Port Engine Dies in Reverse

Hi All,

Something I experienced over the this last weekend. When I placed the port engine shifter in reverse and added throttle, the engine died. I was performing a turn, placed the the port transmission into reverse -- gave it a little power and it died. It started right up, but happened a few more times. The boat is still new to me (Jan 2015), so maybe I need roll gently into the higher RPM.

Does anyone have any thoughts? Idle set too low, gremlins?

Chris

How does it behave in forward?

What kind of engines?

Forward is fine, no problems at all.

The engines are Isuzu 135 Hp with low hrs.

While impossible to diagnose long-distance, are you letting the shaft(s) come to a complete stop before shifting from forward into reverse? We measured this time on our boat, an it takes about 3-4 seconds at idle rpm. If you are going straight from forward to reverse the immediate load on the engine could be enough to stall it.s, to say nothing of being hard on the transmissions. We always pause for a moment in neutral to let the shaft stop spinning.

Idle too low has been mentioned and is a possibility. On the other hand, you don't want it too high as that can cause eventual damage to the transmission(s).

If it didn't do this before and now it's started doing it, if it was us this would mean time to call the diesel shop as I am not a diesel or transmission specialist.

Transmission was okay during the survey, so maybe a pause between shifting might help.

ChrisL said:

Forward is fine, no problems at all.

The engines are Isuzu 135 Hp with low hrs.

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Sorry, I can't help with the issue you're having, but I'm very interested in those Isuzu engines. I presume they were swapped into the boat? Displacement? Turbo four? Engine designation? Who sells it? Is it available with more power? Is there an info source where I can find more data? Thanks (apologies for the semi-hijack).

Well, I believe they are the originals, but they have been rebuilt (117 hrs). Isuzu 6bb1 6 cyl. No turbo and very economical. I bought the boat n Jan and from the info I found on the boat I think they are the originals or from what I have discovered.

If it was the starboard engine, you'd really be in trouble. You're port engine might have a too-low idle, but that is a low likelihood. Does the port engine stall when starting from a dead stop? No trouble with the starboard engine when reversing? Maybe its idle is too fast. Try to avoid "jerking" the shaft(s) when changing directions.

ChrisL said:

Well, I believe they are the originals, but they have been rebuilt (117 hrs). Isuzu 6bb1 6 cyl. No turbo and very economical. I bought the boat n Jan and from the info I found on the boat I think they are the originals or from what I have discovered.

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Thanks for that. I'll look them up.

Check idle rpm with a phototach. If idling too low, it is easy to stall. There is also a "buffer" screw on the injection pump, if it has the pump I think it does. That setting can affect stalling. I don't think that pump likes idling down to like 600, it needs to be up around 700 or idle is unstable. You normally notice it when snatching from fwd straight to rev and engine goes "poop".

ChrisL said:

Transmission was okay during the survey, so maybe a pause between shifting might help.

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It should not stall going into reverse. Especially if as you say, it happens after you are in reverse and you are then adding throttle.

No engine should quit because you need to pause before going into reverse to stop or slow the shafts from spinning. What would happen in an emergency? You would tell every thing to hold on a minute while you wait before you shift?

Check your idle rpm with an optical tach and see if it needs adjusting. You don't have anything wrapped around your prop do you?

Hi Capt Bill,

Correct. I'm in reverse add throttle and it dies. Starboard does not stall in reserve, so I'm thinking rpm.

Ski NC, I'll check on the buffer adjustment.

I get the hull cleaned monthly, so I'll ask my diver to check for any fouling.

So it stalls when you add throttle, not when you shift into gear? If that's the case then I doubt idle speed has anything to do with it.

I would check the throttle linkage and control cables ends. Perhaps there is something loose such that the initial nudge of the throttle actually causes the control on the injector to move back before it goes forward? Or maybe it is causing a short to a stop control?

Short? Interesting. For the record, it starts right up, no hesitation or long cranking.

I forgot to mention this is happening from the fly bridge controls. Out of desperation, I went down below to the lower helm area to see if was any better, and it was. It never stalled from the controls from the lower helm area.

So, maybe it is a short or maybe the shifter on the fly bridge reacts differently. Thoughts??

Are the shift controls totally mechanical or are there any electronics involved? What about the engine controls? Does the boat have engine synchronizers? Is the fuel shutoff mechanical or elecrical/solenoid?

Shift controls are mechanical.

I am not sure about a engine synchronizer or even what it is. I guess I would say no.

Fuel shut off is electronic (push button).

An engine synchronizer syncs the engines automatically as opposed to the operator having to do it manually.

Nice! I might have to invest in one of those.

neutral safety switch out of alignment? if it does it from one station and not the other it could possibly be a culprit..
HOLLYWOOD

ChrisL said:

I forgot to mention this is happening from the fly bridge controls. Out of desperation, I went down below to the lower helm area to see if was any better, and it was. It never stalled from the controls from the lower helm area.

So, maybe it is a short or maybe the shifter on the fly bridge reacts differently. Thoughts??

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If it works from down below and not on the flybridge, you appear to have isolated the problem. The upper shifter normally moves the lower via cable, and the lower then shifts the gearbox via a second cable. I'd guess there's slop in that first cable and you're not getting the lever on the transmission making a full throw. So the shift valves get stuck in some no man's land. In any case, I'd investigate the cable adjustment...

Could also be cable adjustment causing the idle to drop lower from one helm than from the other helm. Some set ups have two cables making it all the way to the engine.

This will take two folks, one moving levers and another at injection pump seeing if lever goes all the way to the stop.

And a phototach.

Very strange if engine stalls when advancing throttle lever above idle. That is not a normal problem with diesels. To the OP, are you sure of that?

ChrisL said:

Nice! I might have to invest in one of those [engine synchronizer].

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It's my understanding that it can be added to just about any set of engines, even the old Lehman 120s. I have no idea what the cost is. We've never seen the need for them on our twin-engine PNW boat as we find syncing our engines manually to be a simple two or three second excersise by ear and feel.

I went on the sea trial of a boat some friends of ours ultimately bought. It had twin Volvo diesels (don't know which model) and and an electronic engine sychronizer. We noticed that at low rpm and idle the synchronizer "hunted" a bit, with the engines going out of sync for a few seconds at random intervals and then back in. The dealer/broker said this behavior was common for this particular syncronizer system.

Ii don't know if this is typical behavior of all syncronizers or not. We have them on another boat but I've not had enough experience with that boat yet to really know how the syncronizers behave.

Marin: we had a glen denning sybchronizer on my boat and that was not to be engaged until approx. 1,000 rpm mark, or conversely, turned off when going below 1000.

The beauty of a synchronizer is the ability to control both engines with the use of just one throttle lever. Once forward is engaged, the synchronizer is switched on. Then the "slave" throttle is fully advanced and the "lead" throttle then controls both engines.

I thought dual-engine boaters liked the feel of twin throttles in hand: synchronizing the engines with minute palm action. Isn't that part of the fun?

markpierce said:

I thought dual-engine boaters liked the feel of twin throttles in hand: synchronizing the engines with minute palm action. Isn't that part of the fun?

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I do. I can't speak for anyone else.

And since synchonizing multiple boat engines is dirt simple and takes but seconds, I can't really see the value in the price of a synchronizer system. Unless..... one's power levers don't stay where one puts them, in which case a synchronizer would make sense as the alternative would be constantly fiddling with the power levers.

The mechanical power levers on our PNW boat don't move from where they've been set so synchronizing is a one-time function for us when a power change is made.

Neutral safety switch? Mine only interupts the START circuit to the start solenoid. Would it cause interruption of the Run circuit? We are all just guessing and probing for symptomatic information i know. (Love your avatar hollywood.) provokes happy thoughts.
Similar note my last boat with worn out gas engines has similar problem of dying while docking. That was just a barrel of laughs... AFTER we got it in, of course. culprit was very low compression. Rebuild engine solved that .
Take it out in open waters and repeat the conditions several times from bridge and lower helm. Make sure it is consistant not coincidental.
Good luck interested to hear what you find.
Dave.

Rope/wire wrapped around one of the shafts? Tightens in reverse and gets tighter the faster the shaft turns.

Thank you everyone. My mechanic will be at the boat on Monday. Let's see what happens.