Yanmar 3GM30F – Tapping/Ticking/Knock Noise at Idle

[JonathanC]

Hello All-

I’m trying to track down a Tapping/Ticking/Knock noise at idle on our 3GM30F. The noise goes away when the engine comes up to RPM and it also goes away when we remove the #3 cylinder (by either the decompression value or removing the fuel load).

Here is where we are:
Have done a Valve Adjustment.
Have removed and had fuel shop check all Injectors.
Have removed and had fuel shop check Injector Pump.

Attached are two videos. One is the engine running and using the decompression valve to eliminate the noise (along with bringing the engine up to RPM). The second is removing the fuel load and having the noise go away.

I’ve done a lot of research online and have not come across any good info on the issue. I've read a few similar issues (a few on this forum also) that have the same type of noise, but nobody as mentioned they've been able to isolate it to a cylinder and the noise goes away when you use the decompression lever or remove the fuel load from that cylinder.

I’m headed down the boat next weekend to continue the journey and thought I’d see if anyone here has had a similar issue?

Any insights or advice is much appreciated.

Video #1
Video #2


Thanks

JC

[skipperpete]

Your audio links are missing. The 3GM is a rattler of an engine from new but if you’re able to pin a noise down to one specific cylinder it could be as simple as a tapping from an injector pipe not held by the line clamps or as complicated as a damaged precom chamber. Is there a notable loss of power, smoky exhaust or hard starting?[ATTACH]

[JonathanC]

Originally Posted by skipperpete

Your audio links are missing. The 3GM is a rattler of an engine from new but if you’re able to pin a noise down to one specific cylinder it could be as simple as a tapping from an injector pipe not held by the line clamps or as complicated as a damaged precom chamber. Is there a notable loss of power, smoky exhaust or hard starting?[ATTACH]

Hey SkipperPete
No smoak, loss of power or hard starting.

If you click on the Video 1 and Video 2 it will take you to my YouTube videos.

Thanks for taking the time to reply.

JC

[deblen]

The noise really sounds like a valve clearance/tappet noise,but I see you have adjusted the valve clearance.
The tap goes away when you apply decompress lever. The decompress lever holds the exhaust valve open & tightens that valves lifter mechanism.


I am not sure what you are doing with the fuel in second video.Could indicate HP fuel pump or injector trouble.



Have you tried operating the engine with the valve cover removed-to try & narrow the tapping location? Try pressing down on the rocker arms,etc. Look for loose/moving rocker shaft assy.



Use a mechanics stethoscope or long screwdriver held to ear to narrow the noise source.



Cheers/Len

[Emmalina]

Sure sounds like tappets to me but if its not causing any problems I would leave it. My engine has one cylinder that makes a lot of noise on tick-over been like that for 15 years LOL

[Fore and Aft]

JonathanC we have the Yanmar 2GM20F and its not as noisy as your engine. But it is noisy for the first 10-15 minutes then it seems to warm up and settle down? Certainly after a few good hours running it starts to sound like a sewing machine and just purrs along. What has a mechanic said? I have surveyed a few boats when mechanics have been onboard and what to me sounds like an issue they just laugh at my ignorance.
All else fails just turn the stereo up.
Cheers

[JonathanC]

Originally Posted by deblen

I am not sure what you are doing with the fuel in second video.Could indicate HP fuel pump or injector trouble.



Have you tried operating the engine with the valve cover removed-to try & narrow the tapping location? Try pressing down on the rocker arms,etc. Look for loose/moving rocker shaft assy.



Use a mechanics stethoscope or long screwdriver held to ear to narrow the noise source.



Cheers/Len

Thanks Deblen...
The second video, I'm cracking the fuel line to remove the fuel load to the #3 cylinder.

I'm headed back down to the boat this weekend and plan to use my stethoscope to pin point the noise.

JC

[JonathanC]

Originally Posted by Fore and Aft

JonathanC we have the Yanmar 2GM20F and its not as noisy as your engine. But it is noisy for the first 10-15 minutes then it seems to warm up and settle down? Certainly after a few good hours running it starts to sound like a sewing machine and just purrs along. What has a mechanic said? I have surveyed a few boats when mechanics have been onboard and what to me sounds like an issue they just laugh at my ignorance.
All else fails just turn the stereo up.
Cheers

Thanks Fore and Aft....
The mechanic that did the mechanical survey felt it was a Tappet Issue, which is why my first action was to do a Valve Adjustment.

After talking with another mechanic that knows Yanmars well, he felt if it was not a tappet noise the next route was fuel knock. That is when I decided to remove the fuel load to the #3 cylinder and the noise went away. We had the injectors checked out and they all were good. Then I pulled the Injector Pump out and had it checked. All good there also. He (current Mechanic) is having me put everything back together and check valve lash one more time and also do a VERY CLOSE inspection of everything on the top side of the head. Making sure all push rods, valve springs, rockers... ect look good.

And yes turning the stereo up is a tried and true method I used for years in wheeling Jeeps on the Rubicon.

JC

[SY Harmony]

I wouldn’t run it much more testing. It’s soo easy to pull the head and look inside. If you have decent pan access you can even pull that piston in place.

[JonathanC]

Originally Posted by SY Harmony

I wouldn’t run it much more testing. It’s soo easy to pull the head and look inside. If you have decent pan access you can even pull that piston in place.

Thanks SY Harmony....
We are quickly approaching that route. I've really not taken a good look at my pan access, but am going to look this weekend.
JC

[aqfishing]

Originally Posted by JonathanC

Thanks Deblen...
The second video, I'm cracking the fuel line to remove the fuel load to the #3 cylinder.

I'm headed back down to the boat this weekend and plan to use my stethoscope to pin point the noise.

JC

A short length of common 1/2” garden hose works wonders for this. Hold one end to your ear and move the other end around to locate the knock.

[JonathanC]

Originally Posted by aqfishing

A short length of common 1/2” garden hose works wonders for this. Hold one end to your ear and move the other end around to locate the knock.

Yes Sir... I have a piece packed along with my scope. I normally use a piece of 5/8 Heater Hose I keep around that is a pretty good length for me.

JC

[Scubaseas]

Might be a loose prechamber issue. Try taking the valve cover off and running it while pushing down on the push rod side of the rocker arm. This should help narrow it down to if the noise is lifter or pushrod related or not.

You could try adding a sealing ring/gasket between the injector and prechamber just to see if that changes the noise or not.

[JonathanC]

Originally Posted by Scubaseas

Might be a loose prechamber issue. Try taking the valve cover off and running it while pushing down on the push rod side of the rocker arm. This should help narrow it down to if the noise is lifter or pushrod related or not.

You could try adding a sealing ring/gasket between the injector and prechamber just to see if that changes the noise or not.

This is an interesting thought and a line of thinking I'd not considered. Thank you for replying.
JC

[SY Harmony]

Listening to your videos, the tap seems stronger than a valvetrain issue. I’d suspect a little water ingress from the head gasket or a low oil pressure / rod issue that clears with rpm and more oil.