Nissan 6hp - lower unit stuck - driveshaft stuck in powerhead?

[marke14]

Hello everyone,

I wanted to see if anyone here has any suggestions for how to overcome this problem I have with my Nissan outboard.

Details:

2005 Nissan 6hp
Model: NSF6A2S

We last ran this motor in saltwater approximately 5 years ago, and I am mortified to report that I failed to flush it before storing it. At the time I had planned to use it again a week later, and that never happened.

Fast forward to last weekend, when I decided to fire it up and see what was working and not. It started straight away (with choke which is normal) and it pulled a little water - very little. I shut it down pretty much immediately, seeing it was not peeing much water from the discharge. Presumably the thermostat needs replacing, and the water pump needs servicing (the impeller needs replacing at minimum), and perhaps the water tube needs descaling or replacement. Plus gaskets and seals as indicated in the manual, of course.

Anyway after following my shop manual instructions in terms of removing the lower unit bolts (2 bolts on the bottom side of the cavitation plate), and removing the rubber plug in the side of the exhaust housing to loosen the shift rod connector, I found that the lower unit is stuck and won't drop out. With the bolts removed, the lower unit separates at the seam and it can rotate left-right (constrained internally by the driveshaft, water tube and shift linkage), but I cannot get it to budge downward.

Things I have tried so far:

* reassembling, running for a short time to generate heat in the powerhead, and then trying it all again
* careful prying with screwdrivers and pry bars (a small gap is there, so I can get these into the gap)
* light hammering with a rubber dead blow mallet on the top of the cav plate, trying to drive it downward
* light tapping with the same dead blow mallet near the drive shaft (I think) up near the powerhead

Most recently:
* drained the engine oil, turned the whole thing upside down, and sprayed a good amount of PB Blaster through the access hole in the exhaust leg (access hole for shift linkage), aiming the PB Blaster tube to spray straight down the drive shaft, with the goal of having it seep into the splines, to break the bond I presume is causing this.

So this is both a question specific to this motor, but is also a more generic problem from what I have read online.

This fellow seems to have the same issue (fast forwarding to the 6:40 mark or so):

There are some interesting comments in there - and a lot of stuff I would love to avoid.

Does anyone here have any experience with this kind of problem? Please let me know any advice you may have - thanks!

 

[pvanv]

All these (not just Nissans) get the driveshaft stuck in the powerhead. Use wedges and a lot of patience.

 

[marke14]

Thanks for the reply, Paul - I appreciate it.

I currently have the motor hanging from a strap in the garage - the strap wrapped around the cav plate/prop, with the bolts inserted and backed out about 1/3 of an inch, to "catch" it if/when it separates. This upside down position allows the PB Blaster to hopefully penetrate along the driveshaft into the splines (now "below" the rest of the shaft). I keep tapping around where I believe the splines insert into the powerhead, with a small dead blow mallet.

I have ordered a set of small SS shims that I will build up on either side of the gap, and try to pry it apart. I actually got this idea from the comments in a video about this problem. Wisdom from the strangest places ...

In terms of patience, thankfully I have no real need to use the motor, and a garage, and I intend to salvage this thing so I will definitely proceed cautiously.

If anyone else has any other ideas please share them, thanks all!

 

[William01]

I’d be inclined to use wooden wedges, less chance of damaging the aluminum?

 

[marke14]

When I tried using some wood shims, they began to splinter and I am concerned about that. I will be carefully using the SS shims. I will update this thread as I hopefully make progress in this project.

 

[marke14]

The shims I bought were a bust, much too thin for the job. I tried and failed with them, they would build up and then buckle and/or the other side would pop out and spill all of them I managed to get in so far.

Any tips out there on specific types of wedges or wedging techniques I can use on such a small area and gap?

 

[William01]

I guess I should have been clearer when I said wedges. Imagine a 2X4 8-10” long, cut the 2X4 along the 2” side from corner to corner. Your wedge would be 4” wide by 8”-10” long, the longer the wedge the flatter the slope, each cut gives you 2 wedges. Hardwood is best but anything wood would work. Now you have 4”(width) sitting on the lower unit. I would start with a tap, tap, tap and if you have to escalate the wedge will handle it. The question is how much escalation will the aluminum handle?