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Discussion Starter · #1 ·
So, after a few weeks of researching the procedure, I decided to tackle a valve adjustment on my '06 MDX. It has ~157k on it and, so far as I can tell, it's never had an adjustment (I bought it ~10k ago and no such service is on the carfax).

The symptoms that I was trying to correct were a mild vibration at idle and substandard MPG (11-12 city, though with a 2-mile commute, I expect poor MPG). Besides, without knowing whether or not it had ever been done, I wanted the peace of mind of knowing it had.

I should go ahead and say up front that I'd never done a valve adjustment before, which is why I researched it for a while before attempting it. I'm only documenting my experience in the hopes that it helps somebody else; I'm in no way claiming any kind of expertise, this is just a recounting of how I did it. YMMV.

Also, most of the document is about getting down to the valve covers (there's a lot of stuff to take off/get out of the way, so actually that's a lot of the job). I don't know how to explain how to adjust the valves to anybody apart from repeating what everybody says: insert the proper feeler gauge and adjust until you feel a slight amount of drag. I didn't really know what that meant when I started and figured that it was something you just had to experience to understand, which I think is about right.

Oh, and I didn't actually intend to document this process at all when I set out. However, after I did it and then put everything back together, I had one bolt left. :( I looked and looked and could not figure out where it went, so I tore everything apart again, taking pics and notes of everything this time, until I figured out what I'd missed. Since I had all the pics, I thought why not write it up.

So, apart from that how did it go? Not too bad. I took it slow, so it took 4-5 hours (plus another hour for the aforementioned SNAFU), but it's probably more like a 2-3 hour job. In the end, my vibration is almost completely gone (I can almost swear that I can feel something now and again, but other times is so still that I could swear its not even running) and my MPG seems to have gone up (I haven't driven it enough yet to say for sure, though). Plus, it's pretty satisfying to have done the job, so that's a plus. :)

All in all, it's a pretty straight-forward job if you take your time. It's difficult to work on the rear cylinders thanks to some very cramped quarters, which was not helped by the fact that I had to stand on tip-toes to reach back there so the next day my calves were killing me, but apart from nuisances like that, it's wasn't that bad.

What I used to do the job:

Valve cover gaskets (2) and spark plug tube gaskets (6) (get from your favorite source; I think the OEM part # is 12030-RCA-A01)
10mm socket
12mm socket (thin walled; there's one bolt that's in a tight spot and a thicker walled socket won't get to it)
19mm socket
3/8" socket wrench
1/2" socket wrench (for turning the crank)
needle-nose pliers (I used both angled and straight, but only the angled is necessary)
#6 hex/allen wrench
spark plug socket
3" extensions for 3/8" socket (2)
6" extension for 1/2" socket
10mm wrench
stubby flat head screwdriver
feeler gauges (.008-.009" & .011-.013")
 

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Thank you so much for this. At 147k I need to do it to (dealer has no record of it being done and I just got the vehicle a month or two ago). Much better than paying 400-500 bones to have the dealer do it :).
 

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I commend you on taking that on! I usually do my own service but the valve adjust looked overwhelming. I recently had the dealer preform a valve adjustment on my 2005(136K miles). Total was right around $650. I was having rough idle at cold start and multiple random misfires. I did save $400 by replacing my brakes and rotors all the way around : )
 

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Discussion Starter · #5 ·
I forgot to mention the PCV: I removed mine before taking the front valve cover off. I wasn't sure if it was necessary, but since it's dead simple to do, I figured why not. 10mm bolt, it's on the outboard side of the valve cover next to the dipstick. Takes 10 seconds to remove, just as easy to put back in.

Several days post-procedure, the vehicle still feels noticeably improved. Vibration at idle almost completely gone and MPG holding steady at ~2MPG better than before (again, that's on a 2-mile city commute, so about as good as I could have hoped for I think). Given that the majority of the expense for this job is the labor (gaskets don't cost all that much), it's a huge savings to be able to do it yourself. Obviously doing it wrong will end up costing you a ton more in the long run, but I found it to be pretty straightforward.
 

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It is a wonderful feeling to see a job completed successfully. And the education you gleaned will prove useful when you are called on to troubleshoot a future problem.

Good job.
 

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I will do my own valve adjustment on my MDX when the time comes but I just wanted to add the following for people to understand.
I did my own timing belt. That wasn't so bad because it didn't involve "Feel". I've been doing my own valve adjustment every two years since 1996 on my 96 Yamaha Virago and never "feel" comfortable or good about the outcome.
 

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I'm thinking I'll do this Sunday. I have a little hiccup at idle that survived a plug change/throttle body cleaning, and I can hear the valves just a little at idle. Maybe I'll throw some meat on the smoker at the same time so I can feel like I'm accomplishing two things at once.

Thanks again!
 

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I have it apart now. It only took about an hour to get to the point where I can start adjusting the valves, so I took a break for lunch and to run to the auto parts store for the valve cover gasket set. Done eating now so I'll go back out there and start adjusting here shortly.

It wasn't difficult at all to get to this point, though you're certainly right about the rear valve cover not having any wiggle room. I'm not sure how I'm going to keep the gasket in place when I'm wrestling it back in :).
 

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Done. It seems like the valves are a little louder than they were, but the noise is more consistent. It's an even sound instead of some being louder than others, and whatnot. Not ticking, just can hear them if you listen.

Some things to note:

Cylinder 1 exhaust valves were a b1tch to measure with my feeler gauges. It took me the longest because I couldn't get the right angle to tell how much it was dragging.

At 147000 miles, all of the exhaust valves were too tight, and about half the intake valves. None had no play though.

It helps to have a bearing/seal seating set to install the new spark plug seals in the valve covers. I didn't realize they were reinforced with metal and pressed in. No big deal really.

If you disconnect the hose from the PCV solenoid instead of taking it off of the plenum, remember to connect it again, or you'll have stinky burning oil smoke and a loud POPOPOPOPOPOPOPOP sound and a feeling of dread thinking about having to rip it apart again.

Disassembly/reassembly is a piece of cake, really. The longest part is easily the actual adjustment of the valves. I checked them all twice (went through them a second time) and found that I'd adjusted a few exhaust valves too loose. I'm glad I double checked my work.

It took me all day to do this because I screwed around a lot, took breaks, ran to stores, etc. I can't see how a dealer can charge 500 bucks for it, though. My guess is I put about 3 hours of actual work into it, and it was my first time.

The tip to use a phone to take a pic of the marks on the cam pulley was spot on. There's no way I could see the number on the pulley without that. I can post examples if anyone wants to see them.

Finally, all the intake gaskets were in great shape so I reused them. The valve cover gaskets probably would have been fine too, but the spark plug seals and the seals on the bolts were not in perfect shape so they did need to be replaced.

Don't fear this service. If you work on your car at all you should be able to do this. Make sure your feeler gauges are angled!

Cheers

Chris
 

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Good job
My 2007 has a pretty decent vibration at idle even after replacing all the motor mounts. Looks like I should probably do this job. There doesn't seem to be any other fix for the vibration...
 

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I have a very minor blip in idle, guessing a couple of valves are tight at 115k, Fully motivated to attempt this in a couple of weeks and in process of ordering gaskets. I didn't follow your comment on spark plug seals. Do I have to have a specific tool to press those in? how tricky can it get. Also do you see a need for the valve adjustment tool or a stubby flathead and 10mm socket would suffice. I do have the KD tools 163 angled guage for the job.
 

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The seals are rigid around the outside so are hard to press in with your fingers. I used my seal installation tool, but I'm sure a large socket and extension would work as well.

I used a stubby screwdriver and a 10mm box end wrench to adjust the valves. No problems.
 

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Discussion Starter · #15 ·
Not only will a stubby flathead + 10mm box wrench suffice, it's pretty much your only option on the exhaust valves on 4, 5, and 6 (not enough room for one of the specialized valve adjustment tools). The specialized tool is convenient for the rest of the valves, though, so if you have one, go ahead and break it out.

The spark plug seals are a pain to get out, yes. The outer ring is a hard plastic. I ended up just cutting/breaking the old ones out (didn't have a seal puller and wasn't inclined to run out and get one at that time so cut a notch using wire cutters then grabbed with needle nose pliers and twisted until the ring broke and it would pull free) and pressing the new ones in with my thumbs (it's a tight fit so that's easier said than done, but it seemed to work).

BTW, regarding the lingering idle I reported after doing my valves: this weekend I took off the EGR valve and cleaned it out with a little carb cleaner (it didn't look that bad, but since I had it off I figured I might as well) and that seems to have done the trick. I'll have to see if I feel any vibrations this week, but running around all day yesterday doing errands and I never felt a thing, so fingers crossed.
 

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Yeah, the exhaust valves on 4,5 and 6 were a pain. Mostly because I had a hard time getting the feeler gauges in there at the right angle to be confident of the amount of drag.

I just carefully used a small flathead to pry the spark plug seals out. The new seals for the bolts were sort of a PITA to get forced on the valve cover bolts too. Just had to wrestle them on there (my thumb tip is sore from that).
 

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Guys Wish me luck on this DIY , currently (3/27) in process of opening up stuff for valve adjustment. Planning to use all existing gaskets (since motivation to do came before i could order parts) If i run into issues Acura parts are not not far away.

ONE strange thing on throttle body the vacuum like tube which point towards ground, coolant fluid oozed out when opening, I am thinking this is abnormal. Did you find any liquid that oozed out of there while opening? I have a suspicion that this cars have had that coolant/oil mix situation in the past. which I am hoping was handled in time.
 

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Great job!!! Thanks OP!
 

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I may have to revisit it. They're fairly noisy when it''s cold. When thoroughly warmed up it's not. I might have left them a little loose, I did adjust them towards the larger end.
 
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