The knock... Cam chain tensioner? Valves? My mind?

[MagnaMan]

OK. I know I'm going to be called a bike-rocondriac for this... but my engine has a little knock after it gets up to operating temperature. I've been ignoring it for about the last 4,000 miles.

Here are the conditions:
1. It  starts after the engine is good and hot.
2. Before Mootmag I changed out the plugs to make sure it was NOT faulty ignition. I also synced the carbs and performed the idle drop.
3. To make sure it wasn't the pre-ignition ping. I also switched to a higher grade of gas. In Houston they are cutting 10% ethanol into all the gas. I moved up to Premium and it got quieter... I think. But now even running Premium gas doesn't fix it.
4. The knock went away in Arkansas at MootMag I believe. It was cooler up there and their gas did not appear to be cut with ethanol. It could have also been that I was surrounded by other bikes and couldn't hear it.
5. I don't have a matching knock on the rear cylinders.

Other stuff:
1999 Magna with 12,150 miles.

I used a long screwdriver to listen to the engine at several points and I've isolated where I think the knock is the loudest. I'm attaching a pic from the manual showing the area:
www.staging.andell.com/bike/noise/mystery_noise.jpg

The knock really isn't that loud when sitting on the bike.  I had to get my video camera near the block to record it. Here's a link to an mp3 file: www.staging.andell.com/bike/noise/mystery_noise.mp3

The bike is running great. I've hit the rev limiter a few times, and I open it up wide at least once or twice a day, but when I'm commuting I consistently get over40 mpg. I have no complaints, but I'm wondering if this is a cam tensioner noise or valve noise based upon the location.

Questions
1. Any ideas?
2. Anyone know a good V4 mechanic in the Houston area? I haven' been impressed with my local dealership's knowledge of V4s.

[John Luttrell]

You need a cam chain tensioner; easy fix.

[kdf9511]

Wrenching session?

[MagnaMan]

John. Can the tentioner be adjusted or do you just replace the whole unit?

Does it involve pulling the cam?

Kerry. This could be one heck of a wrenching session item.

[John Luttrell]

It is an automatic tensioner with no adjustment; usually what happens is the spring breaks inside the automatic adjuster. Luckly it is an easy fix.  You do not have to remove the cams to change it; there is a special tool that you can make to install the new tensioner; it is in the service manual.  Let me know if you do not have access to a manual.

[MagnaMan]

Thanks, John. I have the manual. I'll read up on that section. Since I don't have to pull the cams you just saved me some money... I was seriously thinking... "If I have to pull the cams maybe I should get Dave Dodge's cam for a stock engine setup?!"  

I'm still undecided about this. I posted this to another forum and one guy says he has a 2003 that's made that noise every since he bought it. Evidently Honda wouldn't fix it even when it was under warranty. He says he still has the noise and hasn't bothered fixing it.  

On the other hand, another guy had a cam tensioner go out. He thinks my knock sounds like his engine did. Luckily he lived near Dave Dodge. And Dave told him that with the tensioner out the cam chain could've jumped the gear and that would have really messed up the engine.

Hmm.  What to do. What to do.  I've sent the sound file to Dave to ask his opinion as well. We'll see.

[John Luttrell]

I have seen a few tensioners go bad, and not a one of them jumped time; even after a lot of miles on it with a bad tensioner.  In fact if it jumped time you'd know it; it would run like crap and be very hard to start if at all.  Save the money and time; buy a tensioner and get back on the road.

[kdf9511]

I thought it sounded like something you could use help with.  Plus a few others might find it helpful if they ever have to do it.  I know even with it being a 3rd gen watching Mark and BamBam pull his carbs made me not quite as leary about pulling mine.

Edit:  Even if we don't do a wrenching session.  Let me know if you need help and I will see what I can do.

[MagnaMan]

You got that right, Kerry. It's definitely something I would need help with. Plus it would make an interesting wrenching session.

Looks like the tensioner is about $75 from a mail order place. John, are there any other parts I should look at getting? The micro fiche is here:
http://www.staging.andell.com/bike/noise/2947_cam_chain.gif

[John Luttrell]

The part you need is "index 7",  not the "index 4" that you have high lighted. Look at page 8-2 in the service manual, it is index 16 in that diagram.  Page 8-11 covers the removal and replacement, as well as the tool you need to make.

[MagnaMan]

Ah. Index 4 was listed as the tensioner. Index 7 is called the lifter assembly.  That doesn't look near as hard to get to and I do recall seeing that in the manual... And it's only $52.  Even better.

I'm going to take a look at the manual today. Thanks again, John.

[rjb/AKA Bob Barram]

Way to go John!!
I love the way MOOT works!
Bob

[MagnaMan]

Well... Honda of Houston did hear the knock (barely) and they said it could be about 5 things.

The first two are cheap: and that's a valve adjustment or cam chain tensioners. The others involve more serious engine issues which I seriously doubt are the case due to the low miles on the engine.

What they want to do is have me pay for about $3 hours ($180) of time and they're have their V4 guru tear into it and he can figure it out. I was glad to hear they even have a V4 guru.

Otherwise I can wait until the knock gets louder and it's easier for them to isolate.  I'd ignore it exept for the fact that if it's a cam chain tensioner I don't want the chain vibrating around scraping off metal.  Right now I'm thinking I may try the valve adjustment myself and possibly replace the cam tensioner. After all, their V4 guru can't even look at my bike for a week and a half. That gives me two weekends to get something done.

Anyone up for a wrenching session on August 12th?

[Charles S Otwell]

Is the $180.00 to tear into it and figure it out and fix it, or just figure it out? The honda shop in Texarkana won't even work on one as old as my 87 ,but if they did, a valve adjustment it would be about 5 hrs at $60.00 an hr. Greg said figure about half a day to tear into it and adjust the valves,if you add the tensioner how much more time would you be adding?

[MagnaMan]

The $180 is just to figure it out. If it takes less time then they'll charge me less, but I don't expect that to happen.

I'm going to read up on what's involved on the valve adjustment and the cam  chain tensioner, and decide what to do. I think some Mootster down here in the Houston area has done a valve adjustment.