6V71tabs Major or refit with Yanmars or Cats

"I have been quoted $25,000 fo

"I have been quoted $25,000 for a MOH of both my DD 6v71ta's by Detroit Diesel in Tampa. But I am also considering a new refit with either Yanmar 6LY2A-STP's or Cat 3126's. My boat is an Atlantic 47 Motor Yacht 1985. Vibration is heavy, and I am interested in the benefits of a less vibrating 4 stroke vs 2 stroke, improve fuel economy, more hp, and less noise. How much more is the refit going to be vs the MOH ?"

"Nothing runs smother than a D

"Nothing runs smother than a Detroit! You must have some dead cylinders, faulty injectors, or other problems. You better do your home work, 3126 was pulled by Cat for a good reason. and you will find that 25k is not so bad when shopping for new power including labor to install."

"I agree, Your vibrations are

"I agree, Your vibrations are from something else. I would check props first. When was the last time you had them balanced and checked? We did ours this year and got rid of a vibration and they looked like they were in fine shape. Our 671 don't smoke at all. We also had a rudder out of alignment. If you have drug bottom, time to check those props etc. How about barnacles on the props?"

"I agree with the above commen

"I agree with the above comments. Your vibration has nothing to do with DD engine. You don't say if the vibration occurs while you're underway or tied to the dock.

To check the engine itself and determine if one or more of your cylinders don't fire properly, start the engines and increase the RPM from iddle to Max. RPM (2300) in increaments of 100 RPM at the time and observe if the engine vibrates. If it does, most likely one or more of your pistons are not firing properly. Could be a bad injector.
Replace it and the problem will go away.

I would not trade a DD engine with two Caterpilar or four Yamahas.

To educate yourself about Diesel engines I urge you to go to David Pascoe web page and read the articles he has published about marine diesels. You will change your mind fast. Just type in David Pascoe and then go to the articles he has posted (over 150) and read them. While you're there also read the article about Overhauls and what they should include. Print it out and take it to DD and ask them to reprice the overhaul based on Pascoe's list. Good Luck

Olymbitis"