Engine has anti-freeze leak on intake. anti-freeze sits on intake bolts and it is not thermostat gasket. What else could be leaking? Is it the intake gasket, or something on the air supply, or something else?

Sometimes, not the heater coil...this leak usually smells inside the cabin...can you see anti-freeze build up anywhere? These motors are more prone to a water pump leak (needs replaced, inexpensive and not to difficult) or the intake manifold gasket...more costly about $400. for a mechanic to do...you should see some anti-freeze build up around the intake bolts...this assumes that there is no water in your oil...which is far more costly as this indicates an internal cylinder head leak...Could be just a hose leak...a bad radiator cap...or thermostat housing leak, (maybe a cracked housing? Help me help you...do you see any anti-freeze build up anywhere? Hope this helps.

oil in water is usually caused by bad intake gaskets. if the intake leaks, it will let oil in water. anti freeze flows in intake, if gasket is bad it will drain down inside of engine to the oil. good-day ! you may also see a anti freeze leak around outside of intake gasket that mounts to engine. if it is bad enough.

When it is "overheating" feel the upper and lower hoses. If one hose is hot and one is a lot cooler than you have no flow through the radiator. Most likely cause for this is the thermostat.

The thermostat is located behind the housing that bolts to the drivers side of the intake manifold that the upper hose is attached to. It is not the easiest job in the world to replace but it can be done.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

when you're facing the engine its the biggest hose on your left going from the radiator to the intake manifold undo the hose clamp on the hose connected the intake manifold pull the hose off, undo the 2 bolts that hold the thermostat housing on (the part that you just pulled the hose off of) pull the thermostat out it will just be sitting there no wires or bolts holding it down, put new one in same way, scrape thermostat housing clean of excess gasket or gasket sealant aswell as the intake manifold. replace the gasket seal it up with high temp r.t.v sealant (gasket sealer) usually comes in a tube an the color is red. bolt thermostat housing back down connect the radiator house, check anti-freeze level an you're good to go

Not a major task on your Cutlass...trace the upper radiator hose to the top of the motor...(intake manifold) you will find the thermostat inside the housing connection...held down by 2 10mm bolts...your replacement should be rated at 195 degrees...(usually the only one available for your V-6...Be sure to inspect your hoses for wear...you will lose (spill) some anti-freeze while removing the thermostat housing...I also recommend to buy a housing gasket as well as the inside gasket seal...these do not always come with the thermostat...Also use gasket sealant as no leaks are attainable...:) Have some anti-freeze handy to top off your overflow system after the installation is complete...you need to inspect while idling to be sure no leaks, and correct amount of anti-freeze in your overflow...2 measures are engine cold...and engine hot...Hope this helps...:)

intake manifold gasket. when it leaks water will enter a cylinder causing the sprark plug to short out. when the engine gets hot enough the water will cook off in the cylinder allowing spark to take place. 80% chance intake manifold gasket, buy the upgraded part. 20% chance head gasket. Take the intake off and check for broken intake manifold gasket then buy parts.

You'll need to remove the upper radiator hose from the thermostat housing. Unbolt the 2 bolts holding the thermostat to the intake manifold and remove the thermostat housing and thermostat. Clean both mating surfaces and install the new thermostat with a new gasket, reinstall the radiator hose, fill with anti-freeze and check for leaks.

Without knowing what year or engine size is, I/m just guessing??????? But the 3.1L engines are FAMOUS for intake maniflod gaskets leaking. Look where the intake bolts to the heads. A freeze plug is in the block. Freeze plugs dont leak unless you have been running pure water or weak/cheap anti-freeze. They will rust out from behind and its BIG BUCKS to replace them all.

Not alot you can do but remove the intake plenum and have the gasket replaced.

The corners of the intake manifold have coolant pasages. The lower intake manifold gasket will need to be replaced. There is an updated manifold gasket, manifold bolts, and torque specification. Call the chevrolet dealership and see if they will extend the warrant on this repair. It is a very common problem with this engine. Thanks Steve