Life of 6v92 TA

[Docs Holiday]

3000 hrs on my 550 hp DD 6v92.. so I am having them surveyed this week. Brief telephone conversation with mechanic and he mentions "probably time for a rebuild". He indicated and I have read on this forum that these engines are over powered for the size of the Pistons. These motors imo have been babyed...usually running at hull speed of 9 knots (1200)rpm taking them up to 2250 for 10 to 15 mins at the end of the run, maintenance with oil and filter changes at 150 hrs etc. Oil consumption is not excessive but there appears to be some blow by with oil coming out dipstick on port engine. My question is at what point should I consider rebuild...what on survey would be- absolutely needs rebuild vs. you can get another 2,000 hrs before rebuild?

[Glory]

3000 hrs on my 550 hp DD 6v92.. so I am having them surveyed this week. Brief telephone conversation with mechanic and he mentions "probably time for a rebuild". He indicated and I have read on this forum that these engines are over powered for the size of the Pistons. These motors imo have been babyed...usually running at hull speed of 9 knots (1200)rpm taking them up to 2250 for 10 to 15 mins at the end of the run, maintenance with oil and filter changes at 150 hrs etc. Oil consumption is not excessive but there appears to be some blow by with oil coming out dipstick on port engine. My question is at what point should I consider rebuild...what on survey would be- absolutely needs rebuild vs. you can get another 2,000 hrs before rebuild?

1, Your mechanic said " probably time for a rebuild", without looking at the engines? That's sales position, not a surveyor position. I would hope a vendor arrives at the job with an open mind, not anticipating a $20,000 payday in each ER

2, "what on survey would be- absolutely needs rebuild vs. you can get another 2,000 hrs before rebuild?" The wear or defects found. Like cylinder and ring damage/wear, low compression.

The one thing you didn't talk about was poor performance, you only mentioned an oil leak, on what sounded like just one engine.

A premature overhaul is never a bad thing, just expensive.

JM

[SeaEric]

A few years back I sold a Chris 500 to a customer in Fl. She was powered with 6v92 550's with 3500 hours showing on the meters. They surveyed fine with good compression. The engine surveyor commented "I can just about guarantee that these engines have never been run much over 1500 RPM's"

Hours don't tell the tale. If you want to know for sure, you must do a compression test.

[Finalee]

It's really more about fuel burned versus hours.

[rwappleton]

I would not let that mechanic on my boat!

As everyone has said here it's about usage not hours.

How does it cold start? That is the best single indicator of engine condition IMHO.

How long does it crank before it starts?

How long does it hunt (RPM varies)?

How much smoke?

Our 6-71 TI's have 2700 hours and at 55 degrees crank less than 5 seconds, hunt for less than 5 seconds and smoke less than 5 seconds. We are counting on another 2700 easy with good maintenance.

[jim rosenthal]

I hope that the gentleman you spoke of isn't doing the survey. If he is, he's probably already ordered the parts

I agree with a survey and a compression check. (I don't think you can do a leakdown on DDs, or it would be a bit complex- not sure on that one) If you can get a few more years out of them, then why not?

[rsmith]

Hey Doc if you walked into your Docs office and the first thing he told you before any testing was at your age you probably need a quad trouble bypass would you let him cut you open???

[Docs Holiday]

Motors fire up right away and pass
Genesis 30 second smoke test with minimal searching. Port motor is putting out a noticeable "sheen" on the water.
I have updated my galley and galley floor and recently brought her down from Eastport, Me to Florida with no major running problems (if I don't include dinging the props) but I need to replace the sagging whisper walls so I want to make sure there are no major problems with the motors before sinking a lot more money into cosmetics. I have been told that at 3000 hrs the after coolers should be cleaned but with the oil or fuel sheen I wanted to make sure that it wasn't something that requires a major overhaul.
I guess my question is, "is 3000 hrs the average life span of these motors and how accurate will a survey/compression test be as to the longevity of these motors
I think the person I talked to was just telling me what his experience indicated...after all, they probably see mainly the bad ones and get a somewhat skewed perception. That is why I'm asking forum members...for the most part y'all care for and look after your boats.

[Cricket]

Fuel sheen could be from a leaking fuel cooler, need to determine if it's fuel or oil. 3000 hrs on the after coolers sounds like way overdue for a cleaning.

[jim rosenthal]

Hey Doc if you walked into your Docs office and the first thing he told you before any testing was at your age you probably need a quad trouble bypass would you let him cut you open???

Not a chance of it. I'd walk back out. So would any rational person.