Mhillips

I have a 1999 Civic Lx and I believe I have a coolant leak. I was original having issues overheating while idling but over the last month Ive replaced my thermostat, my radiator and cap, all of my heater hoses, my bypass and radiator hoses, and all of my hose clamps. I started overheating again and I noticed it was because I was running low on coolant. I drove it around and it seemed to act ok when I filled it back up, but I had it pressure tested and it didn't hold pressure. I tried running the coolant pressure tester at 12 and at 16 psi (couldn't find how much I was supposed use anywhere) and after about 5 minutes the pressure would drop very slightly.

The only things I can think of that I havnt touched are the head gasket, the water pump, and the heater core. I don't think its my heater. If the head gasket or water pump were busted, would that cause a leak in the system? Would there be anywhere else to check for a leak? Thank you.

black97civic

If you pressure test the best thing to do is clamp off the overflow hose then pump it up to the pressure listed on the radiator cap. Sometimes its listed in "bar" instead of psi. 1 bar =14.5 psi. If you didn't pinch off the overflow then do the test again. If it drops then you have a leak and you should be able to see it unless its a headgasket, then it would leak into the cylinder and you would see smoke at start up. If the water pump was leaking you would see the coolant from the front of the engine.

Mhillips

I dont see any values on my radiator cap, it just has a warning message on it. I would assume around 15 psi would be ok for a 99 civic, but ill see if I can find a bar value somewhere on the cap.
I did not clamp off my overflow, I was wondering how the whole system would be completely pressurized with the overflow because it is not. What would you recommend clamping that hose with? Like a set of pliers?
I don't see any leaks, although I did notice there is a little bit of fluid build up in the front of the engine underneath where the heater hoses connect to the engine and behind the radiator. I also noticed there is two holes, almost like screw holes here. Are there supposed to be holes here? Thank you


EDIT:



This isnt my car, but I circled in green where I noticed the fluid and I circled in red those two holes I was wondering about. Thanks again.

black97civic

I use hose pinch pliers. You can get em for 10-15 bucks. Otherwise you could fold the hose over and put vise grips on it. I'm not sure where the holes are your talking about. Are you sure you filled the coolant when you replaced the other parts?

black97civic

Also my cap says 0.9 so that's like 13 psi.