Checked Valve Clearance on our '06 Civic Hybrid

Discussion in 'Honda Hybrids' started by Mendel Leisk, Dec 7, 2008.

  1. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    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"

    Note, the service interval for this is well, I'm not sure what it is: it's part of the inscrutable Maintenance Minder system. I believe it works out to be over 100,000km, in conjunction with spark plug replacement. But 15 years or so back, the interval was 20,000km or yearly, whichever came first. So, thought I'd give it a go.

    Took lots of pictures, removed the bottom of windshield cowl and cowl cover, to fascilitate access. All-in-all, no major problems.

    Did discover a partial typo in the Shop Manual, in the picture showing orientation of cylinders 1 through 4. Everything in the picture is correct, except for the engine picture itself, which has the timing belt sprocket showing at the wrong end, which could lead to mistakes. The notations for "intake" (nearest the front) and "exhaust" (nearest the firewall) clarify things.
  2. Harold

    Harold Well-Known Member

    Mendel, was the adjustment necessary, or were you practicing? Did not take much adjustment! H
  3. msantos

    msantos Eco Accelerometrist

    Hi Harold and Mendel;

    If I recall correctly, Mendel has been very curious about the valve clearances for a bit over a year of so. I do find it very interesting that was some out-of-spec evidence which even though was not very significant it was still observable.

    Anyhow Mendel, how's the engine running after the adjustment? Were you experiencing any piston slap or additional clatter before?


  4. msirach

    msirach Well-Known Member

    How many miles were on your car? By all the tolerances being in spec or exceeding, it looks like the valve seat/valve face have not worn any.
  5. phoebeisis

    phoebeisis Well-Known Member

    It has screw type adj , not the shims that most of the motorcycles have now? Wow,that is a good thing. Those shim systems take one more maintenance item out of the hands of the DIY.
  6. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member


    My findings were much inline with past experience, checking several Honda Accords we've had. I know it's possible for clearance to tighten up, due to valves seating-in better, but my experience has always been that the clearance goes out of spec to the looser side. Check the stat's in my first post, I give the kilometers travelled.


    I've not noticed any signif. difference post-adjustment. I think it sounding smoother, and I think it has a little more "pick up". It could be just my wishful thinking, but I don't think so. Still, not a whole lot of difference. About what I'd expect considering the gaps were not *far* off spec., and all to the loose side. Still, kind of like going to the dentist for a checkup: no news is good news ;O

    I do know that a few thou's difference can be significant. The very first time I adjusted valve clearance, on a previous Accord we had, I managed to *reverse* the intake and exhaust settings. When I buttoned it up the first time it ran *very* rough ;)

    I'd noticed no noisieness prior to the check. My main motivation was Honda's *extreme* swing in policy regarding the service interval for this service.

    Harold, the last sentence above sort-of answers your question too, I think. It just bugs me to wait 100,000km plus, not knowing the state of the clearance. I suspect the clearance tends to "drift" a moderate amount during break-in, and then settle down.
  7. phoebeisis

    phoebeisis Well-Known Member

    If you tighten up the clearance, you should make a tiny, tiny bit more power, since you get a little more duration and lift.
    Like you say, it would be hard to seat of the pants notice, but if you are really familiar with your vehicle, maybe you can "feel" it.
  8. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    Phoebeisis, that's my thinking too.

    BTW MSantos, your memory is correct, I've been contemplating doing this for some time, per this posting:

    What tipped me was our recent block heater install. While I got the dealer to do it, I read the pdf instruction from end-to-end. It includes a guidance to remove the cowl and cowl cover, which I did, just out of curiosity. Here's a current link to the pdf:

    The lightbulb went on when I had cowl and cover removed: it made the engine top much more accesable. Also, it gives a nice space for the wiring harness atop the valve cover to rotate up and into: you can just tuck it between the IMA wiring harness and body. It helps to disconnect the harness's top clip to the diptstick tube. Then remove the diptick and shift the cord over top to the back side.

    Anyway, it's the first time in my experience I've not needed to pry with a screw driver to get a cover lose. Once all the hold-down bolts are backed out (they don't need to come right out, they're captured by gaskets), the cover is lose, and with a bit of hands-only budging will come off.

    There's a guidance [Dec 13 edit: The guidance is in the Shop Manual, which incedentally, is almost a must for doing this. Alternately, if anyone's interested, I could type out a paraphrased instruction. So far, there doesn't seem to be a lot of interest, tho ;)] to put 2 dabs of liquid gasket at the junctions between valve train cavity and timing chain cavity, which I followed, but I do not think it would be the end of the world if you didn't. It just made me somewhate nervous to get the cover back in place, coupled with a few trial attempts.

    One other wrinkle is the upper right valve cover bolt, which is partially obscured by a black plastic component. That item has a 10mm (wrench size) bolt in a pocket, down it's side. Just loosening that a bit allows you to flex the component out of the way just enough to put a socket on that upper right corner valve cover bolt. Which will save you some time over labourious wrenching, and allow proper torquing on re-install.

    The procedure involves turning the engine over, once per cylinder. There is a 19mm (wrench size) bolt head available to do this, at center of accesories pulley, accesible through the passenger side wheel well, for this. You should always turn clockwise.

    I'll maybe put together and post a step-by-step on this, in the next few days.
    Last edited: Dec 13, 2008
  9. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    Here's the car at beginning. Note the angled wheel (the engine turning bolt is accessed through the wheel well), and the wipers in up position (to be clear of the cowl cover during it's removal).


    Now the cowl cover (plastic trim piece framing bottom of windshield, with washer nozzles) is more or less removed. A washer fluid tube still needs to be disconnected.


    Now the cowl (stamped black metal) has also been removed.


    Sparkplug activators pulled off, the wiring harness disconnected from valve cover and rotated up and out of the way. Note, the wiring harness top clip to dipstick tube has been disconnected, to gain more freedom of movement.


    Target in sight!

  10. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    Here's 5 pages from the 2006 Civic Shop Manual relating to Valve adjustment:

    Note, the first image, from page 6-10, shows an overview of the engine and id's the cylinders. This view is taken from the front of the engine, as you would see it standing at the front bumper. The engine is shown with camshaft chain sprocket on the right side. This is in error, it should show at left side.

    It's really immaterial which cylinder you start with. Just put a 19mm socket on a long extension through the opening in the front passenger wheel well, and crank the engine clockwise till one of the configations lines up. There's always a fight to get the engine through the compression cycle, but once you do, go very slow and easy: it's easy to go too far, and it's best to not turn the engine back, counter clockwise. It could screw up some tensioner, I believe.

    The images looked to have been downsampled quite a bit when uploaded, but still just legible.
    Last edited: Jan 9, 2009
  11. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    Here's a quick text summary:

    Valve Clearance Adjustment

    Note: Adjust the valves only when the cylinder head temperature is less than 100 F (38 C).

    Valve Clearance:

    intake: 0.15-0.19mm (0.006-0.007 inch)
    intake: 0.24-0.28mm (0.009-0.011 inch)

    Piston Order:


    1 2 3 4


    Front of vehicle

    Adjuster nut torque: 14 lb/ft


    1. Remove the cylinder head cover.

    2. Rotate engine clockwise as needed to set the No. 1 piston at top dead center (TDC). The "UP" mark on the camshaft sprocket should be at the top, and the TCD Grooves on the camshaft sprocket should line up with the top edge of the chain case. Check and adjust valves as needed.

    2. Rotate engine clockwise to set the No. 3 piston at top dead center (TDC). The "3" mark on the camshaft sprocket should be at the top, and one TCD Groove on the camshaft sprocket should line up with the top edge of the chain case. Check and adjust valves as needed.

    3. Repeat step 2 for cylinders 4, then 2.
  12. philmcneal

    philmcneal Has it been 10 years? Wow

    cool it doesn't look hard to do, did you notice more FE benifit/power after the adjustment? What's the worse that can happen if someone were to ignore this DIY?
  13. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    Well, I've ignored mine for 170,000 miles... :eek:
  14. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    "What's the worse that can happen"

    Probably not a lot. The worst would be valve stem to tappet clearance getting too tight, which theoretically could happen, if the valve keeps seating itself higher and higher into the landing area. This could lead to burned valves (due to insuffic. heat transfer) and whatever occurs if the valves don't seal the combustion chamber properly.

    In practice I've always found the clearance becomes looser. When that happens you lose a bit of performance, basically.

    Different cars use different systems for setting the clearance, or go to hydraulic self-adjusting. I believe Toyota's use shims, which are a lot more difficult to adjust for the DIY'r, compared to screw/lock nut system on the Honda's. OTOH, shims tend to be more stable, less likely to need adjustment.
    Last edited: Mar 24, 2009
  15. psyshack

    psyshack He who posts articles

    Glad I saw this Mendel,,,, Thanks
  16. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    Your very welcome ;)

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