Over heating and steam coming out of exhaust manifold. No milky oil on dipstick.

Head or intake gasket is bad check oil and see if it is milky looking.if yes antifreeze is getting in oil. Check antifreeze is it milky or oily . if yesoil getting in antifreeze. Both will be over full.or the head or engine block itself could be cracked.

Water out of an exhaust pipe is usually just hot gasses condensing on the surfaces of cooler metal exhaust pipes, and is normal. White steam or "smoke" however is in indication of coolant entering the combustion chamber and boiling off during ignition. It is superheated water vapor (more than 212 degrees) and turns to visible steam as it cools when leaving the exhaust pipe. This is the result of a cracked engine block or gasket and can be an expensive fix. Check and monitor your coolant level if unsure of the cause. Also check for milky colored oil on the dipstick - this is a sign of coolant entering the crankcase - also not good!

You could have a leaking water pump or blown head gasket

does car heat. if dops water on dip stick it could meen crack in head gasket.milky collour in oil is aways signe water getting in ti sump. watch out for heating. change oil see if colour in oil changes good luck

*White milky oil on dipstick = coolant in oil.
*Coolant on sparkplugs = cracked head or blown head gasket
*White smoke = burning excessive oil in the cylinders, which can be caused by a number of things including valve seals, cracked head or blown head gasket.
***All three of these symptoms together, however, means its the head or head gasket. Both are costly but better the head gasket than the entire head.

According to the service literature I read, the 2003 Montero Sport with the 3.0 or 3.5 L engine does not have O2 sensors listed even in the maintenance schedule. The 2.4 L engine has it on the exhaust manifold though.
---
However, the following lists the par, though for before or after the catalytic converter:

http://www.partstrain.com/store/index.php?VN=4294967180+4294966587+4294964143+&Nr=AND(universal:0)&N=0&Ntt=Oxygen%20Sensor

---
I think that $250 to $300 is reasonable if the Oxygen sensors are stuck in there with rust and the threads are preserved by the technician. Oxygen Sensor replacement can be tricky.
---
Good luck on this repair.

Exhaust Manifold

REMOVAL & INSTALLATION

2.4L Engine

1. Remove or disconnect the following:
   
   
   
   • Negative battery cable
   
   CAUTION
   Wait at least 90 seconds after the negative
   battery cable is disconnected to prevent possible deployment of the air bag.
   
   
   
2. Heat cowl from the exhaust manifold
   
3. Aspirator valve assembly, if equipped
   
4. Oil dipstick and guide
   
5. Oxygen (O2S) sensor connector and ground cable, if equipped
   
6. Exhaust pipe from the manifold
   
7. Exhaust manifold and gasket from the engine
   To install:
   
   
8. Install or connect the following:
   
   
   
   • Exhaust manifold. Torque the M8 mounting nuts to 22 ft. lbs. (29 Nm) and the
     M10 mounting bolts 36 ft. lbs. (49 Nm). starting from the middle and working
     outward.
     
   • O2S sensor connector and ground cable, if equipped
     
   • Exhaust pipe to the manifold. Torque the nuts to 35ft. (49 Nm).
     
   • Aspirator valve assembly, if removed
     
   • Heat cowl to the exhaust manifold. Torque the bolts to 117 inch lbs. (13
     Nm).
     
   • Negative battery cable
   
   
9. Start the engine and check for exhaust leaks.

3.0L and 3.5L Engines

1. Remove or disconnect the following:
   
   
   
   • Negative battery cable
     
   • Exhaust pipe from the exhaust manifolds
     
   • Oil dipstick, guide and O-ring
     
   • Heat shields
     
   • Exhaust manifolds
   
   
2. Clean the gasket mounting surfaces. Inspect the manifolds for cracks,
   flatness and/or damage.
   To install:
   
   
3. Install or connect the following:
   
   
   
   • New gasket and exhaust manifold. Torque the nuts to 33 ft. lbs. (44 Nm) on
     3.0L engines and 22 ft. lbs. (29 Nm) on 3.5L engines.
     
   • Heat shield, Torque the bolts to 10 ft. lbs. (14 Nm).
     
   • Exhaust pipe to the exhaust manifolds. Torque the nuts to 35ft. (49 Nm).
     
   • Oil dipstick, guide and new O-ring
     
   • Negative battery cable
   
   
4. Start the engine and check for exhaust leaks.

If you have to keep adding coolant, it is obvious that you are loosing it somewhere. The best scenario is if you are leaking, since you didn't mention an obvious leak, I am afraid the diagnosis is not the best. Chances are you are loosing coolant either into your oil, or it may be going out your exhaust. This can be caused by either a cracked head, or a blown head gasket, or a combination of the 2. Check your oil in 2 ways, look on the dipstick for a color change in the oil, it will turn milky and will you may also notice bubbles in the oil on the stick. Next you can remove your oil filler and see if you are getting milky residue on the inside of the cap and in the valve cover. To check the exhaust, you may have a drip where the exhaust terminates. Also you may notice steam coming from your exhaust. In less extreme cases, you may be able to hold your hand a few inches from the exhaust termination and see if moisture forms on your hand. To fix, this will require at best a new head gasket, and resurfacing, At worst, you may have to replace the head and head gasket. Good Luck, I wish the news was better. I hope you find this to be very helpful!

could have a blown head gasket or cracked head or worse case scenario, a cracked block letting oil into the combustion chamber and out the exhaust. if it is letting coolant into the oil then pull the dipstick and there should be a milky white look to it where the oil tried to mix with the coolant. but its normal to have water alone drip from the drain hole in the exhaust from condesation. for every gallon of fuel your vehicle uses, it produces about a gallon of water thru the exhaust

Check for external leaks first then check the engine dipstick to see if engine oil is milky looking. If so the coolant is leaking into the crankcase. If dipstick looks okay it could be leaking at the intake manifold. If it is leaking at the manifold coolant can be drawn into the cylinders and go out the exhaust. Other possibility is blown head gasket, cracked cylinder head or cracked engine block. The reason the heater is not working may be that the level of coolant in the system is not high enough to supply the heater core with warm coolant. Could also have air in the system. Internal coolant leaks will usually not get any better, only worse.

You have a blown head gasket.Water in the fuel.This is a classic sign of engine damage.