Honda_Enjineer

I thought this topic important enough to start another thread.

Honda recommends that you check the valve clearances on you car at some incredible mileage eg. 105K miles is often quoted.

Yesterday I checked the valve clearances on my own '06 Pilot and I was horrified by what I found (see the thread I started on P0175) at only 73K miles.

I'm posting this as a new thread to help a few other folks realize that maybe they ought to be considering doing this MUCH sooner (I'm sure it applies to other Honda VTEC engined cars equally). Here is what I wrote in that other thread:

--------------------------------

.....I looked at the options for addressing P0175 in the manual and I decided that checking the valve gaps was something that wouldn't cost me anything except my own time and it was probably worth doing it anyway even if they turned out to be fine at ~73K miles.

Today I spent 3 or 4 hours doing just that and I was surprised at what I found.

My interesting discovery was this -> NONE of the inlet valves needed adjusting. Every one of my exhaust valves had practically NO gap left (this was with a cold engine too) !! Was shocked by this

I adjusted and re-gap'ed all of the exhaust valves and reassembled everything. Did the "idle learn" procedure as outlined in the Honda manual.

All of my fuel trim values are now positive values instead of negative. Bank 1 and bank 2 are now showing similar values for both ST and LT and all are within specs.

Interesting too - throttle position is now lower by a few percents and the vacuum MAP in.Hg value has also decreased to around 8 or 9 on idle. The engine now seems to idle a little smoother to boot.

I was shocked that the valves had absolutely NO gap left! I've done mostly freeway driving - so not sure if that was a factor but I reckon that I caught this issue just before I ended up with a burned exhaust valve or seat.

Anyway, I'm pronouncing the issue now cured and I'll add another entry later to this same thread if the code ever returns.

Otherwise I hope that this info helps out someone else. The task took me a while to do so I'm not sure what a 'stealer' would charge for it but I'm guessing not cheap.

Bob

qwrty

thanks for the heads up..
but it was discussed in other crv forums that they normally
check/adjust their Vs every 30k miles.... as well as the dual pump fluid
if i could remember...


good luck to all!

Dogginator

Checking valve clearances on an I4 K20 CRV is simple compared to the V6 J35.

Honda_Enjineer

What is really surprising to me is that Honda are so far off the mark on this issue in terms of when they should be checked. Is this a big money maker for the 'stealers' or what? My Pilot was never maltreated in any way in case you are thinking that you don't need to worry about this. I also use Mobil 1 fully synthetic oil and filters to give you a hint at how I treat the car.

I'd bet that by 105K miles most of these cars would have burned valves or damaged cylinder heads (or both) if people just choose to ignore the check engine light (and I know that many people do just ignore that light).

I also own an '04 Odyssey with 80K on it (wife's car) - no MIL light or such as yet but I am planning to do the valves this Saturday based on what I now know about this engine.

I'm seeing the same -10% (or more) LT fuel trims and higher MAP pressures on hers that started off my investigation on my Pilot - but the Odyssey seems to have a less sensitive computer so no MIL. I'm guessing that I will find the same exhaust valve issue there once I get the covers off.

BTW, valve clearances are waaay easier to do than cylinder head rebuilds!

Dogginator

How long does it take to adjust the valves? This could be diagnosed with a simple compression test.

Honda_Enjineer

Hmmm... I wondered about that too but then I realized this as follows....

ALL cylinders had valves with almost zero (exhaust) gap on a cold engine - so your compression test would need to be done on a HOT engine to show up the problem. Most people do not do compression tests on a (red) hot engine block so you'd likely completely miss seeing the problem in that case. I'm guessing that you'd get OK compression on a cold engine with the problem.

Valve gaps exist to allow a little space for the valve stem to expand as the engine heats up to normal operating temperatures. With no gap once the engine gets really hot your valves would not be closing properly leading to potential damage. (Same thing they do with train rails)

The diagnostic clue seems to be this >10 in.Hg MAP pressure accompanied by < -12% LT fuel trim on one or both banks. And/or P0172 or P0175 - rich banks!

I did notice an occasional misfire on hot idle but nothing dramatic - these issues are now all resolved. I'll be sure to post again if that changes.

My engine today was idling very smoothly again "like a sewing machine" so I'm pretty sure I nailed it.

The job took me three or four hours - I'm pretty slow but I focus on doing the job well.

Honda_Enjineer

Also, I forgot to add - other problems can show similar analyzer values. But if you are getting up in mileage on a VTEC engine then just do the valve gaps. That's the smart thing to do even if everything seems fine with the car.

And... you're more likely to be sorry later if you don't. My pennies!

TheAsian

Me personally I have never seen a Pilot come in that had the valve clearance out of spec. But Im glad to hear that your problem is solved. Ill keep that in mind w/e anything comes in w/ the issue you are describing.

Ill submit something to tech line also may A Service bulliton will get issued if a lot of techs are coming across this.

Honda_Enjineer

Interesting comment. So about how many have you checked? Their typical mileages?

Well I'll know more about this issue on Saturday night as I am doing my wife's Odyssey on Saturday just in case (same 3.5 V6 engine basically). We'll see then if this was just a one-off aberration or a pattern.

qwrty

guys, you might wanna post up the valve clearances of all honda suv/truck/van
if you may, so this could be a good reference... both intake and exhaust side:
crv gen1 - I-? / E-?
crv gen2 - I-? / E-?
pilot...ody...etc!

thanks!
**some people are too lazy to look for it! LOL!

johnjw

delete

Honda_Enjineer

Hi "TheAsian" -

I just did my wife's Odyssey today and found exactly the same problem! I adjusted the gaps and that car runs smoother too - fuel trims, MAP pressure etc... just like my Pilot did. Obviously this needed doing.

So, I'm not sure which Pilots you have been checking (are they new cars perhaps?) but this seems to be an issue with this 3.5 V6 engine as I suspected and not just a one-off aberration. I'm guessing other VTEC engines would be exactly the same.

Again her inlet valves were all fine but the exhaust valves were all less than .005" gap left - not good! Her car is an '04 Odyssey with 80K miles and she drives it with a feather touch.

So again, checking the gaps at closer to 50K is the smart thing to do. Honda's 105K is waaay too high IMO. You'll avoid burned valves and seats.

Bob

Dogginator

How long did the Odyssey take to do? I'm at 60k right now.

Honda_Enjineer

Why?

Honda_Enjineer

It took me a bit longer today - I ran up to the store for some new plugs and I took a break.

But I'm guessing it would be about 4 hours going at it (for me) - I'm quite slow because I spend time doing unnecessary stuff like cleaning up the covers, wiping out dirt etc.. etc...

I like the engine to look nice when I'm done

ARMED

anyone

Honda_Enjineer

My (V6 3.5L VTEC engined) '06 Pilot and my '04 Odyssey were both:

Intake: 0.20 - 0.24 mm (0.008 - 0.009 in.)
Exhaust: 0.28 - 0.32 mm (0.011 - 0.013 in.)

Not sure about the others....

Allout

I had a problem with my CL-S idle and it turned out to be the valves being too tight and throwing off a bad MAP voltage. I also found out that it's wise to go on the loose side of the adjustment.

http://www.in.honda.com/Rjanisis/pubs/TS/BTS050802.PDF

qwrty

crv gen1(rd1)

Valves Metric U.S. Standard
Intake 0.08 mm to 0.12 mm 0.003" to 0.005"
Exhaust 0.16 mm to 0.20 mm 0.006" to 0.008"

a good link w/ pics: http://home.earthlink.net/~michaelpkeefe/
just click the navi keys on left on the topics that you want that he may
have it on his site..

HTH...

Honda_Enjineer

For the record this really seems to have cured my P0175 MIL problem as well as making my Pilot run slightly better.

I drove 300 miles today and the car is running like a charm again.

Honda_Enjineer

Hey Allout - I just had time to read this PDF you posted. Thanks a bunch! It helped explain for me what I was seeing with my analyzer and in particular why my intake vacuum was improved and my idle smoother.

So, here is HONDA indirectly admitting that these things need to be adjusted much more often

JDM_Ej

My 2000 CRV had an issue because of this. I bought the vehicle last year with 112k for my girlfriend to drive to work. She drives pretty far and it developed a cold-idle issue quickly. Things went downhill fast. Codes started to show misfires on all 4 cylinders. After a week of that the MIL started to flash and the car would barely move.

At this point the car had about 126k on it. I searched around to see the common issues with this model year and found TONS of complaints about the same damn thing, and it all leading back to the valve adjustment - or lack thereof. Only solution was to replace the head. So, I got a 98 Integra LS head from a friend for 100$ and put that on. Runs like a champ now!

So yea.. adjust your valves every 30k.

Honda_Enjineer

Yes, 112K miles is waaaaay too far based on what I have recently learned.

Sorry to hear that you needed the head replaced - that's a much bigger job.

BTW, for anyone else interested both my Pilot and my Odyssey continue to run like champs without any more MIL code's since making the valve adjustments.

So, if you've reached 50K you REALLY need to be thinking about this if you intend to keep your Honda till 100K and beyond.

Bob

JDM_Ej

Eh I've done heads on these motors a few times, so it wasn't horrible. Just aggravating that it had to be done. Car runs better than it did when I bought it though now.

Honda_Enjineer

Yes, I'm also impressed by how solid and regular the idle now is. I remember having an Accord that idled just like that but hadn't noticed that on my own cars prior to doing the work.

These things creep up on you - I don't remember whether it was different when new.