raditor restricted?

I have a 93 Grand Am SE with the Quad OHC engine thats overheating. I changed the thermostat but I noticed that the top raditor hose gets hot while the bottom doesn't. Does this mean that the raditor is clogged or a defective thermostat? Or is it the opposite where the top hose is cold and the bottom is hot? Tomorrow I will take the bottom hose and flush the raditor. I replaced numerous parts on car and just need to get through the summer any suggestions would help. How do you bleed air out of cooling system?

You either have a blockage or a massive air pocket some where, is the over flow bottle filled to the marks? If so I'd go ahead with the flush and refill and hopefully that will take care of the prob. It's going to be the least expensive step. Make sure to use fresh coolant on the refill, you don't want to use the old fluid that was causing the problem in the first place,

Good luck

Welcome to the Forum.

Generally, if the top hose gets warm, the thermostat is doing it's job, when therm. opens, it releases hot coolant through top hose into radiator, to begin cooling process. coolant then exits through lower hose into water pump to begin the cycle all over.

Thus, lower hose should always feel cooler than top hose, but still feel warm vs. as hot as top hose.

If you have blockage, run some good radiator cleaner flush in coolant per flush directions. Get a backflush kit, it simple [sorta, lol] cut a heater core hose and tap into that hose, directions on the kit [Prestone kit is recommended]. Install the kit, it really not hard. Run the flush chemical, then backflush your system.

As Hoags states, use new coolant correct for your system [i.e. for aluminum or regular system].

Does your fan run?

I would say its either you got a blockage or like knifeblade asked does your fan run? If its getting hot in stop and go driving its most likely the fan isnt coming on. If the fan isnt coming on its probably just the sensor. When it goes bad I usely just but it on a seperate switch. Not the best way to fix it but its the cheapest if you have some spare wire and a switch laying around.

Thanks for the responses. The fan does run (new motor) This car has a low coolant warning light and a temp gauge. The gauge sometimes works when it does it reads in the 270 degree in the red but no odor of overheating. The warning light works the way it should. There two sensors One attached to the back of the cylinder head and the other in the theromostat housing. After reading Haynes manual section 3.8 it seems there should be only one or the other sensor depending the type of engine (OHC 4cylinder or 2.5L 4 cylinder this engine is the 138 cu 2.3L SOHC) The manual goes on to read "If a temp. gauge is included in the instrument cluster, the temp sending unit is replaced by a transducer" no mention of where it is or how to test or replace the transducer. Im hoping it is the sensor for the temp gauge I just don't know which one to replace or how to test .

then goto section 4-21, it shows ya how to test the sensor at the therm.

then goto section 4-21, it shows ya how to test the sensor at the therm.
Thanks but my Haynes manual only goes to 4-19 in that chapter.

sounds like my problem too! i started another thread today...

did you figure anything out?

I know this sounds crazy, but have a reputable shop run a dye test on the coolant and see if your head gasket isn't leaking.

GilT

K, testing the ECT [engine coolant sensor]~~~

Ohmmeter the sensor terminals, using the current guessed temp. of engine, resistance at the sensor sould quite low as it gets hot and drop as it is cold.

Generally, say the engine is around 68 degrees temp. ohm read should be around 3500 ohms, at 50 degrees it should be around 5600 ohms, at 32 degrees around 9420 ohms.

Thanks for all the response's. Im now looking at the waterpump as there are no restrictions or leaks. Haynes say's I have to remove the exhaust manifold but I'll just have to getunderneath to see if I can work around it. I'll keep you all posted. Thanks again

Thanks for all the response's. Im now looking at the waterpump as there are no restrictions or leaks. Haynes say's I have to remove the exhaust manifold but I'll just have to getunderneath to see if I can work around it. I'll keep you all posted. Thanks again

Sorry you won't be able to, I've done the water pump on the exact same engine, there is no way around taking off the manifold trust me I've tried. You bled the air out of the system when you refilled the coolant? If not it'll run hot and even show the low coolant light. The complete system takes a tad over 2 gallons so if you didn't put that much in then it's not full yet.

Thanks for the info even if it isn't what I wanted to hear. Whats the best way to bleed air out the system. Im going to flush out the system and hope that will remidy the situation. Thanks again!

To bleed air out of the system fill the system to the right level, start the car and when the thermostat opens up you'll be able to add more coolant. Just keep refilling the coolant until the level stops dropping and/or the coolant stops releasing air bubbles. The way the system is setup it's a real pain that they didn't put in air bleeders (at least they didn't on my 2.3L)

Thanks I thought so, but I needed a second opinion. I'll flush and fill it today.