Took my 97 CL (136K miles) in to garage for check engine light. Code was P0305. Was told it needs a head gasket due to leak down test results on cyln 5. Cold start idle is a little rough, but smooths out very quickly. No anti-freeze leak or burn off that I can tell. Could carbon build up on the valves cause cylinder leak down? Any suggestions?

 

If the shop did a cylinder leak down test then the valves being dirty will not effect the results. If they did the standard compression test then the dirty valves could give false readings. I would suggest going to a shop and having a full fuel cleaning done, the one where they tap into the fuel lines and run the car through the machine. This will clean the valves and it cost less than $100. This might not solve your problem but at least you know your valves and injectors are clean. I can't imagine you need a new head gasket. Are you the original owner, have you ever run the car hot? Ask the shop what the results were when they did the test. You can also rent your own leak test from AutoZone for around $20. A good cylinder leak down test result is 5-8%. Good luck. I can't believe I bet BlackAck to an answer, j/k.

 

does white smoke continually come out of the exhaust? Does the antifreeze level keep getting lower? Those are both signs of a bad head gasket

 

it should do one or several of these things;Overheat, sometimes even with a blown headgasket it will not overheat while moving. Let it idle and see if it gets hot. It might blow steam from the exhaust, accompanied by a coolant smell, take your rad cap off and see if it is pumping water out of the radiator, also check to see if you have heat. normally a car will start to run poorly with a blown head gasket. The plugs get wet and it fouls them out.

 

Friend of mine has a VR6 jetta, we did the heater core in it recently and when he started it up, it was blasting out white smoke. He tells me it always did it when cold and I was like "uhh... that is not good". He played it off until recently he was complaining about having to put coolant in every couple days. I turn to him and said "i told you that your HG is going and you need to replace that before you have a serious problem". Well, 3 nights ago he was on his way home from jersey, temp gauge dropped to nothing, then shot up... car started to bog so he pulled over. Seized immediately.

Moral of the story: Don't ignore coolant issues! I would keep an eye on your coolant levels very closely if I were you. You can also take some sort of flat object and hold it behind the exhaust after the car warmed up to see how much moisture you get, shouldn't get much if any.

 

Thanks all for your replies. Car has not been driven much. When i do drive, I am watching the coolant very closely. It has not lost any coolant that I can tell and no white smoke. I am a bit suspicious of the dealer. I used an OBD tool over the weekend to confirm the code. Sure enough, the generic code is mis-fire on cyln 5. This OBD tool I used also was able to pull the specific code for Acura. This Acura code specified mis-fire on multiple cylinders. Interesting that the dealer did a leak down test on only cylinder 5. I question, "how valid were the leak down test results". Cylinder 5 was not compared to any other cylinders. Wouldn't a valid test compare percent leak down to the rest of the cylinders? Now, if there were multiple cylinder mis-fires, wouldn't that lead you to beleive an electrical issue. I did explain to the dealer, "rough idle briefly at start-up", "smooths out very quickly after running". The plan this weekend is to change the cap and rotor, (plugs and wires are already done). Any feedback would be helpful.

BTW, I ordered a new OBD tool for myself, (Dyno-Scan for PC). I may have some more info next week.

 

Change the cap and rotor button, I would recommend getting these strait from the dealer for I have had issues with proper fit from the local autopart stores. If this doesn't work, have the fuel system professionally cleaned. Good luck.