I just bought a 97 accord special edition and i drove it home and once i pulled into my driveway and shut it down i could hear the radiator boiling. i opened the hood and found steam coming from the reservoir as well as from under the radiator cap. the temperature guage warmed up to about 1/3 the way up and stopped and never indicated an overheating engine. the drive was approximately 6 miles of highway followed by 5 miles of 40mph back roads. and it was 55 degrees out and very little traffic. so there shouldnt be any obvious reasons for overheating.

What i have diagnosed so far is that the primary cooling fan had blown the fuse but there should have been plenty of air flow to not need the fan. The radiator is full of perfectly green and fine radiator fluid and its not oily or anything so i dont think its a head gasket. I rremoved the cap and ran the engine and it bubbled for a minute then stopped and slowly rised until it overflowed. The car had been sitting for a month since before i bought it and the previous owner said that they have no idea why it would be overheating (What a surprise) they did however mention that someone cleaned the engine compartment with a chemical and that since then there has been a few little electrical glitches with the odometer and speedometer.

If anyone has any ideas any help is much appreciated. Im thinking it must be either a t-stat or a sensor or the lines are airlocked.

 

"Im thinking it must be either a t-stat or a sensor or the lines are airlocked. "

Agree. I would start with bleeding. If the t-stat was stuck the gauge (sensor in head) should show something, if the fan switch (on t-stat housing) was bad the gauge should still show something.----something= more than 1/3 on gauge.

 

For the thermostat, check that both of the coolant hoses are hot. If one is much cooler, then replace with one from a Honda dealership. I would replace the coolant as well if you opt for this route.

Also, start the car and turn on the a/c. Check that both fans are running.

You can unbolt the radiator from the top, tilt the radiator back, and check for any debris blocking air flow. Also inspect the fins on the radiator for damage.

Most parts stores will loan a radiator pressure tester with various adapters that will fit on the radiator neck and the radiator cap. The radiator should hold ~15 psi. Check the radiator cap is holding pressure too. The cap is often overlooked.

 

I should also mention that the heat works so it is circulating. the heat works great. According to the carfax the 2nd owner had 3 front end impacts with another vehicle one in 2000, 2001, and 2004 but it has been driven all the way until last month so it must be something recent and most likely something stupid. I have to run some errands tomorrow so i will take my infrared themometer with me and check the upper and lower hoses for temperatures. What would be considered average temperatures? and what would be considered as "oh, sh*t shut 'er down!" im considering just doing some driving around tomorrow and checking it every 15 miles.

 

A bad radiator cap might explain this. Without 1.1 bar pressure, the coolant can boil.

 

How would i go about testing the radiator cap to see if this was the problem? When the radiator was boiling it was steaming from the cap as well but it may have been just the pressure forcing the steam through.

 

The "tester" for a cap is a fixture that looks like the neck of a radiator, but it hooks up to something like a bicycle pump so you can pressurize it. Sometimes you can rent/borrow one from someplace like AutoZone.

There's 3 different seals in the cap. Each one has to have a good seal, including a good surface (not scratched) where it seals.

The very outermost rubber gasket seals against the top of the radiator neck.

Below that is a smaller rubber ring, on a spring-loaded disk. That seals against a little raised ridge just down inside the radiator neck. That's the one that lifts under pressure, allowing coolant to escape over to the reservoir. The outermost gasket is supposed to keep the steam inside so it isn't supposed to steam.

The little central disk is sprung in the other direction - you should be able to pull it 1mm or 2mm away from the cap pretty easily. That one opens to suck coolant back into the radiator as the engine cools off.

Check all 3 of these for crud built up on the seating surfaces, or scratches, or anything that doesn't look nice & clean.

 

Well i took the car out today for a drive to run some errands and i just had the windows down and heat cranked up and the temp guage didnt go as high and whenever i parked i didnt have the boiling sound. So it must be something really stupid. I stopped by autozone and i was told it may be the timing belt or the radiator may need to be flushed. So while i was there i purchased new engine belts and timing belt and balancer belt and some plugs and plug wires, distrubuter cap and what not i also purchased everything i need for an oil change and for a radiator flush.

What do you guys think about the suggestions from autozone?

 

It might be due for a timing belt, but that wouldn't be these problems. Everything else seems like normal general maintenance.

They didn't suggest a new thermostat? I'd probably get one from a dealer anyway.

 

I think Honda distributor caps and rotors are better than the aftermarket.

The factory spark plug wires seem to last for a long time. I usually suggest OEM, NGK, or Denso wires.

What spark plugs did you get? You should only use the NGK ZFR5F-11 plugs.

Before you change the timing belt, you should try to find out when the belt was changed. Maybe your local Honda dealership can check their records, or the previous owner could tell you.

If this were my car, I would get an OEM thermostat, then flush the cooling system. Dist. cap, dist. rotor, and spark plugs are a good idea, but won't fix the overheating.