1995 Isuzu Rodeo 4WD 6Cly leaking water/coolant under water pump. Need help finding leak/cause.

Sounds like a bad freeze plug. There's like 8 freeze plugs around the engine. 3 on each side and 2 in the rear between transmission. The only way to findout is by visually tracing the leak source.

Go to the dealer and have them put a dye in the radiator. Run and drive vehicle. Take vehicle back to dealer they will use a UV light and determine the location of the leak. I have done this several times to multiple vehicle and it works all the time. The dye will glow.

You will have to clarify behind the oil pan. Front of engine towards fan. Rear of engine transmission side. Or above the pan towards engine side. If there is coolant leaking from behind the engine (between the engine and trans) and is not running down from above eg head gasket or hose connection, chances are good that there is a frost plug leaking on the rear of the block.

Use a cooling system pressure tester to apply pressure to the system. This will speed up any present leak and allow you to see more clearly where it may be coming from.
Check for water presence at the throttle body and thermostat housing.

the temperature gauge range of movement is still considdered an acceptable range and depending what weather conditions and other loading on vehicle eg going up hill also while towing. But some things ive come accross like possibly the water pump, at higher speeds the impeller could be loose on shaft and with pressure it may not be turning at proper speed, I would replace the thermostat for saftey measures also, while you looked at the water pump. Check out the heater hoses and pipes that run behind the engine to the other side for leaks also. check connections of temp sender unit wire on thermostat housing(there are 2 sensors on it) its the smaller of the 2.the other one is for cold starts

look for traces of oil in coolant, usually milky substance. Pull plugs and see if traces of oil or coolant are on plugs. Then do a cylinder leakage test to locate the vacuum leak.

Overheating means not enough cooling due to some blockage from the cooling path.
It is not necessary to have a leak. When the coolant is stagnant, coolant is not able to flow through the water jacket, radiator by the help of the water pump then heat can't be dissipated through the radiator fins therefore engine gets overheated.
You need to check these followings.
1- Thermostat: if it is not open then you get overheat.
2- Radiator: if it gets clogs up coolant can not flow thruogh.
3- Water pump: it the bearing is broken, it can not circulate coolant to the radiator.
Hope this can help.

with my experiance on these engines it's usually the upper outlet hoses running from the heads into a t then into the upper radiator hose they are pain to replace but 3 out of 3 of my v6 isuzu's have had the same problem you'll have to pull off the theromstat and the coil pack the hoses are very small and run from the end of the heads one on each into a t then into the radiator hose just under the housing

it could be leaking somewere else , get your cooling system pressure tested at a shop

There is a plastic heater pipe junction behind the inlet manifold against the fire wall that could be brittle and leaking.