1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

[JimVmd]

A video on youtube shows how easy it is. Remove the powerhead by taking out seven screws, lift off, unhook the shift coupling, drop the lower unit, etc.
But I find front screw underneath is a bolt head. Can't get a socket through.
Do I really need to remove the powerhead on my unit? What is the screw halfway down the exhaust tube about? Is that a decoupler on the shift rod or something?
Anyone with expertise on impeller replacement specific to my model who can advise; would be greatly appreciated.
(I don't see how I can access the front right screw (my case a bolt head) to unbolt the powerhead; I would have to uncouple the upper and lower support bushings off the transom assy to get to it - that is crazy to replace an impeller!)
Thanks again,
JimVmd

 

[Daviet]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

As best I can remember, it was possible for the 7.5 HP in the year 1957 was made both ways. If you have an ovel shaped plate on the exhaust housing with a brass connector for the shift linkage under it, you should be able to drop the lower unit without removing the powerhead.

 

[nwcove]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

havent seen a 7.5 from that era with any option other than removing the powerhead to replace the impeller, it does look like its a tough job, but if you take a second look, the seemingly impossible screw is quite easy to remove.

 

[Daviet]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

I might have been mistaken, but I had a 57 evinrude that I thought had the shift shaft coupler in it. I will have to look it up in a parts manual to check it out.

 

[JimVmd]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

havent seen a 7.5 from that era with any option other than removing the powerhead to replace the impeller, it does look like its a tough job, but if you take a second look, the seemingly impossible screw is quite easy to remove.

Oh my nwcove. I can look at the screw a lot of times and it doesn't get easy. It is a hex head bolt. Needs socket I cannot get through straight enough on. I removed the gas lines and fitting on the tiller assy to neak up on it sideways with a wrench, no way.

The screw hole half way down the exhaust tube (in center of picture) is large enough for a small screwdriver. Inside that open hole, is a slot headed screw (just inside). I don't know what that screw does. I think it may decouple the shift rod? I have a '57 parts list, but the exploded view is off the opposite side of the exhaust tube (hole not detailed).

Anybody know this opposing side where the hole is?

 

[JimVmd]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

I am going to break the 7/16 bolts on the lower unit now and see what happens. If nothing drops, I'm going to hit the subject screw in the middle of the exhaust tube with a screwdriver. Something is different about this AD-11 '57 that is not common. Diving in... will post again soon.

 

[oldboat1]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

Hey Jim -- would help yourself to have a parts manual in front of you. There are online blowups as well (may have seen them). On the Evinrude, there is a two piece plate (lower motor cover) under the powerhead, held in place from the bottom by six(?) bolts. You should be able to remove or sufficiently lower the cover(s) to get at what you need to remove the powerhead. I'm just going to give you the heads-up about the lower cover, because I'm working from memory -- and the Johnson might be a little different under there (but don't think so). Almost have to have the motor in front of me to jog memory, but if you look up under the powerhead, you should see the bolts I'm describing.

Edit: guess you have one. but Wait. Stop. you were on track.

 

[JimVmd]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

After removing the four bolts on the lower unit, I got maybe 1/2 drop. I tried to release the mystery screw, without luck. Quitting 'till when I re-approach with solid info.
Tks oldboat1, more study needed, 'cause it is more than just a matter of removing seven screws to lift the powerhead (at least on my engine which history has already shown has a number of buggered issues by others so stock can be screwdoodled.) I agree Johnson and Evinrude are the same on this one (should be anyways). I don't have the cover you write about. I can see all seven screws/bolt heads which according to my part exploded view should all be slotted screws (tells me it has prior history with 3 of seven being hex head bolts).

Thanks all, I'll reconvene latter..
JimVmd

 

[HighTrim]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

Ok you confused me here!

Im not sure what you mean by head bolts? Perhaps, you are looking at the wrong screws?

The '57 most definitely needs the powerhead removed to access the shift rod coupler, no way, no how, around it. I guarantee it, done it oodles of times.

Once you do one, you can have a powerhead off and gearcase in the jig in under 10 minutes with ease. It is actually not that big a deal. that is assuming there are no seized screws of course!

There are no difficult to reach screws. All can be reached with a standard straight 6" screwdriver.

Once you pull the powerhead off remove the 2 3/8" nuts off the top of the threaded shift rod, and drop the gearcase, done like dinner.

 

[HighTrim]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

...and I for the life of me cannot figure out what mystery screw you are referring to is? Is it in the pic you posted?

 

[JimVmd]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

Hello Chris,
I don't know what the hole is. Perhaps a punched through mishap over the last 56 years.
I finally got the hardware assortment out. I think only the pan head screw is correct. The others are by others!
Back on track now. No gasket on the powerhead found - just old RTV or such. I have a gasket going back in.
Thanks,
Jim

 

[racerone]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

That hole might be where the upper water tube grommet fits.----Somebody may have seen a leak there and put a screw in there.--Just the way some folks are I guess.-------Nothing wrong with the concept of removing the powerhead for a waterpump change.----Remember this motor is from the 1950's and will run for more years than the modern plastic junk will!!!

 

[HighTrim]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

Yes, as Racerone points out above, that hole is to aid in removing the upper water tube grommet. Does not need plugging in any way, just leads to the exhaust cavity anyways.

Glad you got it! Was the whole carbon seal assembly in place on top of the driveshaft? Ensure that it is all there, and in good condition, before reinstalling. Very important.

 

[Greg O.]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

Ok you confused me here!

Im not sure what you mean by head bolts? Perhaps, you are looking at the wrong screws?

The '57 most definitely needs the powerhead removed to access the shift rod coupler, no way, no how, around it. I guarantee it, done it oodles of times.

Once you do one, you can have a powerhead off and gearcase in the jig in under 10 minutes with ease. It is actually not that big a deal. that is assuming there are no seized screws of course!

There are no difficult to reach screws. All can be reached with a standard straight 6" screwdriver.

Once you pull the powerhead off remove the 2 3/8" nuts off the top of the threaded shift rod, and drop the gearcase, done like dinner.

One of mine broke off. I thought I might be able to weld a nut to the piece still in the power head and turn it out, but after about 8 tries, I gave up , and drilled and tapped the threads. Worked out just fine.

 

[BigB9000]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

(Crankcase Seal; Install)

And, you should be able to get to the power-head with a 1/4 drive socket and an extension:

I know this is a different motor, but its so similar it isn't even funny.

Check out more at
1966 Evinrude model 6603 rebuild

 

[JimVmd]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

I really appreciate the help I get here.
The only thing that continues to upset me is all related to OMC or Johnson/Evinrude "proper parts". I guarantee all, that Johnson was not manufacturing custom orings, seals, or bolts. No engine manufacturer could ever compete in the market if they were doing such! I remarked one time that Sierra owns a micrometer and someone on this site scolded me.
I know better.
For instance, p/n 21X167 screw in the 1957 Johnson Parts Catalog for AD-11 is a 1/4-20 x 3/4 slot headed screw. Seven of those release the powerhead. I bought eight of them Grade 8 at LOWES today for 4 bucks. Grade 8 is high strength automotive carbon steel. I bought hex sockets. So much easier to install than a slot headed screw and upgrade from OEM slot head screws 21X167!
Go figure,
Those that say you need to get original parts are selling them when it comes to O-rings, seals, screws, and bolts!!! Come on, Really?
lol
JimVmd

 

[BigB9000]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

Well, they could have those special parts made, and they probably did.

Did you buy stainless hardware?

Also, a lot of those parts fit many many other motors, it isnt so unfeasible that they had them made.

 

[JimVmd]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

no, I bought carbon steel gr8 like I stated. no ss in those oem or otheryourwise

 

[HighTrim]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

Some of the cosmetic stuff depends on how much of a purist you are. Some guys insist on the proper standard phillister head screw to keep their motor original. On full, cosmetic restorations, I try to keep to this. I have huge totes full of OMC fasteners though, from tearing down hundreds of motors, so I can always find a proper bolt if I need to, that makes it easy.

Now I can guarantee you that some of the o rings and such are in fact custom. Try to find a shift rod seal o ring anywhere, even at a seal manufacturer. Wont happen. There are some situations where you can get close enough to work, but some where it is critical and will leak so you must use OEM parts. I have found many options to use aftermarket items though that I buy in bulk for restorations.

 

[Crosbyman]

Re: 1957 johnson 7.5 hp AD-11 lower unit removal - impeller replace

remember the issue with my 5.5 ...

the back mounting scrw went all the up into the water jacket space almost touching the water jacket.

Jim...Do check out the screws lenghts before reassembling in case you end up with a longer mounting screw at the wrong place.

High Trim .. do you know if the 7.5 has the same qwerky issue as the 5.5 .