Perkins 4.108M DIY Rebuild -- A Narrative - Page 20 - SailNet Community
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post #191 of 275 Old 04-11-2013
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

Thanks for taking the time to do that for me PorFin. Did you use a dial caliper or a micrometer for the measurements?
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post #192 of 275 Old 04-11-2013 Thread Starter
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

My pleasure, Ray.

I used calipers.


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post #193 of 275 Old 04-14-2013 Thread Starter
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

Hey, folks -- been wrenchin' and not writin'...

Here are few money shots (but I'll back-track later and address how I got to this point.)









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post #194 of 275 Old 04-14-2013
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

Motor Porn!
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

What's with that ridiculously long alternator negative lead?
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

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Originally Posted by eherlihy View Post
What's with that ridiculously long alternator negative lead?
It does look pretty foolish, doesn't it?

Once it's back in the boat, the cable's gonna run from the alternator to the negative bus; I've got it bolted to the block now just to keep it from dragging on the ground when I move the motor around.
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

Oh, and before the other obvious questions pop up:

-- I've still got some buttoning up to do before I kick if off (several hose clamps on the cooling circuit; install the thermostat; etc.)


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post #198 of 275 Old 04-14-2013 Thread Starter
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

Chapter 16: Doing the Jabsco Jiggle

OK, the raw water cooling pump.

On many engines the raw water pump is belt driven. Not so on this engine. It's shaft driven off of the fuel pump drive hub.

Now a common sense design would be to make the interface between the two self-aligning.

Of course, Perkins did this but not in a way that was completely foolproof. Go figure...

The pump mounts on an adapter ring (the four inner 1/4" studs.)

The adapter mounts to the timing case cover (there's an inner ring with 5/16" studs that pass though the timing cover, and you sandwich the timing cover between the inner ring and the adapter plate.)

Here's a shot of the components:



So far, so good.

But, there's a little tricky wrinkle here. If you don't get the adapter plate concentrically aligned with the fuel pump drive hub, you run a real risk of breaking either the drive hub or the r/w pump shaft.



In the workshop manual, Perkins says you can get it close to concentric by turning the engine over a couple of revs before you tighten the adapter plate down fully snug. They do, however, recommend getting it fully aligned with a Perkins tool at the first opportunity. They also are kind enough to give an engineering diagram of that tool for those who wish to make one themselves. Now, I don't know about you guys, but I don't have a lathe in my garage. That meant hiring the job out to a shop. I got one made out of aluminum, and it wasn't cheap (but still less than a new raw water pump, so there's enough justification for me )

So, reinstallation is pretty simple. Gaskets on both the inner and outer side of the timing cover, and snug the nuts down finger tight. Mount the timing cover, and insert the alignment tool. Rotate the tool to make sure it's absolutely centered. Tighten the nuts fully to secure the adapter plate. Remove the alignment tool and install the pump.





The good news is that once the adapter plate is properly aligned, you can pull the pump off of the adapter plate without screwing up the alignment. The key is to make sure you are pulling pump and NOT the adapter plate -- HINT: If you are using a 7/16" wrench, you are A-O-K; if you are using a 1/2" wrench, you are heading for heartache.


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post #199 of 275 Old 04-15-2013
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

Great info and porn as always!

My raw water pump is leaking and my boat came with a spare so I thought I'd just swap them out..... You're telling me I need to have a tool made? Lame! Thanks for the how-to and the info on this though. Can I ask what the tool cost to be made? I may have them make me one, and since it's aluminum, shipping to my coast shouldn't be too bad...

MedSailor

PS I'm sure it's just buttoning up but don't forget the nut on the back of the alternator stud.

I have a sauna on my boat, therefore I win.
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Last edited by MedSailor; 04-15-2013 at 12:30 AM.
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

Quote:
Originally Posted by MedSailor View Post
My raw water pump is leaking and my boat came with a spare so I thought I'd just swap them out..... You're telling me I need to have a tool made? Lame! Thanks for the how-to and the info on this though. Can I ask what the tool cost to be made? I may have them make me one, and since it's aluminum, shipping to my coast shouldn't be too bad...
.
Med,

I probably could have written that a little clearer.

You shouldn't need an alignment tool, as long as you don't disturb the outer ring of nuts (that's the adapter plate.)

If you only remove the inner nuts (which hold the pump to the adapter plate) you should be golden.
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