So our 2001 Civic started overheating on a road trip this last Thanksgiving.
Prior to the trip, I paid a friend to replace the timing and serpentine belts, and paid a radiator shop to flush the tranny.
At our first stop, after about 3 hours on the interstate at 75 mph. The car overheated in the rest area parking lot. I noticed the electric fans were not running, so I turned on the AC to get them going and eased it back onto the highway. It overheated almost instantly and after shutting the engine off and turning the key to accessory and turning on the AC the, fans cooled it down I check the radiator. BONE DRY. I hoofed it 2 miles to a gas station got coolant and water filled it up and took off again. I have had to add about a quart every 3 or 4 hours of driving ever since. It has been to two shops (one being the shop that flushed the tranny) and both say that the cooling system is fine. Neither shop noticed the fans not working. After some serious comp[laining one of the shops agreed to pressure test the entire system and block test it for free. They say that the head or block is cracked, and that the coolant is exiting in the exhaust. I am in disbelief because I have no smoke in the exhaust and my coolant and oil are clean. Also the car only has 130k miles. Can I have a cracked head and not have smoke or milky oil? Is there another cause for a slow loss of fluid and overheating? I want to rule out all possibilities before pulling the head off of the block. Any info/advice will be appreciated

 

Get the radiator as full as you can. With the engine cold, take the radiator cap off and start the engine and rev it. If stuff blows out of the radiator, there is a leak in the engine. Often it is just the head gasket not a crack in the metal. Small leaks typically will not generate a lot of smoke or water in the exhaust.

Fans typically do not need to run at highway speed since the motion of the car forces air through. The fans will not start even with the engine overheated if there is no flow through the system due to lack of coolant. You could unplug the A/C compressor so that you can force the fans on with the A/C button but not put additional heat under the hood.

 

Thanks for your response mk378! So it sounds like the head is a likely culprit but it is not necessarily cracked. Do you think the fans are functioning normally? or should I replace any relays or switches related to them when I put the head back on?