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I have a 97 Civic LX with some issues...

Since I've owned it the idle has been rough (about a year). The idle has gotten worse over time and recently it is bucking at around 30-40mph.

HISTORY
The radiator was replaced about 4 years ago and the head was replaced about 5 years ago. In the fall last year I noticed that the RAD fan wasn't coming on. It was OK through the winter but decided that it needed to be corrected in the summer. I recently replaced my RAD Fan Censor. I also replaced the RAD Fan Censor Fuse and it works great. Before and after this installation the temperature indicator never rose above about 1/2 way. Fan comes on now when it needs to. I topped off the coolent too.

Ever since I did this work the car has been bucking at around 30-40mph. The CEL came on and I went to the parts store and they hooked it up and said that Bank 2 was lean. They weren't sure what the problem was. He didn't remove the code but the light went off a few days later on its own. Hasn't come on since. I put a new set of plugs in it (they were due anyway) and it ran better for a little while but it didn't correct the problem. After I changed the RAD Fan Censor I started smelling coolent (burning) too. Maybe becuase I topped it off... (?)

After checking some threads here I think I have narrowed it down to either air in the coolant system or a bad head gasget.

I am going to do a couple things to narrow it down...
Any thoughts on the problem or solution?

Thanks for your time.

 
Rep Power: 812

if you do the bleeding procedure and the air bubbles never stop coming out, its a blown headgasket. dont forget to clean the fitv and iac valves near or on the throttle body. they control idle speed when the gas isnt pressed.

 
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Thanks for the reply.

I started the bleed test but didn't take the time to finish it. It didn't exaclty bubble but did continue to rise the entire time. I didn't loose much coolant.

I have always had the idle problem but the bucking at 30-40mph just started after I topped off the coolant. The overflow was dry proir to topping it off.

When I changed the plugs they did not have white on them which makes think that either the head gasket just went or that's not the problem. I am going to pull the new plugs to see what they look like...

I will clean the Fast Idle Thermo Valve and Idle Control Valve like you suggest.
Are there any DIY directions (with pictures) that I can use to locate them, etc.

Thanks!

 
Rep Power: 812

usually they are on or near the throttle body or intake mani, with some coolant or air lines attached. pretty easy to find and they are smaller pieces held on with bolts or screws.

 
Rep Power: 0

OK here is an update...

I did some tests, etc. and talked to my mechanic. It was determined that, in fact, the head gasket was bad. It took a couple weeks and $1100.00 but I had my mechanic:

• Replace the Head with a used one that was machined
• Replace Thermostat
• Replace Timing Belt
• Replace the water pump
• Replace all three belts
• Replace Valve Cover Gasket
• Clean Throttle plate
• Adjust valves
• Oil Change

The old head had already been machined. We ended up using one of valves to replace a bad one in the new head as well.

My car runs almost 100% now. The sweet smell of buring anti-freeze is gone. (Thank God!)
I have had it now for four (4) days and have driven it around 300 miles. The issue that I am having is with the idle. A couple times after starting it, before it warms up, the idle with go low and kind of sputter and then it will rise quickly. For the first time this morning as I was driving, before it warmed up, it bucked a little bit. After it warms up it is fine and it idles great.

Prior to this work I replaced the

• Plug wires
• Plugs

I read here http://www.honda-tech.com/showthread.php?t=1564019 that since my car is a 1997 I don't have a FITV (Fast Idle Thermo Valve).

From what I've read I do have a an IAC Valve and it could be the problem...http://www.honda-tech.com/showthread.php?t=2254464. The post above suggests that I must remove the Throttle body in order to properly get to the IACV and clean it. I wish that I had mentioned it to my mechanic when he had the throttle body off. It would have been much easier to clean then.

After I got it back on Thursday I filled it up with gas and poured in a bottle of Lucas Oil Upper Cylindar Lubricant and and injector cleaner. I try to put that in a few times a year.

I am going to go get a new PCV valve today and replace it but do you have any thoughts on what it could be if it's not the IAC Valve?

Thanks for your time...

 
Rep Power: 812

yeah im almost positive its the iac valve, which has the two coolant hoses going into it. its pretty easy to remove in most cases, but if its bolted to the throttle body and you cant reach the screws, you have to take off the throttle body. if you have no idea how to even try, then take it back to the shop, he might just do it free since you got alot of work done already. all you do is take it off and spray carb cleaner in the valve to remove the black stuff.

 
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The saga continues...

Since I had the work done the car is running great, except for the minor bucking before it's warmed up. I talked to a local parts dealer and he gave me a couple things to look at in the spring to correct that.

I still have white smoke. I didn't think much of it since it's winter. I kept checking the coolant level, in the reserve tank, and the it hasn't changed. So I figured that it was becuase it was cold out. It smells sweet but it's not the same smell as before I had the head gasket replaced.

A couple days ago my heat stopped working. I stopped by the auto parts store and told them the problem and mentioned that I just had the head gasket and thermostat replaced. The guy said you might have air bubbles in your antifreeze. I went right out and carefully opened the raidiator and it corrected the problem. I noticed that the coolant level was lower than it should be. The next morning I checked the overflow coolant level and it was down. Apparently it was more than an air bubble. The coolant level was down in the raidiator. I filled the overflow tank and it took in a little more over the next couple days.

I noticed that the white smoke stopped when I didn't have heat.

I did the test mentined below, running the car cold with the raidiator cap off to allow any air bubbles to be removed. Nothing. No air bubbles...

When I pull the radiator cap the system does let off air pressure, even after not running for 10 hours. Is that good or bad?

Since I just had the head gasket replaced and the car is running well, why would it be burning coolant still. What could be the problem?

Thanks for your time.

 
Rep Power: 812

to properly bleed the coolant of air, the car must be fully warmed up, with rad cap removed, and heater and fan on full. also the front of the car must be jacked up as high as possible (or park on a hill). ive had to do this procedure 5-6 times for 15-20 mins each time to finally clear all the air out after a coolant change, and i added alot of coolant while doing it. its a pain but in the end its worth it and the heat blows very hot.

 
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Thanks Gearbox.

So do you think that air in the coolant lines is causing me to burn coolant or is there something else?