Land Rover Repair: 1998 Discovery oddity, coolant level, head gasket

Question
QUESTION: John,

My low mileage '98 Discovery has an odd thing that finally bugs me enough to ask about. My Disco has a sloshing, water sound coming from behind the dash. I know what is back there, but I have never heard this on any other vehicle. Seriously, if I didn't know better, I'd think there is a fish tank back there. I know the heater core and lines through the firewall are in there, and I do all my own work, but I have no other problems as in, no major fluid loss, no overheating, no CEL, passed local yearly inspection just two weeks ago, actually. Are you familiar with this? Is it just a nuisance, or sign of trouble?

Thanks!
Michael

ANSWER: The sloshing is characteristic of low coolant level, or aerated coolant from a head gasket or block failure.  Very distinctive and specific to Discovery

---------- FOLLOW-UP ----------

QUESTION: John,

Thanks. I should have checked before I asked - my Disco kinda punked me here. I went and checked after reading your answer Thursday night and found my coolant nearly two inches low. There were streaks all over the tank as if it had blown out from the cap, and a small puddle on top of the water pump - under the top hose to stat fitting. It has been exactly two weeks since I did my quarterly oil change, etc and all was fine that evening. I usually check my fluids weekly to bi-weekly. In these past two weeks, since I can last say I checked my coolant, there have been no over-heating events, or really anything out of the ordinary other than one thing. One day on a steep freeway ascent, I tipped in the throttle to try to induce a kickdown, as my speed was falling below speed limit, and when it did, it went all the way up to 5k+ RPM. I immediately backed off, but could that have been the event? Otherwise, why does coolant want out of my engine so badly, even though no overheating, coolant in oil, etc? It has otherwise run just fine since then, maybe 3-4 days ago.

Thanks again,
Michael

Answer
Your first step is to pressure test the cooling system; to see if you have leaks.  It certainly sounds like you have some points of leakage, and that is a very likely explanation for your trouble.  That may well be all there is to the story.   If you fix the leaks, and the system continues to spring leaks, you need to look to see if you are building excessive pressure.  If you are that is a sign that combustion gases are pressurizing the cooling system and causing the failures.   I've written about that on the Robison Service blog.