Intake manifold leaking coolant at expansion tube nipple

Check the freez plugs.

hermostat, Replace My database showed this for thermostat removal, if database is wrong, my bad. 1. Remove coolant expansion tank cap. 2. Raise and support vehicle. 3. Open radiator drain petcock and drain engine coolant into a suitable container. 4. Close radiator drain petcock and lower vehicle. 5. Remove upper engine cover. 6. Remove protective shield from under engine. 7. Detach and remove air intake tube from throttle body and air filter housing. 8. Disconnect electrical and vacuum connections from intake manifold and its attached components. 9. Remove fasteners at bottom of intake manifold and at connection to cylinder head. 10. Remove intake manifold. 11. Disconnect hoses from thermostat housing. 12. Disconnect coolant temperature sensor electrical connection. 13. Remove thermostat housing from cylinder head. 14. Remove thermostat and gasket from thermostat housing cover. 15. Reverse procedure to install, noting the following: a. Install new thermostat housing gasket. b. Torque thermostat housing bolts to 88 in. lbs. c. Torque intake manifold bolts to 13 ft. lbs. d. Fill and inspect coolant level.

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)

Does your oil look normal? If it has a milky look that means coolant is getting into it somewhere. Do you notice more than normal steam or white smoke coming from the exhaust? Those are signs of a head gasket leak or an intake manifold leak. Do you notice the smell of coolant when you open the hood? They are notorious for have intake manifold leaks. There is also a heater hose fitting on the intake manifold that is notorious for leaking. I would test the cooling system with a pressure tester. You may be able to rent one. They are simple to use. Just remove your radiator cap and install the tester and them pump it up to the PSI listed on your rad cap. Let it sit and look for leaks. Pay special attention to the intake manifold, water pump, all hoses and radiator. Are you noticing anything inside the cab like the windows always fogging up or puddles on the floor. That could be a sign of a bad heater core. Pump it up and let it sit for a while and watch to see if the pressure drops or you see a leak. You may have to start it after a while as sometimes water pumps will leak when running and not when off.

sounds like hoses going to heater core but they are rubber usually. But it could be the hoses for the degs bottle mounted on the passenger side inner fender.

Coolant Recovery System NOTE: When the water thermostat (8575) is closed, coolant flows through the degas tube and hose assembly from the lower intake manifold to the radiator coolant recovery reservoir (8A080) .

Trapped air in the cooling system must be removed. A pressurized radiant coolant recovery reservoir system is used which continuously separates the air from the cooling system.

• When the water thermostat is open, coolant flows through both the small hose from the top of the radiator outlet tank and the degas tube and hose assembly from the engine to the radiator coolant recovery reservoir.
• The radiator coolant recovery reservoir separates any trapped air from the coolant and replenishes the system through its radiator coolant recovery hose.
• The radiator coolant recovery reservoir serves as the location for:
  • service fill.
  • coolant expansion during warm-up.
  • system pressurization from the pressure relief cap.
  • air separation during operation.
• The radiator coolant recovery reservoir is designed to have approximately 0.5-1 liter (0.53-1.06 quarts) of air when cold to allow for coolant expansion

just replace the intake gasket not the whole intake manifold

heaterhose is in that general area. most common leak is that spraying aroung so it looks like something worse

if the engine is still running lean, I would replace the Oxy sensor (s),
Then check for a vaccum leak, I found a very large leak on my intake manifold... there is a cap on a nipple on the engine side lower intake manifold (very difficult to get to) and I could not see it until I removed the intake and looked at it.
On my engine, this cap made of rubber was rotten and leaking vaccum.

This helped me 100%

This engine has a plastic intake, jsut inside of the throttle body is a tube that comes from the EGR. It will burn through the plastic into a coolant passage located inside of the intake. You will need to replace the intake manifold and if you want there is a revised lower intake manifold with a slightly smaller diameter tube to prevent future burn through that will prevent a reoccurance. However, it is a costly repair for what is a infrequent failure. I suggest just replacing the upper intake manifold. They are now available through the aftermarket.