3GM30F Service Issue

[skunther]

I recently had my engine serviced to see if the source of mild but persistent light bluish white smoke in my exhaust could be addressed. The tech found the injector pump was leaking, so had that rebuilt by a local shop. In the interim I pulled my injectors to have them tested, and two failed and were also sent off for rebuild (I had replaced the other one, which had tested bad the year prior). When the pump was received, the tech installed it but could not get fuel to come out of it, so he sent it back to the shop and it turned out the throttle mechanism had been installed backwards in the rebuild. When that was fixed, it was installed along with the rebuilt injectors, and then the engine would start but extremely roughly and with a lot of darker grey smoke. The service manager checked the engine with the tech and determined that one of the injectors was leaking fuel into the cylinder while at rest and needed to be re-serviced. Once that was addressed, the service manager informed me the engine would start but seemed rough. It seemed that result was to their satisfaction and completed their work.
However, when I went to start the engine, I put the throttle at 1/2 per the service manager’s recommendation and cranked it for 10 seconds, then stopped to give it a break. On the second crank it started, but roughly, after 8 or so seconds. I ran it for 20 minutes and revved it up before cutting it off. I knew the starter battery wasn’t keeping a charge well, so the following day I replaced it with a new one and tried to start the engine again thinking more cranking amps might help. This time it wouldn’t catch or even sputter after 3 consecutive attempts of 10 seconds each. Not wanting to damage the engine, I stopped trying to start it.
In the past, every time I have started the engine up in the spring after sitting idle for the winter, it has started up within 5-7 seconds. Every time I have had the engine running, it has started up the next day instantly.
What could be the issue here? Both fuel filters have been recently replaced. The engine started up fine (though with some smoke, but always within 5-7 seconds of cranking) before the tech started working on it. After a week of unreturned emails and calls to them, I spoke with the GM and he said they would have another tech come and look at it. I don’t know that I have that much confidence at this point though - The service manager tried selling me on some not inexpensive modifications to the engine to improve its starting, but did not address why it now won’t start though it started up well enough before they worked on it.
Any input as to the potential starting issues here?

 

[Davidasailor26]

I wonder if it could be something as simple as washers having been reused or connections not having been tightened properly allowing air into the lines. That would explain some rough running, and also explain why the engine started once (maybe still close to when it was bled) but not again.

 

[Don Crowther]

I would check your work order for parts used or replaced. Like David said it could be old washers or fittings not tightened. You could try having a 12 volt inline electric pump installed. Just a thought.

 

[kloudie1]

Besides air leaks, just wondering if the injection pump timing is correct..?

 

[PNWE36]

Hello, I had this engine in my previous sailboat a Beneteau 331 which I owned from 500 hours to 2200 hours. I did most of the maintenance myself with technical advice from the local Yanmar dealer.
I started it once a month in the winter. Only time it was hard to start or ran rough was when it was less than 40 F and that was less than a minute. When it was warm it always started within a few seconds and ran smooth. Around 1800 hours it was getting harder to start at warmer temperatures and ran rough longer. I removed the injectors and the Yanmar dealer sent them to a local specialty shop. It was determined new ones were required. This corrected the problem.
It goes without saying that cleanliness is critical when working on fuel systems. A simple trick a Yanmar mechanic suggested that I did after changing filters and every spring is fill the primary filter bowl with injector cleaner and ran the engine for 20 min to let it work through the fuel system.
Do you know if the Techs checked the engine compression? This is critical on these engines and hard starting can be an indicator of low compression.
Also has anyone checked the condition of the exhaust elbow?
Lastly you might want to cut your losses and find a good Yanmar mechanic. The 3GM30F is an extremely reliable engine that is very easy to maintain/service. There must be other choices in the Bellingham area.

 

[PNWE36]

Also here is a link to an article on this engine in Practical Sailor magazine published Feb 29, 2024. I subscribe but an not sure if it will without a subscription. What Can Go Wrong With Your Yanmar? - Practical Sailor (practical-sailor.com)

 

[skunther]

[

Also here is a link to an article on this engine in Practical Sailor magazine published Feb 29, 2024. I subscribe but an not sure if it will without a subscription. What Can Go Wrong With Your Yanmar? - Practical Sailor (practical-sailor.com)

Hello, I had this engine in my previous sailboat a Beneteau 331 which I owned from 500 hours to 2200 hours. I did most of the maintenance myself with technical advice from the local Yanmar dealer.
I started it once a month in the winter. Only time it was hard to start or ran rough was when it was less than 40 F and that was less than a minute. When it was warm it always started within a few seconds and ran smooth. Around 1800 hours it was getting harder to start at warmer temperatures and ran rough longer. I removed the injectors and the Yanmar dealer sent them to a local specialty shop. It was determined new ones were required. This corrected the problem.
It goes without saying that cleanliness is critical when working on fuel systems. A simple trick a Yanmar mechanic suggested that I did after changing filters and every spring is fill the primary filter bowl with injector cleaner and ran the engine for 20 min to let it work through the fuel system.
Do you know if the Techs checked the engine compression? This is critical on these engines and hard starting can be an indicator of low compression.
Also has anyone checked the condition of the exhaust elbow?
Lastly you might want to cut your losses and find a good Yanmar mechanic. The 3GM30F is an extremely reliable engine that is very easy to maintain/service. There must be other choices in the Bellingham area.

Mixing elbow was also replaced. Compression was determined to be low, at ~160 per cylinder, but it would have had the same compression prior to work being performed, at which time the engine would start up fine.
Interesting regarding injector cleaner. Seems it couldn’t hurt, once I can get it started.
I wonder if air entering the system somehow is the culprit, as others have mentioned.

 

[Davidasailor26]

You didn’t mention any smoke after the last set of repairs. If that was the case and you’re also not seeing much unburnt fuel on the start attempts that leads me even more toward lack of fuel, like from air, rather than excess fuel or bad fuel spray like from bad injectors.

 

[skunther]

I did see some whispy white smoke hovering around the exhaust port after each failed attempt. See pic.

 

[Scott T-Bird]

When you pull out the injectors, there are 5 little parts inside each chamber that probably should be replaced any time you remove each injector. They are just little bits that I pulled out with a dental pick. It wouldn't surprise me if the mechanics didn't bother replacing these things. There is a copper washer, a little thing called a rear chamber, an isolator, a cover (a little thing that just looks like a little fabric washer). and an o-ring. I pulled all my injectors, had them tested, and then re-installed with all new parts (except the injectors because they tested fine). I did all this only because I had just purchased the boat and wanted to replace everything anything that was looking suspect (and I had an oil leak through the gear housing). I am not even close to resembling a mechanic, but with enough attention to detail, I found that there was a lot that I could accomplish and the engine ran like a top when I was done. I'm not suggesting that these little parts would have made a difference, but I wouldn't count it out either. Something tells me that finding a throttle mechanism installed backwards in the injector pump is just plain on the ridiculous side. Who makes that kind of mistake?

Hopefully, you have a better mechanic looking into it now. I found that the Parts Catalogue is just as important as the service manual for our engine. The service manual certainly provides instructions on how to service things, but the service manual does not come with a description and part number for every single part that goes on the engine. Only the Parts Catalogue defines every single part, no matter how small, and the diagrams show exactly how each part is assembled. For a rank amateur such as myself, the Parts Catalogue was essential.

 

[skunther]

On Thursday the shop sent another tech to check out the engine. First crank of 10 seconds produced nothing. He put a heat gun on the air intake, and it sputtered to life on 1 or 2 cylinders after 6 or so seconds cranking on the second try. One (or two) cylinder(s) wouldn’t catch though, and after 5 seconds of the engine running 3/4 throttle at 1200rpm, I reduced the throttle to 1/4 and the engine cut out. Tech, who seemed competent, was perplexed and said he heard some clanking while cranking which possibly indicated valves sticking, which he later determined was not the issue. We got it started again, and after the rough start, it did ultimately idle fine and sound normal.

He did say the low compression (160-180) of the cylinders may have been working well with the pre-rebuilt injector pump, and that the higher pressure of the rebuilt injector pump might not be interacting well with the low compression cylinders, resulting in the hard starting issue. Has anyone heard of this? It seems strange that rebuilding a leaky injector pump would cause the engine to start poorly when it was starting fine before.

Also, the compression didn’t pose a problem to the engine starting prior to them working on it. Could the compression somehow have dramatically dropped or suddenly become an issue to starting the engine after they started working on it? They’ve suggested the compression could be the cause of the poor starting, but the engine started fine before they worked on it.

Could I damage my engine by just powering through the rough start? Could they have damaged it in the same manner while working on it? As I said, the engine now seems to idle fine. The shop seems stumped about what is causing the hard start. They’ve suggested removing the injector pump and injectors to have them tested at another shop.

I just want my engine back...

 

[jssailem]

You say rough starting in cold weather, Do you have glow plugs?
When you look at the exhaust is there any fuel on the water (looking for too rich setting, unburnt fuel)?
You have changed several parts on the engine all associated with fuel delivery. I’d take some time to assess the performance of each of the changes before jumping further.

 

[skunther]

You say rough starting in cold weather, Do you have glow plugs?
When you look at the exhaust is there any fuel on the water (looking for too rich setting, unburnt fuel)?
You have changed several parts on the engine all associated with fuel delivery. I’d take some time to assess the performance of each of the changes before jumping further.

There is fuel sheen on the water at startup. This sheen subsequently seems to persist while idling.
No glow plugs. And rough starting period. This issue presented after work was done by a local shop starting last November. I don’t know that this is a cold weather issue as it hasn’t gotten warm yet. Regardless, I never had this issue before, whatever the weather.
All work has been done by a local shop. I removed the injectors, but they had them rebuilt and reinstalled them.

 

[Calif. Ted]

They’ve suggested removing the injector pump and injectors to have them tested at another shop.

Only had an injector pump rebuilt once on a Perkins decades ago, they sent a "tech" with white gloves to remove and take to the "Lab" for rebuild and "recalibration". You indicate they failed on the first attempt, if there is somewhere else this may be your best recourse. After using other diesels I was quite impressed with how quick Yanmars start.

 

[jssailem]

I had my high pressure pump and injectors serviced at.

https://www.seattleinjector.com/

 

[marcham]

Was the rebuilt pump correctly aligned
/ timed with the engine???

 

[jssailem]

Great query @marcham. Unless the mechanic was thoughtful to mark the pump timing position prior to removing it, and then made sure the marks were properly aligned it could be th source of your issue.

Here it a link to the Service Manual on the referenced engine number. Yanmar 3GM30F Service Manual - Catalina 320 International Association
Page 115 is the beginning of the Fuel Injection Pump. Page 118 shows an exploded image of the 3GM30 (F) pump. Timing is specified as 18º plus or minus 1º. The manual references a timing shim used to set the timing.

Timing could account for starting difficulties and unburnt fuel.

 

[Scott T-Bird]

Was the rebuilt pump correctly aligned
/ timed with the engine???

Excellent point! Yes, the timing shims are important. I pulled mine off carefully and originally intended to re-use them (as encouraged by at least one service advisor). It didn't matter how carefully I pried them off, they came off just a bit crumpled and deformed by some mild corrosion, I suppose. I debated with myself if I should re-use them or attempt to replace them in kind. I measured thicknesses very carefully and decided to buy the replacement kit and replace the exact number and thicknesses. My timing came out fine so I was happy about the decision to replace them.

It's a great question if your service technician made any changes in that regard.

 

[NCBrew]

I recently had my engine serviced to see if the source of mild but persistent light bluish white smoke in my exhaust could be addressed. The tech found the injector pump was leaking, so had that rebuilt by a local shop. In the interim I pulled my injectors to have them tested, and two failed and were also sent off for rebuild (I had replaced the other one, which had tested bad the year prior). When the pump was received, the tech installed it but could not get fuel to come out of it, so he sent it back to the shop and it turned out the throttle mechanism had been installed backwards in the rebuild. When that was fixed, it was installed along with the rebuilt injectors, and then the engine would start but extremely roughly and with a lot of darker grey smoke. The service manager checked the engine with the tech and determined that one of the injectors was leaking fuel into the cylinder while at rest and needed to be re-serviced. Once that was addressed, the service manager informed me the engine would start but seemed rough. It seemed that result was to their satisfaction and completed their work.
However, when I went to start the engine, I put the throttle at 1/2 per the service manager’s recommendation and cranked it for 10 seconds, then stopped to give it a break. On the second crank it started, but roughly, after 8 or so seconds. I ran it for 20 minutes and revved it up before cutting it off. I knew the starter battery wasn’t keeping a charge well, so the following day I replaced it with a new one and tried to start the engine again thinking more cranking amps might help. This time it wouldn’t catch or even sputter after 3 consecutive attempts of 10 seconds each. Not wanting to damage the engine, I stopped trying to start it.
In the past, every time I have started the engine up in the spring after sitting idle for the winter, it has started up within 5-7 seconds. Every time I have had the engine running, it has started up the next day instantly.
What could be the issue here? Both fuel filters have been recently replaced. The engine started up fine (though with some smoke, but always within 5-7 seconds of cranking) before the tech started working on it. After a week of unreturned emails and calls to them, I spoke with the GM and he said they would have another tech come and look at it. I don’t know that I have that much confidence at this point though - The service manager tried selling me on some not inexpensive modifications to the engine to improve its starting, but did not address why it now won’t start though it started up well enough before they worked on it.
Any input as to the potential starting issues here?

Your post sounds exactly the same as the problem I have, Same engine , white/bluish smoke.I have done much work on this engine. At this time I advance the throttle a slight amount and it starts with some smoke. I had the high pressure pump serviced and they said 2 of the pumps valves did not function and when I put it back on it started better. Also have the injectors serviced and mech said 2 of the 3 needed work.
I am starting to believe the mechs tell you this just to reassure you that you did the correct thing.
After reading your post and others replies, I am going to replace the shims under the high pressure pump, which controls the timing.
I will let you know if it starts better.

 

[skunther]

Excellent point! Yes, the timing shims are important. I pulled mine off carefully and originally intended to re-use them (as encouraged by at least one service advisor). It didn't matter how carefully I pried them off, they came off just a bit crumpled and deformed by some mild corrosion, I suppose. I debated with myself if I should re-use them or attempt to replace them in kind. I measured thicknesses very carefully and decided to buy the replacement kit and replace the exact number and thicknesses. My timing came out fine so I was happy about the decision to replace them.

It's a great question if your service technician made any changes in that regard.

The shop reused the same shims that were there before the pump was rebuilt. They said the timing should therefore be the same. Would rebuilding the pump necessitate re-setting the timing from scratch? Or should reusing the same shims be fine? The shop said when pumps are removed and replaced It is typically not necessary to adjust the shims once timing has been set initially.

Note that the engine, once started, seems to idle and run more or less fine. I plan to take it out of the slip tomorrow for a sea trial and see how the engine performs under load at cruising rpm, so I’ll have a better idea of how it is actually running then.

The tech did mention to me that a rebuilt injector pump can interact with cylinders differently than before, and that I possibly could have had a situation in which the pre-rebuild injector pump was somehow interacting better with the low compression cylinders (160, 170, 160) than the rebuilt injector pump is, resulting in poor starting. Does this make sense? I have a hard time wrapping my mind around this one. It doesn’t make sense to me that fixing a poorly running injector pump would cause the cylinders to suddenly fire improperly at startup.

Is compression of 160-170 problematic for these engines? If so, then why would it start up fine before, and what could have caused it to have such low compression? Engine had 2595 hours.

The startup does seem a bit rich, but really not much richer than it was before, when the engine was starting up fine. There is some light sheen in the water from some discharge, and some bluish whitish smoke, but not a ton. This was how it would start up before, the difference being it would always start up on all cylinders within 5-7 seconds of cranking, no matter how long it had been sitting. Now it won’t even sputter after 3 attempts of 10 seconds each.