My car:
01 civic LX with 212,000 miles on it.

Last night my check engine light came on. It is P0302, (cylinder #2 misfire). For about the past week, my engine has been idling rough. It only does this after it's been off for a significant period of time (an hour or more). This goes away after about 30 seconds to 1 minute of running it. It only happens at idle RPMs, when I run it much above 1500, it is perfectly smooth. It has nothing to do with whether or not the engine is warm, it happens both at running temp and when the needle is all the way on "c".. It has maybe gotten a BIT worse over the last week, but nothing significant. And it's not misfiring on every revolution. It's kind of random.

ALSO

I have problems with my cooling system. The overflow tank is, well, overflowing, and not returning any coolant to the radiator. Therefore I am slowly losing coolant. I have to top it off about once a week, or it will get low enough to where the engine will start to overheat. I see no foamy bubbles in the coolant or in the oil. There is no blue/gray smoke coming from the tailpipe. However, the rate at which it loses coolant HAS gone way up in the past couple of weeks, oddly coinciding with the CEL problem.

My question:

Is the ANY way that this isn't a blown head gasket?

If so, what should be the first thing I look at repairing?



Thanks in advance for your help guys!

Rob

 

have u noticed any spotting on the ground when u pull away from ur parkin places or any wet spots on the shrouds .....its possible u have a leaking hose or crack in the radiator somewhere..........usually u can smell coolant burning if its leakin on the engine.....check ur oil if its lookin like some choclate milk then ya u got blown headgasket


ps best of wishes

 

My oil and coolant both look normal. There is no fluid on the ground. It's definitely leaking out of the overflow tank (which is completely full) when the car is running. I replaced the rad cap and this hasn't fixed it. There is no coolant vapor coming from the exhaust pipe.

My check engine light has turned off then back on a couple of times (not when I'm driving, but sometimes I'll start the car and it just won't be on, then I'll start it later and it's on again)...

The cooling fans work fine, the only time it begins to overheat is when the coolant level gets too low.

I am going to try flushing the cooling system next. But how does this explain the misfire in cylinder 2? I'm hoping that the two are completely unrelated. If I can get my hands on the proper tools I am going to do a pressure test and change the plugs.

I am stumped.....

 

Have you replaced the thermostat and bled the cooling system?

Have you inspected the #2 plug? Have you tried swapping the #1 and #2 plugs to see if the problem follows the plug?

Have you tried swapping the #1 and #2 fuel injectors to see if the problem follows the injector?

 

I don't have much reason to believe the thermostat needs replacing.. I mean, the only time the temp acts funny is when the coolant level gets too low, othe than that it's perfect...

Is there a bleed valve? I tried to bleed it just by taking the caps off and running it for half an hour, and there were definitely air bubbles (big ones, not little sudsy ones)... This morning I was happy to see that the overflow tank level had gone down significantly. Maybe due to the new cap and bleeding it?? I'll keep u all updated on this...

I have yet to procure the necessary tools to remove spark plugs, something which I am trying to do ASAP.. when I do I will try those things u mentioned. As far as the fuel injectors go, should I try fuel injector cleaner??

I had only assumed these two issues were related since the misfire started atbthe same time that the cooling issue suddenly got way worse..

Thanks for the help! I will post updates...

 

If you can't envision that the engine is losing coolant as a result of overheating, then you may as well compression test the cylinders and do a leak down test to check for a blown head gasket. You must come to the same conclusion if you also truly believe that overheating is causing the misfire.

 

Hello, My civic dam near pegged the temp guage when I was almost to to work. That was 6 months ago so I parked it. Just got around to messing with it. Decided to try K and W block sealer. On startup it would blow a geyser of fluid out the cap. After the K and W sealant, it doesnt do that anymore. I dont know how long thats gonna hold though. Tested compression and #1 is 185, #2 is 110, #3 was 270???( I think that was caused by the oil the spark plug let in the cylinder when I unscrewed it due to leaking valve cover seal?), #4 is 185. #3 dropped to 180 after I ran it.
Im still thinking of doing the head gasket but wanna know what to expect. Does the head usually warp when a head gasket is blown? Is there anything else I should check? Car has 150,000 miles on it. Good head gasket set to get? whats milling a head involve/cost? I will do this myself, cant afford to have someone do it for me.

 

we have a few members that have just had a head gasket replacement
its not to hard. yes it has a blown head gasket.
just buy a oem stock gasket from local part store.
when head is off take dizzy and cam gear off also make sure valves arent sticking out
a mill is just them giving the head a slight shave to make it perfectly straight it usually costs from 50-100$ depending where you go.

 

The symptoms that you described were the same that I had. It was the dreaded blown head gasket.