Gen3 Valve Clearance Adjustment

Sorry about the long post… here’s a write-up I just did on adjusting my valves. I am a novice, so the information below is just my experience and opinions. I just wanted to share my story… maybe it will help you if you’re planning on doing this yourself as well, or be entertaining to read if nothing else.



I just finished up a valve clearance adjustment on my 2005 Odyssey EX-L (VCM). I’ve never done a valve adjustment on a car before, but I have done it many times on my 1975 CB750 Honda motorcycle. I figured this should be familiar territory… I was mostly wrong.


It was a lot more work than I had anticipated. I’m glad I did it, but it literally took me all day. I think over half the job was just getting everything removed (and then put back together). I really had to wrestle with those wire connectors. The rear coil connectors were a real pain, as were a couple of the connectors on the side of the intake manifold. Maybe there’s a trick to disconnecting them that I’m not aware of… I just squeezed the release tab as hard as I could and wiggled the connector back and forth until it came off.


The valve adjustment is an exercise in extreme patience, but I was expecting this. The biggest challenge is getting the valve clearance correct after tightening the lock nut. Sometimes you get lucky and it doesn’t change, other times it gets tighter… and other times it’s looser after tightening the nut (it’s not consistent). Again, maybe there’s a trick that I’m not aware of, but this was similar to my experience on my motorcycle… you just have to play with it until it’s correct. Expect to spend a lot of time doing this.


Most of my valves exceeded the clearance specifications – none were under (car has 101.6K miles)… with the rear bank having the most (0 .016” measurement on the exhaust, and 0.013” on the intake – on average for the rear bank). The Front was better with two of the front cylinder’s exhaust valves within spec and most of the intakes were around 0.011” – 0.013” as I recall.


I used the “interference” method to measure and set the clearances. Basically, I would work my way up in feeler gauge sizes until I couldn’t get one to fit… then noted the size of the previous feeler gauge. I’ve read posts were they say it should be just a slight tug, but I’m not able to get consistent readings when I try it that way. The challenge I see with the limited space and visibility is sometimes it feels tight but you don’t realize you’ve got the gauge at a slight angle. The best suggestion I’ve read on the “feel”, is it should stutter/shudder when you pull it.



This is what worked well for me:


When setting the intakes (0.008-0.009”) I set it so it was pretty tight on the 0.009” gauge (I could pull it, but it was hard to push it, and it would feel stuck sometimes when I inadvertently had the gauge at a slight angle). I then confirmed the 0.010” wouldn’t fit… or I could just wedge it in a little bit. I then checked the 0.008” to see if I could get the stutter/shudder feel (make sure it wasn’t too tight).


When setting the exhaust (0.011” – 0.013”) I again set it so it was pretty tight on the 0.012” gauge – but not quite as tight as I did on the intakes (I realize that’s somewhat ambiguous) but I would get a feel for it so that after I set it, the 0.013 would just fit in, the 0.014 wouldn’t, and the 0.011 would only have a slight stutter/shudder.


Some things worth noting:


The service manual doesn’t explain how to actually remove the valve covers. It tells you to remove the coil wiring harness bolts, but it doesn’t explain that this is only to give you some extra room to try and slip the valve cover underneath it (at least I didn’t see how you could actually remove the wire harness). This makes it challenging to get the valve covers off and back on… especially the rear one with the VCM hardware. I really had to wrestle with the rear cover and I was getting worried I was damaging something in the process. I removed a wiring bracket from the front the engine to help give myself more room on the front bank.



There are a few plastic wire holder clips you need to remove. I broke two of them before I wised up and used an angled needle nose pliers to squeeze the tabs from behind.


The TDC indicator is challenging to view (I could only view it with a small shop mirror), but after turning the crank a few times I got a feel for when a TDC was approaching. The crank gets really hard to turn and then right after that it requires a little less force. It’s at this point I would stop and look at the indicator, and I was usually close… with just a couple of small turns required to get it to line up on the mark. I left the spark plugs in... [FONT=&quot]but I think the resistance is mostly due to valve spring forces, so I suspect the same feel would be there even with the plugs removed.[/FONT]


The service manual shows a picture using a mirror to measure and adjust the rear bank exhaust tappets. I found using a mirror very difficult, and I would only use it to check every now and then to confirm what I could feel. I found that if I pushed my forehead on the back edge of the engine compartment/hood interface, I could see the top of the tappet so getting a short screwdriver to adjust the tapped wasn’t too bad. I would use both hands to feel around and guide the gauge in. It was difficult, but after a while I got the hang of it.


Replacing the spark plug oil seals in the valve covers was tough… I ended up using a large flat head screwdriver and a wooden shim to carefully pry them out. It worked, but took a lot of time and I couldn’t avoid marring the bottom surface (I was able to not mar the sides, which I believe is the critical sealing area.) I also used an old seal to help drive in the new seal.


I’ll try to post a couple of pictures.

Chris