Fingers crossed!!

duane.mosley

my one vacation a year is Norris lake in Tennessee for a full week. Third day here and I Developed a knocking noise coming from the rear of my engine and I really hope  its just the coupler. Does not  seem to be there while at idle but just a little bit of throttle and it makes itself known. Hope I didnt spin a bearing but either way the engine has to come out. Not much room in the bilge on an 06 250 to pull it forward and check coupler. Oh well, all part of boating right!! 

212rowboat

man, condolences....

check the coupler is well greased and there is nothing that has fallen into the little gap between the actual coupler shaft and housing... I actually found a lost socket in mine that was making a heckuva noise, and was lucky it didn't snap the grease zerk off.... 

also, though, and for what it's worth... sound can travel right up that shaft and make an issue with the outdrive sound like it's originating in the engine (especially the back of the engine)... the shaft turns all the way into the bottom of the upper while in neutral, so anything in the upper can make that sound... so can a slightly stretched shifter cable that is trying to drop the drive into gear (either side, forward or reverse depending if kinked or stretched)... makes a terrible knocking sound... 

rasbury

good luck, dealing with a coupler myself. I did not notice any noise prior to it going....

youstolemybeer

Do you have oil pressure? If so its the coupler

duane.mosley

youstolemybeer said:

Do you have oil pressure? If so its the coupler

I noticed oil pressure was low so  first thing I checked and it was a qt low. Not sure where it went because the engine usually doesn't burn oil.  Was holding 40 lbs when last started so most likely not a bearing. 

youstolemybeer

when you say low oil pressure, how low is low? If the engine is a gm small block, they only need something like 15 psi not to rattle. I think actually its lower but too lazy to look it up. More than likely it is the coupler. Have fun with the boat until it breaks

aero3113

I actually think any pressure above 0 at idle is acceptable.

212rowboat

i think it's 10psi per 1k RPM safe zone with a ceiling of 60 on a warm engine- but actual requirement is 6...  ya don't want to see HUGE pressure- obstructions cause the pressure... volume of flow is what's important, but that isn't easy to measure w/o some pretty expensive parts- so- pressure is what is observed, the issue with pressure is obstructions that increase it, and which decreases flow.... 

if you're pushing 40psi @ WOT, you're okay... on an SBC/BBC @ operating temperature, pushing 10@idle is good enough. 

back to his issue:  I've not heard of a coupler knocking... it could, I guess, but in my opinion it's more likely in the upper drive- or, the cable is hanging between gears in neutral (which would be stupid simple to test by seeing if the knocking disappears while idling in forward or reverse)... if this were me, I'd pull the vent plug (on the upper) and see if the magnet has any metal chunkage on it.   

duane.mosley

Oil pressure is 40lbs at idle and there really isn't much of a noise until I take the throttle up to about 1500rpms. I can put the boat in gear and it will putt along in gear at idle without any noise. When the problem presented itself, the oil pressure dropped below 20lbs. When boat was operating fine it would be 60lbs at wot, usually around 40 when cruising. Shift cable was just replaced in June.  Boat is still in the water until tomorrow. We have a house on the lake with a private dock that was paid for in full 3 months ago, wasn't letting the boat ruin the trip so we are here til tomorrow. I will be digging in when I get home to find my issues. 

212rowboat

I'd pull plugs 7 and 8 and give them a look over. What you describe sounds like a collapsed lifter or a bent lifter rod.  A collapsed lifter makes a sharp and loud tic more so than a knock.  It will still run and power loss will hardly be noticeable on just one cylinder and just not lifting as high as it cold.  

Don't get me wrong, I'd just about rather do a coupler... if you have the facility, drive off engine out coupler swapped alignment drive back on is simple and maybe three hours... pulling the intake and replacing lifters is about four, and it's Hella messier. 

212rowboat

A bent lifter rod can take out a rocker, and it can take out a valve seal... valve seal will allow oil to leak into cylinder which will be apparent on the plug. Bent lifter rod disallows oil to pass through it, actually decreasing pressure across the board as the oil finds somewhere (the valley) to spray instead of the lifter pumping it through the rod.  

It will be apparent if you pop the covers and peek.  

About your shifter cable... was it oe or aftermarket?  The Chinese have an aversion with pre-stretching cables, is why I ask. 

youstolemybeer

cross your fingers and check to see if you have a branch, crap pot, midget stuck on your outdrive.   I had a branch trapped on my outdrive once that did about the same thing

duane.mosley

No branches but it putted right along at 1000 rpm 3 miles to the ramp. Got it on the trailer and getting it home. Time to build a lift to get the engine out. Have any of you experienced a broken flywheel? I've had one on an old bronco  and the boat is making the same type of noise. If I tried taking it over 1000rpm it would get louder but was almost not present when under 1000rpm. It had plenty of torque to put it on the trailer so coupler doesn't seem to be bad. if I'm up to it I will dive in tonight and start investigating. 3 hour drive still to get home so it might wait til tomorrow. Thanks for ideas and thoughts. Will keep you posted. 

Michael T

Yes, fingers crossed! Good luck! It sounds like you are a pro at R&R ING an engine.....but be careful with that lift. My brother in law and I were dropping a rebuilt engine into his Alfa Romeo and the lift collapsed .....so we actually did drop the engine in! About 5 minutes before we were both in the engine bay getting lines etc. ready!

212rowboat

fwiw- I built a gantry type lift... two of them, actually.   used 4x4x16 side posts w/2x6x16 on either side to make it a 8x6x16... the beam across is two 2x6x16's w/ 2 2x10x16's on the outside of them... I then cut 2 2x6x6's at proper angle to join the beam with the posts, and in the cavities both those build-ups created.  after I joined them, I filled the rest of the upright cavity w/ a 2x4 and both sides of the beams cavity with 2x4's as well... 

for the feet, I ran a 14' 2x8 flat, and one on it's side, along with 45* supports on either side of the posts... 

I ran a winch, attached by throwing a chain around the top of the beam and kept in place by taking two stacked 2x8x3's across the center.... 

the whole thing took about two hours to make, and it'll hold a lot more than the wimpy 5/16's cable strung through that winch (ran double to increase capacity).... that is my only concern about this thing- If that thing hangs around (i've buddies who are all about using it- one for his outboard, another for his car) I'll restring that winch with 3/8's inch cable.... 

it's freakin' nice to have my own facility.  I can take my time with projects and do them right instead of relying on others schedules and/or renting a booth and trying to do it all at once.  

Michael T

That's sure a safe rig!