Rep Power: 0

First off....yes I have read the overheating sticky and I'm still stumped.

My daughter has an 01 CivicLX with the 1.7, 140k miles, and I am charged with figuring out this overheating problem and fixing it

She can drive it all over town and it stays in the normal range, however when she comes to visit me she must climb from basically sea level to 4500' (California's Sierra Nevada). About 30 minutes into her trip at the 1500' level it begins overheating and will progress to pegging the gauge. Both times I have had to rescue her the recovery tank was full and pressurized with boiling coolant and the radiator was low (obviously).She had started the trips with the radiator full and the recovery tank between the min and max.

This is where I'm at so far....
There are no signs of any leaks in the cooling system.
I changed the thermostat. (not oem)
I changed the rad cap (not oem)
The fans are both working normally.
I cleaned the radiator of any debris.
The water pump was changed at 105K with the timingbelt and I think it's OK.
I checked the sparkplugs for signs losing coolant through the head gasket.They looked OK though one had a little white to it....Hmmmmm
I did a compression test on a warm engine, throttle wide open. I was hoping that would reviel the problem.........nope....135,133,140,140 and the suspect cylinder was 140.
I just did a check for exhaust gas in the radiator....negative.
Also just found that the heater is not blowing hot at idle.

I've done a lot of reading and was fairly sure it was the HG, until the gas test turned up nothing. I'm at my wits end...can anyone help me? Where do I go from here? I don't want to take it to a shop if that can be avoided....my daughter is already broke

 
Rep Power: 811

change the thermostat and radiator cap to new oem and see if that helps. i've had serious problems using stant and other aftermarket parts that were completely solved after swapping in an oem part. the oem thermo opens way more than the aftermarket.

if those dont help, then its prolly a small headgasket leak. it will not show most of the usual symptoms, altho the exhaust gas test is easy to do wrong and get a good result if there is any air leaking from the syringe.

my first bet is on the thermostat. our accord had the same problem. it would drive fine, then under heavier load like freeway it would start climbing to the HOT mark, which means the radiator isnt doing its job (thermo was barely opening about 1/2 what it should be, so coolant was not being cooled). dont forget to bleed the air when youre done or you will have problems.

heater might not even be related. open the hood and start the car, then have one person inside the car turn the temp dial from full cold to full hot while someone else watches the heater valve in the back of the engine bay to see if its moving and opening (this is the metal valve in the heater hose just before it goes into the dash, and there is a blue cable attached to it). if it doesnt move, try spraying it with silicone. if it still doesnt move, either you have a bad valve (try turning it by hand) or a bad temp switch.

 
Rep Power: 366

yeah, mine was just loosing coolant (did not do the gases test, i had to do the timing belt anyways). - no overheating. ur daughter's case, the climb will just push it over the edge.

But do try using OEM parts as GB said. it's cheaper to try.

I did bit the bullet anyways and no more loosing coolant.

 
Rep Power: 0

I'm going to go ahead and change the cap and T stat to OEM, but I don't have a good feeling. After the change with the after market parts the symptoms were exactly the same. I hate to say it but I think it is a small leak in the HG that takes a while to overheat the engine.

Why is no heat from the heater listed as a HG symptom? How exactly does it cause no water to heater core?

I had never done the gas test before, but I drew air through the tube for at least 20 seconds when the engine was hot. Hell...I turned the blue liquid yellow just by blowing through a straw for about 5 seconds. Don't know how I could have scewed that up.

Thanks for the help guys. Anyone else got anything?

 
Rep Power: 0

I have the same issue.

I also checked for gases in the coolant and the fluid stayed blue (negative). I took the device to the exhaust and it turned yellow almost immediately. It seems to be working properly.

I changed the thermostat to a fail safe (stays open when fails). It overheated right away after changing so that didn't fix the issue.

I then opened the radiator cap and let the air bubbles out and kept it topped off. This process took about 10 or 15 minutes with the car running. I was surprised to see how much antifreeze needed to go in. I'd say around 1/8 of the bottle (1 gallon i think whatever the standard size is).

I turned on the ac and both fans came on.

I could not get any fans to come on while just idling for about 10 to 15 minutes. The temp now seems to stay in the appropriate position.

It has not overheated yet after purging the system of air but I only drove it about 4 miles. I did leave it idle at the car store while I purchased the combustion leak tester. It stayed in the normal temperature range.

The heater seems to be working fine blowing hot air while idling now. The air was not super hot though before I started driving (after idling until normal operating temp on the gauge was reached). It was super hot after driving a block or so and continued to be quite hot when parked after driving 4 miles or so.

I checked the old thermostat in boiling water and it worked fine.

I am not confident that the problem is solved. Since the old thermostat is working fine then I didn't do anything other than purge the system of some air.

Could this have fixed the problem?

I'm worried that there still is a head gasket leak that is intermittent and that this would not show up on the leak test with the air from the radiator.

Please help.

How can you confirm this kind of problem is fixed?

Do I just wait until the car overheats again and then try the leak test again? How long would I wait for the car to cool before trying to open the radiator cap so I could test it?

Should I replace the radiator cap with a Honda original? Is there a way to test the cap? Would a bad cap have the symptoms I have had (cold air in the am for miles (happening for over a year), now overheating after towing a motorcycle the day before)?

 
Rep Power: 0

I also have this problem. My next move is the intake manifold gasket. There's another post out there from another member that solved a problem like this by changing the IM gasket. I'm not too sure about your engine, but my car has the d16Y7. There is a coolant passage very near the intake for cylinder 4. Apparently, the gasket can deteriorate in this area and cause some of the problems that look like a blown head gasket.

My car stops having problems when the weather cools down for some reason so I'm probably not going to try changing the gasket until next year.

 
Rep Power: 0

Like most of the HG leaks that take place on the 7th gens its going to be small and take time to purge enough coolant to overheat. The tell tale sign is "purging coolant into the overflow" while the HG isn't always the culprit its in the high percentile. Both of my 7th gens went at roughly the same time just got the 2003 head back on today.






note the scoring from the exhaust gasses on the head, and the space in the buildup on the cylinder. This car tested negative on exhaust gas test and had less that a 10% difference in pressure when tested.

 
Rep Power: 811

yeah mine was a very small coolant leak too. just enough to cause a minute of misfire on cold start, then it ran fine with no other problems. never pushed coolant out but i could see all the white dried antifreeze in the chamber, plug, and exhaust. seems to be very common on these engines and it usually starts as a small leak that normal tests will not catch. i finally realized for sure when coolant started being burnt slowly and i had to keep adding to the overflow tank to keep it topped at max every week.