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bartosxxx

Put my boat in reverse going 30 mph! Help!

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bartosxxx

I need a little help as my boat its smoking from the rear end and i have no idea what it is!

last weekend i saw a log ahead of me and paniced and put my boat in reverse! it shut down but i started it up again and i thought all was good!

then this weekend we went for one surf and the rear of the engine started smoking like burnt rubber!

forward and reverse both worked but when i went to give it full throttle the boat just would smoke and go very slowly!

Does anyone have any idea what i could have done!

is it tranny isuues? seals? or the engine? much help appreciated

Bartos

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David78337

Did your sea water pump freeze up? Could be your belt smoking on a seized up seawater pump pulley.

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Baddog

What actually happened when you crammed it into reverse at that speed?

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JasonK

I'd guess that the smoke is unrelated to the reverse usage.

Does the engine compartment smoke or just out the exhaust?

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HRemington

I doubt it's the tranny...the Hurth manual even says you can do that in emergency cases. Possibly water up your rear end got where it's not supposed to be...but I guess by definition water up your rear end is already where it's not supposed to be.

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nuttyskier2002
I need a little help as my boat its smoking from the rear end and i have no idea what it is!

last weekend i saw a log ahead of me and paniced and put my boat in reverse! it shut down but i started it up again and i thought all was good!

then this weekend we went for one surf and the rear of the engine started smoking like burnt rubber!

forward and reverse both worked but when i went to give it full throttle the boat just would smoke and go very slowly!

Does anyone have any idea what i could have done!

is it tranny isuues? seals? or the engine? much help appreciated

Bartos

What color is the smoke and where exactly is it coming from? (exhaust, inside engine bay or other).

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68Slalom

What have you checked so far?

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Sandbagger

It is possible you now have bent valves, possibly when the piston slammed up against them with the initial force against the motor when slamming in reverse. Could be a blown head gasket.

What color is the smoke and what does the engine sound like?

Edited by Sandbagger

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SacRiverRat
It is possible you now have bent valves, possibly when the piston slammed up against them with the initial force against the motor when slamming in reverse. Could be a blown head gasket.

What color is the smoke and what does the engine sound like?

Serious?!? Dontknow.gif When you go into reverse, the engine doesn't run backwards.. :lol: Only the transmission would be at risk here...

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WakeGirl

Possibly the vdrive unit as well.

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Ronnie

It's a long shot and I hesitate to suggest this because the reversing shouldn't have caused it but what you are describing sounds like a shredded impeller. Little or no water cooling the exhaust hoses and limp home mode since it's hot. BICBW

Dontknow.gif

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Sandbagger
It is possible you now have bent valves, possibly when the piston slammed up against them with the initial force against the motor when slamming in reverse. Could be a blown head gasket.

What color is the smoke and what does the engine sound like?

Serious?!? Dontknow.gif When you go into reverse, the engine doesn't run backwards.. :lol: Only the transmission would be at risk here...

Ok, whatever, who said the engine was running backward anyway. Obviously he could have a problem with the tranny or vdrive but how would that cause the smoke (which I assume is coming out the exhaust)? Since ur the expert maybe u could explain the forces on the vdrive, tranny and engine when jamming into reverse at 30 MPH. Seriously, think about it and let us know what u think.

Or maybe TOP could better explain what he experienced when he shifted.

Edited by Sandbagger

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WakeGirl
It's a long shot and I hesitate to suggest this because the reversing shouldn't have caused it but what you are describing sounds like a shredded impeller. Little or no water cooling the exhaust hoses and limp home mode since it's hot. BICBW

Dontknow.gif

I had had the thought that maybe water wasn't getting pulled in while this was happening, but I can't explain how I think that could happen other than a sudden decrease in speed would change the water flow over the intake. Possible air lock? Not likely, but I guess it could happen. If it was enough & with the engine revving in reverse, maybe that could cause the shredding of the impeller & then the consequent overheating issue. The impeller is easy enough to check, might be worth pulling it apart to see.

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Ronnie
It's a long shot and I hesitate to suggest this because the reversing shouldn't have caused it but what you are describing sounds like a shredded impeller. Little or no water cooling the exhaust hoses and limp home mode since it's hot. BICBW

Dontknow.gif

I had had the thought that maybe water wasn't getting pulled in while this was happening, but I can't explain how I think that could happen other than a sudden decrease in speed would change the water flow over the intake. Possible air lock? Not likely, but I guess it could happen. If it was enough & with the engine revving in reverse, maybe that could cause the shredding of the impeller & then the consequent overheating issue. The impeller is easy enough to check, might be worth pulling it apart to see.

Sort of my thoughts too. I'm picturing the boat lifting out of the water a bit in the rear and the prop sending lots of air bubbles toward the pickup. The OP didn't say how it ran right after the incident, just after the next outing IIRC.

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WakeGirl
It's a long shot and I hesitate to suggest this because the reversing shouldn't have caused it but what you are describing sounds like a shredded impeller. Little or no water cooling the exhaust hoses and limp home mode since it's hot. BICBW

Dontknow.gif

I had had the thought that maybe water wasn't getting pulled in while this was happening, but I can't explain how I think that could happen other than a sudden decrease in speed would change the water flow over the intake. Possible air lock? Not likely, but I guess it could happen. If it was enough & with the engine revving in reverse, maybe that could cause the shredding of the impeller & then the consequent overheating issue. The impeller is easy enough to check, might be worth pulling it apart to see.

Sort of my thoughts too. I'm picturing the boat lifting out of the water a bit in the rear and the prop sending lots of air bubbles toward the pickup. The OP didn't say how it ran right after the incident, just after the next outing IIRC.

Exactly. Add lots of cavitation at the prop & you've got a really bad scenario for water intake.

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David78337

How big was the log? I was taught that when dealing with water hazards its best to put boat in natural and keep steering. As long as you can keep the log away from your prop, shaft and rudder what’s the worst that could happen, a little gel coat damage? Was onboard an MB when it struck a dead head (stump just under water level) at 32mph pretty jarring blow. It lifted the rear of the boat out of the water causing large fracture in the gelcoat and some spider web, but no leaks. We boarded the rest of the day. It’s not recommended but probably better then throwing it in reverse.

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bartosxxx
I need a little help as my boat its smoking from the rear end and i have no idea what it is!

last weekend i saw a log ahead of me and paniced and put my boat in reverse! it shut down but i started it up again and i thought all was good!

then this weekend we went for one surf and the rear of the engine started smoking like burnt rubber!

forward and reverse both worked but when i went to give it full throttle the boat just would smoke and go very slowly!

Does anyone have any idea what i could have done!

is it tranny isuues? seals? or the engine? much help appreciated

Bartos

Thank you all for the help but so far my boat mechanic says is that it is the water pump but it has done a lot of damage! so hopefully that is all that is wrong!

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Baddog

This does nothing to solve the problem, but couldn't you have done a power turn instead of slamming in reverse?

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Soon2BV

post-7974-1248840873_thumb.png

Here is a basic picture of a very simple transmission. I am not sure how to "show it" inside this post, so i will attach it and talk to it.

I am far from a transmission expert, and there are a few questions that maybe someone else knows the answer to.

The engine (blue) is connected into the transmission (blue frame box) by a driveshaft (grey). There are two drive gears hard connected (welded) to that shaft (blue) and (purple).

Both of these shafts turn whenever the engine is turning (there might be a clutch in there - not sure - but i dont think so in a boat).

If the engine is turning clockwise (CW), this shaft is turning CW also. This direction never changes.

The red shaft is connected to the prop.

The two gears (yellow) and (green), are on bearings and spin on the red shaft. They are meshed with the two drive gears above, so they always spin.

But, since they are on bearings, they do not cause the red shaft to rotate. The extra small gear (light blue) is an idler gear. This gear "reverses" the rotation of the green gear.

So, the yellow gear spins Counter Clockwise (CCW) (it is meshed with Blue spinning CW), and the green gear spins CW, because the idler (light blue) spins CCW.

When the transmission is shifted to forward, the black "dog gear" will slide forward on the red shaft. It is splined to the shaft so that if this black gear rotates, the red shaft rotates.

This dog gear has "teeth" that engage into the yellow gear, so that the black dog gear willl rotate, and the propeller (dark blue) will rotate. The dog gear is an elaborate design so that it will easily mesh into the yellow gear.

When the transmission is shifted back to neutral, the black dog gear dis-engages, and the prop slows because there is no power to it.

When the transmission is shifted to reverse, the black dog gear engages into the green gear. Like above, this causes the rotation of the dog gear because the green gear is rotating. Because of the idler gear in the series, this gear is spinning the other direction, so the prop spins in reverse.

There must be something to restrict the dog gear from engaging in the green gear when the red shaft is spinning in the forward direction. If not, except at very slow speeds, the teeth that engage the black dog gear to the yellow gear would shear off - you would be trying to instantly reverse the direction of a shaft rotating at a few thousand RPM and those teeth would take that load. This is where someone with better knowledge of these transmissions can help.

So, the reason the service guy had said "no problem" to go quickly to reverse could be that the gears won't engage until the propshaft slows down, regardless of the power level when you pull into reverse.

NOTE - about the only difference in a V-drive setup would be that the prop shaft goes into a second gearbox with a set of bevel gears in it, to reverse that shaft direction. i dont think there is anything but this one set of gears and some bearings in the V-dive box.

Edited by Soon2BV

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mlange

Very nice explanation.

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Baddog

Now just add animation and we will understand the theory much better.

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SMERRILL
I doubt it's the tranny...the Hurth manual even says you can do that in emergency cases. Possibly water up your rear end got where it's not supposed to be...but I guess by definition water up your rear end is already where it's not supposed to be.

Thumbup.gifClap.gif

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Daggertime

I just did something similar. Accidentally hit reverse at 15 mph. Then unable to put in gear. Had to get towed in. Now I get to figure out how to get it on a trailer and to the shop. Sucks!  Hopefully nothing major. 

Edited by Daggertime

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Eagleboy99

Didn't Mythbusters do a whole scene on shifting into reverse at speed?  Deemed impossible.  BTW, many years ago I took off and some dumb bunny   hidden behind another boat took off perpendicular to me, cutting me off.  I slammed it ito what was supposed to be neutral, but turned out to be reverse.    I  freaked and immediately shut off the engine.  Started back up and all was good.

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RyanB
34 minutes ago, Eagleboy99 said:

Didn't Mythbusters do a whole scene on shifting into reverse at speed?  Deemed impossible.  BTW, many years ago I took off and some dumb bunny   hidden behind another boat took off perpendicular to me, cutting me off.  I slammed it ito what was supposed to be neutral, but turned out to be reverse.    I  freaked and immediately shut off the engine.  Started back up and all was good.

Going back a number of years, but I can tell you it wasn’t impossible. Was driving down a mountain road in my 2001 Dodge Cummins, and an elk ran across the road. My 90 pound dog went crazy, and hit the gear shift and knocked the truck into reverse. Stalled the engine. 

Fortunately for me, it started right back up and never caused me problems in the remaining time I owned it. 

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