3GM30F Problems

onecoolair · Mar 23, 2013

Pheidingsfelder said:
Some of you may remember a thread I started a while back on my H34 3GM...

http://forums.hunter.sailboatowners.com/showthread.php?t=129163

Well, I completely rebuilt that one with about $2k in parts alone. Every thing that could be replaced was. Once it was all back together awaiting being dropped back into the boat, it was stolen.

Yep, stolen right out of a shed of my parents' sometime before Thanksgiving last year. (we got the call from the police Thanksgiving afternoon!)

Fast forward to today, I was able to find a local 3GM30F that I picked up for $900. It was from a marine salvage guy so the condition was unknown, only thing he said was it would crank but ran very rough.

I put a new starter, had all three injectors rebuilt and other random missing doodads.

I finally got a chance to try to get it cranked today. First issue was the electronics, I think the main switch on the panel is no good. Using a starter push button switch we were finally able to get it to turn over.

The engine will not turn over without having the decompression levers open. I'm not sure if that's a power connection issue, a valve issue, or a timing problem? I'm going to build some temporary battery terminals for troubleshooting instead of the jumper cables we're using.

I'm able to get it started by opening all the levers, spinning it, then closing them one by one. Closing #2 first seems to be the best every time.

Once it does get going it is running very rough and smokey. I'm not sure where to go from here as I don't really know the symptoms that lead to this state.
I do know 2 of the three injectors were totally bad and the third was on its way out. So, I'm contemplating pulling the injection pump to have it tested/rebuilt.
Only other idea would be to just go ahead and pull the head to have it rebuilt.

I put a couple of videos on youtube of it running so that may help with any advice!

http://youtu.be/oS01KBOjK0c

http://www.youtube.com/watch?v=7tBB-oyIvxU&feature=share&list=UU4rKWOguIdzujanL_-iKDiA

For a minute I thought you were going to say you bought it back your motor from the pawn shop

..... I hope home owners insurance covered your loss?
BTW...The only video that would play for me was about a hurricane. Running Windows 8

joker460 · Mar 23, 2013

Looks like white smoke which can be an indication of unburned fuel.
The unburned fuel condition can be caused by insufficient compression pressure (do a pressure test of each cylinder) or injection timing may be off (check timing).

Another condition that can cause white smoke is coolent leaking into the combustion chamber.

Good Luck

kloudie1 · Mar 23, 2013

Really bad luck !
Could hear on the video that it is running on 2 cylinders.. Start with the injector.. just because it was rebuilt doesn't mean that there is not something wrong with it now..It looks like a lot of fuel may be getting into #1 but not burning. You are probably correct with the valve diagnosis .. you can see an issue if you pull the cover off..and watch as you slowly roll the engine over. other than that and the possibility of a cracked head or blown head gasket, I wouldn't know.. A compression check is probably in order .. sorry to hear that your rebuilt was stolen.. Ya might want to report the serial number to Laborde in the event someone tries to buy parts..

joker460 · Mar 24, 2013

Correct, raising or lowering the injection pump retards or advances the timining.

I would suggest if you want to do this on your own, get the "Yanmar Diesel Inboard Shop Manual" from Clymer. You can get it on Amazon.com for about $25. It goes into detail on how to adjust the timing.

Good Luck

tomgrigsby · Mar 25, 2013

wondered if you've run a compression test yet? Also, might want to swap the #1 injector with one of the others and see if the problem moves with it. A good compression test and an injector swap will confirm what it isn't, and then consider going after the injection pump.

Snotter · Mar 25, 2013

If you do pull the high-pressure pump to get it rebuilt, you may not have to reshim the pump. I pulled the pump off of my old Onan engine to get rebuilt. City Diesel in Decatur, Al said they didn't think I would have to re-time the pump. I put the pump on using the old shims. The engine runs great and doesn't smoke.

anchorclanker · Mar 26, 2013

You have several indications of low compression that should be checked before going any further, until then everyone is guessing. I would also check the battery, cables and starter connections, make sure the starting system is up to snuff and spinning the engine fast enough.

The injectors can be disassembled and cleaned. You can visually, or with a magnifying glass, determine worn injector parts to a great enough degree you wont notice running performance problems. You can check spray pattern by turning the injectors away and cranking the engine. Most diesel shops or places that sell tractors can test the injectors after you clean them, to check break pressure and leakage.

In the following order... Check starting system. Check valve clearance. Compression check. While injectors are out, service them. Check pump timing. If compression is good and injectors pass muster, and after all checks are made problems continue, then, and only then look into the injection pump.

anchorclanker · Mar 30, 2013

If the engine only has 200 hours, its odd it has such low compression. Obviously you found an adapter for testing compression. If you can rig up a pressure supply and put each cylinder at TDC on compression, you could test for leakage and verify its the head or rings before pulling the head. If its the rings and its really that new of an engine, its possible that running it hard it could restore itself.

Don Crowther · Mar 30, 2013

If you can push the piston down. I think you could have a wrist pin problem or connecting rod bearings. Looks like you have it sitting on the ground so not to bad to pull the oil pan. If you pull the pan you can put an oil drain in while it's out.

tomgrigsby · Mar 31, 2013

Yup, you need to go into the bottom. Pull the pan and pop the bearing cap off for that piston. Mark bolts/nuts/rod for orientation so that everything is reassembled in the exact position it is now. Hopefully the crank isn't damaged. Check rod bearing clearance with micrometer or plastigage. Might be wrist pin. Let us know what you find. Glad you posted pictures.

anchorclanker · Mar 31, 2013

Woah woah woah. There is no possible way you have 1/4 inch play in the bottom end. First, the rod bearing couldnt offer that much room unless it was not there at all. The wrist pin could have that much, theoretically, but the bottom line is that the engine would have made so much knocking noise they would have heard it clanking a mile away!

Turn the crank by hand until each piston, in turn, is half way in its bore. Now, carefully and slowly rocking the crank right or left without moving the piston will indicate if there is in fact any reasonable play. Note also, the rings will make some noise as the piston reverses direction, often a clicking/snapping sound. But as noted, if the motor is out, just drop the pan and look at the rods and main bearings. NAPA sells "plastiguage", ask for it by that name. Get two or three different sizes. You remove a bearing cap, place the string on the bearing, reinstall the cap and re-torque the bolts. The string is squished flat to a width indicative of bearing clearance. Now remove and read the scale on the paper envelope the string came in. It will indicate oil clearance and is a very good indication of bearing wear as well as taper (wider or narrower across the face of the bearing).

It doesnt look like the tops of the pistons are wet with oil, so it appears it wasnt pumping oil past the rings. I would take a good look at the valves. Plain rubbing alcohol, carefully poured onto the inverted combustion chamber sitting on a bench so as not to spill, you should not see any leakage in the exhaust or intake ports through the valve seat. I am not sure what your seeing on that one piston, regarding play, but you may watch the crankshaft as you push and note if it turns. There should be minimal play at best. But if its out of the boat, now is the time to make it right, whatever that entails.

joker460 · Mar 31, 2013

Just an observation, What are those marks on the top of the piston head. They look like marks or stains caused by the Valves. These marks are absent on the other cylinders. Do you have photos of the heads?

3GM30F Problems

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