I Imagine this topic has been covered a lot on here so I apologize in advance. My fiancee has a 1999 Honda Accord 4cyl. The radiator recently failed and I had to replace it. The next day I noticed the engine was overheating and idle and so I did a little research and decided to replace the thermostat. That solved the problem well enough. This was about three weeks ago and had been running fine until today when she had the car idled in a parking lot (very hot summer day, if that has anything to do with it) and the car over heated again. She observed some light brown fluid leaking from underneath, I'm out of town right now so I didn't get a chance to see it but im assuming it's one of the oil leaks the vehicle has. The vehicle has well over 100k miles on and it does have some minor oil leaks but for the most part has been a pretty solid little car. Anyone have any ideas what this could be?

 

did you bleed the cooling system system properly? radiator cap replaced too? happen to notice if the fans came on after you did the work? could be a waterpump leaking?

 

First time poster, apologize to mods for placing in wrong forum.

Im going to to try bleeding it again. I just noticed I didn't put the temp on heat when I bleed it last time, hopefully that'll fix it.

Just making sure I got these steps right: 1. Heat on high, no fan on. 2. Open bleeder valve located near thermostat housing. 3. Top off coolant until excess comes out valve, then close valve. 4. Turn on car with radiator cap open until bubbles stop (if any). 5. Top off again.

Radiator cap is replaced. Will check on fans when I get home, they were working as of 3 weeks ago but no idea about now.Not sure how to make sure the pump isnt leaking other than simple observation.

 

Not correct.

1) top radiator off, close cap
2) heat on (fan on or off does not matter)
3) start car
4) open valve
5) wait till hissing stops and coolant comes out of valve
6) close valve
7) top off coolant tank (not radiator - do not open radiator)

Done

 

What mikemike stated is relatively consistent with owner's manual instructions. Generally, you pour in coolant while the car is off till it comes out of the bleed valve.

 

See excerpt from owner's manual:

 

Thanks for the input everyone. Ill keep ya'll posted on how things turn out.

 

You can leave the radiator cap on (but, not all the way tight) or off during the air purge. Owner's manual says to put back on the tighten to first stop, whereas service manuals usually say to leave off. Doesn't make a big difference, as long as the cap is not all the way tight.

 

Redbull --

Those instructions are CRAZY!

It says to run the car with the cap on until the fans come on twice

Then shut the car off and then open the cap!!!

NO! That is very dangerous.

You never ever ever open a hot radiator cap.

The way I do it makes much more sense.

With the bleeder open, which is at the highest part of the cooling system, any air in the system will make its way to the bleeder and out. Once nothing but a stream of coolant is coming out of the bleeder all air is removed and the system is bled.

Would you disagree with me?

 

1. With the radiator cap not fully tight, the system will not get pressurized like it would if it was fully tight. So, the chances of getting scalded is minimal. You can use a rag to hold the cap so not to touch a hot cap. Even with the newest Accords (i.e., 2008 - 2012), the service manual instructions says to have the cap loosely on during purging. So, not much danger there. I personally leave the cap off to make it easier to keep refilling during the purging process.


2. Even with the bleeder bolt opened and steady coolant stream coming out of bleeding bolt, this does not necessarily mean all air is out of the system. Most of the air purging happens when the thermostat opens and larger pockets of air start coming out engine block and then the radiator. The reason I believe Honda states to run till radiator fan turns on twice is because that should be around the time the thermostat has fully opened the first time it turns on. -- A lot of Hondas don't even have bleeder bolts.

When thermo-switch A (located on or near the thermostat housing) reaches around 194 - 205 degrees F, the radiator fan suppose to turn on. That would be approximately when the thermostat is fully opened. The thermostat should start opening around 169 - 176 degrees F and be fully opened at 194 degrees F.