Yanmar 2gm question

[Tartan 30]

Hello,
New to this site, so I hope this question hasn't been asked and answered already.
(didn't find it with the search function)
I have a new-to-me tartan 30 with a yanmar 2gm. It starts hard and has some miles, so I'm thinking I might pull the head and clean it up.
I've done some research and have ruled out many of the usual suspects: air leaks, dirty filters, bad fuel.
So my question is this: does anyone know roughly how long a job like this takes. There are a couple of youtube videos on it, and i'm guessing it might be about two six hour days.
Does that seem reasonable?
Thanks for any insights,
Gary

 

[heritage]

I would remove the injectors and have them checked before removing the head. Cleaned injectors solved my 2gm20f starting problems.

 

[seadaddler]

What is removing the head going to do.
Did you check anything else like the mixing elbo or fuel filters
or did what else have you checked.
Nick

 

[Charles Erwin]

Compression test numbers? Excessive oil consumption? Water in oil? If these things measure up leave the head in place. But do set the valve lash.

Charles

 

[kloudie1]

timing more like 3 days.. unless you are familiar with the engine, have great access to it, and have all the correct tools..

 

[Tartan 30]

Thank you for all of your responses.
I'm thinking that I will back up a bit and go over some of the things you mentioned, like injectors, compression and the mixing elbow – and then pull the head if the problem persists.
I''ve always had atomic fours, so I've got a lot to learn about diesels. I like to jump into things like this, and sometimes jump to quickly.
So, I'm sure I will have lots more questions and you will hear from me soon.
Thanks once again,
Gary

 

[Sailm8]

What is your starting procedure? Mine starts easiest if I give it a little throttle. Also does it turn over at a decent speed of does it crank slowly? You could be suffering from low voltage at the starter. Some owners have installed a dedicated wire from the switch to the solenoid. Check the archives for more info.

 

[Benny17441]

Yanmars do not have glow plugs so they ignite the fuel by compressing and heating the air. The engine builds compression by a number of successive revolutions until adequate heat is built up. An engine with low compression will be harder to start but there are also other factors that could cause hard start. A starter motor that is cranking at slow speed due to worn brushes, bad bearings or low battery voltage. A very thick oil in the cranckcase combined with low water temperatures will act like molasses and slow cranking speed. Low compression in an engine could be due to worn compression rings or sticking or leaking valves or using too thin an oil. First determine if the engine smokes or has excessive back pressure. Look at the exhaust for gray smoke and remove the oil filler cap and place the palm of your hand about 3-4 inches from the opening. If you feel strong pulses of air your rings are likely worn and a gentle pulse and no smoke would signal they are OK. I have given engines with worn rings an extension in their useful life by switching to a thicker SAE oil. A thicker oil will increase compression by reducing blowback. To thick of an oil will also slow engine cranking so a balance must be maintained. Try a 20W40 with a thickening oil additive. Make sure the air filter and the intake tube are not restricted. I would only consider pulling the head if it was determined the valves needed honing or replacing. As far as clearing carbon take the boat out and run at WOT for a couple of hours. Hope to have given you some ideas.

 

[Terry Cox]

The 2GM engine on our previous boat was always hard starting when cold. She fired right up when warm. When cold I had to move to at least half throttle before beginning to crank. It then took five to seven rotations before she would even begin to fire, but she would always start..

 

[Tartan 30]

Thank you, all.
I took the boat out today and ran it for more than an hour at 2,500 to 3,000 rpm. It still starts hard, but there is a definite difference in the way it sounds: quieter and smoother.
I'm thinking it might be an injector because it sounds like one cylinder wants to get going pretty quickly, but the other is failing to catch until the fifth or sixth try.
I haven't pulled the injectors yet, but plan to in the next couple of days.
So, my question now is: Are they hard to disassemble, clean and reassemble.
I've watched a couple of youtube videos, and it seems pretty straightforward.

 

[Mickstr]

Mixing elbow. I had the exact same problem on my 2GM20F. The mixing elbow is probably clogged pretty good. Symptoms for me was hard starting, and some white smoke in aft cylinder (closest to mixing elbow) injector suffering from back pressure. Take the mixing elbow off (4 bolts, easy access) and take a look. I replaced it and my problem was resolved.

 

[heritage]

I took my injectors to a diesel shop. They replaced the nozzles, cleaned, and tested for less than $200 for the pair.

 

[JimInPB]

+1 on taking your injectors to a shop that has a flow bench. I used to have a guy in Phoenix that would referb injectors for $50 a pop.

 

[NYSail]

Start by pouring a half can of sea foam in your primary fuel filter and the rest in the tank and run engine..... it will do a pretty good job cleaning the injectors. Check the mixing elbow.... a clogged elbow causes many problems. And remember just because you get good water flow doesn’t mean the exhaust side isn’t clogged...... and again as mentioned check batteries.....
Start simple.... that’s usually where the problem is.

Good luck
Greg

 

[dLj]

I do almost all work myself and would never do my own rebuild on injectors. I feel injectors are best rebuilt by a pro in a shop setup to work on them. Just my 2 cents...

dj

 

[JimInPB]

About 8 or 10 years ago, I was in a place where I had access to a small machine shop, but not access to an injector shop. I googled around & found some information on building a flow bench. Then I built one. I managed to get my own injectors fixed back up again & the motor ran well after that, but I would not duplicate that little adventure if I had a viable alternative. Getting the flow bench right was not a 5-minute job. +1 on the above statement. Let a pro do it.

 

[NYSail]

Injector rebuild..... anchor redesign...... I leave this stuff to the guys that do it for a living. Just have to find the right guy.