Yanmar 3GM30F – Tapping/Ticking Noise at Idle

[JonathanCarlos]

Hello All-

I’m trying to track down a Tapping/Ticking 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’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

 

[Loren Beach]

Interesting that you can cause it to appear and then disappear. Which boat model?
Where located? And about how many hours?


Puzzling indeed.

 

[JonathanCarlos]

It’s in a 36c

 

[Pete the Cat]

It seems to be affecting the intake valve of that one cylinder. Seems like either the valve spring or guide might be compromised or just dirty on that intake valve. Or it could be the injector has been compromised--dirt or spring. Not sure if you are supposed to try to run that engine with the compression release valve open--on some diesels this is a no no. . Based on what I see, i might try switching an injector to see if the problem moves to rule out injector problem. If it did not, I would more carefully test the valve gap with the engine running to see if it is fulling seating. I am thinking it might be just some crud fell in the guide or a little something under the edge of the valve seat that compresses when accelerated. Could be dirt in the line between the injector pump and injector (has it been off recently?) so the cylinder is getting enough fuel to fire at some RPM but not enough at low RPM to completely fill the cylinder. Hard to diagnose with out hands on. Start with the easiest possibility first. You can run the injector out of the engine to test it--should produce a pear shaped mist of diesel always--never a dribble at low RPM. I know I have given too many options. This does not seem serious.

 

[JonathanCarlos]

Interesting that you can cause it to appear and then disappear. Which boat model?
Where located? And about how many hours?


Puzzling indeed.

It’s a 36c with 900 hours. Located in Southern California.

 

[JonathanCarlos]

It seems to be affecting the intake valve of that one cylinder. Seems like either the valve spring or guide might be compromised or just dirty on that intake valve. Or it could be the injector has been compromised--dirt or spring. Not sure if you are supposed to try to run that engine with the compression release valve open--on some diesels this is a no no. . Based on what I see, i might try switching an injector to see if the problem moves to rule out injector problem. If it did not, I would more carefully test the valve gap with the engine running to see if it is fulling seating. I am thinking it might be just some crud fell in the guide or a little something under the edge of the valve seat that compresses when accelerated. Could be dirt in the line between the injector pump and injector (has it been off recently?) so the cylinder is getting enough fuel to fire at some RPM but not enough at low RPM to completely fill the cylinder. Hard to diagnose with out hands on. Start with the easiest possibility first. You can run the injector out of the engine to test it--should produce a pear shaped mist of diesel always--never a dribble at low RPM. I know I have given too many options. This does not seem serious.

All good trains of thought. My trip down next weekend I plan to do a super inspection of the springs, push rods and rocker arms. Also taking a bore camera and try to get a look at the valve seats.
The injectors and Injector Pump have been sent to a fuel shop in Southern California and checked out great.
JC

 

[JonathanCarlos]

Alright everyone… here is the current update. Just returned from 3 days on the boat.

Got the rebuilt Injector Pump installed along with the cleaned and rebuilt Injectors. I did not mess with the sims under the pump so the timing should be the same as when I took it all apart. I installed new insulator and copper thin washer between the injectors and the precombustion chambers. The precombustion chambers actually came out pretty easy so I was able to look under them. Not a lot of carbon build up, which was nice and also why they came out so easy.

Also installed all new fuel filters. Bleed the system and started it up.

The noise is still there. However now when I use the decompression lever or remove the fuel load buy cracking the supply line the noise does NOT go away… What? Took me by surprise for sure. So now I’m getting deep into research one what are all the eliminates that can cause fuel knock? Is the timing correct?... has it been wrong for some time? Is something going on under the precombustion chamber? Am I getting air in the system somewhere? I’m spending lots of time on the web reading anything I can about this.

I also took a piece of hose and listened anywhere on the engine I could try and get a radiating sound from. The only place I could get the audible knock/tap noise from was the snout of the crankshaft where it attaches to the pulley. Which still give me a broad spectrum to go off because a lot is connected to that. The noise radiating there could be, rod bearing, crank bearing, fuel knock, piston slap, wrist pin slap… anything that is connected to the rotating assembly.

I also forgot to mention earlier that I had an Oil Sample pulled and tested. It came back totally fine which give me hope there is not a bearing going bad. I can share those result if anyone is interested.

Thanks again for taking this journey with me….

JC

 

[Frank Langer]

Wow! Pretty impressive diagnostic work! I hope you find the source soon.
Frank

 

[bigd14]

Fascinating. It will be interesting to see what you find in the end.

My M18 sounds like that all the time, which I understand (hope?) is normal for the Universal Diesels.

 

[Greg J]

It could potentially be a sticky lifter or a push rod issue. I'm not super familiar with yanmars though, but I have plenty of experience with other diesels.
Is the engine running oddly at all?

 

[JonathanCarlos]

@GregJ
Engine runs good outside the nosie....

 

[Pete the Cat]

I take it you are convinced it is not valve guide or valve spring problem. Did the problem suddenly appear or has it been gradually getting worse?

 

[JonathanCarlos]

I inspected the springs and they look good. Valve guide could be an issue, but with less than 900 hours on the engine I would not expect a failure?
The engine was like this when I bought the boat. PO said it was like that when he bought it in 2020 and was told it was just a noisy Yanmar. He brought it down from Portland to So Cal with it and had to motor a lot. Never bothered him, I just want a smooth engine.
JC

 

[goldenstate]

My Yanmar 3GM30F sounds the same idling at startup.
After warming it up and motoring at higher RPM the tapping goes away.
I do not worry about it excessively and it has never been a problem.

It does seem interesting that the noise goes away when you open the compression lever on the first cylinder.
I'll have to try that and see if it makes any difference.

 

[Pete the Cat]

I inspected the springs and they look good. Valve guide could be an issue, but with less than 900 hours on the engine I would not expect a failure?
The engine was like this when I bought the boat. PO said it was like that when he bought it in 2020 and was told it was just a noisy Yanmar. He brought it down from Portland to So Cal with it and had to motor a lot. Never bothered him, I just want a smooth engine.
JC

In general, according to my grizzled old diesel mechanic friends, hearing a bit of valve clatter from a small diesel at start up is better than having an absolutely quiet valve train at that point. I think their thinking is obvious. As long as the engine idles smoothly the the noise is unlikely to be hurting anything if it is not severe. My 25XP has a bit of clatter for the first minute or two at start up and I ignore it. I have Yanmar 3JH4E on my Tartan that makes some minor noise at startup in the same manner. i have set the valves on both to spec. FWIW.

 

[bsangs]

My 3GM30F - from 2003 - makes this exact noise during startup, but it eventually subsides. My mechanic, who specializes in Yanmars, says there's nothing abnormal about it, and there's no need for concern.

 

[Christian Williams]

I wonder if Loren's brand new Beta diesel makes any ticking sounds at idle. My Universal diesels (M25 and 5432), to a worried ear, can sound like bottle tops caught in an InSinkErator. But to a non-worried ear, it's just noise. Improved sound insulation reduces it. And Bose noise-cancelling headphones, if trying to sleep....

Once real issues are eliminated, I take comfort in the vast numbers of noisy diesels in the industrialized world. And in this sort of rationale...

 

[Loren Beach]

I have not noticed any worse pre-detonation than our former Universal, but that M25XP model was also based on a Kubota block. All these engines seem to smooth out as revs go up and when they are put under load. A mechanic friend of mine refers to the clatter at idle as "popping" and sez that's (completely) normal and expected.
One nice thing about the new Betamarine (and perhaps any other brand of new engine) is the generally lower noise lever overall. Absent any "new" sounds unexpectedly coming from it... it is indeed all just 'noise' to me.

 

[JonathanCarlos]

So the latest on the noise:

I had the injector pump and all 3 injectors checked and rebuilt.

Reinstalled everything leaving the same shims for the pump along with new insulators and packing for the injectors. Installed two new fuel filters. Bleed the system. She fired right up. The noise is still there and now I cannot get it to go away when I do the decompression valve or eliminate the fuel from the #3 (or any) cylinder. What? The only thing I did was make the injector pump and injectors better and I feel like a took a step back. Gotta love engines.

Interesting to say the least. Headed back down to the boat this weekend to scratch my head more.



JC

 

[Pete the Cat]

So the latest on the noise:

I had the injector pump and all 3 injectors checked and rebuilt.

Reinstalled everything leaving the same shims for the pump along with new insulators and packing for the injectors. Installed two new fuel filters. Bleed the system. She fired right up. The noise is still there and now I cannot get it to go away when I do the decompression valve or eliminate the fuel from the #3 (or any) cylinder. What? The only thing I did was make the injector pump and injectors better and I feel like a took a step back. Gotta love engines.

Interesting to say the least. Headed back down to the boat this weekend to scratch my head more.



JC

Would it be possible for you to post a video of the engine with sound at various RPM? I just chased down a knock in my 25XP at a certain RPM that your posts had caused my mouth to go dry: turned out to be a sympathetic rattle in a door frame--this suddenly appeared and sounded for all the world like it was coming from a rod bearing. Not suggesting that there is any parallel in your case, but it would be interesting to hear the actual noise. There is a particular sound of combustion that is different from valve train noise, I am told. Not sure I could tell. At some point, I might suggest you try to find a very old, very experienced marine diesel mechanic to put your mind at rest. But I would be interested in a video of your most recent sounds and motion. Yanmars have very different motor mounts than the converted tractor engines and they shake at idle like crazy. Yanmar engineers have told me this is their commitment not to transfer the natural violent vibration of diesel combustion to the boat--but that shaking should not affect the sound--at cruise RPM they should be somewhat quieter.