CONTINUOUSWAVE

On a 2006 Mercury Optimax 75 water comes up and out the top of the swivel assembly where the shift shaft threads.







I only see this excess water during flushing, at boat speeds greater than 30-MPH, and at engine speeds greater than 5,000-RPM.

Is this normal?

Did I miss a gasket or seal when I removed lower unit to replace water pump?

The problem is recorded in two presentations I made:

https://www.youtube.com/watch?v=DaV2fEBS5to

https://www.youtube.com/watch?v=sYZ_AtFybnU

First off the steering tube has no connection to the water pump, meaning that no water should be pumped from the water pump out of that tube.

The tube is hollow and if the water running by the bottom while unerway somehow causes the water to rise from the tube, I'd say this happened before, but you never noticed it. Some motors have a foam like dounut that sits in or on that tube or a rubber boot for this reason, but depending on the design, it could interfere with your shift shaft and probably the reason it's not incorporated on your motor. I'm noticing your steering tube is steel and that may also be a reason not to have the foam dounut as use in salt water would saturate the foam and it would act as a rust accelerator when the boat is stored.

After watching your second presentation make sure the copper tube that seats into the waterpump housing is seated correctly.

D-

dtmackey wrote:First off the steering tube has no connection to the water pump, meaning that no water should be pumped from the water pump out of that tube. The tube is hollow and...

After watching your second presentation make sure the copper tube that seats into the waterpump housing is seated correctly...

Understood, the steering tube is not connected to the water pump but somehow water is projecting itself up the steering tube towards the swivel only at high speeds. You might be right, maybe I just never noticed before but something still seems wrong. I'm wondering if that's why my swivel bracket is so rusted?

Like you say in your last comment, the water seems to be coming up (blue arrows in the image below) from where the shift shaft spline enters the lower unit. What would be causing this? I am not sure what the copper tube you are referencing is? Is it the "Pin dowel" I have highlighted in the parts diagram?

Could the "donut" be a solution? Would the "donut" be located where I circled in the picture?

In Figure 3 what is the legend for callout 9?

In figure 3, call out 9 is the Swivel Pin Assembly (Part #99661A35)

https://www.crowleymarine.com/parts/6469.cfm

I had similar behavior on a 1987 Mercury two-stroke-power-cycle engine.

In the water, and when in neutral and revving the engine, water would be projected upward in a stream from a hole directly in front of the shift shaft. I also had overheat alarms at higher engine speeds.

I ended up pulling the power head and replacing all of the gaskets. It was lots of work but the problem was fixed after that work.

If a gasket fails up in the adapter plate under the power head water can enter the foot of the motor and find it's way out.

Your engine is not very old.

Have you checked the bushing andthe seal for the shift shaft?

MarkCz wrote:Have you checked the bushing and the seal for the shift shaft?

If there were a water leak around the shift shaft where it exits the sealed part of the gear case, I would be surprised that the volume of water and the water pressure existing at the leak would both be sufficient to push a column of water up the hollow center of the steering tube and cause a spray.

A simple way to test if the water is being forced up the shift tube from a leak at the shift shaft would be to increase the engine speed while the engine is in neutral and the boat is stationary.

Also, it is not clear to me if the opening at the bottom of the shift tube is completely sealed off from the seawater. If the bottom opening of the steering tube is open to the sea, then in order for water to rise to the top and be coming from a leak at the shift shaft exit from the gear case, the volume of water and the pressure would have to be monumental to maintain so much water above the waterline of the engine in the sea.

I watched the two recordings. Your water leak looks very similar to the one I had. Mine was fixed by replacing the adapter plate gaskets and any other water cooling seal I found as I took the engine apart. The easiest thing to check is if the water pump outlet is correctly aligned to the rubber coupler on the water tube.

I would imagine the symptoms of that not being correct would cause similar symptoms but should trigger an overheat alarm.

Q: If you are in neutral and rev the engine. does the water shoot up like in the high speed video you posted?

I ask to see if your engine is mounted too low and when running causing water to be directed upwards.

Keep us posted on what your doing.

Watch my recording of a flush test that shows the flow of the leak did not change with engine speed when the engine was being run out of the water--I'm completely at a loss.

Per recommendation, I checked the flow rate of the leak at various engine speeds. The flow of leak didn't change with engine speed.

Q: Should I just accept the fact that this might just be normal?

I am fairly confident the engine was installed at the correct elevation.

[The behavior shown in the recording is] good news.

With my engine water leak, as the engine speed increased a much larger amount of water would exit and shoot all the way up the swivel tube.

[Your engine] may just have a small leak at the top of the housing for the water pump.

As long as [the engine temperature is in the normal range the engine is okay]

And [if you are] not overheating you may be ok [too].

MarkCz wrote:[The behavior shown in the recording is] good news.

With my engine water leak, as the engine speed increased a much larger amount of water would exit and shoot all the way up the swivel tube.

[Your engine] may just have a small leak at the top of the housing for the water pump.

As long as [the engine temperature is in the normal range the engine is okay]

And [if you are] not overheating you may be ok [too].

Thanks for the reassuring info. [The 2006 Mercury Optimax 75-HP engine has not given] any high-temperature alarms--or any alarms for that matter--in the [six hours] of runtime since last water pump replacement.

Q: should I continue to monitor [the water leak]?

Q: can I assume [the water leak] is normal?

CiancioloNauset71 wrote:Q: can I assume [the water leak] is normal?

To conclude that water shooting out of the top of the swivel tube is a normal behavior does not sound reasonable to me.

Water shooting out of the swivel tube is not normal behavior but a small leak down by the shift shaft area is not uncommon. I have not watched your last recording/ I will watch that soon.

Thanks JimH and MarkCz.

I made another recording, this time on the water at 30-MPH. It appears as though the swivel tube "leak" is not coming up from the shift shaft.

It's more likely that the rushing water is deflecting off the engine mount and lower unit, then making its way up the swivel tube only at [a boat speed that is greater than] 30-MPH.

As I said previously, it seems the only fix is to put some type of gasket. in the bottom of the swivel tube.

Should I just forget my initial concern about this [water deflecting off the engine mount]?

The only portion of your recording that shows the big flow of water is the five seconds or so beginning at

https://youtu.be/hvSQlvqC3i0?t=21

How high your engine is mounted on the transom?

Is the engine transom bracket sitting directly on top of the transom?

Or, is the engine mounting height raised by a few holes?