Yanmar 3gm 30 engine seized
- Thread starter hunter healer
- Start date
If you can turn it 30 degrees it’s not really “seized” in the frozen /corroded sense. If you have the injectors out and still have the problem it’s not hydrolocked or in need of decompression. I don’t know exactly where the valves are relative to the piston travel, but my guess is that a valve is stuck open or something like that, stopping rotation. If that’s the case then when you pull the head it should spin freely. Then you just need to figure out what was stuck.
Thank you, I'm not a master mechanic but have been around cars since I was a teen. I'll keep you posted, tx
"bumping" the pistons with a hammer and a wood block will likely loosen things up, if this is the reason for it not turning over, but there is a very good chance you will also break the rings while doing this, be prepared to do a rebuild.
Thank you, I was able to open the link to the manuals on my smart home but when I tried to forward it to my laptop I could not get it to open. Would you please be able to re send it to my email again then I will open it on my laptop. Many thanks,
I'm getting ready to pull the head Off the yanmar 3gm. I am curious if there is something that moves as the crank rotates like the pinion gear shaft gear that operates the fuel injection pump I'm still puzzled on this. Thinking there is something
You can check for a stuck valve with out pulling the head. The valve would have to be stuck in the open position to interfere with the piston (and stop rotation). Check the rockers for a really loose one.
When you rotate the crank 5 degrees back and forth does it stop soft (friction increasing) or like is it a hard stop (hitting something )?
Other things to check that might help diagnose.
does the camshaft rotate at all when you rock the crankshaft?
any really loose rockers?
does the raw water pump turn at all when you rock the crankshaft? (assuming you have a gear driven pump)
is the transmission in neutral?
any tight push rods that cannot be rotated in their passages? Use a cloth and pliers so as to not nick the rods when trying to turn them.
Good luck
When you rotate the crank 5 degrees back and forth does it stop soft (friction increasing) or like is it a hard stop (hitting something )?
Other things to check that might help diagnose.
does the camshaft rotate at all when you rock the crankshaft?
any really loose rockers?
does the raw water pump turn at all when you rock the crankshaft? (assuming you have a gear driven pump)
is the transmission in neutral?
any tight push rods that cannot be rotated in their passages? Use a cloth and pliers so as to not nick the rods when trying to turn them.
Good luck
It has been 5 years or more since it turned over. I have been recovering frim car accident and im back on it again. Last thing i did was load the crankcase and cylinders via the injector ports with a mixture of marvel and acetone. I took the valve cover off and removed the rockers and push rods i can now move the crankshaft pulley 30-40degrees both ways with a breaker bar! I never tried to remove pressure by decompressing valves! Is that necessary if the rockers and rods are removed? I was thinking maybe the injection pump could be rusted and i was concerned about removing it as i may do more damage???? Thank u for all ideas!!
Etone
Etone
If the injectors are out of the head you do not need the decompression values. BTW, they work by opening the exhaust valves so if you have the rockers out they are non-functioning anyway.
Thank you for your reply! I was in a bad car accident and I’m recovered to the point where I’m starting to take a look at what project I started and where I’ve been and I see that I spoke to you in 2017 but may not have replied I’m very sorry about that it’s hard to believe that I’ve been out of commission so long but I’m trying to get my boat to go in and appreciate any help you could give me I’m going to put back together the train the valvetrain and hopefully when I try to turn it over I can decompress it and any other thoughts you have would be great help thank you
You do not need to put the valvetrain together to decompress. Just leave the injectors out and you have 0 compression. Someone asked if it was a hard stop like hitting something or a soft stop due to increasing friction. That is important info to know because they tell a lot. Hard stop is likely something broken. Soft is likely rust on cylinder walls. In either case, your best action would be to pull the head.
@hunter healer did you attempt any time recently to turn the motor with the starter? did it turn? and now it won't?
First, and foremost, I'm sorry to hear about your accident. Glad you are feeling good enough to get back in the game!
Don't try to spin it with the starter.
Where was the engine stored during the 5 year period? What type of weather was it exposed to?
Was it stored with the injectors out (all cylinders open to atmosphere)?
Is anything still connected to the crank (gearbox, water pump, alternator, etc)?
I would be tempted to pull the injector pump just in case.
If you have a bolt that won't release, try hitting it on the head sharply with a ball peen or other small metal hammer and a drift (if you can't strike it directly). This will often break one loose that is seized and save you the trouble of breaking it off.
I suspect you have extensive rust in the cylinders. If so, you may be able to save it, but it will have to come apart.
Water in the intake manifold (your original observation) would put any cylinders with an open intake valve in a high humidity environment. Same for water in the exhaust system. It's been seized for too long to trust - even if you could work it loose now. Likely best case - cylinder hone and new rings (if you don't find other damage). Middle of the road - bore it and new pistons. Worst case - you have a new anchor.
Don't try to spin it with the starter.
Where was the engine stored during the 5 year period? What type of weather was it exposed to?
Was it stored with the injectors out (all cylinders open to atmosphere)?
Is anything still connected to the crank (gearbox, water pump, alternator, etc)?
I would be tempted to pull the injector pump just in case.
If you have a bolt that won't release, try hitting it on the head sharply with a ball peen or other small metal hammer and a drift (if you can't strike it directly). This will often break one loose that is seized and save you the trouble of breaking it off.
I suspect you have extensive rust in the cylinders. If so, you may be able to save it, but it will have to come apart.
Water in the intake manifold (your original observation) would put any cylinders with an open intake valve in a high humidity environment. Same for water in the exhaust system. It's been seized for too long to trust - even if you could work it loose now. Likely best case - cylinder hone and new rings (if you don't find other damage). Middle of the road - bore it and new pistons. Worst case - you have a new anchor.
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Hi, stored in nj. Injectors out but packed with paper towels. In the hard close to the great river and i hour to ocean. Gearbox and wster pump still connected starter is out. Alternator is removed. Orig some water in the air cleaner and intake manifold passages. Gear box is in neutral, If I remove the injector pump is it going to open up like Jack-in-the-Box with PARTS flying everywhere or are they all concealed
If you did not try with the starter how do you know the starter is fried?
I am not suggesting you try, that would be a really bad thing to do, what I am suggesting is, if you tried and it turned even a bit a valve or valves may have been rusted open and one of the pistons bent a valve on its way up, just a thought.
But realistically it sounds more like the cylinder walls are rusted