Alright Honda-Tech, I'm stumped. My '95 Accord F22B1 is losing coolant somehow and I can't find the leak. Just in the last two days I've replaced my water pump, thermostat, and the hose that goes directly under the distributor into the head on the passenger side, which was the previous source of the leak. I drove it to school today and I heard what sounded like a boiling sound coming from same hose I replaced last night. I checked my coolant and I didn't have any. Car didn't overheat though. What could it be?

 

When you refilled the system did you turn the heater to full hot and did you open the bleed nipple on the intake manifold to remove all air?

 

No I didn't, I'm not very experienced with these motors and couldn't find the bleeder, we just ran it with the radiator cap off and filled it as the air bubbles came out. I filled it back up and it only took about a 1/2 inch of water from a gallon jug. Might've just been air bubbles, but the boiling sound I mentioned sorta set me off.

 

When you were filling up the radiator after changing your water pump/thermostat, did you run the engine with the rad cap off long enough to get up to operating temperature where the thermostat would open? If not, then there was still quite a bit of air trapped behind the thermostat from where it was drained for repair. The boiling sound you heard was probably coolant rushing past the thermostat as it opened, filling in the air-trapped space, consequently lowering the coolant level in the rad. I would suggest just filling up the radiator again and checking it often. If it stays full, the the problem is probably what i described above. If it repeatedly goes empty, you have an external leak. Can you see any obvious wet spots from coolant on the engine or your driveway?

 

http://www.hondapartscheap.com/parts...er-pump-sensor

Pop open the bolt at part number 12 in this illustration and close it as soon as it streams out only coolant and no air. Should be a 12mm bolt.

I'm guessing you replaced part number 2 in this illustration.

http://www.hondapartscheap.com/parts...el/water-valve

To properly bleed air from the coolant, you jack up the front of the car as high as it will go. Turn the heater temperature **** inside the car to full red. Crack open part number 12 in the first illustration. Fill the radiator until it streams out of the bleeder bolt in a steady stream, close the bolt. Continue to fill up the radiator until it's full. Close the cap. And you're done. Fill the reservoir halfway to the "full" mark.

If you can't find the leak there is a chance it could be leaking at the heater core inside the car. If when the car is completely warmed up and you turn on the heater and turn the switch to "defrost" and your windshield fogs up and there is a slimy film on the windshield it's probably the heater core leaking.

You may need to rent a coolant pressure tester and use it to pressurize the system and then check for your leak.

 

Yea, the thermostat opened up two or three times with the cap off. I haven't found anymore leaks, and I have a dirt driveway so it's a little difficult to see a leak when I get up in the morning, but I haven't found one yet. I 'm keeping my eyes open though.

 

Yep, that's the one. It may be leaking from the heater core. I'm in the middle of doing a bunch of repairs on it to get it ready for another week of driving to school, but I'm going to test if the heater core is leaking like you suggested.

 

You may have a slight head gasket leak. The boiling sound could have been the excess pressure in the system caused by compression leaking into the system and bleeding off when you stop the engine. Fill the radiator and run the car with the cap off. Watch for a steady stream of bubbles coming to the top of the radiator.