Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag pole

[familyguy]

My engine makes a sound just like a chain clanking against a flag pole in the wind. So, it's not really a "ping", but more like a "pong, p-p-pong, p-pong". It only starts after the engine warms up, and is only audible from idle 'till about 1,500 RPM at which point it's either gone or drowned out by normal engine noise. Otherwise, the engine starts, idles, and runs smooth. It seems like I'm always working on the boat, but the most recent repair before this started was a fuel pump replacement (it was definitely busted, refer to thread: http://forums.iboats.com/showthread.php?t=446061 if interested)

What I've tested:
-Used mechanics stethoscope all over the engine - unable to isolate origin of sound. I can't even tell if it's louder on one side of the engine or the other.
-Pulled the spark plugs. Noted to be correct ones per manual. Facing aft on right cylinder bank plug 1 tan colored. Plug 2 & 3 look charcoal black. The plugs down the left bank appear just like the ones on the right in the same order.
-Checked idle mixture screw on carb - found to be set rich -turned out from its seat twice what is spec'd in the manual. Set properly. No change in sound.
-Checked compression. Cylinders down right bank all around 170 psi. Cylinders down left bank are 185 psi on first 2, 180 on 3rd.
-Checked timing by total spark advance wihout shunt installed. Found to be retarded 4 degrees more than spec'd at 600, 1000, and 1500 RPM with engine warmed up. Turned distributor barely at all to set correctly. Still no change in sound.
-Pulled plugs again. On right bank plug 1 tan, plug 2 tan/black, plug 3 charcoal black (?). On left bank plug 1 cleanest of all - slightly tan, plugs 2 and 3 tan/black.*

Any ideas at all would be great. I'm going crazy.

 

[pwpns]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

Is the sound rhythmic or random?

 

[dakine]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

The only chain in your motor is your timing chain.
Usually, they just break without any noise to warn you.
Fairly easy to check.

 

[texomatom]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

Sounds like the exhaust flappers to me. Does the sound come from the exhaust Y-pipe (Up high, near the rear of the motor. I'm sure someone more post savvy can put up a picture

If so, it's nothing to worry about.

Tom

 

[GLENN M]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

diagnosing a sound you cant hear is tough,unless you have alucky guess,if its metal on metal sound i would start taking apart until i found problem,only other option run it til it breaks or fixes it self goodluck

 

[Bondo]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

diagnosing a sound you cant hear is tough,unless you have alucky guess

Ayuh,... Gotta Agree with that,...

Sounds like shutters, 'cept for the "It only starts after the engine warms up," part...

 

[familyguy]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

Thanks for the replies guys. It's not rhythmic. I listened with a mechanics stethoscope right where the exhaust flappers are and it wasn't obvious this was where it was coming from. It does sound like metal on metal. It only starts after the engine has warmed up. It sounds distinctly like a flagpole chain clinking in the wind.

 

[Lone Duck]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

Is that a metal or wooden flagpole? could it be a bearing rattle ?

 

[familyguy]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

Metal flagpole. When I get a chance, I was going to go over the engine again with my stethoscope - timing chain cover, exhaust flappers. I must admit, I'm not particularly fond of the idea of "just running it 'till something breaks", or "tearing down the engine 'till I find something" ideas, cause I can imagine kicking myself in the arse later when I go down either of these paths. There must be something to the fact the sound only surfaces when the engine is warmed up. It's much more audible in low RPM idle and really becomes difficult to hear around 1500 RPM. Anyone ever heard of a timing chain stretching out and causing a similar sound or maybe a valve rocker arm. Thanks again for the help.

 

[Don S]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

Might have a look at the starter. If the bendix isn't coming back all the way, the flywheel could hit the bendix as the engine vibration moves the bendix slightly.

 

[familyguy]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

Awesome. I wouldn't have guessed that in a million years. I did have the starter rebuilt (new bearings, brushes, drive, solenoid, bushings, used armature) about a year ago after it failed. I didn't want to trouble with shims installing an aftermarket one so went with a rebuild. The shop mechanic said he had to tear it down several times because he was having trouble with something rubbing inside it - said unexpectedly it was the armature.

It's dumping rain here and I'm working this weekend, but I'll pull the starter and check it the first chance I get. Thank you.

 

[telstar1]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

My 470 did exactly what you are describing after I changed to a different vibration damper. Figured it had to be timing chain but dissassembly showed no evidence of slack or hitting anything. Finally got rid of noise by changing to another vib damper.In my case the noise was more pronounced at front of eng. with stethescope but not all that much.

 

[familyguy]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

I'll check that also, thank you.

 

[familyguy]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

Thanks again for the replies gentleman, but...

...hats off to Don, you're spot on man.

Went over the engine again with the stethoscope - listened real close to the timing chain cover and exhaust flapper area. I think my starboard side flapper isn't too far from needing replacement. I hear a definite irregular rap from that area with the scope, but regarding the chain and flagpole sound described in the first post, it is not...

...I pulled the starter off and sure enough that starter ring gear slides forward on the pinion way too easily and when I take a metal object and tap the visible part of the flywheel it sounds dead on the same.

Too bad freezing weather is setting in tomorrow. Had to decommision the boat right when the fall striper run is really heating up. Oh well, there's always next year.

 

[familyguy]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

So, I took apart the starter to check if there was anything obviously misplaced or broken before taking it to the shop that did the rebuild a little over a year ago. Everything looked great though I did not notice any springs within the inner workings.

How does the starter pinion/ring gear that engages the flywheel get pulled back into the starter housing without the presence of some kind of return spring? Is the business end/movable plunger of the solenoid supposed to move freely, in and out of its body when not assembled to the starter or is the plunger supposed to remain extended until electricity is applied?

 

[Lou C]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

If you remove the solenoid there is a big spring inside that keeps the starter gear retracted until the solenoid is energized and then when the gear is moved into position the starter engages, that spring has to be in good shape.

Notice the position of the gear in this pic, that's how it should look when it's retracted, you can test it by hooking up a spare battery to the starter plus terminal and ground, then run a jumper wire from the plus battery cable to the S terminal on the solenoid, the starter gear should move foward and the starter should engage...

 

[familyguy]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

Copy that...

...is this starter (Delco Remy) off my boat supposed to have the spring on the drive or in the solenoid?

...Thanx!

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[Lou C]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

Could not see the attachments. The spring I am referring to is inside the area where the solenoid bolts to. If you take off the solenoid it should be right there. I can't imagine someone leaving out the spring, so maybe it broke and/or lost tension? Some replacement solenoids come with a new spring...

 

[familyguy]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

Thanks for the help. Yeah, there was no spring at all found when disassembled. I typed the OEM solenoid part # 3850216/3859054 in Google just a little while ago and all the pictures show the plunger extended so I think the return spring is inside the solenoid. When I hold the solenoid with the plunger out and shake I hear something rattling in there. The "new" solenoid the shop installed is a ZM 186012V. I'm wondering if I should just buy an OEM one or go back to the rebuid shop and get a discount priced one. I just want something that is going to last. I have only put about 13 hours on the engine since the last starter rebuild in 8/09.

 

[Lou C]

Re: Volvo penta 4.3 engine makes a sound just like a chain clanking against a flag po

Thanks for the help. Yeah, there was no spring at all found when disassembled. I typed the OEM solenoid part # 3850216/3859054 in Google just a little while ago and all the pictures show the plunger extended so I think the return spring is inside the solenoid. When I hold the solenoid with the plunger out and shake I hear something rattling in there. The "new" solenoid the shop installed is a ZM 186012V. I'm wondering if I should just buy an OEM one or go back to the rebuid shop and get a discount priced one. I just want something that is going to last. I have only put about 13 hours on the engine since the last starter rebuild in 8/09.

IF they worked on the starter last they should just put a new spring in for you and then test the starter to make sure the solenoid is good. I had a solenoid get rusted up on my MES starter because a bit of salt water dripped from the manifold drain right on the terminals and I just replaced the solenoid with a Sierra one for like 32 bucks, you can get them here on iboats or other vendors, it's a pretty easy job. Two bolts hold on the solenoid and there is a bolt that goes into a pair of terminals that has to be removed and replaced, that bolt has a copper tube on it and the bolt can be a little tricky to line up. If you do replace it yourself make sure the gasket is in place (you can put some sealer on it).