4.9. Overheating (long post)

rp0420 · #1 (**permalink**) 10-19-09, 01:45 PM

So im just driving around the neighborhood lastnight and my car out of nowhere says its overheatd and almost instantly i see white smoke from under the hood. Shut it off let it cool down and drove home. First thnig i thought of was a thermostat, and the upper rad hose didnt feel too hot so i changed the thermostat. drove the car about 3-4 blocks and parked for 5 minutes, and it happend again. Checked the hose and it felt like it should again. the white smoke appears to be coming from the valve/head area in front and behind the motor, so i began to think head gaskets but what are the odds of both of my head gaskets going at the exact same time while im not even beating on the car?? i was driving down the street at maybe 25-30mph btw. Also the car has been leaknig from the water pump seal so ive been adding to resevoir. So i go to add more and test it out again and still overheats, now this time i open the hood and theers what seems like coolant/water on the intake, distrubutor, dripping from the hood.. I also noticed that the level in the resevoir didnt drop when the car overheated. what are the possibilites? if ind it weird that through the summer my car didnt overheat but now getting into the cold months it does out of nowhere

drewsdeville · #2 (**permalink**) 10-19-09, 05:39 PM

Make sure this isn't the problem that you already know about.

your 1994 Deville has a crossunder pipe that goes under the engine from the front exhaust manifold. If your leak from the water pump is making its way onto this pipe, there will probably be steam everywhere with all of the coolant burning off on the exhaust pipe.

Otherwise, it's somewhat common for the "T" that splits into the heater hose going to the heater core to crack and leak. This is right above the rear exhaust manifold and almost always results in quite a steam show.

steelybill · #3 (**permalink**) 10-19-09, 05:51 PM

A couple items could be the problem, like the water pump getting worse than it was, and slinging water around, and maybe the intake gasket? I know that in the 4.1 there coolant transfer passages in the intake manifold, so maybe the 4.9 is similar. You may be able to start the engine and wait/watch where the steam or coolant is coming from.
The fans on the radiator may be blowing coolant around, making it difficult to find the source.

HUF · #4 (**permalink**) 10-19-09, 10:53 PM

Start the engine, open the hood and lift the throttle lever up with a finger to increase RPM to some 3500-4000. Watch carefully for leaks. The plastic T (called heater valve) may leak UNDER PRESSURE. It is on top of the engine behind throttle body. Some connections, radiator side tanks, etc. are known sources of leaks as well.
I am pretty sure yo have got an external leak, leave the headgaskets alone for a while. The T is a very possible source of the leak taking into account your symptoms. The white smoke is the coolant hitting the hot exhaust manifolds.
I would also replace the radiator cap.

**Ranger** · #5 (**permalink**) 10-19-09, 11:06 PM

From what you are saying it sounds like it is spraying like a garden hose. Should be pretty easy to spot. Next time don't shut it off before having a look. BTW, it ain't the head gaskets.

rp0420 · #6 (**permalink**) 10-20-09, 01:07 PM

well it turns out thers a hole in my radiator. hopefully that will solve it. If not are these "t" peices expensive?? or is it just that little black thing near the firewall?. Thankyou for the help. So now on to saving for the radiator, cap and water pump. Correct me if im wrong, this would cause it to overheat since it lets the water boil right??? The hole is from the fan rubbing the rad after the accident.