OMC 400 outdrive - Impeller question

I'm new at this, but no stranger to wrenching, just need some advice on the best way to tackle replacing the impeller. Motor is OMC 120 HP with the 400 OMC outdrive. I'm pretty sure it's fine, but I know it hasn't been replaced in at least 8 years, according to the previous owner. It got really hot last week, but the guage read normal (180), and seems to runs much cooler after I replaced the thermostat yesterday. I took off the hose that delivers water to the engine and verified a solid stream, so I know that the outdrive pump works (for now).
I have had different tell me different things, but the manual indicates that the entire outdrive needs to come off then remove the ball gear, and not just the lower gearcase like othere have said. It's on a mooring, and if the marina near my house wasn't so busy I would probably take it there, but they are backed up 2 weeks at least. If this is something I can do in a day I'll get it out of the water but it's kind of a hassle because I don't have a truck, blah blah blah........so I just need an expert to tell me what I'm in for if I tackle this myself. Thanks!

is this an electric shift model? when the motor is fully up, is there a cable running thru the area above the main center exhaust and into the upper gear unit? If so, you can change the water pump without removing the whole damned thing but its a real biatch. You can do it in the water but make sure its shallow!

Nope not electric shift.

Motor fully up? Do you mean the motor trimmed up (funny trim system mounted to front of motor) or outdrive tilted up?

If I'm going to try this it won't be in the water, too hard to find bolts and tools down there lol

On a trailer if all you want to do is pull the water pump in the drive is tilt the drive halfway up.

Remove the very top 5 screws on the drive the whole exhaust shield and lower will drop down place it on tble or cooler or chair you placed next to the drive.

Now you can access the pump in the upper drive.

You can lower the nose of the boat on the trailer and raise the drive a bit also i sit on a milk crate.

Chieftan... do you have any ideas how in the world I could figure out why my 120hp electric shift OMC won't cool while in drive? (only in neutral.)

Maybe i am missing the question ?

You want to know while you are running the motor the drive is fully down and you are in gear on the water the temp goes up the faster you go ?

Be clear in the question please ! Am i correct ?

Please start a new thread Neo

Chiefalen,

That sounds straightforward enough. Being a noob to this sort of thing, please realize I'll be asking a bunch of dumb questions, but I'm still trying to decide if 1)I have the time to deal with this 2)Is it really as simple as it seems. Not that I don't trust the advice given, but I will being doing this in the back yard and although I'm a pretty good car mechanic I'm no more familiar with this than what I've read in my shop manual. I'm considering bringing it to the marina shop, but if I can do this myself in a day then hell yeah I'll give it a try. BTW, how much does this drive weigh?

Also when you drop the lower make sure you have something underneath it or it will come crashijng down. As stated it is failry easy but you should aslo get a manual so you see how to put the impeller into the case. There are some things that are important to do....

mercedglen said:

Also when you drop the lower make sure you have something underneath it or it will come crashijng down. As stated it is failry easy but you should aslo get a manual so you see how to put the impeller into the case. There are some things that are important to do....

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Do you know how much the sucker weighs?

Merced CA? I've been there a bunch of times to visit my brother in law.

Just the lower and the exhaust shield i would say around 20-30 pounds maybe alot less.

I do not find it overly taxing lifting it.

Awesome, thanks for the help and advice. Maybe the hardest part of this is actually finding the time, but the money I'll save is a good motivator

Yes, I live in Merced but don't hold it against me. Originally a Southern California guy, Orange County. I have a great job here so I guess I will retire and then maybe N. Dakota or something isolated and quiet.....