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  1. #1

    Checking Valve Clearance on fairly new 06 Civic?

    I know the official interval for check of the intake/exhaust valve clearances is way down the road, and now with Honda's Maintenance Minder there is no official date or mileage specified. Also, Honda says to only check them sooner along with other services "if they are noisy". For the record we're around 24000 km's now.

    It concerns me that a overly-tight clearance will not be noisy, but is a possibility, since valves may be riding high on their seats when new, but after a few thousand kilometers/miles of break-in will be seating better, and closing up the clearance. I know my Honda Hurricane motorcycle specified a valve check as part of the first services.

    I have the shop manual, and am thinking to check them. I've checked valves on a few previous Honda cars we've owned. It's always been fairly easy to get the valve cover off. With our 06 Civic Hybrid however, it's looking to be very awkward.

    The main problem I see is dealing with the plastic encased wiring harness that runs along the top of the valve cover. It's cables continue off at the left (dipstick) and right ends. The left end cables connect to the dipstick tube. Removing the dipstick and the top clip between the dipstick tube and cable frees this end up enough to get it well out of the way of the valve cover.

    Things aren't as easy at the right end, though. The right end cables are thick and go only a short distance, into another plastic encased harness running vertically down the right side of the engine (the drive chain end). This vertical harness case also partially obscures the back right valve cover hold-down bolt. Without getting this shifted, the only way to get a grip on that back bolt is by reaching around with an open-end crescent wrench.

    It concerns me also that even with all the valve cover bolts removed and the cover loosened, it will be a fight to get it out from under the two harnesses. The bolts for this vertical right side harness were buried beside the air cleaner (see where this is going? ), so I tried, just as an exercise, taking out the air cleaner. This was a bit of a fight in itself, but got it done. Then I was able to access the 2 bolts securing that vertical harness. I backed them both out, and then was able to shift the vertical harness maybe 1/2" to the right, barely enough to get a proper socket on an extension past the harness and on to the right rear valve cover bolt.

    At that point, I just buttoned everything up, we had to get somewhere. I'm really not to impressed with the valve cover access. I haven't mentioned but there are also the (8!) sparkplug actuators to contend with. The back row (exhaust side) actuators get increasingly awkward to remove, going left to right. The back right one seems impossible to remove at first. No matter how you turn and angle it, it's clunking against the rear lip of the engine compartment or the firewall. It is a fight. It can be done but it is very close. Getting it back in is even more fun.

    Anyway, that's where I'm at. I do think it is a good idea to an early valve clearance, but am waffling, not looking forward to it. Anyone else done this themselves? Any opinions on the value of such an early check of the valve clearances? Any opinions on the likelihood of there being a tight valve or two in there, due to break-in and the valves fitting better on their seats?

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  3. #2
    Junior Member
    Join Date
    Oct 2006
    Yes, valve clearance could be a concern. As some folks already noted, the engine is a little noisier in colder temperatures. Once it warms up the noise appears to subside. In contrast, those that use block heaters may not notice the difference that much which appears to confim the temperature as being an issue. However you're still at 24000 which given the recommended service interval may still be too early to perform a corrective adjustment-unless you suspect something may be wrong.

    When I first looked at the clearance (among the other tune-up checks) I too was both impressed and also concerned. The valve clearance for exhaust is 0.24-0.28 mm and the Intake is 0.15-0.19 mm. This test must be performed at less than 38C and more than 15C ... and if you can perhaps perform that measurement... then that will put your concerns to rest as well. However, if you don't want to do your own test then I would only be concerned about about the valve's proper seating if (and only if) you notice the tell-tale signs that such an adjustment is necessary.

    The cables should be easily removed as they are all socketed. Yes, it is awkward to work on the cylinder head, but it should be easy if you lift the hood and hook it vertical (or better yet, remove it). The other plastic trim surfaces should also come off as they open up the engine bay a little.

    Since there are too many checks/tests in the recommended routine, I figured I may as well have them do it. There are also some dedicated tools that if absent do not allow for a complete tune-up sequence. Anyhow, It is interesting to know.

    Over time the seating should improve in very few cases. In the majority of cases it should deteriorate but just slightly. When it comes to engines Honda has gotten these things down to a science of precision. I doubt these engines ever made their way off the assembly line with any measurable potential for improvment.



  4. #3
    Thanks MSantos.

    I think there's two factors at play: tolerances in the rocker arms/cam shaft, and the interface between the valve and it's seat.

    The former would increase the clearance, and in past checks of other cars this is what I always found, when valve clearance was out of spec. Also, once I've adjusted any that were on the loose side, they tended to stay close to spec.

    The latter (I would speculate) would decrease the clearance. In practice I never found this, so I'd suspect the seating of the valves tends to stay pretty constant.

    Regarding: "The cables should be easily removed as they are all socketed", you got me going out to the garage to double-check. The 8 cables connecting to the spark plug actuators are all (naturally) connected with sockets, but at the left and right end of this harness there are conduits that have no connectors. Facing then engine from the front, the left end conduit is about 3/16" dia, and easily unclipped from the dipstick tube to improve movement of the harness. The right end conduit however, looks problematic, per my tome above.

    The first thing I thought of when I started (trying) to unbutton this harness was that socketted connectors would have been a very good idea, but as far as I can see, there aren't any.

    I'd just like to satisfy my curiousity as to what those clearances are. I've got the spec'd liquid gasket on hand that you're supposed to dab in two corners next to the cam chain cavity. But, it's looking like a royal pain to get in there. Even with the valve cover removed, you have that harness in your way as you work to check the valves. I think the smart money is to do nothing, and trust the clearances are close to spec. But I like a challenge

  5. #4
    Junior Member
    Join Date
    Oct 2006
    Quote Originally Posted by Mendel Leisk View Post
    I think the smart money is to do nothing, and trust the clearances are close to spec. But I like a challenge
    My thougts exactly.

    The other "fun" aspect about these cars is driving them. I (like many) intend to continue enjoying every minute of it.



  6. #5
    So true, it is a fun car. I'm hooked on achieving good mileage, and do think a signif. factor in that endeavor is the in-dash feedback, both the realtime and accumulated per trip. Also, it's satisfying to nudge into electric-only mode. I understand that's a lot easier with the Prius.

    Anyway, had another look at cable harness that goes over the valve cover, and think it's all doable. The left end conduit from that harness clips to the dipstick tube at several locations. Up to now I only disconnected the topmost clip. But looking it over more yesterday I see that if I disconnect the next one or two clips of this conduit, along the length of the dipstick tube, it becomes increasingly easy to rotate the whole harness back and out of the way of the valve cover, into the exhaust manifold area. When (and if) I get around to pulling the valve cover off, I'll likely also take the air cleaner out as well, so that I can also loosen the vertical wiring harness on the right side of the engine block. Then I'll have everything pulled out of the way as much as possible, and be able to get a socket drive on the right rear valve cover bolt.

    If I get to it, I'll post the clearances I find.

  7. #6

    I checked our 2006 Civic

    I checked our 2006 Civic Hybrid Valve Clearance today. I'll maybe post a more verbose report if anyone's interested. Here's some preliminary info:

    Sunday, December 07, 2008
    km: 58370
    * Checked valve clearances. Existing clearances measured:
    * Set intakes to: .006"
    * Set exhausts to: .010"

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