Jon Petersen

1995 Civic EX coupe, EJ1 chassis, D16Z6 engine.

Recently, I've been going on 4 hour drives to and from the town I'm going to college in to get things set up. This means I take the 4 hour trip down, do stuff for ~4 hours, and take the 4 hour trip back. Roughly 8 hours of highway driving. I've done this twice now.

The first time, all was well until I got off the freeway coming home. I noticed that (a) the temperature was slightly sporadic when I'd sit at a stoplight and (b) it would return to normal after accelerating. When I got home, I popped the hood and noticed that (a) the radiator cap was hissing, probably indicating a pressure loss and (b) the coolant overflow tank was overflowing; full to the brim.

I kept an eye on it for the next 6 weeks. It would regularly be low and I would fill it, though the temperature wouldn't fluctuate as I drove it. I replaced the radiator cap, the thermostat, and drained, flushed, replaced, and bled the cooling system.

During the second trip, when I got off the highway, I parked and let her idle for a few minutes, and the temperature started to fluctuate again. I shut her off as soon as I noticed and let her cool down for 10 minutes or so. Upon inspection, the coolant in the overflow tank was above the max line, though no pressure was leaking that I could hear. I turned the engine back on and carefully revved it up. I noticed that when the temperature was high, revving it would bring it down. After I left the parking lot I was in, the temperature remained constantly where it should have been.

When I returned, I popped the hood and found that (a) the coolant was too high in the overflow tank but too low in the radiator and (b) the dipstick brought up no oil. I turned over the engine for just a second to see if there was *any* oil at all, and some splashed onto the dipstick. I poured in about a quart-and-a-half to get it back to an acceptable level. Also, (c) I assume it had to have been burned since I couldn't see any leaks under the car. Another thing to note is that the oil level was fine the week before I went on the trip.

TL;DR: Coolant overflowing & oil loss after long roadtrip.

Any help is appreciated. Thank you so much!

GolNat

iTrader: (7)

Could be a possible head gasket leak.

Can you do a compression test?

How many miles was this road trip?

Colin42

Probably the head gasket, and while the head is off you should pull the pistons out and replace the rings

Jon Petersen

I think I can do a compression test. I've never done one, but I've got the manufacturers' manual and I'm sure I could rent a compression tester at Autozone or something, if not just buy one from Harbor Freight.
The trip was a little less than 400 miles round trip.
EDIT: added an apostrophe after manfuacturers.

ezone

Sounds like it has a blown head gasket.

And it probably has an oil consumption issue, although you didn't say how long ago the last oil change was.



Compression test would be a good thing to do, but it isn't likely to prove it has a head gasket problem.

GolNat

iTrader: (7)

I asked about mileage because you can burn up to a quart of oil per 1000 miles and it be ok. This is assuming it was full before your trip.

It can pass a compression test and still have a head gasket issue so it could be a waste of a test. Like ezone said it most likely won't prove a HG issue.

Jon Petersen

Last oil change was at 140k, currently at 143,400.

Jon Petersen

What *will* prove a head gasket issue?

ezone

Test for why it's doing what it's doing.




A compression test is a good idea though. At least you'd have some sort of baseline..... If you have a low cylinder then you will need to figure out why (valve job?)