engine shakes

[chuck stas]

Good Morning, Does anyone have or had this problem ?
I have a 1983 P303 with a yamar 13hp diesel. When I start it [ Starts easy ] It run great. When I put it in gear the engine shakes a lot, than when I bring the RPM's up it stops. At 1st I through there was something stuck on the prop. When it stops I'm good to go went 14 hours with no problem.
Cutlass bearing was tight. When I checked it before it was put back in the water.
Any ideas of what I should look at.
Thanks for any help

[Valor]

Maybe a bad motor mount.?

[chuck stas]

I'll take a look,  not sure how old they are.
Whats the best way to check them ?

[Last Resort]

not sure how much shaking your talking about, but I've never been able to run my 2gm20 between 2200 and 2500 rpms without some vibration/shaking. Just seems that one spot that won't run smooth.

[chuck stas]

Thanks for the input. It shakes a lot. But then stops and runs smooth. I don't think its the engine that runs smooth. Can't figure why it just stops shaking than runs OK.
Wish I could help you with why yours is not behaving at 2000-2500 RPM. If I hear of something I'll let you know.

[JustinAlenScott]

I don't know much of anything about this engine, but is there a chance that when you throttle up high like that it's getting a lot more air until the fuel catches up and evens out the mixture?