getrdunn

iTrader: (7)

Did you use the old stick/bar method up to your ear to try and pin point the noise. It couldn't be a u-joint could it? It's one of those calls you have make. Either pull it and inspect the lower end or leave it pinned for a few minutes. LOL... That would at least rule out the internal wonders...

FIXX

iTrader: (2)

I have had a similar noise on cars,it turned out to be the starter's Bendix was to close to the flywheel,the bendix would be barely touching the flywheel's teeth..pull the starter and inspect the flywheel's front side of the teeth,should be shiny if the starter's bendix is making contact..

Also check the distributor bushings,they also go out,could be the rotor chaffing the cap..

olysan

Not u-joints. I pulled the outdrive yesterday and started it for a few seconds because I suspected u-joints or maybe gimbal bearing issues. i did run it up to 3000 rpm for a couple minutes yesterday, and it sounded really good, but at that speed it's hard to really issolate any strange noise.

I won't be able to get back to it until Wednesday. I'm thinking that I'll triple check my valvetrain and then check it again. Probably spin the oil pump with a drill to see if I'm getting oil at every push rod. If I don't find anything it's coming out next weekend.

BadDog

Sounds like you are on the right track, keep cutting the problem in half till you find it. I like your idea on running with the drill pump. Pull your spark plugs and use a remote start to roll your engine while priming, sometimes it needs to see a new hole to get the oil to flow well. I had a 454 in my Suburban that carried on with rattle when cold at low RPM. Sounded like a rod knock but finally tracked it down to fuel pump lobe on cam. You said noise sounded like rear near distributor so not that.


Pull one spark plug wire at a time while it is running and see if there is a change?

olysan

I did pull the plug wires one at a time while it was running Friday and there was no change.

olysan

I'm planning on takinng another run at this on Wednesday, and would like some input on what to check.

1. Would it make sense to do a vacuum test?
2. I plan to run it and use a stehoscope or something similar to try and pinpoint the noise. If I do great.
3. If not I will pull the exhaust and then valve covers and triple check valve adjustment.

If i still haven't figured this thing out I'm wondering if I should try pulling the heads before I take the entire engine out of the boat. It will probably end up being just about as much work but I won't have to go rent the lift which is a plus.

I'm leaning towards pulling and rebuilding because I wouldn't want to go through the trouble of pulling the heads etc and finding it's a bottom end problem.

Any and all feedback is appreciated.

Mike

BowenCT

I had a buddy with the exact same issue and was stummped the same way you are. He had a tick or clatter at idle and just over idle that sounded exactly like it was related to something in the valvetrain. As the RPMs came up, the sound would diminish.

He did head gaskets, all new valvetrain, lifters, pushrods, springs....they were checked, and tripple checked, everything was fine. Checked the flex plate, drive, distributor, timing, etc. You name it, it was looked at. Used a stethescope......everything! Oil pressure was good. Cut the oil filter to look for metal thinking maybe it was a bearing that had gone south.

After weeks of trying to diagnose, the motor was finally pulled and torn down. Turned out to be a broken piston ring! Off for a complete teardown and rebuild.

racer-x6

Have you checked the rocker arm to valve spring cap clearance. I have had a wrist pin start sticking one time the made the same noise, #8

TWIN-SPINS

how about an exhaust manifold leak,,,it will sound like a lifter ticking

olysan

Thanks for the replys.

Bowen - I'm seriously thinking that I might be in the same situation. Chasing this thing for weeks and ultimately pulling it anyway. I'm really thinking I should just yank it and disassemble this weekend.