I've been posting about this for a few months now -- becuase I keep thinking I've got it fixed. There's obviously something small I'm missing here somewhere but I just can't figure it out or what's causing it.

1995 accord LX - automatic
problem: overheats when at idle for not a very long time. not to the point of smoking, but it rises into the red. cools down immediately when i start driving and/or turn on the defroster on full heat.

what have i done: replaced t-stat, replaced t-stat housing fan-switch, bled & flushed radiator countless times.

see here's the thing. the fans work fine. after i replaced the t-stat, nothing improved. i replaced the switch. nothing happend. i flushed & bled the radiator and nothing happened. 2 days after the radiator flush, it worked perfectly for 3 weeks - never overheated (for the first time in 2+ years) even in the most extreme stop-and-go hot downtown-denver-driving conditions.

i forgot to tighten a hose apparently after the radiator bleed, and all the coolant leaked out. i overheated hardcore -- my fault totally. problem back to original status.

I checked fans again - tested switches, flushed & bled radiator. nothing. 2 days after bleed - works perfectly again - 2 weeks of perfection. No leaky hoses this time , but last night - it starts overheating at idle again. fans are coming on when they're supposed to. I'm stumped.

PLEASE help - I'll buy you a twinkie.

 

Did you use a factory Honda thermostat and place the jiggle pin in it's correct position? Makes a difference what kind of thermostat you used.

 

Have you confirmed that your waterpump is working correctly?

 

maybe a whole new radiator????

 

I didn't use an OEM t-stat, I've heard that before....is it a possiblity that my t-stat is just sticky (can that happen or am i making things up?)?! I'm not the best with cars - so i must ask - what the hell is a jiggle pin?

As for the water pump - I don't know how to test that on my own - not even sure where it is - can someone give some tips?

I have no plans all weekend so have it as my goal to get this fixed once and for all!

 

its gotta be the water pump. same thing happened to my step-brothers streetbike (car, streetbike, same thing)

 

to check if is ur water pump is working. remove the hose on top the radiator, ull loose some coolant but.... . start ur car and now there should be a gush of water coming out if there isnt, then is your water pump, by the way the water pump is located inside the timing belt housing...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fleetmack &raquo;</TD></TR><TR><TD CLASS="quote">... what the hell is a jiggle pin?</TD></TR></TABLE>If you put in your own t-stat you may have noticed a little pin out near the edge of the disk that rattles.

On my cars the t-stat only really fits into it's housing one way. But I suppose if you get physical you can stuff it in wrong. What about the t-stat gasket? You know it fits over the edge of the t-stat disk, so it seals on both sides of the disk...

When it's cold, squeeze each of the big radiator hoses. For either one, if there's air bubbles inside you'll hear some sloshing sounds. The hoses feel different when they're air-filled, too. There should be no sound except for a small rattling noise when that jiggle-pin rattles in the t-stat.

Even genuine Honda t-stats can be defective. Cheapies probably more often...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ram0869 &raquo;</TD></TR><TR><TD CLASS="quote">to check if is ur water pump is working. remove the hose on top the radiator, ull loose some coolant but.... . start ur car and now there should be a gush of water coming out if there isnt, then is your water pump, by the way the water pump is located inside the timing belt housing... </TD></TR></TABLE>

You can continue the verification process by including your thermostat in this test. start the car, let the engine run until it hits operating temperature that would open the termostat, once the thermostat is open the fluid in the radiator will start to "move." This is the fluid going thru its full cycle thruout the engine, hoses, radiator, yadda yadda. If the engine hits normal temp and not flow, then the termostat did not open. Also, I don't know if this applies to Hondas, but thermostats have different temps, at least for American V8 engines, 160, 180, 210 degrees. Make sure your thermostat opens at the right temp.

 

Yes, you can buy different temp thermostats, but as long as you got the one for your car it should be the OEM temp. I would have to agree that unplugging your upper radiator hose and letting the car heat up would be the best bet. If your pump is working you WILL know very quickly. That's pretty much the last item in the cooling system.

You covered fans, thermostat, leaks i suppose, your cap is good if you're not leaking fluid, that's about it. How about the radiator? Many bent fins or anything? I'd have to go with pump so far.

 

if you overheated your engine bad enough you can weaken the headgasket or even blow it. I would test it with a block tester. This tool is mounted on top of the radiator, it has a special chemical that changes in color when exhaust gas is present in the cooling system, thus having a blown headgasket, does the car run rough? check the tail pipe for white smoke, does it burn coolant. since u covered everything else try checking the head gasket.

 

my car did that like 3 years ago and i changed the radiator and it fixed the problem...

 

My Last car overheated for 2 years fan worked fine did all the same things your doing nothing would fix it, The radiator had a clough in it. that would be my guess but my last car was a chevy so nothing ever worked right

 

What about air pockets in the cooling system? Have you bled the system yet? There should be a bolt-head with a hole in the niddle of it where your top radiator hose connects to the engine. Loosen that while engine is idling. Manualy rev engine, using throttle cable, until you see coolant coming out of the hole. Tighten bolt.

See if that works.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fleetmack &raquo;</TD></TR><TR><TD CLASS="quote">As for the water pump - I don't know how to test that on my own - not even sure where it is - can someone give some tips?</TD></TR></TABLE>
#1 is the water pump with it's o-ring gasket.

You're looking at the backside of the engine (see the thermostat housing). To get the water pump, you have to take off all the timing belt stuff on the front end of the engine. So you may as well do a timing belt change.

The only 2 ways I've seen waterpumps fail, they don't quit pumping water...
1) The shaft seals start leaking, so you get a puddle of antifreeze on the ground. But it still pumps water (until there's no water left).
2) The bearings get loose, so the impeller rattles around. It makes noise, maybe the impeller even rubs against the volute housing. But it still pumps water.

I've heard where someone's pump had corroded so badly that there weren't any vanes left on the impeller. Then it wouldn't pump. But I've never seen that firsthand...

 

Fleet, have you determined that the car is actually overheating? Does it actually blow coolant and steam or is all you've ever gotten was this erratic action from the gauge? If its all gauge, I'd suspect a temp sensor is defective.

 

I checked all the hoses last night and they seem to be free of air pockets, and they're both warm to the touch with the lower being much warmer than the upper one -- I think that's normal though?

As for the water pump -- I'm not leaking any anti-freeze as I've never seen a puddle before and just to check -- for the past about 3 months I've bled the radiator about once a month to check it and it's free of air pockets every time and the coolant comes pouring out the bleed (on the t-stat housing) the second I pour it in the radiator....

I've ruled out a head gasket -- I have been looking for the white smoke from the exhaust since this problem started, and I had a friend who knows a lot more than me (but not as much as you) look at it last week and he ruled that out - not sure why.

As for the water pump being broken - I'll test that tomorrow.

And as for me knowing if it's actually overheating -- no I can't say if it is or not. It goes about halfway between the halfway mark and the top mark on the guage within 30 seconds of idle at a stop light. The only time it overheated fully is when all the anti-freeze leaked out (due to a user (me) error - I'm an idiot) -- that's the only time I've ever seen smoke. So you think it could be a short or something to my guage? Where is the temp sensor and what does it cost - easy repair? I'd prefer that to pulling the t-stat again, that thing's a ******* PITA to get to on these accords! (which happens to be my only complaint about this car, btw - after 5 years and 120K miles i've put on her)

 

Sender for your gauge is (I think) #5 up there. Anyway it should be a 1-wire connector. It's as easy as unscrewing & replacing. Some coolant will come out the hole, so be quick with the new sender. First, you could look for a flaky connection in that plug.

I always thought those sensors just plain quit working. Then your gauge doesn't work at all. I don't know about that thing giving false readings at idle, then pretending to work OK while you're driving. But you've already ruled out so many 'normal' problems...

 

I don't have my shop manual here to check, so you'll have to check each of these by grounding method to see which one operates the gauge. There are three switch/sensors for the cooling system you can check on the motor. One is on the thermostat housing. Another is on the housing where the upper radiator hose attaches to the engine. The third is just behind the second one above at the hose outlet, and is inserted into that box like part that the hose outlet is attached to on the left side bottom. I think that this third one is the one you want. May have a single red wire connected to it, if so, with ignition on, ground that pup and see if it sends the gauge to full hot, if so thats your sensor. Its about $32 to replace.

 

Be careful... My Helm book says to ground that wire, watch the gauge climb, but DON'T LET THE GAUGE GO ALL THE WAY UP. That'll fry the gauge.

 

the one on the t-stat housing is the switch that tells the fans when to turn on -- mine was defective so i replaced that one.

i agree with jim blake though - why would the temp guage sensor think it's overheating when i'm idle but work perfectly at all other times? that doesn't seem to make a lot of sense.

 

The sensor is a grounding device, and its function when it goes bad will typically be erratic behaviour. When you stop the cars motion you stop air flow over the engine and through the radiator. Its temp will rise quickly. The sensor will try to adjust and make a reading adjustment. This reading is erratic, so one should assume the sensor is defective. I can tell you one thing for sure. A blocked radiator will not suddenly plug up then open up, and that goes for a hose too. The same for the water pump, its not going to suddenly start acting up then get better. Those parts go bad slowly over time and they do not "correct" themselves. From what you've posted, the symptoms sound suspiciously like a sensor gone wild. These problems as your experiencing are a SOB to figure out and fix. For $32 the sensor is worth a try.

 

Check the acidic level of your coolant

sounds like a warpped head to me..

or your timing is WAY off(not likely)

 

water pump is kosher -- haven't overheated since i posted this thing. this is so intermittent - i wish i could find a pattern. guess i'll leave it alone for now - then if it goes bad again switch out the temp sensor.

 

it sounds to me that you might have a bad ground (I didn't read all the posts so if this is a repeat sorry). I think something is not hooked up right or something is grounding out. I doubt that you are overheating. check all of your grounds to see if they are tight, my old civic went nuts like this when the starter geeked so possible it is not cooling-system related at all.