98 Trooper instead of filling with gas I have to worry about filling with coolant! No leaks, nothing in oil, runs perfect, but going through gallons of coolant. No mechanic I have had look at this has any idea where the coolant is going. Nothing out the exhaust. All timing components have been changed, no noises, engine runs smooth and starts perfectly and runs perfectly, nothing leaking on the outside or heater core inside or on the ground. No signs that it is burning coolant or leaking through the heads. Where can all this coolant be going. Someone said I was blowing it our while driving 75 down the interstate but I would think that the bottom would be coated and I will get some outside leak noticeable on the ground if this was happening but noting is wet underneath the truck and nothing on the ground after a long drive.

Has anyone ever heard of anything like this happening to any engine, not just a Trooper V6

 

You could have a cracked head or blown head gasket and be burning it, what does your exhaust look like? Cracked heads and gaskets are fairly common on the Isuzu V6 and other engines, like the Toyota 3.0 V6 and 2.4 4 cyl.

 

The exhaust looks fine, I can smell some oil when I first start and it uses a little oil, a guart every 1000 miles or so but I have had the plugs changed and there was nothing to indicate it was burning anything other than fuel. I was also told if it were leaking into the fuel it would not be running properly. This truck will start in any weather first turn of the key with no problem and idles smoothly and cruises at 75 down the road no problem. Never felt any misfire on any cylinder. I can say that I drive about 80 miles commute every two weeks and after that drive running 75 the coolant tank will be empty. Running around town at low speeds it does not seem to loose as much. I guess it could be mixing with the fuel and buring it but it sure runs awfully good to be burning half water mixing with the fuel!