Perkins M20 103.06 Reassembly

[RandySmith]

I have recently purchased a 1994 Catalina 270 with a Perkins M20 103.06 diesel engine. The Perkins was disassembled when I purchased it. I have rebuilt it and I'm in the process of reassembling it. I do not know the proper place for the spring loaded lever that contacts the throttle arm that connects to the injection pump from the throttle control under the front cover. Does it go under or on top of the throttle arm? I have attached photos that shoe it in both positions. Can anyone tel me the proper placement, please?

[DougR]

The spring loaded arm sits on top of the “tab” as shown in the last two photos.

When the engine is running and you activate the stop lever to kill it, the spring loaded arm presses the tab against the cast aluminum pillar, which pulls the linkage and thus the injection pump fuel rack to the no fuel position and the engine stops running

[RandySmith]

Thanks so much for the information. I have never rebuilt a Perkins motor like this one before. So, the small spring loaded lever is the stop lever and the larger lever below it is the throttle lever, is that correct?

[DougR]

Couple other “heads up” items just in case, as you didn’t take the engine apart....
- there is one more spring that goes in the governor linkage that isn’t in place in your photos, and that’s the “starter spring”. It’s a soft spring that connects between the linkage and the timing case. It’s purpose is to pull the linkage back to the “run” position after the engine has been stopped. One end of the spring goes in the empty hole seen by the linkage pivot pin, and the other end hooks in the blind hole in the timing case in the upper portion of the photo. Frequently the spring end is held in the hole during assembly with a small piece of foam rubber which then becomes captive by the gasket after it’s all closed up.

- make sure the roll pin which you see in the recess of the timing case lines up with the locating hole on the oil pump

- correct on the levers
Good luck with it!

[RandySmith]

Thanks, I appreciate the information

[RandySmith]

I found this spring at the bottom of a box of bolts and screws. I think this looks like what you're describing and installed it as shown. As far as aligning the roll pin on the oil pump, I put some dykem blue on each side of the hole in the aluminum plate to see where the pin was making contact. That helped me align the pin and the hole.

[DougR]

Yep, you have it right.

As mentioned upthread, I have seen engines with a small piece of stiff foam rubber pressed in the blind hole to help keep the spring in place during installation, and the foam becomes captive after installation. Another recommendation is to turn and hold the stop lever during installation so that the spring is under tension until the cover is in place.

[RandySmith]

Thanks, I have dry fit it a few times and that works well.
It seems that the throttle arm doesn’t move much when everything is at rest. I can feel it pulling against the heavy spring, but nothing else moves. Is that normal?
I can move the arm from stop screw to stop screw, but it doesn’t seem to move anything other than the arm.

[deblen]

http://www.svpartyoffive.com/perkins_100.pdf


https://www.dieselmann.no/files/H%C3...%20Manuals.pdf

[RandySmith]

Originally Posted by deblen

http://www.svpartyoffive.com/perkins_100.pdf


https://www.dieselmann.no/files/H%C3...%20Manuals.pdf

Thanks for those links. The dieselmann workshop manual is exactly what I was looking for!

[deblen]

An older helpful post by Doug R


https://www.cruisersforum.com/forums...em-206645.html

[RandySmith]

Originally Posted by deblen

An older helpful post by Doug R


https://www.cruisersforum.com/forums...em-206645.html

Interesting thread, that answers my question about how the throttle works, thanks.

[RandySmith]

Here’s another question about the Perkins motor. It was removed from the boat and disassembled because it would not turn over fully. There was a hard stop as the rear piston came to TDC. When I got it, the rear exhaust valve seat and exhaust chamber in the cylinder head was so full of carbon, it had raised level of the valve to contact the top of the head. The rest of the motor was pristine inside reflecting the 672 hours on the motor. I replaced the pistons since the rear one was slightly damaged and all the main and rod bearings since I had it apart.
I was able to recover an acceptable valve seat and I thoroughly cleaned out the exhaust port with a die grinder and installed new valves and springs.
What could have caused the excessive carbon buildup in the exhaust port and seat on only one cylinder?