Jeff F
Guru
- Joined
- Nov 5, 2015
- Messages
- 2,437
- Location
- Canada
- Vessel Name
- Escapade
- Vessel Make
- 50` US Navy Utility trawler conversion
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?
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?