[jln007]

Hi,

Can anyone speak to the reliability of Detroit 8v92TI motors? Thanks.

[Pascal]

friend of mine has 8V92TIs, I run that boat sometimes

no better, no worst than others.. teh BIG question is how they have been run... if they've been run hard and hot, on an overpropped boat they're not going to last long, but this is true of any diesel...

I believe the 92s have wet liners and are a little more sensitive to overheating than 71s, but that woulnd't be a deal breaker for me.

[Capt J]

I have run lots and lots of Detroit Diesels. I have encountered very very little issues in terms to major issues. Of all of the yachts I have run with them, I have only had an internal failure with one of them and we were able to run it a day easy to get to a service yard. (split tip on an injector).

One thing about Detroits, you can bet that they will always get you home as long as you have fuel and compression. Even if you have a dead cylinder they'll still run. I know of one boat with a 6v71 with a dead cylinder and the owner (crab boat) took out the connecting rod for that cylinder, disconnected the rocker arms so the injector didn't fire, and ran it for 2,000 more hours on 5 cylinders. They're not the cleanest, you're not going to have a spotless bilge, but they are reliable.

[K1W1]

Originally Posted by Capt J

I know of one boat with a 6v71 with a dead cylinder and the owner (crab boat) took out the connecting rod for that cylinder, disconnected the rocker arms so the injector didn't fire, and ran it for 2,000 more hours on 5 cylinders.

Hi,

I think that there is more to this story than simply jerking out the slug and stopping the injector.

He would have also needed to stop the exhaust valves opening or the exhaust from other cylinders would have got into the crankcase.

Also as the crankpins in thise have 2 Conrods a piece and they were never designed to have such a heavy load applied off centre to the pin for long times (2000Hrs)


How did this guy seal off the inlet ports and stop the charge air from pressurising the crankcase?

[NYCAP123]

Originally Posted by K1W1

Hi,

I think that there is more to this story than simply jerking out the slug and stopping the injector.

He would have also needed to stop the exhaust valves opening or the exhaust from other cylinders would have got into the crankcase.

Also as the crankpins in thise have 2 Conrods a piece and they were never designed to have such a heavy load applied off centre to the pin for long times (2000Hrs)


How did this guy seal off the inlet ports and stop the charge air from pressurising the crankcase?

Even if he could why in the world would he?

[Capt J]

Originally Posted by NYCAP123

Even if he could why in the world would he?

He did it because he was a poor commercial fisherman that couldn't afford to rebuild it.

It's a 2 stroke diesel. If you disconnect the connecting rods and pin the piston in place, it shouldn't scavange anything because the piston is not moving and the air in the cylinder has nowhere to go. I don't know how he did it exactly, but a mechanic was telling me about it. If you disconnect the rocker arms from the cylinder head, the injector will stay shut, and so will the valves. I have seen the boat and the guy ran it for years, it was a natural and he ran it easy rpm-wise because all he was doing was pulling traps with it. I am sure if you turned it up to maximum rpm's it would have grenaded into a million pieces due to the lack of proper balance on the crankshaft.

I've seen 4 stroke engines with a dead cylinder that people ran easy for a long time, as long as they replaced the oil it kept losing.