I have a 2005 Civic VTEC that I rebuilt the engine in about 6 months ago. A few days ago, I started having an overheating and very little to no heat problem, mostly at idle. I was in traffic and the coolant temp was normal, 190-200 as the fans cycled. Then the temp went up to 220, so I turned the heat on to try to cool the engine. There was no heat and the temp went to 225, so I pulled into a gas station to see why it was overheating, and by that time the temp was almost 230. I popped the hood and checked the coolant level. It was full, so I started the engine to try to bleed the system since I thought there might be air in it. Then I started the engine and turned the heat on and let it idle for 10-15 minutes to get the air out. It had no heat, so I revved the engine to around 3K RPM and it started making heat. I let it idle and the heat started to go away. By that time there was very little traffic, so I headed for home with the heater on the whole trip. The car ran at a normal 180-185 on the highway on the way home, the engine ran normal and the heater worked well. But as soon as I got off the highway, the heat quit working. I revved the engine and it made a little heat, but not much. The temp never got above 200 on the way back, but the heat was intermittent after I got off the highway. I installed a new OEM thermostat and Gates water pump about 2 months ago, so I don't think those parts are the problem. Any help is appreciated. Thanks.

 

When I had intermittent and no heat it was a pretty big air pocket in the system. Mine was due to a bad head gasket.

Check your coolant in the morning after the engine has cooled, would not be surprised if you need to top it up.

Interestingly enough, the engine the gasket went out on was allegedly rebuilt not long before I put it into my car. As clean as it was inside and out, it's hard not to believe it wasn't rebuilt to some degree.

Long story short, even a rebuilt motor can have a failure of the head gasket in a short amount of time.

 

Thanks. I went to the a store about 30 minutes on the highway earlier today, and the car did great on the way there. On the way back, I got stuck in traffic and the temp started to go up, so I pulled over and by the time I pulled over, the temp was at 242 and the car was puking coolant out of the reservoir. I let it cool off, put more water in the radiator and continued home with the heat on. The car did good on the way home until I stopped for a red light. The heat quit working and the temp went up to 224. Once I got moving, the temp went back to normal. Do those symptoms sound like a blown head gasket to you? There is no misfiring, no water in oil, no oil in water, no smoke from the exhaust or any other indications of a bad head gasket, although bad head gaskets on D17s don't always seem to show in the usual ways. Thanks for your help.

 

https://honda-tech.com/forums/honda-...hicle-3309336/

^^ Probably why.

 

So you're telling me that pulling a trailer with my car is likely the cause of an overheating problem that started almost a month later? If so, that's absolutely ridiculous.

 

Well, pulling an overweight trailer could be. And, to be honest, a month later really isn't all that large of a time frame for symptoms to start showing.

 

So if the head gasket blew while I was pulling the trailer, it may take a month for the car to start overheating? I don't understand.

 

That's right, head gaskets don't give up all at once to full failure.

A tiny micro pinhole occurs that lets the tiniest amount of combustion gas through, and as you drive, that hole becomes larger and larger until it's big enough to show the symptoms you describe.

It's very much how my car went. First, no signs beyond light coolant loss that I thought was the silicone hoses to overheating and intermittent heat when not moving to overheating anytime I forgot to fill the radiator with water.

I know I drove at least a month on a blown head gasket before it was to the point of being too much coolant in the cylinders to start up.

 

Have you verified the fans are working? Jump the fans with a looped paper clip and see if they kick on. Next thing would be to Ohm check the fan switches, if you're getting different values this could be your issue.

How are you bleeding the car? I suggest you invest in a Lisle Spill free funnel.

 

I have tried both of those things. I removed the thermostat, jumped the fan switch and bled the air out and it still overheats, but it takes longer to overheat. Also, a Lisle spill free funnel is a great suggestion. I don't have one yet, but I did use a regular funnel that I held in the radiator to bleed it, and I lifted the front of the car and I ran the engine for about 30 minutes, varying the RPM to promote the movement of air. Great suggestions though.