Ok...having some issues with my 94 Accord. Recently started over heating at idle the temp only goes down when accelerating. Theres no coolant leaking so I changed the thermostat. Thought it worked but car started overheating when I left it running lastnight. The fan kicks on and the waterpump is farely new, tops 6 months old. Any ideas where to go from here?
94 ACCORD w/OVER HEATING ISSUES.....NEED SOME HELP
- Thread starter JDMchic
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f22b1 coupe
Junior Member
Yep. Your radiator fan motor is bad. If it's not spinning while it's hot, that's def it. Well, theres a control module for it behind the glove box but the odds of it being the motor itself are much higher. The radiator fan is the one on the left if you're looking at the engine, it's on the transmission side.
f22b1 coupe
Junior Member
One other thing- be sure you're not burning any- no white smoke right? If you got it hot enough before it may have blown the HG. But try the stuff they said ^ Most likely place for there to be obstruction, if there is any in the system: radiator.
Ok... this week im just gonna drain the whole system. So K2e2vin, I should disconnect the upper hose from radiator, add the coolant in the hose? Then connect it back and then fill the radiator?.....Also like I said, theres nothing leaking, how can I tell if the radiator is bad?
f22b1 coupe
Junior Member
It's difficult to see the radiator in accords, but do this, as it is relatively easy: loosen the bottom bolt and remove the top two in the condenser fan motor assembly (the one on the right as you face the engine working). This gives you a better view of the radiator. Often Accord radiators will start to oxidize horribly- it would be apparent with a visual inspection. The fins turn into the consistency of dry leaves and flake out when you run your finger or a screwdriver across them. If the fins are that bad, the actual coolant passages in the radiator are not far behind. You begin to suffer from significantly reduced cooling ability because the fins are no longer dissipating heat at the same rate, and the actual passages inside the radiator can become clogged as the radiator releases debris internally as it breaks down, and the passages in the radiator are also the most narrow in the entire system- meaning if there is junk in there, that's where it gets stuck, again reducing cooling efficiency.
If you are running AC all of the time, I personally had an Accord that would only overheat at idle with the AC on- turned out it was simply the heat of the condenser actually contributing so much heat that the car would overheat at idle. Then of course while driving the condenser did its job and cooled the freon, eliminating the problem. I mentioned the radiator fan for that reason, it would create that same "idle only" overheating issue. As I mentioned before the radiator timer control unit is located behind the glovebox and I would not rule out that it could be failing.
In a nutshell, here is the exhaustive list of all possible culprits with those particular symptoms, and you can of course rule out what you have already checked:
-Radiator Fan
-AC Condenser Fan (only if problem occurs exclusively at idle with AC on)
-Radiator reduced flow/extreme erosion of fins
-Radiator Fan Timer Unit
-Radiator fan wiring (perhaps damaged and repaired in an accident at some time? Occasionally you'll find front end wiring harness components have been spliced thanks to an accident)
-Thermostat (Only if thermostat were faulty and somehow the increased pressure of higher RPM's was forcing it open while driving, but at idle there was insufficient pressure being generated by the pump to compensate for a thermostat that is too stiff)
The last few are definitely highly unlikely, but take all that for what it's worth. Good luck and keep us posted. Oh and as for bleeding, for what it's worth, I have always had the best luck squeezing the upper and lower hoses frequently as I add coolant, and running the car then adding more and repeating that a few times if you are really trying to be sure. I have never had a pocket that I know of after just filling once, then filling again after running it for a few moments.
If you are running AC all of the time, I personally had an Accord that would only overheat at idle with the AC on- turned out it was simply the heat of the condenser actually contributing so much heat that the car would overheat at idle. Then of course while driving the condenser did its job and cooled the freon, eliminating the problem. I mentioned the radiator fan for that reason, it would create that same "idle only" overheating issue. As I mentioned before the radiator timer control unit is located behind the glovebox and I would not rule out that it could be failing.
In a nutshell, here is the exhaustive list of all possible culprits with those particular symptoms, and you can of course rule out what you have already checked:
-Radiator Fan
-AC Condenser Fan (only if problem occurs exclusively at idle with AC on)
-Radiator reduced flow/extreme erosion of fins
-Radiator Fan Timer Unit
-Radiator fan wiring (perhaps damaged and repaired in an accident at some time? Occasionally you'll find front end wiring harness components have been spliced thanks to an accident)
-Thermostat (Only if thermostat were faulty and somehow the increased pressure of higher RPM's was forcing it open while driving, but at idle there was insufficient pressure being generated by the pump to compensate for a thermostat that is too stiff)
The last few are definitely highly unlikely, but take all that for what it's worth. Good luck and keep us posted. Oh and as for bleeding, for what it's worth, I have always had the best luck squeezing the upper and lower hoses frequently as I add coolant, and running the car then adding more and repeating that a few times if you are really trying to be sure. I have never had a pocket that I know of after just filling once, then filling again after running it for a few moments.
78civic
Junior Member
Could be the sensor that kicks the fans on, bypass it with a jumper wire so it's on with ignition.
Try and turn on the air cond too to see if both fans come on.
Did you 'bleed' the system? I think it's near the dizzy and looks like a 12mm bolt with a hollow tower in the middle.
By any chance, is it showing any codes?
T-stat stuck shut? I usually drill a couple of 1/8" holes in the outer portion, so there is ALWAYS some water moving thru.
E
Try and turn on the air cond too to see if both fans come on.
Did you 'bleed' the system? I think it's near the dizzy and looks like a 12mm bolt with a hollow tower in the middle.
By any chance, is it showing any codes?
T-stat stuck shut? I usually drill a couple of 1/8" holes in the outer portion, so there is ALWAYS some water moving thru.
E
f22b1 coupe
Junior Member
Oh yeah, the coolant temperature sensors could also be faulty, that one slipped my mind. There are two- one located in the thermostat housing and one in the water outlet mounted to the head at the engine end of the upper radiator hose. Also unlikely but worthy of checking if you find that the radiator fan is not kicking on.
f22b1 coupe
Junior Member
Yeah the temperature drops when you move because the fan only exists to provide airflow when the car's motion isn't.
Some other people here may be able to tell you how to test the coolant temperature sensors and the fan timer control unit, but I cannot. I can say it is far more common for the motor itself to simply stop working 100% of the time. I made reference above to having replaced a condenser fan motor (the one on the right) and here is how I tested it: When the car was at idle and hot, and the fan should have been running but wasn't, I manually grabbed the fan blade and gave it a shove- it took off and actually started up immediately. This was because the motor was on its way out.
While you may get the same results, I will say even if the fan had not caught and started running, I probably still would have replaced it just because it is the most likely thing by far to be causing your problem.
My advice to you is to replace the radiator fan motor, it suffers the most wear and tear of any of the parts that could be causing your problem. Then, if it is still only running intermittently, then replace the fan timer unit located behind the glove box. You could probably get one from a salvage yard or ebay for like $10. But honestly replacing the radiator fan is simple and I would say 95% chance that's what it is. All you have to do is remove the two upper bolts in the fan housing (10mm bolts). Then jack the front end of the car up, and loosen the two bolts holding the fan to the lowest part of the radiator, also 10mm bolts. An end wrench is generally the best way to get to those bolts. You only need to loosen the lower two, then you can slide the fan straight up and out. There is a power wire going to it, and possibly another wiring connector anchored on it, but they are easy to disconnect, just make sure you don't yank the fan up without disconnecting the wiring first. And that's really all there is to it, installation is the reverse of removal. If the splash guard is already missing then that's one less step to mess with.
Some other people here may be able to tell you how to test the coolant temperature sensors and the fan timer control unit, but I cannot. I can say it is far more common for the motor itself to simply stop working 100% of the time. I made reference above to having replaced a condenser fan motor (the one on the right) and here is how I tested it: When the car was at idle and hot, and the fan should have been running but wasn't, I manually grabbed the fan blade and gave it a shove- it took off and actually started up immediately. This was because the motor was on its way out.
While you may get the same results, I will say even if the fan had not caught and started running, I probably still would have replaced it just because it is the most likely thing by far to be causing your problem.
My advice to you is to replace the radiator fan motor, it suffers the most wear and tear of any of the parts that could be causing your problem. Then, if it is still only running intermittently, then replace the fan timer unit located behind the glove box. You could probably get one from a salvage yard or ebay for like $10. But honestly replacing the radiator fan is simple and I would say 95% chance that's what it is. All you have to do is remove the two upper bolts in the fan housing (10mm bolts). Then jack the front end of the car up, and loosen the two bolts holding the fan to the lowest part of the radiator, also 10mm bolts. An end wrench is generally the best way to get to those bolts. You only need to loosen the lower two, then you can slide the fan straight up and out. There is a power wire going to it, and possibly another wiring connector anchored on it, but they are easy to disconnect, just make sure you don't yank the fan up without disconnecting the wiring first. And that's really all there is to it, installation is the reverse of removal. If the splash guard is already missing then that's one less step to mess with.
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f22b1 coupe
Junior Member
Oh yes and there is also a radiator fan relay, its found in the relay box over the passenger's fender under the hood. It can easily be checked and replaced, you can swap it with another unimportant relay just to see if the symptoms remain.
My advice is this, If the fans are coming on at some point, your fans are fine. This sounds like you have air in the water system or your temp sensor on the side of the cylinder head is bad. This temp sensor/switch is cheap even at the dealer. I would replace it. To see if you have air in the system you should have whats called a bleeder valve on top of the thermostat housing, if not then you must do it from the top of the radiator by keeping the cap off and just letting it idle for a while to get all of the air out of the system.
Ok I drained the entire coolant system..filled it...and let it run (radiator cap off) all air came out...put the cap back on and waited. Car started getting hot, tapped the fan, didnt come on. So...for what u guys have been saying, I should check the relay next. **Does anyone have a fuse/relay diagram?** My fuse box cover doesnt have it
