loud valve chatter

[munkee]

My top end sounds like it is starving for oil?! I first noticed the sound last week when it was stalling. I don't have a problem with it stalling anymore but on occasion it makes a lot of noise. I test drove it yesterday for about 15 minutes and at the end of my drive, when I would come up to a stop you can really hear what sounds like the valve noise (chattering like and electric typewriter, cards in bicycle spokes, etc.)from inside the car. You can't hear it above 2500 rpms and every time I hear it I pull over to get under the hood and figure out where it's coming from. When you rev it it stays constant with the revs. After about 15 seconds at idle the noise goes away though and I can't tell exactly what it is. I pulled the oil fill cap off and no change in the noise and I could see oil. Any ideas? Can the oil pump be clogged or bad? I took it to the sho-dak meet in sioux falls today and I didn't have any problems or notice any noise all day until we got back home. I didn't notice any chatter when we got off of the interstate but it was definitely there 3 miles later at a four way stop. Where do I start with this problem?

 

[DavidT]

WOW! You have described to a T what I have! I sent a video clip to some sho knowledgeable people, and was told to inspect the timing chain tensioners. (slapping the valve covers). Of course, I have yet to open up the top end Without the aid of a stethoscope, the sound appears to be coming from under the rear valve cover on the drivers side.
Boy, when it wants to, it will make you cringe, won't it eek!
It is very spoaraidic (sp.?), but I think what sets it off is high rpms/ driven hard, not sure though.
I too am wondering about clogged oil passages. I installed an oil pressure guage to check the oil pressure. It appears to be fine. shrug
I am 400 miles into my first treatment of Auto RX. Wouldn't you know it that Friday when I pulled in the driveway it was going crazy! Keep us posted! ANd good luck! thumbup
EDIT* I noticed your model of sho... I wonder if that is coincidence??? Mine is a 1990 (white) with 156K miles.

<small>[ April 20, 2003, 10:53 PM: Message edited by: dkautumna ]</small>

 

[Off Road SHO]

Both you guys,

It's your timing chains at the back of your engine.

Get a long (3') , round wooden stick if you can't afford a mechanics stethescope. Put the stick up against the bulge in the valve cover at the back (driver side) of your engine. Put your ear up against the other end of the stick. You will here that intermittent knocking that you are describing.

You guys (everybody) really need to get a stethescope. You can pin point those pesky noises so easily with one. In fact I too have found that dreaded knock with my scope and am not looking forward to pulling everything apart. I might as well do the 60k top and bottom while I have it apart.

Tom

 

[munkee]

I think what sets it off is high rpms/ driven hard, not sure though.

I didn't really think about that before but I believe your right. Tom, I will probably be picking up a scope this weekend. I usually don't think about it when I am at sears or I would have gotten one a long time ago. Usually by the time I get the hood up though the noise is gone. It eases my mind knowing it's probably not something horrible. Thanks for the info!

 

[DavidT]

Usually by the time I get the hood up though the noise is gone.

Exactly! By the time I was able to start recoding the video clip, the scary noise had subsided, and just a little bit of it was left to document. shrug

 

[Off Road SHO]

Originally posted by dkautumna:

Boy, when it wants to, it will make you cringe, won't it eek!
It is very spoaraidic (sp.?), but I think what sets it off is high rpms/ driven hard, not sure though.


What probably is happening is after a "spirited" run, the cam chains are heated up and therefore longer. Because of this extra length, the intake to exhaust timing is out of synchronization.

It will "cycle" through tight and loose sessions with the loose sessions allowing the chains to slap against the tensioners. Just a guess, but you would do well to pull the covers and check to make sure you still have the plastic rubbing surfaces on the tensioners.

Tom

<small>[ April 22, 2003, 08:14 AM: Message edited by: ThomasDooley ]</small>

 

[sdpatt]

Slapping against the tensioners or against the underside of the valve covers? Only if the tensioners are not providing proper tension on the chains. This could be due to the rubbing block being excessively worn or the spring load against the block not being applied. Even a 269,000 mile old Gen I block looks like the one below. I have seen images in the Forum though, of the orange tinted blocks being completely worn down to the metal plate after far fewer miles.

<small>[ April 22, 2003, 12:21 PM: Message edited by: sdpatt ]</small>

 

[AutoSHO]

sdpatt:
Slapping against the tensioners or against the underside of the valve covers? Only if the tensioners are not providing proper tension on the chains. This could be due to the rubbing block being excessively worn or the spring load against the block not being applied. Even a 269,000 mile old Gen I block looks like the one below. I have seen images in the Forum though, of the orange tinted blocks being completely worn down to the metal plate after far fewer miles.

I am pretty sure it has to do with driving hard. When I changed the rod bearings in teh last car, I found the 2 ends of one of the cam chain tensioners in the oil pan. That car only had 94K miles on it, but had been supercharged before I got it. It did explain the weird noise I was hearing though!

 

[DavidT]

munkee, did you open up your valve covers and inspect the tensioners?

 

[oh_SHO]

What is the deal with the "oragne tinted" motors?

 

[munkee]

David, I did change my front tensioner on sunday and it made a difference. I put in a used tensioner in the front head. I figured it was the front head because I didn't have the noise until I put it in. While I was expecting to find lots of slop in the chain and a worn out tensioner, the problem is that the tensioner was fully extended and wouldn't compress. The chain was starting to eat through it in a hurry. I didn't change the chain and I wonder if maybe I should have because I still have a tapping noise on occasion but not nearly as bad as before. Whenever I shut the car off while it is tapping, it will also start tapping when I start it again, but it will only do it for a few seconds and then go away. I am wondering if maybe I have a partially blocked oil passage or something floating in the oil? I had to clean a lot of sludge out of the oil pan when I did the rod bearings because of the bad valve. Oh-sho, the orange tinted engine is caused by dirty oil leaving deposits baked onto your engine. A good oil (like castrol gtx) changed regularly will keep the engine nice and clean and keep wear parts from wearing out as fast.

 

[sdpatt]

oh_SHO:
What is the deal with the "oragne tinted" motors?

That was a reference to the orange tinted rubbing blocks on some timing chain tensioners versus the black blocks on others. I have found that the orange blocks wear more quckly than the black blocks.

 

[Yamaha V6]

Well, they're white blocks (new) now. wink

 

[DavidT]

did you take any pics?
Also, how hard was it? Can you give a quick step by step procedure... if so, that would be great!
Thanks for the update!

 

[DavidT]

munkee,
so was the source of most of your noise from the chain grinding on the fully extended tensioner? How could you tell it was fully extended? Is it suppose to be able to compress and relax when you have the valve covers open? (by hand?)
Did you buy a brand new tensioner to swap in there?
Was the valve train clean and shiny... OR brown and dirty?
Good job so far!

 

[munkee]

Well, I didn't take pictures. I probably should have. I unbolted the intake and propped it up with a 2x6 then removed the valve cover. The chain was tight and I tried compressing the tensioner but it wouldn't budge. When I got it out it finally loosened up and I could compress it fully with my fingers. The block was starting to look pretty shredded. I used the tensioner out of another head from a parts motor. First things first, I made some reference marks on both cams so I could be sure everything was lined back up when I was done. I used an inch and a sixteenth wrench when I had to turn the cams, a crescent wrench would work too. I didn't have metric wrenches that big. I removed the four 10mm bolts that hold the tensioner on, then removed the two 10mm bolts that hold the sprocket on the intake cam. (since the timing belt was on at the other end, I knew it wasn't going anywhere) That gave me plenty of slack in the chain to wiggle the old tensioner out, the replacement in and then reinstall the intake cam sprocket and bolt down the tensioner. You might have to wiggle the exhaust cam back and forth with the wrench to get enough play to remove the sprocket bolts. And if you can, wait till the engine is cool. wink I was surprised at how clean the head was. It was a lot dirtier when i put it on two weeks ago. It took me right at an hour from start to finish, and I was kind of surprised. Usually things don't go that well for me. No flying wrenches this time thumb ! The noise is pretty much gone now. I still get a tapping sound once in a while but it is a different sound and not nearly as bad. Hope your problem is fixed as easily.