Very loud rattling/knocking noise under load

cruiser83

Seaman
Joined
Feb 2, 2020
Messages
73
So took boat back out, installed new fuel pump, filter, and tried different hardware to push propeller out because it looked like it was rubbing. And nothing changed, so I retarded timeing and seemed like it helped alot. Then when I would trim all the way down it seemed non existent. And I could rev t out fine. But if I trim up some it would do it. So we cruised t a while with trim down messing with it and playing with timeing. I didn't do timeing because t didnt have a diming degree marker on it. Just the one to set motor at tdc. But after cruising for a little bit we stopped to fish and eat. And then after we went to take off again and it would feel like it pops out of gear or slip at around 2500 rpms until I throttle down and it would kick back in or or grab again and no matter what I do it would do it...also I lost the zinc anode. Would that cause it to slip?
 

cruiser83

Seaman
Joined
Feb 2, 2020
Messages
73
I talked to a buddy and he said I might of slipped my prop bushing because when I ease out of throttle I can lug it. But if try to get on a plane it just slips and spins. But there is a bit of vibration I feel in floor
 

cruiser83

Seaman
Joined
Feb 2, 2020
Messages
73
I was able to get to 45 before hub slipped or whatever the new issue is. I'm pulling outdrive today to check u joints and shaft splines
​​​​​​
 

cruiser83

Seaman
Joined
Feb 2, 2020
Messages
73
So got the outdrive off and man what a pain that was. It didn't just slide out. It fought the entire way like the motor isn't alligned with gimbal bearing at all. And the gimbal bearing felt like it's bad too. Definitely doesn't spin smooth. And had water in it, I think the shift cable Bellow came off.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,464
Ayuh,..... Time to access the damage, 'n order parts soon,.....

With a flashlight, look at the tops of the splines in the coupler, through the gimbel bearin',......
They should be nice little square tops,......... Not pointy,.....
 

Rick Stephens

Admiral
Joined
Aug 13, 2013
Messages
6,118
Bondo is right. No more test runs, especially at speed, without fixing obvious stuff. Inspect everything. Make it right as you go. Do testing in the driveway instead of at 45 MPH. Under way and at speed is a great way to break something spendy.
 

cruiser83

Seaman
Joined
Feb 2, 2020
Messages
73
That's the plan, definitely spun the prop, can see the melted rubber falling out of bushing, whipped up a stand for the outdrive and got the allignment tool on the way. Gunna play with allignment, I'll check it again when I get the new bearing in. Sooo I watched every video I can find on doing bellows and gimble bearings, seems pretty simple and easy asking as you have the right tools. Now I think shift cable Bellow is good, but and water got into out drive from water impeller oring, and nothing looks rusted, just wet. But there is a nice little bit of sand built up around the shift cable. But that's the lowest spot on in the outdrive. So I'm thinking previous owner ran it in some shallow sand. So will pull impeller once I get it back on the boat.
 

cruiser83

Seaman
Joined
Feb 2, 2020
Messages
73
I did a real quick compression test just to see if there was any big difference in compression. I just pulled one plug at a time. I know this isn't the correct way. And not most accurate but I figure it would atleast show any cylinders the have much lower compression. And most of the cylinders were around 120-125 except
cyl.
​​ 1- 105psi
3- 105psi
5- 110
4- 115
i got a nice 383 stroker in my 84 suburban.I had the motor built to tow my 10k lbs toy hauler on 700 mile round trips. And I only put aaround 5000miles on it. And changed the oil 4 times now with Lucas and zddp additives. I'm probably going to change the cam in it and maybe put some thicker head gaskets on it to lower compression (10.1) to around 9... Has true roller rockers with world product sportsman iron heads with 64cc Chambers and 2.02 valves. The cam is extreme energy cam 12-242-2
int. Lift 477
Exh lift 480
Duration 224-231
Lobe seperation 110
 
Last edited:

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,296
I did a real quick compression test just to see if there was any big difference in compression. I just pulled one plug at a time. I know this isn't the correct way. And not most accurate but I figure it would atleast show any cylinders the have much lower compression. And most of the cylinders were around 120-125 except
cyl.
​​ 1- 105psi
3- 105psi
5- 110
4- 115
i got a nice 383 stroker in my 84 suburban.I had the motor built to tow my 10k lbs toy hauler on 700 mile round trips. And I only put aaround 5000miles on it. And changed the oil 4 times now with Lucas and zddp additives. I'm probably going to change the can in it and maybe put some thicker head gaskets on it to lower compression (10.1) to around 9... Has true roller rockers with world product sportsman iron heads with 64cc Chambers and 2.02 valves.

Would need to have specifics of the 383 prior to being able to comment. However first comment..... If it wasnt built as a boat motor...... NO
 

cruiser83

Seaman
Joined
Feb 2, 2020
Messages
73
I should add that I live at 7+k elevation. So the compression numbers are lower then what they would be at sea level.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,464
And most of the cylinders were around 120-125 except
cyl.
​​ 1- 105psi
3- 105psi
5- 110
4- 115

Ayuh,..... Even at elevation, that's a rebuildable core motor, not a runner,......
 

Rick Stephens

Admiral
Joined
Aug 13, 2013
Messages
6,118
Be kind of fun to drop a stroker in that hull. Need to analyze all the components to know whether the one in the chev is suitable without a lot of mods. The current motor would be a good candidate to build up.
 

cruiser83

Seaman
Joined
Feb 2, 2020
Messages
73
Ya hopefully I'll have the motor pulled and apart and go from there. But I just noticed this long crack along the bottom of the hull....not to sure what I should do about it? I started a post on this in the hull repair section. Not really sure how I should go about this.
 

Attachments

  • photo325080.jpg
    photo325080.jpg
    65.8 KB · Views: 0

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,296
as I wrote in your other thread. you must restore the hull. you have rot in the structure. time to start reading the restoration DIY links.
 
Top