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Yanmar 3qm30 experience required

Fortin024

Fortin024

Member
Good day all,

The oil pipe (steel line) running from the right side of the engine to the rocker valves at the top of the engine failed on me a couple days ago. I’ve ordered a new line, but I’m in a pinch for time so I’m trying to see the job ahead of time.
The line seems to run fairly tight to the exhaust manifold and I’m wondering if any of you have ever changed it and if so, did you need to remove the exhaust manifold when removing the banjos bolts at the rocker valves?

Cheers,

Mike
 
Mike

Are you talking about the breather pipe that runs from the plate above the injector pump across to the other side of the engine to the intake air manifold?

Jim
 
Mike

Here is a page from the 3QM30 manual showing the breather pipe.

Jim
 

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Mike

Here is the explanation of that breather pipe.

Jim
 

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Hey Jim,

Sorry I had not noticed someone had replied yet. I’m talking about the oil pipe that feeds the rocker valves. I came to the conclusion I had to take the manifold off to get her off… I was trying to avoid that to not have to regasket everything but oh well. Here’s the picture of the pipe.
 

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Mike

I am searching the diagrams in the engine manual and can't seem to be able to find a view of that oil pipe. I will be stopping out at the boat this week and will look over the engine to find it's route. Get back to you.

Jim
 
Mike

I went to the boat yesterday to check out the oil piping. It looks to me like the exhaust manifold will have to be removed or at least loosened to unthread the three fittings. When you get the new piping, look at the amount of threads that go into the head. There just may be enough space to remove the fittings if the number of threads are small. How did the oil pipe fail in the first place?

Jim
 
jimcleary said:
Mike

I went to the boat yesterday to check out the oil piping. It looks to me like the exhaust manifold will have to be removed or at least loosened to unthread the three fittings. When you get the new piping, look at the amount of threads that go into the head. There just may be enough space to remove the fittings if the number of threads are small. How did the oil pipe fail in the first place?

Jim
Click to expand...
Hey Jim,

I ended up removing the manifold and replacing the line that way. The line failed due to corrosion, it got a pin hole in it. Lucky it happened at the docks.
 
Mike
Be very careful with the exhaust manifold. Replacements are not available. I'm going to keep a sharp eye on my oil piping now that I know where it is. Thanks.

Jim
 
Jim,

Thanks, while I have you here and on the subject, do you happen to have the torque specs of the nuts to the studs of the manifold to the engine?

I’ve put new gaskets and torqued it but it’s letting smoke through and I’m worried to tighten more and break a stud.
 
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Mike

Combing through the engine manual, I can find no specific reference to tightening the exhaust manifold bolts. What I found is a torque reference for a number of items except the intake and exhaust manifolds. On that list there are bolt sizes and the associated torque. For M8 bolts the range is 2.4 to 2.9 kg/m For M10 Bolts the range is 4.0 to 5.0 Kilograms/meter. For M12 bolts the range is 4.5 to 6.0 kg/m. The best I can find is that the studs are M8 but I might be wrong. Also I have no idea how to convert KG/M to FT/LB. Maybe one of the engineer types here on the board have that answer. Hope this helps.

Jim
 
Jim,

Thanks, I couldn’t find anything in the manual either. I found this in the 3gm30 manual, my understanding is that it’s the same block so one would think it’s the same torque spec?
 

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Mike

I just found a conversion thing on my phone. It says 4.5 kg/m equals 32.5 ft/lb torque. Does that sound right to you? That appears to be kind of light. What do you think?

Jim
 
Jim,
Looking at the manual of the 3gm30, it seems to be matching what you are saying, 32.549 exactly… I would of thought it’d be a bit more than that too, but I’d be a very unhappy sailor if I was to break a stud so I think I’ll go with that for now.
So glad all of this happened at the dock doing my regular engine run. That would of been a bad day out there.

Cheers,
Mike
 
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