Need help removing lower lower unit on 79 OMC

[Aaron_M]

Well, I just bought my first boat and I'm trying to get it fixed up. I took it to a mechanic and had the oil changed and had him check out the engine. The engine runs great but the impeller was not sucking any water. He said he did not remember exactly how to get to the impeller but belived it was just the six bolts holding on the lower portion of the lower unit that needed to be removed to access the impeller. Welp, I removed all six of the bolts (sort of) but every single one of them broke even with wd40 sprayed all over them the night before. I can take the broken bolts to fastenal for replacements but first I have to drop this lower unit. Does anyone happen to know if there is anything besides the six bolts that need to be removed? The boat is a 1979 Mackie with the original 79 OMC I/O 140 hp. I already ordered a new impeller kit with seals and I would really love to have this thing running by Saturday but I have to work on it in stages and I really need this impeller out. If you guys could help me out that would be great!! Thanks!
Aaron

 

[Aaron_M]

Re: Need help removing lower lower unit on 79 OMC

If anyone knows where I can find a diagram that may help as well

 

[Aaron_M]

Re: Need help removing lower lower unit on 79 OMC

Woops, forgot to attach the pictures...

 

[boatguya1]

Re: Need help removing lower lower unit on 79 OMC

Don't do alot of old stringer drives, so I'm not sure, but I think there is a bolt or two under that exhaust hsg towards the back of the drive. If all 6 of the other bolts broke off I predict alot of cursing/crying/general disapointment as this job progresses.

James

 

[bruceb58]

Re: Need help removing lower lower unit on 79 OMC

The pictures that Aaron put up are for the electric shift model. Yours is different.

 

[boatguya1]

Re: Need help removing lower lower unit on 79 OMC

The pictures that Aaron put up are for the electric shift model. Yours is different.

If that was for me, I don't/won't own a stringer mount omc. I just thought there was a bolt or two holding the lower on up under that giant trim tab exhaust thing. Like I said I could be wrong. I'm at a marina and mostly see newer stuff. I can say be carefull with the electric shift wires when you try to drop that lower.

James

 

[td8]

Re: Need help removing lower lower unit on 79 OMC

The impeller is in the lower part of the upper gear case. You need to take the five bolts that hold the exhaust housing on the bolts on the main top of the drive. Then you need to pull the upper gear case out. The impeller is on the main bottom of the upper gear case.

 

[Aaron_M]

Re: Need help removing lower lower unit on 79 OMC

The impeller is in the lower part of the upper gear case. You need to take the five bolts that hold the exhaust housing on the bolts on the main top of the drive. Then you need to pull the upper gear case out. The impeller is on the main bottom of the upper gear case.

Ok so I got the 5 bolts out (4 more broke). The only thing that is keeping me from setting the lower unit on the ground is a wire which I guess goes to the electric shift. Does this have a disconnect somewhere? That would help alot.
Thanks for all the replies guys!!

 

[Aaron_M]

Re: Need help removing lower lower unit on 79 OMC

Hope you guys dont mind if I bump this but I'll be working on the boat here in the next hour and a half so I hope someone can tell me how to disconnect that wire.. Thanks again!

 

[bruceb58]

Re: Need help removing lower lower unit on 79 OMC

If that was for me, I don't/won't own a stringer mount omc. I just thought there was a bolt or two holding the lower on up under that giant trim tab exhaust thing. Like I said I could be wrong. I'm at a marina and mostly see newer stuff. I can say be carefull with the electric shift wires when you try to drop that lower.

James

Sorry James I got all confused.
Aaron is aking about a 79 OMC but the one in the pictures is of a drive that is way older than a 79 and is the electric shift model.

Sorry for the cornfusion.

 

[bruceb58]

Re: Need help removing lower lower unit on 79 OMC

Ok so I got the 5 bolts out (4 more broke). The only thing that is keeping me from setting the lower unit on the ground is a wire which I guess goes to the electric shift. Does this have a disconnect somewhere? That would help alot.
Thanks for all the replies guys!!

Just have to follow the wires(two within the insulation) and look for a bump. May have tape wrapped around it.

Aaron, you need to figure out the year of your drive. Electric shift models were used until 77 or so. 78 was the first year of the mechanical shift.

 

[Aaron_M]

Re: Need help removing lower lower unit on 79 OMC

Just have to follow the wires(two within the insulation) and look for a bump. May have tape wrapped around it.

Aaron, you need to figure out the year of your drive. Electric shift models were used until 77 or so. 78 was the first year of the mechanical shift.

Oh... Ok, I though the drive was the original one. The seller never said anything about it being replaced and it looks just like the 79 OMC one I found online. How would I figure out what year it is?

 

[bruceb58]

Re: Need help removing lower lower unit on 79 OMC

You are going to need and find a serial number or model number and then find someone who knows what to do with it! Sorry that I can't help with that. I used to have your exact drive. It was a 75.

 

[Aaron_M]

Re: Need help removing lower lower unit on 79 OMC

Well that really sucks. I ordered a impeller kit for a 79...... Damnit.

 

[td8]

Re: Need help removing lower lower unit on 79 OMC

Ok so I got the 5 bolts out (4 more broke). The only thing that is keeping me from setting the lower unit on the ground is a wire which I guess goes to the electric shift. Does this have a disconnect somewhere? That would help alot.
Thanks for all the replies guys!!

You don't have to take those bolts out to get to the upper gear case. The five bolt on the main top of the drive.

 

[td8]

Re: Need help removing lower lower unit on 79 OMC

Well that really sucks. I ordered a impeller kit for a 79...... Damnit.

All the stringer drives have the same impeller so you should be ok.

 

[wvwarlock]

Re: Need help removing lower lower unit on 79 OMC

if it is a manual shift, on the top rear of the engine there will be a shift converter that your shift cable is attached to that will run through the hull and into the outdrive. tht is the easiest way to tell. check the pages i emailed you for the details.

 

[Aaron_M]

Re: Need help removing lower lower unit on 79 OMC

if it is a manual shift, on the top rear of the engine there will be a shift converter that your shift cable is attached to that will run through the hull and into the outdrive. tht is the easiest way to tell. check the pages i emailed you for the details.

Did you just now email it? I havent received one??

 

[bruceb58]

Re: Need help removing lower lower unit on 79 OMC

if it is a manual shift, on the top rear of the engine there will be a shift converter that your shift cable is attached to that will run through the hull and into the outdrive. tht is the easiest way to tell. check the pages i emailed you for the details.

it's not a manual shift...look at the pictures he posted!

 

[rs2k]

Re: Need help removing lower lower unit on 79 OMC

How does the mechanic know the outdrive's impeller doesn't pump water? That outdrive doesn't work with muffs and I see that it hasn't been modified to accept a hose port. Did he dunk it in a tank? Unless the impeller is below water level it won't suck any water at all.

I have two mechanical shift OMCs and one electric shift OMCs. It is not uncommon for a mechanical unit to be replace with an older electric shift unit. The mechanical shift low ends are harder to find and not as strong as the older electric shift models. To replace the impeller is a chore, and you either need a helper you you have to be strong and good enough to wrestle the heavy low end back onto the top end when your done. It took me an hour of bruising my arms and legs to get mine on today when replacing the impeller, and I've done it twice before.

You have to remove the exhaust port/rudder and under that are hiding 2 more bolts. Make sure you leave at least one of the 6 side bolts halfway threaded so the low end doesn't fall when you get all the bolts undone.

You have two options on the wires that will be hanging onto the low end. You can do it the correct way and detach then at the mid drive which means spending 30 minutes fishing back through the mid drive when your done, or you can do it the "other" way and just keep the low end hooked up and in your way.

Next you have to take the top of the out drive off. To do that you remove the the 5 bolts on top and it just falls down. You can then access the pump housing.

You will remove the 4 very large bolts and then the pump and housing will come off with some persuasion.

Then, simple replace the impeller and reassemble the out drive. Make sure you twist the impeller the proper direction. It won't last long if you put it in backwards.