Hey everyone, have a question.. 98 civic 148k miles.

It seems to be losing coolant, but very very slowly, and I mean over the course of months.

Absolutely no leaks, everything is dry, oil is clean. Did block test, its good. Pressurized cooling system, holds pressure. Have not done a leakdown test yet, but not sure if it would give a different result. No leaks from heater core it seems

Changed radiator and hoses, just as preventive maintenance.

Since coolant is obviously going somewhere, it must be the head gasket, but at such a slow rate? This has been happening since the vehicle was purchased a year ago. Enough coolant has been lost twice to get the car to overheat (not totally overheat though), so figure several months to drop a significant level.

Has anyone experienced such a small leak with no other symptoms? I am tempted just top it off once a month and keep driving, since it hasn't gotten worse in at least a year (maybe been like this with previous owner too).

I have no problem changing the head gasket, but my "to fix" list is very long and I rather not add to it (other things / vehicles, not this one)

Input appreciated. Thank you


edit: WOW, been member since 2004, but this is my first post!!

 

No leaks
And slow coolant leakage
Very small head gasket leak
Replace HG

 

Or have you checked for leaks under the dash
Possibly leaking into the car from heater core

 

if you have a sweet smell coming from the AC/Heater vents then I would think heater core. I have seen leaks that slow from heater hoses as well.

 

could be from somewhere else imo don't worry about it yet if it's not noticeable. Or replace it if you're sure it's the HG.

 

figured as much, thanks

heater core is ok

 

bars leak makes a stop leak that is supposed to work for head gasket leaks as well.

 

Check if radiator cap is cracked or the water pump is going bad.

 

Yes I have, and sometimes they can go a very, very long time without getting any worse, just don't take that as a guarantee that it will last.

Stop leak sucks. Sometimes it sorta works but it tends to make a big mess.

I put an engine in an '03 Ram for a guy this summer that had stop leak put in it. I ended up having to replace the rad too as it was plugged solid and the owner had to have the heater core flushed no once, but twice before he got any heat out of it.

IMO stop leak is really only good for something that's just not worth fixing and you need it to last a few more months. If you actually intend to do the job right all it's going to do is cause you a bunch of headaches and more money at that time.

 

And when it does go, it might just result in a glorious(ly expensive) destruction of your motor. OP, you caught the problem early - fix it early, and fix it the right way.

 

Its a combustion leak in the head gasket. Very common. I had it in my 97 civic i drove it 2 weeks without over heating. Then i got sick of worrying about. So just replace it. It only a 3 hr job. With old fashion hand tools. But with power toolss less than an hour

 

DO NOT PUT STOP LEAK IN YOUR CAR!! it will cause you more problems later on.

have someone sit in the car and with it running outside have them rev it up a little and see if you notice a funky sweetish smell coming from the exhaust... if you notice anything this will tell you that your leaking into the cylinders.

also try renting a coolant pressure tester from the auto part store and pull your spark plugs add pressure to your cooling system and let it sit for a few hours take a flash light and look down the spark plug holes to see if there is any coolant on the piston.

these are to easy ways to tell if the headgasket is leaking into the cylinders