I have a 2001 Civic EX, which has been simply the most reliable vehicle I've ever had. Now I have a brain teaser:

If I don't check my coolant level religiously every week or so, the CEL come on, and when I look, the reservoir looks empty, and the radiator looks pretty empty. (At least I can add a fair amount of coolant to fill both up.) The temp gauge never goes higher than the bottom of the icon. If I add coolant, after a few starts, the CEL goes out again. I never see coolant dripping.

I discussed this with my mechanic. We replaced the thermostat. He pulled the plugs to look for a gasket leak (Negative. And I don't have sputtering, missing or and power issues. He doesn't have an adapter for doing a pressure check on the Honda.) He pulled the bottom radiator hose and ran a garden hose into the top to see if there was a blockage (None that he could detect).

The last few times I checked the coolant level, the reservoir was full to the top, and so was the radiator. In fact there was pressure (cold engine) enough to make coolant spurt through the relief valve when I loosened the radiator cap. When hot, there's some leakage from the reservoir cap (which doesn't seem to be designed to handle pressure). That actually spoots a small amount of coolant down into the battery tray.

I'm testing the results of the last tries (check plugs and flushing the radiator w/ hose), and the CEL has gone out, but I don't know what else to do if it does it all again. Has anyone else had this weird problem?


Thanks,

G00k

 

I have a 2005 Civic Ex- had the same problem, which spanned over nearly 2 years. Had to fill my coolant weekly- tried everything to figure it out. No cracks in the radiator, no puddles, no steam. . . replaced the thermostat and about everything else that 7 garages combined could think of, and ultimately it was determined I had a blown head gasket. Bad news = fairly big chunk of change. Good news = I've now got 225,000 miles on my car (replaced the head gasket at 175,000) and haven't had any issues with it since, knock on wood. Good luck!

 

It should not be coming out of the reservoir cap unless you overfilled it. Check the hose and elbow fitting for leaks.

Also merely running out of coolant doesn't typically turn the CEL on.

 

When the CEL comes on, are you checking what the code is? I'm curious to know what it brings us.

If the radiator and overflow are both full, take some coolant out of the overflow. Watch it over the next few days to see if it fills back up.
After running the car to temp, check out the overflow. Does it have air bubles bubbling?

 

Does the mechanic you mentioned do the automobile maintenance for living? I find it kind of odd reading the post.

May be it is just me,,,,,

 

Thanks, 225Kcivic, mk378, PunisherInOKC, and maachan513!

Well, I have 285K on my 2001 Honda Civic, and my mechanic has been very straight with me about what he can and can't do in the 20 years I've been associated with him. He retired from a career servicing heavy equipment maybe 25 years ago, and I'd put him up against just about anybody. He's a one man garage, not specializing in rice-burners, and has the humility to discuss weird problems with colleagues in the area. He sent me to a dealer for my AC conversion. (Yeah, I think he's capable. Maybe it is;-). No offense.)

If the CEL comes back on, I'll get the codes and post them. And I'll try the bubbles watch.

Thanks again.

G00k

 

Thank you for clearing this. I kind of understand now for what he (your mechanic) did and why,,, I was not intending to discredit him by asking the question.

If the car has that much mileage, I would start thinking of replacing the head gasket, considering it is losing coolant and there is no sign of external leak, if it was me. Or, buy another car with lesser mileage.