Heating and cooling system leak under intake manifold. I cannot see the heater hoses without removing the intake manifold. What should I be looking for, this is a major leak.Thanks, Eric

flushing a cooling system is the same method as any other motor

do it without the thermostat fitted
or water pump opening

sacrifice an old radiator hose to adapt a garden hose fitting
for radiator flush

air in system fix
your thermostat housing has no air bleed valve
no top radiator cap

old school way
heater on full
run motor till thermostats fully open
burp radiator hoses
wait till water is running up into over flow bottle without bubble
replace cap
turn off heater
correct level in over flow bottle

why still over heating
you fitted everything i would have ... yet still overheat
possibles
leaking inlet manifold gaskets
hose clamps loose
cooling fans spinning too slow
thermostatic fan switch faulty
aluminum radiator is a big one
air ..fins bent or some water channels blocked

or possible head gasket leak

Is the leak under the dash ?

Yes there are cooling system hoses under the intake, here are instructions to remove the intake.

Instructions

1. Remove the Intake Manifold
   • 1Drain the cooling system and relieve the pressure in the fuel system. Disconnect the negative battery cable, the air intake duct, the IAC valve connectors, the throttle position sensor and switch connectors, and the EGR solenoid valve.
     
   • 2Pull the EVAP canister vacuum and purge hoses, the vacuum hoses from the EVAP, the brake cylinder, pressure regulator and EGR tube. Tag and disconnect the spark plug wires. Remove the distributor cap.
     
   • 3. Take out the three left bank injector connectors, the thermal transmitter, the ground harness, breather pipe and the upper manifold. Disconnect the fuel feed and return lines and plug them with golf tees to prevent fuel spillage.
     
   • 4Locate the right injector harness connectors and disconnect them as well as the fuel rail and injectors. Remove the coolant temperature switch harness connector and the water hose from the thermostat.
     
   • 5Loose the bolts on the lower manifold in sequence. Remove the bolts and left the intake manifold from the engine. Remove the gasket and discard it.
     
   • 6Clean the mating surfaces by scraping the old gasket material and carbon deposits. Clean the surfaces with solvent and inspect them for damage.
     
   Install the Intake Manifold
   • 7Put a new gasket in place and install the lower intake manifold to the engine. Tighten the bolts in sequence as follows: first pass-35 inch pounds; second pass-78 inch pounds and third pass 70 to 84 inch pounds.
     
   • 8Connect the ECT sensor connector, the fuel supply manifold and the right bank injector connectors. Connect the fuel lines and then install the upper intake manifold. Put the breather pipe in position.
     
   • 9Install the intake manifold ground cable, the thermal transmitter, the left bank injector connectors and the distributor. Reconnect the spark plug wires.
     
   • 10Continue reconnecting all the components, reversing the order in which they were removed. Connect the negative battery cable to the terminal. Refill the cooling system with the appropriate coolant.
     
   • 11Start the engine. Check for fuel or vacuum leaks.
     

Yes, there are expansion plugs (freeze plugs) on both sides of the engine block and at the rear of the engine block between the engine and transmission. There are also a couple in the ends of the cylinder heads.

With all that said, I would like to add that many times with that engine, the heater tube and connecting hoses can leak and be mistaken for a rear expansion plug leaking. I would definately check this before pulling the transmission out.

There is a tube that runs from the back of the water pump under the intake manifold and out the rear of the engine where it hooks up to the heater hose/heater core. This tube has a small hose connecting it to the back of the water pump. There is also a hole in the back of the engine block that will allow antifreeze from under the intake manifold to leak into the transmission bell housing area. When this tube or hose leaks, it often gets mistaken for a leaking rear expansion plug.

It is very easy to check for this. Remove the serpentine belt and remove the alternator and look under the intake manifold down in the "valley" between the cylinder heads. If there is antifreeze in there, the hose or the tube is leaking. Look at the picture below. Item #3 is the tube and hose assembly I am talking about. Usually, just the hose is leaking. It should be replaced with a short piece of SILICONE heater hose. On some of the vehicles, there are 2 hose clamps. On others, the end of the hose that is attached to the tube has a crimped collar on it. If yours is like this, you can fix it by carefully cutting the crimp collar off and replacing the hose using band clamps. (screw-type)

Also look for antifreeze leaking into this area from the front intake manifold runner. They tend to leak on the front runner near where the thermostat housing is located. These will also leak into the valley area and run out the back of the engine. If the manifold is leaking, chances are it is warped. DORMAN makes a replacement intake manifold kit just for this purpose because it has been so common. It is also very easy to check for this with the alternator removed.
The DORMAN part number for your vehicle is 615-178 (See second picture below)

I dont believe the intake manifold has to come off to replace this hose, i believe the water pump will have to be removed and then you should be able to access that hose. As far as the thermostat issue, i would recommend replacing it, especially after flushing the cooling system. Also check the water pump when you remove it and make sure it is functioning properly (all the fins on the inpeller are intact, if you can see them).

Hope this helps...

You need to get or rent a coolant system tester and identify where it is leaking from. They are very simple to use. You just remove your radiator cap and install the tester and pump up the cooling system and then you watch for where the coolant is coming from. Look closely at your water pump, intake manifold gasket, radiator, heater hose coupler on the intake manifold, and coolant hoses. Those are all the common leak areas.

First is to check to see if it's your intake gasket, pull the dip stick and look at the condition of the oil. Look for excessive sludge and milking, look under the oil cap and look in to the valve cover, also pull the PVC valve and look at the condition. Check to see if there is sludge and milking, if there is then you have antifreeze leaking in to you engine crank case which is very bad. The antifreeze is corrosive to the engine bearing and will soon cost you a new engine if there is no indication of antifreeze in your crank case, then it's a leak somewhere else through out your cooling system. If you see the leak from the out side then that's good, it may just be a bad hose clamp that needs to be tightened. If your not sure and want to buy some time, add about 3 table spoon of common kitchen Black Pepper. The black pepper will work it's way throughout the cooling system and will plug up the leak for now and the great thing about pepper is that it will not leave any residue when you flush out the system, not like the radiator stop leaks out in the market. Good luck and keep me posted, it could be the heater hose to the heater core.

Coolant leaks can occur anywhere in the cooling system. Nine out of ten times, coolant leaks are easy to find because the coolant can be seen dripping, spraying, seeping or bubbling from the leaky component. So open the hood and visually inspect the engine and cooling system for any sign of liquid leaking from the engine, radiator or hoses. The color of the coolant may be green, orange or yellow depending on the type of antifreeze in the system. The most common places where coolant may be leaking are:Water pump. A bead shaft seal will allow coolant to dribble out of the vent hole just under the water pump pulley shaft. If the water pump is a two-piece unit with a backing plate, the gasket between the housing and back cover may be leaking. The gasket or o-ring that seals the pump to the engine front cover on cover-mounted water pumps can also leak coolant. Look for stains, discoloration or liquid coolant on the outside of the water pump or engine.Radiator. Radiators can develop leaks around upper or loser hose connections as a result of vibration. The seams where the core is mated to the end tanks is another place where leaks frequently develop, as is the area where the cooling tubes in the core are connected or soldered to the core headers. The core itself is also vulnerable to stone damage. But a major factor in many radiator leaks is internal corrosion that eats away from the inside out. That's why regular coolant flushes and replacing the antifreeze is so important.
oses. Cracks, pinholes or splits in a radiator hose or heater hose will leak coolant. A hose leak will usually send a stream of hot coolant spraying out of the hose. A corroded hose connection or a loose or damaged hose clamp may also allow coolant to leak from the end of a hose. Sometimes the leak may only occur once the hose gets hot and the pinhole or crack opens up. Freeze plugs (casting plugs or expansion plugs in the sides of the engine block and/or cylinder head). The flat steel plugs corroded from the inside out, and eventually eat through allowing coolant to leak from the engine. The plugs may be hard to see because they are behind the exhaust manifold, engine mount or other engine accessories. On V6 and V8 blocks, the plugs are most easily inspected from underneath the vehicle.
Heater Core. The heater core is located inside the heating ventilation and air conditioning (HVAC) unit under the dash. It is out of sight so you can�t see a leak directly. But if the heater core is leaking (or a hose connection to the heater core is leaking), coolant will be seeping out of the bottom of the HVAC unit and dripping on the carpet. Look for stains or wet spots on the bottom of the plastic HVAC case, or on the passenger side floor.
Intake Manifold gasket. The gasket that seals the intake manifold to the cylinder heads may leak and allow coolant to enter the intake port, crankcase or dribble down the outside of the engine. Some engines such as General Motors 3.1L and 3.4L V6 engines as well as 4.3L, 5.0L and 5.7L V8s are notorious for leaky intake manifold gaskets. The intake manifold gaskets on these engines are plastic and often fail at 30,000 to 80,000 miles. Other troublesome applications include the intake manifold gaskets on Buick 3800 V6 and Ford 4.0L V6 engines.
INTERNAL COOLANT LEAKS
There are the worst kind of coolant leaks for two reasons. One is that they are impossible to see because they are hidden inside the engine. The other is that internal coolant leaks can be very expensive to repair.


visit for more info:

http://www.aa1car.com/library/coolant_leaks.htm

The hose is a cooling by-pass hose. It makes a big horseshoe and attaches under the front of the intake maniold. I think that if you have small hands and a lot of patience you can likely replace it without haveing to take half the engine apart. (You have to pull the head to pull the intake manifold).
I think if you remove the battery, and have a small bright light you will be able to see where if attaches under the front of the intake manifold. Advance auto sells the by -pass hose for
around $12.00 I think.

Becare if you are probing around there are way too many vaccum lines under the manifold.
If they come off and you don't know where to put them -- you are in deep kim chee. I know I am
in super deep Kim chee now.

Hope this helps