Used Prestone Super Flush per instructions:
Drain coolant, add the 1 qt super flush & rest with H2o (approx. 2-3qts),drive normally for 3-6hours, Drain & refill with 50/50 coolant.
While driving for the 3-6 hours noticed a big difference in temp needle significantly lowered & stayed consistently at normal range of 30-40% (Unlike prior to doing the flush).

After draining the super flush, adding the 50/50 coolant & purging the air out of the bleeder screw. I noticed the temp needle running normal at high speeds but at an Idle position/stop light it quickly raises to 70-80%, when i put the car in neutral & rev it for a while it quickly goes down to normal temps.
No leaks & fans turn on OK. Questions are:

1. Maybe I didn't bleed/purge the air out right?
2. Should I run 100% water? (It ran consistently at normal range with the flush & 100% H2o)
3. T-stat replacement? (I bought a new t-stat but returned it since it didn't overheat anymore with the Flush/H2o in the radiator)
4. Radiator Cap replacement? Cap looks kinda worn out & old.

Thanks for any advice,
Jr

 

1. That's most likely. Did you have the heater control set to full-hot to get air out of heater core?

2. Don't run 100% water. That's asking for corrosion. Look at the bottle of anti-freeze for temperature range of, say, 30%/70% or whatever. I forget where you're located (climate??)

3. No. A sticky T-stat should allow it to overheat while driving. That's when the engine makes (by far) the most heat. Overheat while idling sounds more like the radiator may be still plugged.

While it was drained, did you try to look into the radiator (fill neck & hose nozzles) to see if the insides are clean? Maybe you need to clean again, or maybe(?) it's beyond help? How do the fine little fins between the tubes look? If they're crumbling apart the radiator is shot.

4. Probably not. Bad cap could do a few different things:
- leak coolant when it's hot?
- suck air in when it cools down (instead of sucking coolant from reservoir)?
- let the pressure get TOO high & burst a hose?
- BUT... a new cap is pretty cheap for peace-of-mind.

Last... Revving in neutral brings the temperature quickly down? Maybe the water pump? I've heard of impellers corroding & becoming less effective at pumping, but I think that's not very common.

 

i have to disagree with you on this one my friend,, a sticking closed t-stat will make car overheats wether it is at idle or while driving ..

are both fans coming on ?? read this se if it helps ...

https://www.hondaaccordforum.com/OVE...m_20999/tm.htm

 

Desert Hit the Target with the correct info on this one...give the Desert Man a Gigar..

You beat me to the post on this one Desert..Thanks for the correct input!

WheelBrokerAng [sm=americanasmiley.gif]

 

i appreciate the offer f the cigar but i DO NOT smoke at all...

 

I had the same problem, replaced the tstat and all is right witht the world. One thing I've read alot about, is people having the same issue, and using after market tstats. Then still having issues, and then Going genuine honda tstat and being okay. So I'd say genuine honda tstat and you should be okay.

 

Good thing I'm not the only one answering posts...

Oh well, it happened that way to me once (long time ago). T-stat would open far enough to handle idling load, but it couldn't open wide for the full heat load of driving. Anyway, check the T-stat.

 

if everything else checks out.... has the car overheated recently?

if you have an exhaust leak into your coolant, this could happen.

 

Thanks for all the replies.

I wanted to state that I live in So Cal where the temp has been 90-105 degrees in the last few days. My commute is approx 50miles one way (approx 1.5hours).

Driving home yesterday was not a pleasant one, My car constantly got hot near the 80-90% point of overheating. Whether at hi-lo speeds (thank GOD for the heater).
When i got home I checked the fans & all was OK, I re-bled the air & added H2o.
Driving to work this morning the same thing it would get hot whether at hi-lo speeds.

If it is the T-stat why did it not give me the problems when i had the super flush & H2o in the radiator?
Could it be that it is being inconsistent in opening/closing?

I looked inside the radiator & the fins do still look coroded with white build up around the fins.
Should i change the radiator? what are the signs that a radiator is bad?

Thanks for anymore advice anyone can give.

Running the heater full blast when it's 100+degrees out is not fun, especially when my commute is 1.5hours.

 

I had a similar problem on my old car a few years ago. Sounds like air in the system to me. I had to replace the heater core and flush the whole system (the stupid plastic heater core pipe burst) Once I got the air out, it ran fine and kept cool. It seemed to do just like your car, heated up mostly when idle but would occasionaly get warm when driving.

I ran the car in the driveway for a bit with the purge tank cap open (it was a Grand Am, had no radiator cap).....every now and then the level would decrease dramatically and there would be some air bubbles. I would then add antifreeze/water to fill. After a while, it quit and I closed the tank and allowed it to get up to pressure. All was fine.

Another note, do not run long term on 100% water. Not only the corrosion factor, I noticed a huge difference in running temperature. The antifreeze mixed at about 40-50% would run cooler and the water was boiling.

Hope this helps....