I’ve just gone through my 2006 Accord V6 (non-hybrid) with automatic and replaced timing belt (yes, the crank bolt was a bear) and valve adjustment. Searching this forum was very helpful, so thought I’d contribute a data point on the valve adjustment at 106K miles.
I’m used to working on high performance motorcycles, and even my 2000 Tundra has shim under bucket valve adjustments. It was nice and easy having screw type adjusters, and mine were out of spec on several valves. As posted by others, I’m unclear on the direction from Honda to only adjust the valves if they are noisy, given the number of mine which were tight.

Values in thousandths
Intake spec- 8-9 As found: 10,9,10+,10,9,9,8+,8+,10,10+,10+,9
Exhaust spec- 11-13 As found:11,10+,10,10,11,8+,10+,11,8,11,10+,11

Didn't like finding that 8's on the exhaust side. Looking at the values, I was glad I made the effort. Thanks for the help. For what it's worth, Toukow

 

Tight seems to be the prevailing theme when it comes to the exhaust valves. Quite a few were tight when I did the adjustments on my 03. I didn't check to see exactly how tight. I doubt we were in danger of burning valves. But, finding most of them out of spec, and needing adjustment, did give me the sense that it was time well spent. Now I have piece of mind that I'm good to go for another 100k miles, and no longer wondering what I have. So if any of you have the means to do this yourself, or have someone you trust to do the job right, I would suggest going ahead and checking the clearances at around 100k miles. Don't fall for the "only if noisy" IMO, because that would never happen with the exhaust valves.

 

If you are able to do them yourself I would go every 50k. I have seen many at 100k where there was 0 clearance on exhaust valves causing misfires galore.

 

You bring up a good point- when does the burning of valves begin on this particular engine? I've never seen it discussed or stated. I've always assumed the first 1/1000th was a gimme, but after that don't have a clue. As a mechanical engineer at work said, you don't see a lot of claims on these engines for burnt valves. That seems reasonably true. Given the adjustment mechanism is as basic as it gets, this is a good engine to work on for your first time.

Actually, I think it worth checking on 'shim under bucket' style of valves even if you intend to have others do the work, given many times no adjustment is required. They still bill you the same amount of money if you go to a shop (at least that's my understanding). 110K miles on the 2000 Tundra, and all were within spec. Of course, it depends on how much disassembly is involved just to do the checking. This engine requires a significant amount of disassembly compared to many others.

I'm surmising that valve burning had started at zero clearance. Fortunately, the only time I've seen a zero clearance situation was a Generac standby propane generator, and hope it remains that way. Thanks, Toukow

 

I think if the clearance was even close to 0 (5 thousandths or less) the valves might stay open too long, or not close fully on every cam revolution. The longer the engine runs with very little clearance might make the situation accelerate, but I really don't know. I've only done this a couple times, but I find the easiest way to adjust them is to tighten the tappet all the way down onto the feeler gauge, then back off slowly, till I get the right amount of drag. That way I get a feel for how far the tappet has to back off, before the clearance is where I want it and I'm always turning in the same direction.

As far as bringing it to a shop, for someone else to adjust the valves, IMO, it's anyone's guess, as to what you'll get for your money. Some techs probably don't like doing this job, are rookies, or just plain no good at it. I'm sure they will always charge full price, whether they adjust any valves or not. There is a good amount of work, just to get the intake and valve covers off.

 

The thought process for adjust only when noisy is strictly so they can show maintance costs are lower because it is a pricy job to do.

 

I've been thinking about doing this next summer (130k right now, doubt its been done, bought at 100k). Big job? Need to remove Intake Manifold to get at the covers? Can you give me an estimate of how long it took you guys for the DIY?

 

Thats really not neccesary. Ive adjusted the valves on 4-stroke dirt bikes probably hundreds of times and all you really need to do is tighten them until you feel a slight drag on the feeler gauge and youre good to go. I suppose theres nothing wrong with your method but youre adding another step that isnt neccesary.
IMO, adjusting the valves every 50,000 miles is a bit excessive (although I know how **** some of us are about our cars). With today's engines, you cant always go with the adage that it needs an adjustment just because the valvetrain is noisy. Theres lots of modern engines that make a lot of valvetrain noise, even if the valves are in spec. 100,000 is probably a good rule of thumb though.

 

I know it's not necessary, but I find it's easier that way. I insert the correct clearance feeler gauge, turn the tappet all the way down, then reposition the wrench on the lock-nut so that I can easily tighten it in one motion, as I go slightly counterclockwise with the screwdriver. I just like the repetition of going one direction for each valve, rather than clockwise on one, then maybe counterclockwise on the next. Once the tappet is against the feeler gauge, I have to turn very little to get the correct clearance, so I'm not repositioning my hand on the screwdriver or the wrench while adjusting the drag.

 

I guess you could say it's a big job. Not timing belt big IMO, but it took me a few hours. I'm never in a hurry working on my car, cause I'm kind of picky and want everything to be just right, and I'm not exactly a professional at this stuff. Yes, you have to remove the intake, because the valve covers will not come off with the intake in the way, since you have to lift the valve covers over the rocker arms to get them off. I could have probably reused all the gaskets because they looked to be in good shape, but like I said, I'm picky and didn't know if I would damage one. Be careful installing the rear valve cover, because it's difficult with the wire harness in the way, and you can easily tear the spark plug tube seals (don't ask me how I know this lol).

 

Whatever works for ya.

 

Cool, did my timing belt two summers ago, so I should be able to tackle this then.

 

This was the first time I've ever dealt with spark plug seals like this and I thought they were a b*tch. Either that or I worry too much. I had a heck of a time making sure the seal was around the tube before bolting down the covers. Perhaps that's what happened to you, but it seems like it could pinch and tear as you mention. I actually took a small screwdriver and dulled the corners/edges, and used it to work the seal around the tube prior to bolting in place. Someone else had the same experience as you and posted, otherwise I don't think I would have caught it.

I agree that I could probably have reused the gaskets, but when there is this much disassembly involved, I spring the cash for new ones. Also, I tend to buy cars new and keep them until they're toast, which means I get to deal with any problems that occur much later.

I agree, whatever works for you. I didn't bother trying to go to one end of the range or the other depending on intake or exhaust. I guess it would make sense to put the intakes to the tighter side, and the exhaust to the looser end of the specified range,given their respective tendencies to loosen/tighten. If they were within spec, I called it good.

Agreed that this is much easier than doing a timing belt as well, and the repercussions for failure much less . Toukow

 

Yes, bent valves from a bad timing belt job, would be worse than burnt valves from valves set too tight. Bent valves could damage other things (pistons, head, etc.). An expert told me that when it comes to valve adjustment, loose is better than tight. Loose valves just make noise, whereas tight valves burn.