Removing outdrive and motor

[tordway]

I have a 91 Mercruiser 4.3 175hp #OD504322 with I believe an Alpha 1 drive. The motor has a bad piston so motor has to come out. Does the outdrive have to come off also?

 

[TilliamWe]

Re: Removing outdrive and motor

This question has been asked a million times, but I'll answer it the same basic way as always.

If you have a lot of room in front of the motor to move it forward after you unbolt it, then you can take it out without removing the outdrive.

But, removing an outdrive is SO SIMPLE, that's it's silly not to.
Get yourself the OEM manual from Mercruiser, read it, and you'll be fine.

P.S. How do you know the motor has one bad piston?

 

[Bondo]

Re: Removing outdrive and motor

If you have a lot of room in front of the motor to move it forward after you unbolt it, then you can take it out without removing the outdrive.

Ayuh,... Problem with that is,....
You can't put the motor Back In,....
The Outdrive Has to come Off,... 1st....

The outdrive is Only 6 or 8 nuts,+ it's Off,....
And,...
A $6. gasket set to put it back On...

 

[tordway]

Re: Removing outdrive and motor

I took the boat out last week and it was running rough. Was told it might be bad gas from last year causing it, so put in some new gas with some Stabil and it ran fine for awhile. After about 2o min at 3/4 throttle it started running rough again so I shut it down ,waited a bit then trolled in. Pulled plugs and they were not in good shape to say the least. While the plugs were out I did a compression test and had no compression in #1 and#3. Thinking bad head gasket I had head pulled and low and behold #1 piston is bad. My friend is an experienced mechanic so he is doing the motor for me and I wanted to know should I remove outdrive before he pulls the motor. I will pull it to check water pump and u-joints etc... My first time doing it so any hints would be great. Thanks

 

[dubs283]

Re: Removing outdrive and motor

search the forums for threads about pulling alpha drvies and pulling motors. lots of info on this board about that

 

[TilliamWe]

Re: Removing outdrive and motor

"While the plugs were out I did a compression test and had no compression in #1 and#3. Thinking bad head gasket I had head pulled and low and behold #1 piston is bad."

That's too bad. Usually zero compression is "just" a valve issue. Not a headgasket issue or a piston issue. Sounds like it got run a long time with bad valves? What was wrong with the piston? Did it have a "valve sized" hole in it?
Hints: yes, check everything, bellows, gimbal bearing, u-joints, shift cables. Also check your exhaust manifolds, risers, and exhaust shutters. Clean the bilge real well. Check the wires for the trim that go through the transom, then tend to corrode/break in a spot that's nearly impossible to reach with the motor in. Inspect the steering sytem and especially the tiller arm/shaft for excessive play. All kinds of things to check when a motor is out and an outdrive is off.
Good luck with the rebuild.

 

[tordway]

Re: Removing outdrive and motor

The piston was starting to disintergrate around the edge. Hopefully tomorrow we will get the block out and piston out and get it ready to reassemble. I will pull the out drive before we pull the motor and check that out as well. Once again any tips would be helpful. Thanks

 

[dubs283]

Re: Removing outdrive and motor

tips?

as far as pulling the drive, manual #6 is what you need to get from the adults only sticky.

pulling the motor - pull drive (see above), disconnect everything connected to the motor - water, fuel, electrical, mounting bolts, shift/throttle cables (3 total), remove engine from boat