3GMF Problems

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May 7, 2011
45
Hunter 34 Long Beach, MS
I've just recently acquired my father's old '84 Hunter 34. Which had an owner between us. The boat went through Hurricane Katrina unscathed, the previous owner had the Yanmar 3GMF rebuilt. Im currently trying to get the motor turning over. I believe the pistons are seized possibly due to water intrusion through the exhaust during another hurricane we had that the boat may have been tied too tight with the rising surge.

I've pulled one injector but the other two are stuck. I tried bumping the starter but it won't turn over. I tried spinning the crankshaft by rotating the pulley nut clockwise.

I've read here that putting a diesel/oil mix in the cylinders then trying to spin it by hand may work?
Where can I get the special Yanmar injector pulling tool?
Is it possible for water to have risen into the exhaust and into the cylinders and caused them to seize, it's been about 3 years with zero activity. What else should I be looking at rebuild wise?
I hate to pull the heads and all since it was just redone.

Thanks!
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
Sorry to hear that it is stuck.. Yes, the water can come in through the exhaust and into the engine.. There was a lot of discussion on the site about this subject so if you search on “stuck engine” or frozen engine, you’ll find some posts.. Basically, this is a time for patience.. Put some light stuff, like Marvel or WD 40 or PB Blaster into the cylinder through the injector port.. On the other two with stuck injectors, spray PB Blaster around the joint where the injector is inserted into the head.. Let that sit a couple of days then tap the injector gently to break it free.. and pull it. Once you have those out, put light oil in those cylinders and let it sit a couple of days.. Pull the valve cover and make sure the valves are free by pushing down on the valve end of the rocker arms.. they should move and return when you release the arm.. It is OK to tap gently on the rocker arm (valve end) to un-stick You’ll have to pull the head if the valves can’t be freed up.. After the engine sits a while with the oil in the cylinders, try turning it over.. rock the crank clockwise and counterclockwise .. should break free.. Remove the raw water pump drive belt and the pump so you don’t flood the engine again by spinning it.. Replace the impeller while you have it out. (spinning the engine while the pump is functioning but without exhaust to blow the water out will flood the engine again) ..once you get the crank to turn, spin it over with the starter, decompression levers engaged, to pump oil to the bearings and stuff, and to clear the oil from the cylinders.. Re-install the injectors and bleed.. keep the decompression levers engaged because any residual oil in the cylinder will ignite if the engine is spun (even by hand or with a wrench) with compression .. This will hurt if you are doing this by hand, and it will throw a wrench! Be very careful.. After the injectors are in and bled, turn the compression back on and she should fire up.. Don’t run it longer than a few seconds .. kill it and re-install the raw water pump.. turn on the seacock.. Another caution.. know where the fuel kill lever is and be ready to use it if the engine wants to overspeed.. if the governor has rusted, the engine will “run away” unless it is stopped by turning off the fuel, or sticking a rag in the air intake. BE CAREFUL be patient and you’ll get her free ! Run till warm then change the oil and filter.. do that again after 5-10 hours.. Good Luck .
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Before you go tearing of more stuff lets diagnose the problem.
Is the problem that the engine will not turn (crankshaft is frozen) or you can't get the starter to turn it over? You said that you tried to turn it by hand but did not say if it turned. If it turns even a little you can probably get it started as it is not frozen. If it is frozen solid then they you have to proceed down Kloudie’s route HUGE difference in effort fixing one over the other.
Try this, compression rings leak but they leak slowly compared to how fast the engine is moving so it works at engine speed. You can apply torque to the crankshaft and slowly turn over the engine even if there is water filling the cylinder. The water just leaks past the rings and into the oil sump. Course you could also just hold down the compression release lever and accomplish the same thing. Some engines do not have compression release however.
So get the engine to go through one complete cycle (two revolutions) first by hand. If you can’t get it to turn then we will have to determine why it is frozen.
Good luck
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Did you pull some oil out through the dipstick? If water got into the cylinders then it would find its way into the oil. You should see beads of water on the dipstick. It will be hard to pull cold oil out of the pan but I would try before I started the engine with water in the pan.
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
Bil, 3 GMF does have compression release. I would not try to turn it over without pulling the compression release .. if it is hydro-locked, you can push the water out by turning it over with the compression pulled. .. but ya really have to stop the incoming water before ya do anything else.. pull the raw water pump..
Bill is right .. if it is hydro locked, it will behave as you describe.. I forgot to tell ya to pull the exhaust hose off the exhaust ell and make sure all the water is out of the hose before putting it back on.. Again, good luck ..
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
Why yes, I did hydro lock my 3 GMF while bleeding the diesel side.. It took a lot fewer revs than I guessed !! (yes I am embarrassed to admit that !!)
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
At this point we don't even know if it is rusted frozen, hydro locked or as I suspect just has a starter problem.
We have to determine what is wrong before we try and fix something that is not broken.
Pheidingsfelder did not mention that water came out the one injector that he managed to get off. I'd think he would note that fairly significant observation. He THINKS he has hydro lock but has no evidence to that effect.
So before we tell him to rebuild lets assertain the facts
 
May 7, 2011
45
Hunter 34 Long Beach, MS
So, when I tried to spin the engine by hand it wouldn't budge at all, either direction. That's what led me to believe it is locked up and possibly rusted. When I got to the motor the center injector had been broken free and was just loosely in the mount hole. The tip of the injector was wet and it was NOT diesel, with a slight rust. The previous owner monkied around with it and I think got fed up when the two injectors wouldn't come out. He suggests pulling the entire motor out, which will be my very last resort!
The motor isn't turning over by hand or the starter.
I'm going to proceed down Claude's directions as it seems to be exactly what I'm seeing on this motor.
Thanks again for all the info!

Pat
 

MitchM

.
Jan 20, 2005
1,009
Nauticat 321 pilothouse 32 Erie PA
a local yanmar dealer can order you up the service manual and parts manual on this 3 Gm , and can also get you the injector pulling tools that you amy need. yanmar east coast distributor MACK BORING in union nj has a tech assitance team that you can call and they can help you (at no charge) if you get stuck.
good luck...these are tough engines, a friend's got stuck underwater in FL after a hurricane and 2 months later they hauled it up and replaced the electrics, it was then running fine ..
 
May 7, 2011
45
Hunter 34 Long Beach, MS
Y'all are great! I figured I'd give a quick run down on the history of this boat and why I'm so excited to have the opportunity to have it back!

My father bought the bought after Hurricane George in Biloxi, MS around 1998/99. It sustained some hull damage to the port side, midship. It spent a few weeks/months in the yard with us glassing it piece by piece. I was about 15 at the time. This was not our first boat or Hunter for that matter, I've been sailing since before I could walk. This boat got me through high school! We had a great time on her.

I can't remember why we(my dad) decided to look for another boat, but we soon had a Hunter 40 that was trucked over from Jacksonville, FL and sold the 34 to a guy that became a family friend. He learned how to sail on her and loved every minute of it. After Hurricane Katrina the 40 had been destroyed and this 34 was gone, nowhere to be found. A few weeks into the Katrina aftermath here in MS, my dad gets a call from the Coast Guard saying they found his boat. Well, we knew that wasn't the case because we had already found it and scavenged what we could. Turns out they had found the H34 that was still in his name! This thing rode out the storm, rose with the tide and was gently let down between two small pine trees in the middle of nowhere! The owner at the time put some work back into her, but never really loved her again as he should.

The boat's been 3 slips down from my(and my father's) boat for the past 3 years and I've been eyeing it ever since! The owner got a super low offer from someone else and called us up to see if we wanted it back instead. Of COURSE I had to jump on it!

So besides the engine, it's going to need some other work but nothing extremely major, lifelines/stanchions, bow/stern pulpits, slight glass work, roach spray, etc, etc.

Thanks everyone for helping us get this boat back in shape and in the family!! Didn't intend to be this long, and probably should have put it in a better spot in the forum, woops!
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
Ahh.. Good note !! Good luck on the refit.. she'll do you good !!
Meant to mention that ya probably want to take off the exhaust riser at the back end of the exhaust manifold and get all the water out.. The exhaust manifold cannot drain because of the riser/elbow and will stay in there and can give you some heartburn before ya het it running.. and while ya have that off, make sure the insides of the elbow and the water injection entry are all clear.. Probably clean because of the fresh rebuild, but just takes a few minutes (remove hoses and pull 4 bolts on the back of the manifold) to make sure.
Again, welcome aboard and good luck.
 
May 7, 2011
45
Hunter 34 Long Beach, MS
I was planning on pulling the elbow and inspecting, but will make sure to drain any water in there as well.
I was also thinking of pulling the heat exchanger and possibly getting it cleaned out for good measure. We had tremendous problems once with a Perkins 4-108 until we got the heat exchanger thoroughly cleaned.
Does that happen often on these 3GMFs?
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
An additional techniques to free a stuck piston or crank.
Try an impact wrench on the crank (do not go overboard with this on)
take out the injectors to gain access to the piston tops (not always possible on all engines BTW), stick a brass rod that has been rounded on the end into the hole and contact the piston (pick the piston that is not at top or bottom dead center you want the one that is half way down the cylinder) and LIGHTLY tap on the rod with a mallet (don't go overboard with this one either)
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
My experience is that on a 3 GMF, the heat exchanger does not readily foul.. I have had mine out twice in the 20 years that I've owned the boat.. It was clean the first time and the blockage in the elbow was the problem.. It was clean the second time and the culprit causing the overheat was a leaking raw water strainer which allowed air in at higher RPM.. but was fine at lower speeds.. The strainer showed a very slight weep sometimes but I didn't think that could cause overheating until I read a post on this site a couple of years back about that exact thing.. If you do pull the heatex bundle, get your new gaskets before ya do that.. I would do it just to make sure there aren't pieces of a long ago impeller on the inlet side. You can use a 38 caliber brass pistol cleaning brush to clean out the tubes ID.. The OD is not easy to see because of the shroud over the tubes.. don't try to take the shroud off.. You should be able to see enough of the tube OD to see if it is fouling.. you can get a radiator shop to "boil" it carefully if you hve concerns about what you see.. OD side of tubes is the antifreeze side so it is usually fine..
 
May 7, 2011
45
Hunter 34 Long Beach, MS
Thanks again! Did a little more monkeying around this afternoon. Injectors are still stuck, I got a slide hammer on them but still no go. I pulled the valve cover and tried all the valves and they all operate just fine. Also checked the dipstick for water/oil and didn't find any signs of water in the oil.

I'll keep with the daily taps and PB Blaster on the injectors.
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
I think the decompression lever unseats the exhaust valves.. If ya can't soon get an injector out, you can pull the exhaust manifold/heeatex shell and squirt marvel into the bores through the exhaust ports..but.. I think you'll be able to get the injectors out with judicious applications of PB Blaster and taps and time.. Good luck.
 

lr172

.
Mar 24, 2011
56
Hunter 34 Lake Michigan
I had a similar water intrusion issue, but saw it happen and addressed right away before rusting / seizing. However, my injectors had never been out in 25 years. The issue on mine was the moderate corrosion on the surfaces (a tight tolerance fit) to a lesser degree and the the larger issue being the fusing of the o-ring to both steel surfaces. This oring takes out the slack and froms a tight fit. This makes vibration stiyle pulling ineffective. Get a wrench on the injector (there is a boss for this) and start going back and forth (clockwise / counter-clockwise). this worked for me and am confident will work for you.

I do a lot of engine work and unsticking cylindrical parts is almost always easier with radial force over axial

BTW, don't keep waiting for the PB blaster stuff. In deep corrosion, it just doesn't penetrate very far. I have pulled heavily rusted bolts via mechanical means that I had sprayed for days. Upon removal, it was apparent the stuff just didn't penetrate far (maybe 1/4" at most).
Larry
 
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