Where to drill casing to access driveshaft/crank? OX66 250HP

[DennisG01]

Does anyone happen to know where on the side of the casing (is it called the "midcase") I could cut a hole to access the spot where the driveshaft splines into the bottom of the crankshaft?

Or, instead, does anyone know how long the driveshaft is - maybe in terms of how far the driveshaft extends vertically above where the lower unit separates from the midcase?

I can find pictures online that tell approximately where the driveshaft is, front to back. It appears to be roughly inline the forward edge of the "grooves" for the water inlet opening. But I'm not sure how tall the driveshaft is. Worst case, I can make an estimate with a hole just big enough to stick a snake cam in there.

[ausnoelm]

What do you want to inspect with the camera?

[DennisG01]

What do you want to inspect with the camera?

Not so much about the actual "inspection"... I want to try spraying some PB Blaster up there to seep into the apparent corrosion in the splines. Having a heck of time trying to get the lower unit off. The camera thing would just be if no one knew the location/measurements so I could figure out where to cut an access hole. If thats the case, hopefully I get lucky with the inspection hole and that it's in a good spot to inssert the spray needle. I'm not too worried about a 3/8" hole or even cutting a larger inspection hole as it can be repaired, but obviously it's better to drill fewer holes than more.

[99yam40]

If it is stuck good then cut the shaft and pull it out of the crank after you get the power head off.
if you just want to soak it turn the motor upside down and spray the shaft and let it run down the shaft to the crank

[DennisG01]

If it is stuck good then cut the shaft and pull it out of the crank after you get the power head off.
if you just want to soak it turn the motor upside down and spray the shaft and let it run down the shaft to the crank

Cutting the shaft is certainly an option (I do have a spare lower unit, as well). But I'm holding that option to last.

Me thinks that cutting a hole in the side casing and squirting some stuff in there (which will creep/seep/wick uphill) over the course of a few weeks is easier than removing the engine and turning it upside down... Although, if I cut a big enough access hole I could create a dam around the shaft to allow a puddle of PB to stay in contact with the splines.

[ausnoelm]

I don't think any amount of spray will help a really stuck drive shaft, have you tried the wedges and start the motor method? I know it sounds drastic, but I have found it works, just make sure ALL the bolts are out, make up some wedges the tap into the gear case join, lower motor right down, place some wood and rag under the gear case to protect it "if" it comes free, connect up flushers and start the motor, make sure the wedges are in tight.

[99yam40]

that stuff does not creep up hill well, but you can try

[TownsendsFJR1300]

The LU drive shaft is literally up INSIDE the crankshaft (where it's apparently frozen). IMO, drilling a hole is pointless.

Plus one on running the engine, bolts VERY loose (I personally wouldn't remove them all fully).

Run the motor on muffs AND flushing attachment AND SHIFT INTO GEAR, in and out, (try and break / vibrate some of that rust up)


BTW, you have the most leverage right now vs just a cut off shaft.

[DennisG01]

Aus, I should have mentioned that I've been through all the steps that are normally taken. One thing I have yet to try is to put it in water and shift quick and hard from fwd to rev a few time... run it hard in reverse... on the assumption that going into rev might "shock" it loose.

99, if you know of a better penetrating oil, I'm all ears. Maybe Deep Creep? I might even try to get some white vinegar or Rydlyme in there... especially if I can create that dam (tape a piece of plastic around the spline joint and fill the plastic, for example).

EDIT: Scott - looks like I was typing as you were - yes, I would run with the bolts loose.

[boscoe99]

If you look very carefully just above where the top engine mount bolts are you should be able to see the drive shaft. Turn the motor one way or the other to its extreme position might help you see it better. It might even be possible to get a sawzall blade in there to cut the drive shaft without damaging the mid-section. Perhaps an impact gun with an appropriate tool on it could be used to hammer the drive shaft while the lower unit is unbolted, to try and get it to fall free.

[rodbolt17]

as the powerhead is dowl pinned to the adapter running it with the bolts loose is rather pointless.
I typically sawzall the shaft just above the til;ler. then remove the powerhead. drill the shaft,tap it and use a puller. then hope there is enough spline in the crank to have a viable project.

all over 5 bucks worth of grease once per year..

[boscoe99]

as the powerhead is dowl pinned to the adapter running it with the bolts loose is rather pointless.
I typically sawzall the shaft just above the til;ler. then remove the powerhead. drill the shaft,tap it and use a puller. then hope there is enough spline in the crank to have a viable project.

all over 5 bucks worth of grease once per year..

What does the power head being bolted to the adapter plate have to do with anything?

The only thing holding the lower unit to the base of the mid-section are the lower unit attachment bolts. And maybe just a tad of friction between the shift shafts, the speedometer tube/socket and the water pump tube. If all of the bolts are removed, in the OP's case the only thing seriously holding the lower unit in place appears to be corrosion between the drive shaft splices and the crank shaft splines.

With the bolts loosened a quarter of an inch or so (weight of the lower unit now pulling down on the corroded splines) running the motor in this configuration might, just might, help to break the corrosion free. The crank shaft heats up and expands the splined area. The vibration from the motor might help to break the corrosion free. Gravity might, just might, then do the job.

Or might not. Worth trying before damaging the motor but cutting the drive shaft.

[DennisG01]

I didn't realize I'd be able to see the driveshaft - thanks, I'll check on that in the late Spring when I get to the boat (it's in ME, I'm in PA). Cutting is definitely last resort! I hadn't thought of an impact tool (like an air chisel?) to vibrate the shaft stub loose... I was thinking of just tapping it with hammer. BUT also hadn't really thought about how to pull the stub back DOWN... drilling/tapping and using a puller/slide hammer sounds like a good idea.

I really don't care about cutting a hole in the mid casing - it's easily fixed and it doesn't bother me one bit to have a patch plate on it. Heck, I have a spare mid case if it started to bother me!

[ausnoelm]

I guess what it all amounts to is, the shaft is stuck, anything is worth a try to get it off, whether that is wedges, starting motor, hitting with air tools, bolts in or out or anything else, it's worth a try, failing that, it's a cut the shaft job, cutting is relatively simple, but the work to replace it is considerable, of course there is the easy option of not removing it at all until it really needs to come off!

[pstephens46]

I guess what it all amounts to is, the shaft is stuck, anything is worth a try to get it off, whether that is wedges, starting motor, hitting with air tools, bolts in or out or anything else, it's worth a try, failing that, it's a cut the shaft job, cutting is relatively simple, but the work to replace it is considerable, of course there is the easy option of not removing it at all until it really needs to come off!

Based on his previous threads/posts, the shaft has been "stuck" for some time. It's probably weighing on his mind....Impeller etc....I don't envy his situation.

Local guy here with a nice F200 V6 had a hell of a fight getting the damn lower to drop. So easy to remove once a year for grease. So easy....

Surprised we never had Solo show up crying about seized driveshafts. Most abused F225 motors I know of.