JigsN Joints

Car in question: '97 Accord 2.2L non-vtec 5-speed

Ok so when im in traffic or stopped at the bank or something my car starts to overheat. When I start driving again it cools back down. I have let it overheat in the driveway and felt both rad hoses and they were both hot which leads me to believe that T-stat is good still. One thing I have noticed is that radiator fan does not ever come on while im driving, it only turns on when I shut the car off which makes me think one of the 2 sensors is bad.

Which sensor runs the radiator fan, the one on the T'Stat housing, or the one on the front of the block?

poorman212

The one one the t-stat is is for when the car is running. The one one the front of the block is for when it is off. Before replacing it (t-stat), pull the connector (green?), jump the wires and see if the fans come on. If so there is something else going on.

JigsN Joints

Ok I jumped the wires and the fan came on.. What would I check next?

holmesnmanny

If your fans work, which they do if they come on when the car is off, then the problem should be the fan switch/termperature sensor on the thermostat housing. This is the one where the lower radiator hose attaches to towards the back of the engine.

Remember that coolant direction goes from the back of the engine past the thermostat, through the lower radiator hose into the radiator, back up the radiator, and out the small upper hose into the engine, through the water pump and along the back of the engine into the thermostat etc etc. A lot of people think it's the opposite way.

S2Integra

I think you may need to top off the coolant

JigsN Joints

I replaced the temp sensor on the thermostat housing with no luck. And what your saying about radiator flow is that the coolant comes in the lower rad hose and out (into the engine) through the upper rad hose? When I let the car over heat the upper rad hose is hot and almost burns on the touch, while the lower is still hot but not hot enough to burn you. What else would not make the rad fan come on?


what makes you think that? my coolant doesnt leak or anything. Should you be able to see the coolant when you pull the radiator cap off?

holmesnmanny

Yes. It should come up to the point where it would otherwise run into the reservoir.

First thing I would do is pull the thermostat, run without it, and see if the fans start working. Perhaps the thermostat is only opening enough to let a very small amount of coolant in, not enough to hit the thermo switch to turn the fans on. If they still don't come on then you either have a problem with the sensor or from the connector to the relay.

cudleeman

I had a similar problem with my '95.
On mine, it turned out that the radiator didn't flow over the entire thing.
AKA: bumb radiator.

My father in-law is a Ford Master-tech and used a thermo gun to temp a couple sections of the radiator. It turned out that the bottom left corner (opposite of lower hose) never got any hotter than the engine bay ambient temp.

nus_dogg

I thought the coolant flow is from the top of the hose down to the lower hose and into the thermostat then into the engine and out to the top rad hose then back into the radiator again to get cooled.

Notice the upper hose is always hot then gets cooled by the radiator by the time it reaches down at the lower radiator hose?? Thats how I tell.

mavvrik

A cooling system works by sending a liquid coolant through passages in the engine block and heads. As the coolant flows through these passages, it picks up heat from the engine. The heated fluid then makes its way through a rubber hose (upper) to the radiator in the front of the car. As it flows through the thin tubes in the radiator, the hot liquid is cooled by the air stream entering the engine compartment from the grill in front of the car. Once the fluid is cooled, it returns to the engine to absorb more heat. The water pump has the job of keeping the fluid moving through this system of plumbing and hidden passages.

It wouldnt make sense to have it start form the lower, cool thru than enter the upper. Thats completely working against gravity

nus_dogg

^^ Thats what I'm saying is where it starts at the bottom hose through the thermostat, into the block, through the upper hose(hot) then into the radiator to get cooled and back down to the lower rad hose(less hot).

And yes, coolant is what picks up the heat and brings it into the radiator to get cooled.

mavvrik

haha yeah nus_dogg i know what your sayin and i completely agree

holmesnmanny

That's incorrect, guys. That's why cars overheat from a thermostat getting stuck. The coolant goes from the water pump side through the pipe through the thermostat(hence the problem when it gets stuck) then up the radiator into the engine and across the water pump again. Since the coolant goes in the direction of the thermostat that's why cars heat up so fast, assuming the thermostat works, blocking the flow of coolant until it reaches the right temperature, then opening up.

holmesnmanny

Then why doesn't the lower hose get hot when cars thermostats get stuck?

There isn't a thermostat in between blocking the lower and upper hoses so why isn't the lower hose getting hot? The lower hose stays cold because the thermostat isn't allowing coolant to get to it. The upper hose is close to the engine with nothing in between blocking coolant, that's why it gets hot.

Also, the radiator can't possibly completely cool down the coolant. It only cools it so that no damage is done to the engine.

Kimi012

It wouldnt accomplish faculty to accept it alpha anatomy the lower, air-conditioned thru than access the upper. Thats absolutely alive adjoin force

MrGiggles

I agree with you. When I flushed my engine, it would suck water out of the bottom hose and spit it out the top.

mavvrik

Agree to disagree i guess.
Your makin it sound like it starts from the bottom and works up the radiator thru the top hose etc.... It does start from the bottom yes, but it doesnt go thru the radiator against the laws of gravity. It works thru the motor, to the upper hose, than down the radiator thru the bottom hose