DD 6V92TA won’t start

[Jabba]

Hello everyone, cry for help from the Netherlands. I’m not a mechanic… I recently bought a Mondomarine Arrow 50 with rebuilt twin Detroits 6V92. Engines hadn’t run in over 5 years, possibly longer.

The Starboard engine fired up right away. Runs fine, but high rpm in neutral (1500). As soon as I put the engine in gear the rpm goes to a steady 600 rpm (could this be the injectors?).

Bigger problem is the Port engine. It will not start. As soon as I crank the engine, blue smoke comes out of the turbo intake… No smoke or cooling water coming out of the exhaust while cranking… Fuel pump and fuel lines checked ok. Turbo as well. Had a mechanic look at the engine but he couldn’t figure it out. Does anybody have an idea what could be wrong? Injectors here as well? Exhaust blocked?

Appreciate the help forum members. Big thank you in advance from across the pond.

Andre

 

[Sleeping Bear]

Detroit

Just a stab in the dark, but these engines will actually run backwards, causing smoke to come out the intake, so check it is turning the right way.

Also, there is an emergency shut down flap in front of the blower in case the rack gets stuck (a DD fault because of the way the injection system is designed) so check that. Once it is tripped, you have to reset it on the engine, pushing the cable back down doesn't do it.

Sounds like the other engine has some kind of fuel problem too like a leaky injector causing higher idle, they have also been known to run on the oil leaking from a leaky turbo, so the shut down flaps are the first thing I check to make sure they are operational when I see a DD engine.

Love their sound!!!

 

[Lepke]

You need someone that knows Detroits, not the average marina mechanic. They have no idea what makes it run. Maybe someone that knows old diesels with mechanical injectors. The fuel is constantly circulated thru the system including the injectors. The injector has a piston that makes the high pressure needed for combustion. The fuel is an essential part of the cooling of the injector tip.

Before starting a long sitting 2 cycle Detroit, remove the valve covers and operate the linkage by hand to verify the injectors are working and not stuck. The injectors are controlled by the governor. When you move the throttle, you're actually moving the governor setting. From the other side of the world, I'd say look at the governor on the st'bd engine. Get a service manual, you can find them on ebay.

If the port engine has a block heater, turn it on for a few hours. Or find a way to heat the engine. Some rings contract when sitting for long periods and don't contact the sleeves well until the engine starts again. If you have fuel to the injectors, it sounds like poor compression.
Normally if a Detroit has fuel and the temperature is above freezing, they will start and then run for a couple decades. When the engine is cranking, the fuel pump is circulating fuel thru the filters, lines and injectors. It's self bleeding, but you could have started with empty fuel lines. Verify you have fuel at the injectors.

 

[AlanT]

You need someone that knows Detroits, not the average marina mechanic. They have no idea what makes it run. Maybe someone that knows old diesels with mechanical injectors. The fuel is constantly circulated thru the system including the injectors. The injector has a piston that makes the high pressure needed for combustion. The fuel is an essential part of the cooling of the injector tip.

Before starting a long sitting 2 cycle Detroit, remove the valve covers and operate the linkage by hand to verify the injectors are working and not stuck. The injectors are controlled by the governor. When you move the throttle, you're actually moving the governor setting. From the other side of the world, I'd say look at the governor on the st'bd engine. Get a service manual, you can find them on ebay.

If the port engine has a block heater, turn it on for a few hours. Or find a way to heat the engine. Some rings contract when sitting for long periods and don't contact the sleeves well until the engine starts again. If you have fuel to the injectors, it sounds like poor compression.
Normally if a Detroit has fuel and the temperature is above freezing, they will start and then run for a couple decades. When the engine is cranking, the fuel pump is circulating fuel thru the filters, lines and injectors. It's self bleeding, but you could have started with empty fuel lines. Verify you have fuel at the injectors.

This man knows his DDs.

 

[Peter B]

Welcome to TF, Jabba. I have also taken the liberty of moving your thread into the most relevant section of the forum, so it gets the best exposure, and therefore, hopefully, the best possible replies.

 

[Jabba]

You need someone that knows Detroits, not the average marina mechanic. They have no idea what makes it run. Maybe someone that knows old diesels with mechanical injectors. The fuel is constantly circulated thru the system including the injectors. The injector has a piston that makes the high pressure needed for combustion. The fuel is an essential part of the cooling of the injector tip.

Before starting a long sitting 2 cycle Detroit, remove the valve covers and operate the linkage by hand to verify the injectors are working and not stuck. The injectors are controlled by the governor. When you move the throttle, you're actually moving the governor setting. From the other side of the world, I'd say look at the governor on the st'bd engine. Get a service manual, you can find them on ebay.

If the port engine has a block heater, turn it on for a few hours. Or find a way to heat the engine. Some rings contract when sitting for long periods and don't contact the sleeves well until the engine starts again. If you have fuel to the injectors, it sounds like poor compression.
Normally if a Detroit has fuel and the temperature is above freezing, they will start and then run for a couple decades. When the engine is cranking, the fuel pump is circulating fuel thru the filters, lines and injectors. It's self bleeding, but you could have started with empty fuel lines. Verify you have fuel at the injectors.

Many thanks Lepke, I’ll follow your advice and have a DD specialist look at the engines.

 

[Jabba]

Sleeping Bear,

I actually mentioned to the mechanic that it looked liked the engine was turning the wrong way (smoke out of the inlet, no cooling water or smoke from the exhaust) and we heard a lot of ‘bubbling’ water at the ‘cooling water intake location’ during cranking…

This was after we took the Starboard starter engine (Port engine had faulty starter motor) and put it on the Port engine.

Could this really be? Like I said, I asked the mechanic, but he said that was impossible. How can I figure this out (again, I’m not a mechanic).

Andre

 

[utclmjmper]

The above post makes it highly LIKELY that the starter motor is the wrong one,, you may have COUNTER ROTATING engines so the starter motors won't be the same..>>>Dan ( Your mechanic is nuts,, Detroit powered boats were commonly fitted with counter rotating engines.)

 

[rslifkin]

It is possible that one of your engines is reverse rotation. If that's the case, then with the starter swapped from the other engine, it will actually be turning backwards from its intended direction.

 

[Jabba]

Tx for all the great advice?? Hope we didn’t mess up anything by turning the engine the wrong way. I’ll be checking on the cw/ccw of the starters when I get to the boat. Keep you posted, thank you all again from Holland??

 

[utclmjmper]

In some cases,, running a two stroke DD backwards CAN damage valves..>>>Dan

 

[Jabba]

Let’s hope for the best����

 

[utclmjmper]

As to post #2,, The DD 92 series did not have the shut-down flapper arrangement installed.. That went out with the 71 series engines.>>>Dan

 

[Jabba]

This is the engine set-up. Don’t know if this points to the engines being counter-rotating?

 

[utclmjmper]

All the changes are internal,, many times the info you seek is on the valve covers,, but may have been lost over time.. You can see the engine rotation at the front pully's with the engines running..>>>Dan

 

[Lepke]

Modern engines control the rotation in the transmissions. Older Detroits and others had engines that ran in the opposite direction for twin installations. But engines setup for one direction won't run in the opposite direction. Hydraulic transmission ended the need for opposite turning engines.

Even older engines had levers to change the cam position to reverse the engine direction, had no transmission, and were directly connected to the shaft. They were air starting, air was injected into the cylinders by a special valve that turned the engine over until the diesel ignited. WWII subs, locomotives, etc., used this method of starting.

By the time the DD 92 series were made, hydraulic transmissions had been around for decades. I've never seen or heard of a left hand 92.

 

[psneeld]

RH and LH cranks...


https://www.google.com/aclk?sa=l&ai...hUKEwjO-7jpysD3AhV_kWoFHcXcB044FBDRDHoECAwQAQ

 

[rslifkin]

Modern engines control the rotation in the transmissions. Older Detroits and others had engines that ran in the opposite direction for twin installations. But engines setup for one direction won't run in the opposite direction. Hydraulic transmission ended the need for opposite turning engines.

Even older engines had levers to change the cam position to reverse the engine direction, had no transmission, and were directly connected to the shaft. They were air starting, air was injected into the cylinders by a special valve that turned the engine over until the diesel ignited. WWII subs, locomotives, etc., used this method of starting.

By the time the DD 92 series were made, hydraulic transmissions had been around for decades. I've never seen or heard of a left hand 92.

Even with hydraulic transmissions, not all are meant to handle counter rotation. Early hydraulic Paragons are directional IIRC. Non-CR2 Velvet Drives definitely are (gearing is slightly different in reverse and the reverse clutches are weaker, so they're fwd/rev rather than just an A and B direction).

Modern stuff will all handle counter rotation, but up through the 80s, only some transmissions did. So counter rotating engines were still seen in some applications. Reverse rotation 92 series were probably uncommon as there were transmission choices that didn't require it by then, but from a little searching, it looks like they were available in reverse rotation.

 

[utclmjmper]

One who hasn't seen a left hand Detroit has never seen a GMC bus and many motorhomes with the 92 series DD..>>>Dan

 

[slowgoesit]

As to post #2,, The DD 92 series did not have the shut-down flapper arrangement installed.. That went out with the 71 series engines.>>>Dan

Interesting, the 1984 Hatteras on our dock has DDV92's and it definitely DOES have the shut-down flappers . . . I suppose they could have been added after market, but I highly doubt it. . . . And a tripped flapper was the reason the new owner couldn't get the left engine started, until it was reset . . .

 

[Ken E.]

The flappers are a very good potential cause. One of my 8v71's wouldn't start for that very reason. The flappers are deployed by a T handle at the helm, but they can't be retracted by shoving the handle back in - you have to do this at the engine. At least mine were that way.

 

[markrkrebs]

One thing I didn't see was a check of the water pump. That should run in either direction and if it's failed, you have trouble. There should be raw water in the exhaust. Older detroits always sold in counter-rotating pairs I believe. Hard mistake to make: unlikely fault.
Warm engine idea is a great one. Mine are awesome, but don't like to start cold.

 

[Sleeping Bear]

Dd92

Andre, you will want to be careful you have not sucked water into the engine through the exhaust.

I would bar the engine over to make sure no hydro lock, then when you get the starter repaired and start the engine check for water in the oil, (foam, condensation on the filler cap after cool down) and change the oil if there is water (better change it anyway, oil is cheap).

Don't wait too long to do this as water in the engine damages it very quickly.

Dan, i have also seen the flaps on 92's.

Rod

 

[Jabba]

Tx again for all the advice! Finally found the engine models: 8062-7403 and 8062-3403, so indeed counter rotating engines with unique starters.
In two weeks I’ll try (super cramped corner…) to swap the right starter to it’s original engine and install the original left (relay was burnt) CCW-starter to the left engine.
Hope that will help starting the engine and prevent smoke out of the intake…
I don’t think I sucked up any water through the exhaust, as the exhausts are quite a bit above the waterline.
I rechecked the flapper valves (they are installed on these 92’s), they work correctly.
Still trying to figure out the high rpm (1500) in idle/neutral. Could the engine also be sucking false air?
Big help forum members��
Andre

 

[Jabba]

See pics for engine models, rotation and explanation of model numbers.

 

[Jabba]

Some more pics of starter and rotation. Andre

 

[Sleeping Bear]

Andre, wrt the high rpm's, that is over fueling, diesels rev by the amount of fuel they get, not the amount of air. May be a stickey rack, but it needs to be checked out.

Rod

 

[Jabba]

Oil pump

I read through all of the 6V92 manual, but I can’t find if the engine oil pump was still providing oil to the engine while we were trying to start it in opposite direction. Or that we were trying to start the engine without oil being supplied ?. Anybody?
?
Andre

 

[utclmjmper]

After you get it running,, check the oil pressure and the running temps for abnormalities.. If a bearing has been "spun" due to no oil,, it will show up with no or low oil pressure when running,, an oil analysis will tell the story.. Oil pressure should tell you the damage.. At that time you will have to determine
if to run it in the local area for a while,, or start spending money that you may not have to.. It will be all about how long it was run backwards with no oil pressure..>>>Dan ( It will NOT get pressure running in reverse.)..

 

[utclmjmper]

The most important question is,, did the previous owner also run this engine backwards?? >>>Dan ( He may know something you don't.)