Click for JetForums
Click for MotorCheck
Click for Delta
Click for Dockwise
Click for Elling
Click for Nordhavn
Go Back   YachtForums.Com > GENERAL YACHTING DISCUSSION > Technical Discussion > Cummins v8 na 320hp

Login to YachtForums
Username
Password

Reply

Cummins v8 na 320hp

 
 
LinkBack Thread Tools Rate Thread Display Modes
Old 10-19-2011, 12:39 PM   #31 (permalink)
Registered User
 
Join Date: Sep 2007
Location: hawaii
Posts: 12
The 903's are especially sensitive to coolant/additive mixture, require a special blend to keep the liner O-rings in condition. If the mix is incorrect, or if straight anti-freeze is run, the liners will pit rapidly, and coolant will mix in the oil.
Test strips are available, but what a PITA!

These motors were designed to be tank motors, built heavy to stand up to radical abuse, but if you talk to some old gray bearded military mechanics, you will find that they weren't that great in that app either.

Sportfishermen around here say the 903 noise or vibration or whatever it is raises big marlin, don't know if that matters to you, but some owners baby these motors along just for that value.

Bottom line, if you are really in love with this boat, make your offer to reflect the need of an almost certain repower.
kapnd is offline   Reply With Quote
Old 10-19-2011, 06:18 PM   #32 (permalink)
Registered User
 
Join Date: Oct 2009
Location: New London Ct/Hope Town Bahamas
Posts: 32
All of the above is true regarding the PH and condition of the coolant but it also applies to every wet sleeved Cummins and CAT diesel as well.As long as they are using a clean antifreeze /water coolant mixture and the water filter/coolant conditioners are changed once a year in a rec, boat they will last many,many years without any liner issues.

Besides keeping the cylinder packing rings in good shape conditioned coolant also prevents gas bubbles from being suspended in the coolant,thus preventing the cavitation burning or "air hammering" that causes the pin holes in the liners.Actually this was not as bad a problem in the 903's as it was in the NH and NHT series engines,but when Cummins built the N-14 engine they redesigned the block in such a way that no single liner is exposed to direct coolant flow.Consequently protecting the liners.That coolant routing technique is pretty much the same used by all US heavy diesel manufacturers now.

As far as unreliable? Total nonsense........ The 903 Cummins was not designed or built to be a "tank engine" they were in fact built initially to meet specs, to power the entire fleet of New York City garbage trucks! The truck had to be a super heavy duty cab forward,axle back,ten wheel truck,powered by a V-8 diesel of over 300hp. The engine had to fit under the cab and meet certain noise levels. So Cummins built the 903 and Brockway Motor Trucks of Cortland New York built the trucks.They turned out to be really good engines and they responded very well to increased horsepower requirements,but when they couldn't meet the higher EPA emission standards coming in the late 80's the 903 line of engines were only then being sold to the US Government ie: every USCG 41'-UTB and various military apps, including tanks.

Did the 903 have any inherent problems? Yes a couple. They were known to smoke on a pull as their horsepower ratings rose and they broke a crankshaft now and then,but that was almost uniquely a problem only in trucks and it was caused by drivers lugging them down too low before downshifting.
42hatteras is offline   Reply With Quote
Old 10-20-2011, 05:26 AM   #33 (permalink)
Senior Member
 
K1W1's Avatar
 
Join Date: Sep 2005
Location: My Office
Posts: 6,373
Hi,

Here is one that has had a wee problem in a Tank.

Cummins 903 blew a rod. - YouTube

IFRC, The pure Military Cummins Engines we used to get in NZ from the US were a wee bit different to the genuine Automotive equivalents.

What immediately springs to mind was a 1/8" Bore difference on one of them and a small lump or hollow just under the top edge of the block on the 903's.

It has been a long time and a lot of engines since I had spanners on one so if I have had a brain fart please feel free to correct me.
K1W1 is online now   Reply With Quote
Old 10-20-2011, 06:33 AM   #34 (permalink)
Senior Member
 
Join Date: Oct 2010
Location: Fort Lauderdale
Posts: 353
spanners

Quote:
Originally Posted by K1W1 View Post
Hi,

Here is one that has had a wee problem in a Tank.

Cummins 903 blew a rod. - YouTube

IFRC, The pure Military Cummins Engines we used to get in NZ from the US were a wee bit different to the genuine Automotive equivalents.

What immediately springs to mind was a 1/8" Bore difference on one of them and a small lump or hollow just under the top edge of the block on the 903's.

It has been a long time and a lot of engines since I had spanners on one so if I have had a brain fart please feel free to correct me.
"Brain Fart" you sure have, what the h--l are "spanners"
Yachtjocky is online now   Reply With Quote
Old 10-20-2011, 12:57 PM   #35 (permalink)
Registered User
 
Join Date: Feb 2011
Location: Pensacola, Fl
Posts: 15
I'd NEVER heard of a boat breaking a crank, until March of this year. I bought my boat in January and ran it home from Boca Raton to Pensacola, Fl, about 500 miles. The first trip out, after running fine for maybe 7-8 hours, the port motor, a VTA903, broke the crankshaft between 1st and 2nd rod journals. parts are available, we found everything needed for a MOH. Also, the USCG is still running alot of 903's, atleast in this area. If they ever de-commission them there'll be tons of surplus parts.
AdrenalinJunki is offline   Reply With Quote
Old 10-21-2011, 01:29 AM   #36 (permalink)
Registered User
 
Join Date: Sep 2007
Location: hawaii
Posts: 12
Quote:
Originally Posted by AdrenalinJunki View Post
I'd NEVER heard of a boat breaking a crank, until March of this year. I bought my boat in January and ran it home from Boca Raton to Pensacola, Fl, about 500 miles. The first trip out, after running fine for maybe 7-8 hours, the port motor, a VTA903, broke the crankshaft between 1st and 2nd rod journals. parts are available, we found everything needed for a MOH. Also, the USCG is still running alot of 903's, atleast in this area. If they ever de-commission them there'll be tons of surplus parts.

Even if parts were cheap and available, which, in my experience they are not, I still contend that repowering, say with C-series Cummins of a more appropriate horsepower or Cats, or any brand of comparable modern power will save money, time, fuel, and headaches in the long run, and do quite a bit toward keeping our ocean environment healthy.

As mentioned previously, the 903 is a smoky, leaky motor, and leaves an impressively foul carbon footprint.

As old as the motors are, it is doubtful that they have been maintained immaculately for all their life, and hidden issues are certain to be lurking!

Check out the Cummins factory rebuilds, a fantastic savings on motors that are better than when they were new! (no, I am not working for them, just been there, done that, and am happy with the outcome)
kapnd is offline   Reply With Quote
Old 10-21-2011, 02:19 AM   #37 (permalink)
Senior Member
 
Join Date: Jul 2005
Location: Fort Lauderdale
Posts: 5,884
Quote:
Originally Posted by Yachtjocky View Post
"Brain Fart" you sure have, what the h--l are "spanners"
The British term for what we call open end wrenches.
Capt J is offline   Reply With Quote
Old 10-21-2011, 02:21 AM   #38 (permalink)
Senior Member
 
Join Date: Jul 2005
Location: Fort Lauderdale
Posts: 5,884
Quote:
Originally Posted by kapnd View Post
Even if parts were cheap and available, which, in my experience they are not, I still contend that repowering, say with C-series Cummins of a more appropriate horsepower or Cats, or any brand of comparable modern power will save money, time, fuel, and headaches in the long run, and do quite a bit toward keeping our ocean environment healthy.

As mentioned previously, the 903 is a smoky, leaky motor, and leaves an impressively foul carbon footprint.

As old as the motors are, it is doubtful that they have been maintained immaculately for all their life, and hidden issues are certain to be lurking!

Check out the Cummins factory rebuilds, a fantastic savings on motors that are better than when they were new! (no, I am not working for them, just been there, done that, and am happy with the outcome)

Yeah, except the only problem for a lot of people is they can do major overhauls on their existing diesels for 1/3- 1/2 the price of changing them out and re-configuring the entire boat for modern diesels especially when you consider all of the wiring necessary for the electronic controls and gauges.
Capt J is offline   Reply With Quote
Old 10-21-2011, 03:04 AM   #39 (permalink)
Senior Member
 
K1W1's Avatar
 
Join Date: Sep 2005
Location: My Office
Posts: 6,373
Quote:
Originally Posted by Capt J
Yeah, except the only problem for a lot of people is they can do major overhauls on their existing diesels for 1/3- 1/2 the price of changing them out and re-configuring the entire boat for modern diesels especially when you consider all of the wiring necessary for the electronic controls and gauges.
Hi,

Very well said and to the point.


Quote:
Originally Posted by Capt J View Post
The British term for what we call open end wrenches.
What do you call the tools with a ring at one end and an open end at the other?

What do you call the tools with rings at both ends?

In NZ and Australia they would be called Ring and Open Ended Spanners and Double Ring Spanners.

In the contiguous 48 I would think the last word would be Wrenches for both.

I believe Yachtjocky was just having a dig as he has no doubt been around long enough to have heard these tools called many things often with a prefix that would be shown here as *******

Before the self proclaimed Language experts chime in, here is an old advert we used to see at home.

Sidchrome TVC - YouTube
K1W1 is online now   Reply With Quote
Old 10-21-2011, 05:17 AM   #40 (permalink)
Registered User
 
Join Date: Feb 2011
Location: Pensacola, Fl
Posts: 15
I didn't intend to overhaul that engine. I purchased the boat hoping to get a season or two out of the motors, then re-power. When it broke the crank, it looked like we could roll another crank in where it sat, without pulling the motor out of the boat. Once we got the crank out, then we found more damage. In hindsight, I should've bought a running take-out, and I would've been dollars ahead. I WILL be repowering in a year or two, probably QSM11's.
AdrenalinJunki is offline   Reply With Quote
Old 10-21-2011, 05:40 AM   #41 (permalink)
Senior Member
 
Join Date: Oct 2010
Location: Fort Lauderdale
Posts: 353
spanners

A friend of mine met an english man and after their first date he went around to her house to fix the pool pump hoping to impress her.

She was also hoping to impress him so when he asked her to go to his car and in the boot there was a some spanners inside his wellies off she went, then she realized that she had no idea what he meant......
Yachtjocky is online now   Reply With Quote
Old 10-21-2011, 03:06 PM   #42 (permalink)
Senior Member
 
Join Date: Jul 2005
Location: Fort Lauderdale
Posts: 5,884
Quote:
Originally Posted by K1W1 View Post
What do you call the tools with rings at both ends?

Handcuffs????
Capt J is offline   Reply With Quote
Old 10-21-2011, 04:46 PM   #43 (permalink)
RER
Senior Member
 
Join Date: Jan 2009
Location: Newport Beach CA
Posts: 508
Quote:
Originally Posted by K1W1 View Post
What do you call the tools with a ring at one end and an open end at the other?

What do you call the tools with rings at both ends?

In NZ and Australia they would be called Ring and Open Ended Spanners and Double Ring Spanners.

In the contiguous 48 I would think the last word would be Wrenches for both.
Ring end & open end = Combination Wrench

Ring @ both ends = Box End Wrench or Box Wrench
RER is online now   Reply With Quote
Old 11-12-2011, 12:00 PM   #44 (permalink)
Registered User
 
Jimbo1959's Avatar
 
Join Date: Aug 2010
Location: Stockton, CA
Posts: 67
As to cost of rebuild. We have a customer who was quoted 40K by Cummins to overhaul 1 of his 555 (smaller version of the 903) in a 50 foot Ocean Alexander. Cummins sold him 2 new 5.9 for 32k. After wiring, fuel, plumbing and labor he will be in for approx 70k and have 2 new engines. As to a 903 wouldn't have one.
Jimbo1959 is offline   Reply With Quote
Old 11-13-2011, 04:33 PM   #45 (permalink)
Registered User
 
Join Date: Oct 2009
Location: New London Ct/Hope Town Bahamas
Posts: 32
Having been doing this for a living for a few decades and as a mechanic that prefers Cummins over most,I can't imagine how an overhaul on a triple nickel could cost 40k even if we lined bored the block and bought new heads. It sounds like an intentionally very high price to get the guy to buy a pair of engines.

That being said the decision to repower with a pair of 5.9's is a good investment.They are durable,tough little engines that will last for years.
I have been planning on repowering my Hatteras and replacing the 903's with a pair of 450hp,8.2's when the 903's give me any sign of a problem.So far after 39 years,3600 original hours,one round trip from Ct to Abaco Bahamas every year and one quart of motor oil on each leg for the port engine "none for the starboard", they still start and run like new.

It's not that I don't like the 903's,but at 6'4" and 61 years old it is beginning to get a little tight in that engine room for me.
42hatteras is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are EST. The time now is 09:02 AM.

Click for Bering
Click for Bering
Click for MCC
Click for McConaghy
Click for McKinna
Click for Nordlund


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.

Content Relevant URLs by vBSEO 3.3.2