My 2001 Isuzu trooper 3.0td is flushing water out of the radiator and their is some pressure when I remove the radiator cap the next morning

Remove the splash pan under the radiator

water always goes in the radiator up to the radiator cap and the overflow bottle up to the full mark or about 1/2 way. The fluid capacities for your vehicle are in the owners hand book, workshop manual,(genuine or after market) or available on line under specifications for your make of cart.

You have a water leak from the sound of it or water is draining from over heating. Things to check for, leaks at the hose connections, leaks at heater connections on engine, leaks at water pump and any leaks at head gasket. Assuming there are no leaks check or replace or adjust your water pump belt. Take the thermostat out and run the engine without out it. If the problem is solved replace the thermostat recommended for you car. You can also have it checked as well.

check belt tension on waterpump, make sure radiator and overfill bottle are full to specified level. either the coolant is low or the pump is slipping

You may have air in the system. Let the engine run with the radiator cap off until the thermostat opens. Have someone then get in the truck and bring the rpm up to 1800 to 2000 rpm and hold it there for 15 to 20 seconds while you top off the system with coolant and put the radiator cap tightly back on. Then bring the rpm down to idle and road test the truck. DO NOT BRING THE RPM BACK DOWN TO IDLE UNTIL THE RADIATOR CAP HAS BEEN INSTALLED COMPLETELY. I suggest replacing the radiator cap at this time also.

the radiator cap is giveing out replace it's not holding the pressure

make sure ur fan clutch is puling some air and replace rad cap with new onr u may have to replace radiator long trips not getting enough water cooled

Your radiator efficiency has been reduced by (what is called) blossoming. Blossoming is electrolytic growth of crystals inside radiator duct passages. This typically occurs in the older Troops as gradual overheating probs cause the vehicle to run low on coolant, then water is being used to top off system repeatedly, acid levels in cooling system rise as the coolant protectants degrade and the inside of the radiator ducts 'blossom' with small crystalline growths that reduce the radiators flow and ability to cool the engine. Flushing and blowing out the radiator are temporary fixes. Replacing the radiator is the permanent fix. You did the right thing by replacing the water pump, tstat and radiator cap. An old, original water pump usually fails soon after the radiator is replaced. New Trooper radiators are fairly cheap, $85+. The replacement can be done by any backyard mechanic or DIYer in under and hour. You know the typical warnings about the toxicity of antifreeze and the deadly affects on pets who drink improperly disposed coolant. Good luck to you. It's an easy remove and replace. Your Trooper will thank you with many cool running miles. -Geoff

remove coolant.remove thermostat remove bottom radiator hose to water pump.put a empty container under the radiator.take a water hose put it where thermostat goes flush out the rust in block.watch the water as it come out the water pump .if stream water is small keep flushing until you get a study sream of clear water. also flush out radiator. lower water pressure dont flush radiator it with high water pressure you could burst it. make clean the over flow jug .make sure it not stopped up.put in a new thermostat and radiator pressure cap. fill radiator with half antifreeze and half water.bleed the coolant system.

Drop the tin sump and check the pick up pipe as the pipe can crack and the seal goes hard so lets some air air in for a bit .