Buffalo Dude

There's a rattling sound coming from what I think is the R side valve cover, or more accurately coming from underneath it. It comes and goes, but it sounds like a loose object bouncing around. It's gotten progressively worse, and used to only happen on startup so by the time I started and got under the hood, it was gone. Now it seems to be pretty consistent to when I'm driving. I've tried revving in park with the hood open, but it doesn't make the sound then. Short of something obvious (like a foreign object inside), what should I be looking for that's causing the noise in the valve-train?

Whoops! Meant to put this in C3 tech.

toolman1981

could be the oil baffel that rides between a couple of the rockers directly below the breather tube.

CheezMoe

Rocker Arm adjustment nut backing off. I would remove the valve cover and check all the rocker adjustments.

0Willcox Corvette

It may be some dirt in a lifter or a lifter not pumping up or leaking down.

Maybe a loose rocker arm nut as mentioned. I would pull the valve cover and inspect everything.

At first I thought you were talking about another noise so I posted a picture of the exhaust heat riser.

Willcox

Buffalo Dude

Can I run the engine without the valve cover on or is that going to spray oil everywhere and potentially cause a fire.


Sorry, I'm still pretty noob when it comes to anything outside an oil change.

0Willcox Corvette

You can run it and yes it will squirt some oil.

They make clips that snap on the rocker to deflect the oil, I'm sure Jegs maybe a local parts house will have some.

It might be a better idea to just run the valves again and see if one is loose! Do you know how to adjust the valves? If not post again.

Willcox

Buffalo Dude

Just pulled the cover off, nothing obviously loose. Pushrods still can be spun by hand, but no end play in the rocker arm.

I'm out of ideas. There's no signs of abnormal wear on any parts, nothing is obviously loose, no obvious foreign objects. Unless it's deeper in the cylinder head, like a bad valve, or something external like a loose exhaust clamp.

Thoughts? Ideas? Comments?

toolman1981

What octane gas are you running?.....My 81 diesels on anything less than 91.

This sympton would be more prevalent at startup, and when accelerating while at highway speeds.

Buffalo Dude

89, I've been told it's 10:1 compression. Bump up the octane?

Oil baffle feels pretty solid, but it does sound like rattling sheet metal. Any way to check the internals without destroying it?

toolman1981

Try running a tank of 91 or higher to see if that is indeed the problem.

In 77 the L-48 comp ratio is 8.5:1

while the L-82 comp ratio is 9.0:1

These are stock #s, if you have 10.0:1 ratio definitely bump it up only to point it stops knocking though.

Theres hardly any benefit from increasing to an octane higher than needed although some say it enables you to play with the timing a bit, but who wants to pay more than neccessary ga$?

GD70

Have someone start it cold in the morning with the valve cover off and lots of towels handy. Look & listen and have a socket wrench handy. You may be able to isolate it to a loose rocker and tighten the offending rocker down. If that's not it, you may need to go deeper into the head.
Good luck!
Glenn

my 76 ray

The original post says it comes and goes. It sounds like Wilcox has it right to me. Back in the old days we used "top oil" to clean the lifters. Sometimes it would clean it up and solve the problem.

Buffalo Dude

Still no clue on where the noise is coming from

I thought maybe it was the TC cover, so I pulled it off and it still makes the noise. It seems to only make it when the car is moving, and sounds speed dependent, like a grating sheetmetal noise.

wnmech

Have you checked out the heat riser for possible internal failure? It could possibly transmit a noise sounding like its coming from the valve cover. Just a thought

G dad

This happened to me.The rod that opens the heat riser was loose & rattling.

Buffalo Dude

No heat riser, headers to dual exhaust.

I took it to a shop, the guy looked at it for a minute, and then said it was the solenoid on the starter. I'll crawl underneath again today and take a peek.

Buffalo Dude

I took a peek underneath, and this is what I found:






Some of the teeth look like they have some minor wear on the engine side of the flexplate. The guy at the shop said it was most likely the starter gear flopping loose and rubbing on the flexplate, causing the rattling. What do you all think?

GD70

By the look of those scrape marks, sounds like a possibility. Change the solenoid (sp) as a start.

myk7

Check to make sure all your torque converter bolts are where they are supposed to be. Looks to me like you have something stuck between the flexplate and the engine block.

Buffalo Dude

I'll check the flexplate in detail as I pull things apart. As far as starters, I'd like to go with a mini high torque starter to get a little more clearance from the header. Most are inline mounting, but I've got staggered set up right now. Are those inline mounts that the oil pan is partially covering up? Will that be an issue?