engine overheat

Can anyone tell me what's going on of my nissan pathfinder?
the problem goes like this, I overhaul my nissan pathfinder replacing the cylinder liner and the four pistons and at the same time I calibrated my fuel injection pump. after three months it overheats again, so i decided to overhaul it again. after three months it overheats again so i decided to replace the cylinder liner. after two or three months, it overheats again.

i've noticed every time my rpm goes over 2000 the temperature guage is starting to rise. this happens with or without the aircondition.

i don't know whats going on with my nissan pathfinder, can anyone help me with this? because it really cost money...

did you check your radiator?., was the car running before you overhauled it?.

very true was it running before you overhauled it an2 you can go to grease monkey an get a radiator flush that migh help it help me out tons , an one more then do you use water or coolent in your radiator if you use water try coolent

Anyone know what he's talking about?

all i got was
"was it running before you overhauled it"
and hes asking if the guy used water instead of radiator coolent ( some people do ), thats all i got lol

I meant aunabia.

Now I am just a dumb engineer, but there has got to more to this story. Modern engines do not tolerate poor maintenance like the old ones did, so your overheating may be a symptom of several possible ailments; among others, warpage in the block. What prompted the cylinder liner replacement? Was the head gasket also replaced? Was there coolant in the oil, or vise versa? Hope you are soliciting a local mech that is honest for this, because chains and franchises may loot you for many un-needed stuff and never diagnose properly (long-term customer base is a lost art).

Want to help you get help.

Also having overheating probs. 01 Pathy, original owner, regular oil changes, Nissan checkups, etc. Just turned over 70k miles. Summer '04 started having overheat probs on vacation. Nissan dealer replaced front thermostat removed rear thermostat -- hoped it would solve prob. Didn't solve it. Got home, went to another dealer to put in backordered rear thermostat. Winter came -- no problems. Now it's May 05, took a 400 mile trip and had overheating probs again. Worst on uphills and stop-and-go. Coolant replaced last summer. Otherwise runs fine -- especially if you like the heater on when it's 80 degrees.

Any ideas?