sure which is why i'm writing this. the vehicle has 120K, i don't drive it like i stole it [at least not that hellish anymore]...oh ya and when i crank her up she'll lose compression and die shortly after. ok, enough of my monologue... i'm pissed off and am tired of my girlfriend taking me everywhere....can someone help me?

[240racer]

can you tell why the ignition wires melted?  Do you think they melted because of something like hot water or oil getting on them, or does it look like they overheated themselves and burned up.  If they overheated, then something caused them to short.  Can you pull out the spark plugs and check them out.  Look for discoloration and stuff.  The small amount of smoke sounds like it was only the wires burning.  Did it smell like an electrical fire, plastic burning?  I would look into the electrical side first, from the clues you gave.  Check out the coil and other things, I think it would be unrelated to alternator and battery.  you said that you replaced the charging system, that doesn't include ignition wires, they are sometimes called spark plug wires.  I would look at the ignition system, coil, igniter or whatever.
Adam

[bbp]

I agree with 240racer

It sounds like you didn't assemble everythin together correctly.  Go check everything you touched when you did the overhaul.  make sure the wires and pluged in the right place and check your grounds too.

[junia]

The same thing happened to my friend's car before.  It ended up melting the speedometer cable and even the ebrake cable.  After about a day of trouble shooting we found out that ground cable on the back of the engine was bad.  We changed it out and everything is fine.  I guess my suggestion would be to check all of your grounds and other electrical connections

[ieatcivics4breakfast]

yes, someone did tell me they saw sparks coming from the ground...i appreciate all the input.....better a bad ground than repairing the head gasket...thanx 4 the input