Reply
 
Thread Tools Display Modes
 
Old 09-15-2016, 04:56 PM   #1
Senior Member
 
Jeff F's Avatar
 
City: London, ON
Country: Canada
Vessel Model: Mainship 34 Original
Join Date: Nov 2015
Posts: 333
6bt overheated

I did a completely bone-headed thing and ran my motor with the seacock closed until the coolant boiled over in large quantities. This is in my Mainship 34 with a 1991 Cummins bt6 210 hp. The motor was rebuilt about 1200 hours ago and has been well maintained since, with new belts and hoses, rebuilt water pump, etc.

The overheat happened in June and I pressure tested the cooling system, didn't see any obvious signs of damage apart from some burnt paint on the exhaust manifold, checked the oil for obvious signs of water, and carried on.

I've noticed a very small amount of coolant loss since then, but more ominously now have a lot of blowback from (I think) one cylinder, and oil accumulating in my CCV puke bottle, maybe 10 oz in the last 100 hours since the overheat event. The motor starts and runs fine but is rough at < 1000 rpm, particularly under load. Sounds like it's not running on all cylinders. Oil consumption hasn't been excessive.

Getting ready to lay up the boat for the winter here in Ontario and considering my options. I think I'm going to pull the motor and transmission out of the boat, and feel comfortable tacking that myself.

Much as I like tackling problems in a DIY manner, I think I'm going to need to rely on professionals for a resolution. I sort of budgeted for this sort of thing, but don't like spending more than I have to. But I think this boat is a keeper and I plan to travel far and wide on it so am interested in a proper fix.

Options:
1) find a local shop and leave the motor with them. I'm assuming that the exhaust manifold will need to be replaced in addition to the usual work on the block, pistons and possibly head. I'm thinking that because the Cummins is so ubiquitous it wouldn't have to be a marine shop.
2) replace motor with a rebuilt/remanufactured one.
3) there is a local 6bta 250 hp marine for sale that's never been used at a reasonable price (us$12k for motor and transmission). The transmission on it wouldn't work for me because the gear ratio is too high, so I'd have to find a gearbox as well, but otherwise I think it could be pretty much a drop in replacement. I currently have a BW 72. Not really interested in going faster, but don't see much downside of having 40 more hp available.

I think #1 is the sensible and economical choice, but thought I'd throw it out for discussion here. Advice/experience/recommendations? What should it cost me to have my existing motor put into tiptop shape?
__________________
Advertisement

Jeff F is online now   Reply With Quote
Old 09-15-2016, 05:10 PM   #2
Guru
 
O C Diver's Avatar
 
City: Fort Myers, FL... Summers in Crisfield, MD
Country: USA
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 4,761
Nobody is going to give you much for your engine in it's current condition. I would find a good reasonable Marine Cummins mechanic and pull the head to see what you have. There are lots of 210s on Chesapeake Bay that watermen have treated far worse.

Ted
__________________

__________________
Blog: mvslowhand.com
I'm tired of fast moves, I've got a slow groove, on my mind.....
I want to spend some time, Not come and go in a heated rush.....
"Slow Hand" by The Pointer Sisters
O C Diver is offline   Reply With Quote
Old 09-15-2016, 06:42 PM   #3
Guru
 
High Wire's Avatar
 
City: Cape May, NJ and Englewood, FL
Country: USA
Vessel Name: Irish Lady
Join Date: Dec 2007
Posts: 1,488
Wouldn't a compression test be worthwhile before pulling the head off?
__________________
Archie
1984 Monk 36 Hull #46
Englewood, FL and Cape May, NJ
High Wire is offline   Reply With Quote
Old 09-16-2016, 12:55 AM   #4
Guru
 
City: Between Oregon and Alaska
Country: US
Vessel Name: Charlie Harper
Vessel Model: Wheeler Shipyard 83'
Join Date: Jun 2016
Posts: 584
High coolant temps don't necessarily ruin an engine. Quickly controlled, often no apparent damage occurs. Most high heat damage is usually in the rings and sleeves/cylinder.
A compression test or a leak down test can help you gauge the condition of the cylinder, piston, rings and valves.
Rough running could be many things. It could be as simple as a burnt injector tip.
Even putting in new rings would be cheaper than $12,000.
A non-marine engine usually has a different cam.
Lepke is offline   Reply With Quote
Old 09-16-2016, 08:43 AM   #5
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 3,771
Run engine with oil fill cap off and take note of blowby flow. If "puffing" in sync with once cylinder firing, the rings on that cylinder are not sealing. In that case I'd plan on pulling the engine and going through it. A good first step is to pull head and that way you can assess cylinder condition. Also makes it easier to get engine out of boat.

I'd rebuild the one you have unless it is severely damaged. The 250 has issues yours does not.
Ski in NC is offline   Reply With Quote
Old 09-16-2016, 08:46 AM   #6
Guru
 
City: Fort Myers
Country: USA
Join Date: Jul 2013
Posts: 941
I've seen head gaskets leak after an overheat, not sure a minor leak would show up on a compression test...

I would get a good mechanic on board first before you start pulling everything apart, I agree with OCDIVER.
Marlinmike is offline   Reply With Quote
Old 09-16-2016, 09:08 AM   #7
Guru
 
djmarchand's Avatar
 
City: East Greenwich Yacht Club, RI
Country: USA
Vessel Name: Bella
Vessel Model: Mainship Pilot 34
Join Date: Aug 2012
Posts: 2,733
Expanding a bit on the previous advice:


If you have little blowby, then the overheating event could be limited to a blown head gasket, warped head or cracked exhaust manifold, sort of in that order. Even in the worst case, all three could be repaired in the boat without pulling the engine, much cheaper than the other alternatives you are considering.


So, check blowby as Ski suggests and go from there.


David
djmarchand is online now   Reply With Quote
Old 09-16-2016, 09:16 AM   #8
Guru
 
City: gulf coast
Country: pinellas
Join Date: Jun 2014
Posts: 2,147
If you currently (6bt) dont have an aftercooler dont add one. I dont know what other changes would be necessary if you removed the cooler from that cheap engine.

Why would your old trnny not work with the new engine?

IMO Ski's advice is good. Figure out what's wrong first.
bayview is offline   Reply With Quote
Old 09-16-2016, 10:18 AM   #9
Senior Member
 
Jeff F's Avatar
 
City: London, ON
Country: Canada
Vessel Model: Mainship 34 Original
Join Date: Nov 2015
Posts: 333
Thanks to all for responding. The blowby is most definitely puffing. I checked this immediately after the event and it didn't seem to be an issue but it definitely is now.

So assuming I remove the motor, how important is it that I take it to a marine mechanic rather than a shop that does truck/industrial motors? I've been doing some preliminary research and there are lots of good shops in my area but very few that specialize in marine. Suppose I could ship it off, but don't mind doing some of the simple hands-on work myself.

Keep it coming!
Jeff F is online now   Reply With Quote
Old 09-16-2016, 10:36 AM   #10
Guru
 
djmarchand's Avatar
 
City: East Greenwich Yacht Club, RI
Country: USA
Vessel Name: Bella
Vessel Model: Mainship Pilot 34
Join Date: Aug 2012
Posts: 2,733
The one marine specific component that the non marine mechanic wouldn't know how to deal with that might have failed is the exhaust manifold. But I think with a bit of guidance about how to pressure test it, he could deal with that.


Everything else: pistons, rings, cylinders, etc is common to marine and over the road diesels. But of course when it is all back together and doesn't work right for whatever cause, then what do you do? There will always be the excuse that it is a marine engine.


Does Cummins sell a short block for that engine? That might be a cheaper alternative, particularly if you have cylinder bore scoring that requires boring and oversize pistons.


Ski can probably tell you more.


David
djmarchand is online now   Reply With Quote
Old 09-16-2016, 10:45 AM   #11
Guru
 
City: Northport
Country: USA
Join Date: Aug 2015
Posts: 763
"I've been doing some preliminary research and there are lots of good shops in my area but very few that specialize in marine"


There is a guy on the Baylinerownersclub that did two of these Cummins mostly himself by getting in rebuilds , they were done like 5 years apart or so- he is located east of Toronto likely not too far from your sig address. Here is a link to one of his more recent posts - perhaps ask him via BOC or PM him at the BOC - easy to register.




Bayliner Owners Club - BOC Forum - Topic: Twin Cummins 270B's (1/1)
smitty477 is offline   Reply With Quote
Old 09-16-2016, 01:37 PM   #12
Senior Member
 
BIG CAT's Avatar
 
City: Biloxi,MS
Country: USA
Join Date: May 2016
Posts: 131
pull the injectors and bore scope it and look for 4 point scoring.
BIG CAT is offline   Reply With Quote
Old 09-16-2016, 07:03 PM   #13
Guru
 
O C Diver's Avatar
 
City: Fort Myers, FL... Summers in Crisfield, MD
Country: USA
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 4,761
Quote:
Originally Posted by Jeff F View Post
Thanks to all for responding. The blowby is most definitely puffing. I checked this immediately after the event and it didn't seem to be an issue but it definitely is now.

So assuming I remove the motor, how important is it that I take it to a marine mechanic rather than a shop that does truck/industrial motors? I've been doing some preliminary research and there are lots of good shops in my area but very few that specialize in marine. Suppose I could ship it off, but don't mind doing some of the simple hands-on work myself.

Keep it coming!
Little over 1,000 Km (11 hours) from London, ON to T & S marine in Crisfield, MD. Put the engine on a pallet; in a small enclosed trailer; hook it to the family land cruiser; grab the wife and take her to Florida (by way of Crisfield) for 2 weeks. Pick it up on the way home.

What's not to like?

Ted
__________________
Blog: mvslowhand.com
I'm tired of fast moves, I've got a slow groove, on my mind.....
I want to spend some time, Not come and go in a heated rush.....
"Slow Hand" by The Pointer Sisters
O C Diver is offline   Reply With Quote
Old 09-16-2016, 09:25 PM   #14
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 3,771
Nothing terribly unique about a marine B motor. Anyone who can build a truck or industrial B can build a B210.
Ski in NC is offline   Reply With Quote
Old 09-17-2016, 08:09 AM   #15
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,321
"So assuming I remove the motor, how important is it that I take it to a marine mechanic rather than a shop that does truck/industrial motors?"

I prefer a machine shop that also does work for racers.

They can balance the reciprocating parts far better than "factory" specs .

Just be sure to give them DA Book , (the factory service manual) and tell them the usual cruise RPM area.

The real fine ones will CC the cylinder heads and other refinements.Cam timing height and lift,, crank timing etc.

A good used block will stay in shape after line boring and other machining better than a factory green unit.

Your rebuilt should have longer life than factory new .
FF is offline   Reply With Quote
Old 09-18-2016, 11:19 PM   #16
Senior Member
 
The Other Gary's Avatar
 
City: Toronto
Country: Canada
Vessel Name: Adios Dinero
Vessel Model: Bayliner 3988 2 x 330 Cummins
Join Date: Sep 2016
Posts: 188
Depending on the CPL number you can buy a long block with tin for under $4000 US and put all your rebuilt peripherals on yourself. I am the guy Smitty was referring to and I did most of the work myself and jobbed out the rebuilding of the injector pump and several other items like craning it in and out.
I was fortunate that I could rent space in a marine mechanical shop and do most of it myself.


[URL="http://i18.photobucket.com/albums/b103/gareez/2015-08-05%2010.50.50.jpg"]
The Other Gary is offline   Reply With Quote
Old 09-19-2016, 05:49 PM   #17
Senior Member
 
kapnd's Avatar
 
City: hawaii
Country: usa
Vessel Name: #31
Vessel Model: ex-Navy MUB 50 fish/cruise
Join Date: Aug 2013
Posts: 242
Jeff,
It's an old trick that has been mentioned here before, that if you hang the key on the seacock handle every time you shut it off, you will never forget to open it.
I always close the seacock when I'll be absent from the boat for more than a few days, and so far this method has worked well for me.
__________________
You can lead a horse to water,
But you can't make him ski...
kapnd is offline   Reply With Quote
Old 09-19-2016, 06:15 PM   #18
Senior Member
 
Jeff F's Avatar
 
City: London, ON
Country: Canada
Vessel Model: Mainship 34 Original
Join Date: Nov 2015
Posts: 333
Good advice. I actually leave mine open at all times. But I was crawling around the engine compartment the night before changing filters and fixing some of the wiring and didn't realize I had inadvertently stepped on the seacock and closed it. One of the outstanding issues had been the temperature sender, and I had been religiously checking temps with my temperature gun in earlier trips, and all had checked out fine. When I went out the next morning I was busy checking other things until the cabin filled with steam... Completely user error :-)
Jeff F is online now   Reply With Quote
Old 09-19-2016, 07:39 PM   #19
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 3,771
Another case for a rock-solid reliable audible temp alarm. Factory Cummins alarm is sketchy at best, best to rig your own.
Ski in NC is offline   Reply With Quote
Old 09-19-2016, 09:25 PM   #20
Senior Member
 
Jeff F's Avatar
 
City: London, ON
Country: Canada
Vessel Model: Mainship 34 Original
Join Date: Nov 2015
Posts: 333
Quote:
Originally Posted by The Other Gary View Post
Depending on the CPL number you can buy a long block with tin for under $4000 US and put all your rebuilt peripherals on yourself. I am the guy Smitty was referring to and I did most of the work myself and jobbed out the rebuilding of the injector pump and several other items like craning it in and out.
I was fortunate that I could rent space in a marine mechanical shop and do most of it myself.
Gary, I've read your account of that (twice!) on the Bayliner forum. I like the idea of doing pretty much exactly what you did. It will give me something to do over the winter :-)

I want to take the opportunity to get more intimately familiar with my motor, and AFAIK the turbo, injection system and other peripherals are in fine shape. I also have a slight leak in the rear seal of the transmission so can address that as well.

Now I'm into the usual project scope creep problem - maybe while the motor is out I should also replace the fuel tanks...
__________________

Jeff F is online now   Reply With Quote
Reply

Thread Tools
Display Modes

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 On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 01:41 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012