I have a 2009 Fit with around 90k miles. The check engine light came on with a misfire code on cylinder 3, so I decided I'd replace the spark plugs, coils, and do a valve adjustment while I was in there.

The spark plug and coil for cylinder 3 had a lot of residue on it that the other cylinders didn't have, plus the plug was loose.

Anyway, after doing all that, I went for a test drive. On a short highway stint, got a check engine light and the car was down on power -- I couldn't really go past 30mph. Another cylinder 3 misfire code, I figured I'd open everything up to check my work.

The cylinder 3 spark plug has a bit of oily residue on it that the other plus didn't have.

Continuing on, I opened up the valve cover and saw that a lock nut was missing for one of the intake valves on cylinder 3. Looked around the area for the nut but couldn't find it, drained the oil hoping it would be in there but nope. I guess I didn't tighten it enough and it came off in the 20 minutes of driving.

At this point my plan is to get a new lock nut from Honda, readjust the valves, then reassemble and hope for the best. I figured if the engine hasn't died yet then maybe the nut is somewhere harmless?

My questions are: 1) is there anywhere else I should be looking for the lock nut but that doesn't require disassembling the engine, 2) how screwed am I if the nut is somewhere in the engine, and 3) is there anything else I need to check for the cylinder 3 misfire?

Thanks!

 

Try looking for the nut in the cylinder head it might still be up there?

 

Here's an image of the L15A7 cylinder head.. I do not see too many holes where the nut can fall into the crankcase. So you might be lucky and find the nut still on top in the cylinder head.




L15A7 Cylinder head, cam and rocker arms removed.

 

How hard is it to take the cam and rocker arms off, once you have the valve cover off? The valve adjustment is probably the most complicated thing I've done on my Fit -- would this be beyond my abilities?

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I don't know your level of skill so its hard for me to say. It's really not that hard.. (I think) once you have the valve cover off, there about 10 or 11 bolts that hold the rocker arms in.. Honestly I don't think you will need to take the cam out.. maybe just the rocker arms will give you better access.. if you can get one of those telescoping magnets or a flexible magnetic pickup tool.. You might be able to sweep it around in areas your finger cant reach and hopefully you can grab the nut with that if it did not fall down into the crank case yet.. lets hope that is the case. There is pools of black oil in the head.. so you might not be able to physically see it.. but it might be just laying around.

If it did fall down in the crankcase you can try using the flexible magnetic pick up tool thru the oil drain hole.. and hopefully you might get it that way..

Removing the cam will require removing a lot more stuff.. such as the crank pulley and the associated timing chain stuff.. I think before you remove anything try the flexible magnetic pick up tool.. see if you can get it without having to do extra steps of removing items.

On this forum.. There is a link to download the Factory Service Manual.. review the sections on how to properly remove the rocker arms.. several times so you get a good general idea on what to do before you start tearing it down.

 

Thanks for the suggestion. I'll try removing the rocker arm assembly to get some more room and try the magnetic pickup tool idea... hopefully it'll be there! I'll give an update in a week or so when I have a chance to get to it again.

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Get a strong magnet to check the top It's probably still there. Remember how that works, it's going to be the last place you look!

 

Strong magnet and a powerful light! Best of luck.

 

Just to update everyone...

I took off the rocker assembly for some extra room and uses a magnet to go around the top end, and I FOUND IT.

Of course since I'm an idiot, I used the wrong torque setting and ended up breaking half the bolts when reinstalling the rocker assembly.

So now I'm looking at either trying a bolt extractor or towing it to a shop. I'm afraid I'm just going to break more things at this point... anyone want to take it off my hands for cheap?

 

@clicq I was going to offer congratulations on finding the lock nut, but maybe I'll just go to church and light a candle for you.

 

Dude!!
oh.. oh that sucks.. Well, if you want to be a mechanical person, this is the fork in the road. If you weren't so damned far away I'd help you remove the fasteners. You need a screw/bolt extractor/extractor kit, a drill, drill bits for steel, a center punch (I'd recommend a starette from amazon), some penetrating oil, pliers, cutting oil, and a willingness to adapt to circumstances. Sometimes the fastener comes loose on the drill bit vs. the extractor. Sometimes the fastener binds to the extractor before you've reached reasonable depth. You may also have to drill the entire fastener out to shavings of threads (unlikely since you haven't been heat cycling it since snapping bolts, but possible). At any point, by any means, if it wants to come out then help it along.

Alternatively you can look for a welder, like at an exhaust shop, and they may help you or tell you the above. They may be super cool and say you can drop the car off! If not, and you get stuck visiting a machinist, they'll have you take the cylinder head off, and anything else that would be in the way (cams).. those guys are such jerks.

If you do the extractions, well first post up some good pictures of the damage!! But yeah, a thing of vital importance is getting your center punch as dead center as possible. And holding your drill as true as possible. That way if you do have to drill out the fastener wider than expected, or near fully, you won't damage internal threads in the cylinder head.

Although I don't believe myself to have snapped any fasteners in a while, I've done similar in the past. Did some extractions just last year that required pulling the engine to fit my drill. And yeah, the machine shop turned me out, and the exhaust shop welder told me some of the above.

Was a v6 with 6 or 8 (total) snapped exhaust manifold studs between (for) both cylinder heads. Drilling them all out took at least two days, but every single one came out and no threads were damaged by my work. After which I chased the threads of each hole with m8x1.25 grade 10.9 bolts I cut with a dremel and cutting wheel to put slots in.

Once they're removed and the threads are chased, maybe add some high temp hondabond to the new fasteners. You know, after cleaning them and their respective holes with some rubbing alcohol and letting them dry for a couple minutes. Torque to spec with a decent torque wrench

Edit: Oh, remember to start with the smallest drill bit and work your way up one size at a time until you can fit an appropriate extractor. And for the love of God, don't snap off a drill bit in the fastener or you'll be headed back to the welder in hopes of getting him to weld a nut onto it and work his magic. Use penetrating oil on the fastener at least 24 hours beforehand, cutting oil on the drill bit to reduce likelihood of binding the bit, and stop to re-lube and clean out shavings frequently as they pile up. A regular 3/8 drill can handle the job - drill medium speed, progress slowly. Tear-jerkingly slow. Don't force anything.
Alright, that should cover it.

 

Broken bolts can be a challenge even for a regular mechanic. Best of luck.