Over heating below 3000rpm

[Tippey764]

On the highway today i was crusing around 80mph which is just above 3000rpm in 5th gear. I noticed that whenever i slowed down to 65-75mph; the car would begin to overheat and the temperature gauge would rise. Once i speed back up to 80mph it cooled off. After i got off the highway into a neighborhood it was overheating again so i floored it trying to get it back above 3000rpm again. Instantly the temperature gauge dropped all the way to the normal mark AFTER i floored it. Kind of strange? My coolant level isnt low

The only thing wrong is my bypass hose is kinked. But that shouldnt matter because its a bypass hose, if the thermastat opens that hose isnt even used is it? I know its on my list of things to get but my car has had this hose in it for a few weeks and hasent had a problem so im wondering if maybe somthing else has gone wrong? Anyways what should i start to check?

[cb7remnant]

your temp went down because there was enough air flow to your engine to cool it down, have you ever had just water in the cooling system that could have cause scale build up in there which would prevent it from cooling down or cavitation could be the problem

[dakiid]

maybe your water pump is going bad or the timing belt has to be replaced.

I think the water pump speed is related to how fast the engine is spining or RPM's. So when the RPM's go below 3000 the water pump isnt spinning fast enough or not at all and that causes it to overheat because the coolant isnt being pumped to the radiator.

[dakiid]

your temp went down because there was enough air flow to your engine to cool it down, have you ever had just water in the cooling system that could have cause scale build up in there which would prevent it from cooling down or cavitation could be the problem

at 65 there is more than enough air flow to keep the engine from overheating. so slowing down from 80 to 65 wont cause it to overheat because of less air flow. When my car was over heating 30mph created enough air flow to cool it down and once I stopped then it overheated.

[bcjammerx]

is there water in the radiator? Not being an ass but no one's asked.

What do you mean by "by-pass hose"...and why is it kinked?

need more info/testing

[Joshy]

When he's saying "bypass hose" he means this one, the hose that's part number 4.

[Tippey764]

is there water in the radiator? Not being an ass but no one's asked.

What do you mean by "by-pass hose"...and why is it kinked?

need more info/testing

Ahh i forgot to put that peice of info in there

Yes the radiator is completly full.

If its over heating while im sitting still and i rev it up above 3000 it cools down. Although the car isnt moving.

[degenerate1991]

It wouldn't be airflow, because airflow is not related to engine speed. It sounds like either something in your cooling system is blocked, or the water pump is going bad. When's the last time the water pump was replaced?

[accordztech]

feel both hoses when it starts over heating, then feel it after you revved it past 3k. if all of a sudden it gets hot on both then your thermostat is bad.

get only an oem thermostat. ONLY OEM!

I had the same problem in my van. Also get a new radiator cap, they dont last long.

[bcjammerx]

...number 4...

aaaahhh...guess it feeds the hose for the FITV...or one of two, hondaautomotive calls it the fast idle control hose, along with #5. And I learned something today.

Tippey...glad you've done a test while sitting still.

since your gauge is showing hot, next you'll want to confirm what the gauge is saying before looking for other problems.

I once had an air bubble in my lines, if I sat at idle the temp gauge would rise, once I have it throttle I guess it kicked enough coolant around to hit the sensor (I believe super heated air was building up, air gets hotter than the coolant), my gauge would go down, and pretty quickly too.

In that pic, see the t-stat housing, near part number 21, middle and to the right. First make sure when you open the radiator cap that it's full, then look at that housing, there a bleeder screw there that should be the highest point in the cooling system. Turn your temp dial to hot so the coolant will flow through the heater and push any bubbles out of it too. Then unscrew that bleeder screw. If you don't get any air out then you could park on a hill and let the car run with the cap off, occasionally squeezing the hoses to push air out of them. Usually though that bleeder screw should do it.

If you don't find any air then you may need to flush the block/radiator. You could get one of those flush kits from wal mart...it's nothing more than a water hose attachment that connects to the heater hose. But you have to be slick with it cause if there a blockage you'll have to close off the hoses to get the water to run through everything. Watch the water as it comes out of the radiator and block when you drain them.

[Tippey764]

aaaahhh...guess it feeds the hose for the FITV...or one of two, hondaautomotive calls it the fast idle control hose, along with #5. And I learned something today.

Tippey...glad you've done a test while sitting still.

since your gauge is showing hot, next you'll want to confirm what the gauge is saying before looking for other problems.

I once had an air bubble in my lines, if I sat at idle the temp gauge would rise, once I have it throttle I guess it kicked enough coolant around to hit the sensor (I believe super heated air was building up, air gets hotter than the coolant), my gauge would go down, and pretty quickly too.

In that pic, see the t-stat housing, near part number 21, middle and to the right. First make sure when you open the radiator cap that it's full, then look at that housing, there a bleeder screw there that should be the highest point in the cooling system. Turn your temp dial to hot so the coolant will flow through the heater and push any bubbles out of it too. Then unscrew that bleeder screw. If you don't get any air out then you could park on a hill and let the car run with the cap off, occasionally squeezing the hoses to push air out of them. Usually though that bleeder screw should do it.

If you don't find any air then you may need to flush the block/radiator. You could get one of those flush kits from wal mart...it's nothing more than a water hose attachment that connects to the heater hose. But you have to be slick with it cause if there a blockage you'll have to close off the hoses to get the water to run through everything. Watch the water as it comes out of the radiator and block when you drain them.

Im about to go undo the bleeder valve but

The past few mornings have been cold. So i drove my car hard to warm it up faster. It would never warm up by the time i got to school by driving it hard. If i drive it normally it warms up in a few minutes way before i get to school. Today i drove it normally and saw the gauge start to rise. So knowing my engine was warming i floored it to see what would happen. My gauge was at 1/4th and dropped all the way down to below the C.

[accordztech]

long warmup times points to thermostat.

[dano28]

Check your ignition timing with a timing light. Remember to jumper the service port to check the timing at idle. Un-jumper the service port and rev the engine while using the timing light, does the timing advance from the red idle timing mark??

This sounds odd but an engine with retarded ignition timing will overheat while driving at speed on the highway.

[HorsepowerFreak]

Sounds like it could be the thermostat, assuming the fan turns on.... I have also seen the water pump impeller break lose and cause this type of symptom, and lastly i have had a water pump pulley break lose from the shaft and just spin on the shaft like a broke impeller and make it over heat in the cold at low rpm. just my 2c.

[GsPaDeZ]

Im about to go undo the bleeder valve but

The past few mornings have been cold. So i drove my car hard to warm it up faster. It would never warm up by the time i got to school by driving it hard. If i drive it normally it warms up in a few minutes way before i get to school. Today i drove it normally and saw the gauge start to rise. So knowing my engine was warming i floored it to see what would happen. My gauge was at 1/4th and dropped all the way down to below the C.

Maybe ur o2 sensor could be goon bad...? Have u tried flushing the sytem and adding new fluid ... Could be sediments from hard water build up.. If u were just put h2o onthe radiator... Just a thought