Another Overheating Thread (different symptoms though)

[DrJuice164]

Morning all, been a while since I have been on this board, but what better time to make a return.

So hears the deal, for the past month or so I have had cooling issues. It's a tad difficult to explain so please bear with me. On my ride to work in the morning I would have no issues with temp, but on the way in-between job sites, lunch, or home (anytime the car wasn’t fully cold) I would have overheating issues at slower RPMs (2k-3k). I found a temp solution being that when the revs were raised above 3k the temp would actually fall. Temp would fall to normal whenever on the highway. My theory was that I had a sticky thermostat and by building revs it would build pressure in the system and "unstuck" the thermostat.

After replacing the thermostat the previous weekend, I have had no success; in fact it’s actually worse. Same overheating and same fix but it just happens more often. SOOO I figure I have some air in the lines so I proceed to bleed the system, had the car on a slight incline (not very much though) had the bleeder screw out (wasn't a steady stream of coolant, but more or less lots of bubbles kind of frothy) and rad cap off letting it run with the heat on high. While doing this I check the hoses for temp, the top it mighty warm but the bottom is no where near as close. After going for a ride to put some heat into the motor, the lower hose is still no where near as warm as the upper hose.

Other notes, I do have hot air blowing inside the car. Oil has no coolant in it, and coolant is very clear (no oil). I also do not have a clutch fan; I have been using the AC fan for the past year or so with no ill effects. The motor is a NA dual cam KA with ~150k

So this is where I am stuck, my ideas are still air in the lines, defective thermostat, poor water pump or lastly a clogged radiator so basically everything.

If anyone has any ideas or needs any more info for a diagnosis, please let me know.

Thanks,

Bryan

[H8HONDA]

i would get an infared thermometer. and whule the engine is warm check the rad and everything for hot spots and if there is nothing odd i would replace water pump and see what hapens. if there are hot spots replace rad. as far as air in the lines to bleed system properly i would incline the front end take the rad cap off and let the car idle it will "burp" itself. thats how i was taught at nissan

[marshun]

what have you tried to do so far?

your radiator is working if you see the temp drop when youre on the freeway. have you tried checking your rad cap? that'd be my guess.

[nothing]

This might be a stupid question but why don't you have a fan clutch? Before I read that part all my senses were pointing at a bad fan clutch. Since maybe it wasn't engaging your fan at an appropriate time (when your engine needs to be cooled). What made me believe this was when you wrote that it would drop the temperature when you would rev past 3k rpms or drive in the freeway. Just my two cents.

[DrJuice164]

UPDATEThe motor is overheating more often and at different conditions.IE this morning on the way to work it was overheating on the highway. Yes reving the motor still cools the motor, but it is taking more revs for a longer period of time to get the temps down. I plan on replacing the water pump and doing a coolent flush this weekend unless someone else has any other ideas.

As for the clutch fan question, I use the stock AC condensor fan. Might not be the best idea, but it hasn't failed me in the past so.

[s13dorifta]

man I just finished fixing my GF overheating problem with her 240sx this past weekend well this was actually the third weekend that I was working on it...but anyway yeah my Gf car was doing the same thing your car is doing...the first thing I did was I flushed the cooling system with the prestone cooling system flush...after that it still overheated...so the next thing on the list was the thermostat...changed that and still was doing the same thing...so I was like what the F. Next thing that I did was look around the motor and By doing that I found one of the freeze plugs has been leaking real badly under the exhaust manifold. So I changed it and filled the radiator with coolant and began to let the car idle and it didn't overheat...but as soon as I drove it around the block it started to overheat...and it was back to square one...so what my friend told me was to check the clutch fan...and I did but found it to be ok but I got a replacement one anyway...I also took out the thermostat out again because my friend told me that stant thermostats aren't that good so I got me a gates thermo...I also pulled out the water pump and found the blades to be rusted but the impeller still spun freely. but I didn't want to have to go back and change it later on if it crapped out so I got a new one, I also took the radiator out and reverse flushed it{lotta rust and crap came out after I did that}...so after all that I put the car back together and bled the system and started it up...and the car actually didn't overheat I even let it idle for 30 mins and it still didn't overheat so then I drove it up and down the road and no overheating...but I also found out the new clutch fan was blowing more air than the old one so I guess the old one was defective...so I guess first thing I wound do is go from cheapest to expensive route...do the cooling flush and check your radiator if its plugged up and check the freeze plugs also get a clutch fan having that will surely help cooling your motor. If that doesn't work change the thermo and the water pump...well good luck hope some of my ranting helps

[dc1984]

i would check that water pump. when i first bought my 240 the water pump blades where pretty much rusted away. i would aslo look into doing something about a fan( other than the AC fan. i personally hate the stock 240 fan clutch. when got stuck shortly after i bought my car, and it would be realy loud anytime i went over 2k rpm, i mean in first gear driving in a parking lot my cars fan would be loud as hell. very annoying. so i replaced it, fixed the noise problem for about 3 months then did it again. after that i went with some flex a lite electric fans. those are pretty spendy but there are some other stock ones that u could prob get real cheap at a junk yard. my buddy told me that the ford taurus fan is real good. but that is a two speed fan so the wiring is a little complicated but there are other options for fans. they will definatly help when in slow traffic and idling after youve been driving. i dont even use a temp sensor for my fanse, i just have a switch and i turn them on when i want to( i usually just leave them on always)but all in all, id check ur water pump first and then go from there

[Cone Junky]

UPDATEThe motor is overheating more often and at different conditions.IE this morning on the way to work it was overheating on the highway. Yes reving the motor still cools the motor, but it is taking more revs for a longer period of time to get the temps down. I plan on replacing the water pump and doing a coolent flush this weekend unless someone else has any other ideas.

As for the clutch fan question, I use the stock AC condensor fan. Might not be the best idea, but it hasn't failed me in the past so.

Unfortunately the condenser fan will only operate if the A/C is on. Your symptoms describe the lack of a fan clutch to be the problem. It's fine while driving because you have air constantly flowing through it. But at low speeds you don't have that moving air, so the factory put in a fan clutch. Which you took out...This setup might have worked for you for a while, but it isn't anymore.

If you are sure there are absolutely no air bubbles, put your fan clutch back on for a while and see what happens.

[liquid_cool]

Unfortunately the condenser fan will only operate if the A/C is on. Your symptoms describe the lack of a fan clutch to be the problem. It's fine while driving because you have air constantly flowing through it. But at low speeds you don't have that moving air, so the factory put in a fan clutch. Which you took out...This setup might have worked for you for a while, but it isn't anymore.

If you are sure there are absolutely no air bubbles, put your fan clutch back on for a while and see what happens.

he's rite..sounds like a fan clutch..well since your there anyways...remove that fan and free some HP's...grab your self some electrics from say pepboys and wire em in with toggles...free's up space in the engine bay and you can use 1 for normal conditions and 2 when ya wana burn that civic on the freeway..thats how id fix this.,

[dc1984]

he disnt have a fan clutch on there to begine with. he says hes been using the AC fan.

and yea, i nidnt think about the AC fan only coming on when the AC is on. that cant be too helpfull in some cases.

also, make sure u use a good collant mixture based on where u live. i personaly use a 75 water/25 coolant with a bottle of water wetter but i live on cali and dont have to worry about anything freezin(even in the winter time).figure out if youd rather use conventional or organic coolant and do NOT mix them. u can also use heavy duty coolant that is used on big rig diesel engines. might help a bitdo a little bit of research on your coolant options. a good and correct coolant mixture can be easily under rated.

so, to sum things up, id check that water pump or just flat out replace it(i think they are like around 60 bucks), put on some sort of fan other than the AC fan(i prefer electric) and a good coolant mixture.

let us know

[DrJuice164]

Better late then never, but I figure I post the solution to my issue for the next guy that might need it. Turns out a new pump with a proper bleed ressolved my issues. Although the pump I took off didn't look or feel all that bad, but what do I know.

My opinion is I didn't bleed it properly the first time and I had air pockets/ low on coolent.

Cheers,

Bryan