Anybody know anything about boat motors

junkyardjeff · May 27, 2009, 08:14:13 PM

I have a 1955 Evinrude 7.5 motor that needs a waterpump impeller,I have the parts but no clue on how to do it and no manual and the last time it went out 20 something years ago I paid someone to do it.

wayne petty · May 27, 2009, 08:58:16 PM

Quote from: "junkyardjeff"1955 Evinrude 7.5 motor that needs a waterpump impeller,I have the parts but no clue on how to do it .

got model numbers off the motor...

?/

so i can do a search...

i knew i should have bought that whole batch of outboard motor manuals that was over at opamp books a few years ago...
http://www.marineengine.com/manuals/evinrude/order_pre-1980.html
parts diagrams can be had here with a proper model number... so you can see how it all comes apart..

http://www.marineengine.com/parts/parts.php

Evinrude 7.5 HP Motor Manuals return to top

Year Model
1950 4434
4435
1951-52 4443
4444
1952 4447
4448
1953 7512
7513
1954 7514
7515
7516
7517
1955 7518
7519

in my research.. looks like the 4 hp motor up through 72 uses the same water pump impeller..

here is a link to a parts diagram page for that... do not order 4 hp parts for your 7.5...

just for illistrations... looks like you have to pull the 4 bolts out the lower housing/ gear case... (#33 and #35) drop the gear case... then the water pump can be separated after taking out its housing bolts...

i nabbed a picture...

you probably want to use ANTISEIZE on various bolts ...

i would really examine.. any scratched wear faces for careful sanding and polishing... before putting it back together...

the i did not see a price on the manual for that motor... need more info.. let me know... i got visitors right now.. got to go...

junkyardjeff · May 27, 2009, 09:13:04 PM

Its model number 7518

wayne petty · May 28, 2009, 01:17:52 AM

just in case you miss the point...

4 bolts and the lower gear box drops off with the prop still on it...

a few more bolts and the pump body slides off the shaft.. the impeller comes off also...

you don't have to tear apart the lower gear box.. as far as the picture shows...

if parts are scored... post pictures ...

you might be able to silver solder a layer on... and grind and polish it back to a smooth finish so the impeller does not wear...

as for the pump housing... that is really going to be hard to repair... if there is any corrosion... or wear damage...

i really really wonder if a part could be powder coated and lightly ground back to size... that might take more tooling than you have access to.. its more than i have access too...

chimp koose · May 28, 2009, 02:09:11 AM

If the part is scored you could bore it out and put in a sleeve.I would check to see if there is a torrington sleeve that could be made to fit. I doubt a torrington would ever wear out.If there is an ID that matches you can use a ceramic tool to turn the torrington sleeve OD to match what ever size you bore the case out to. We used to loctite the sleeve to a straight mandrel and turn the OD with ceramic to put hard wearing sleeves in stuff years ago.

junkyardjeff · May 28, 2009, 08:04:21 AM

The only thing that concerns me is the shift rod and where to disconnect it.

Arnold · May 28, 2009, 08:16:45 AM

Quote from: "junkyardjeff"The only thing that concerns me is the shift rod and where to disconnect it.

iirc you have to seperate the lower case and pull it down and there is/was a joiner there on the rod

iirc some you could remove the screen for the w.p intake too.

SORRY there Jeff buddy..Gawd almighty I hate o/b motors from the alte 50
s to the late 60's

Sorry about the rant.

PeterR · May 28, 2009, 12:52:25 PM

Quote from: "junkyardjeff"I have a 1955 Evinrude 7.5 motor that needs a waterpump impeller,I have the parts but no clue on how to do it and no manual and the last time it went out 20 something years ago I paid someone to do it.

This is a very straightforward job and requires only a handful of tools.

If the motor has been in fresh water the whole operation is less than an hour, if it has had prolonged use in salt water it may take a day.

Important!!!! Before commencing any work remove the spark plug lead so the motor can not start while you are working on it.

Also the work is much easier if you have the motor on a stand or mounted on the boat transom rather than laying on the floor.

The bolts holding the foot to the leg casting are SS but they are tapped into alloy, and salt water can cause the alloy to corrode around the bolt thread. If the bolts do not move you may have to heat the bolt head with an oxy torch and allow it to cool naturally then try again. Once you get even a tiny movement just wiggle the bolt backwards and forwards and it will come out. Do not heat the alloy housing, even with a soft flame it will melt before your eyes.

Similarly with the screws holding the pump housing to the gearbox. Though with these you can always sacrifice the pump housing to get to them. If there is severe corrosion it is likely to require replacing anyway.

The pump housing is not expensive, (I am talking here with a 1970's memory) and if the the inside surface is damaged, replace the housing or the new impellor will be stuffed in no time.

Buy a small tube of yellow grease from an outboard dealer. This is waterproof grease that sticks like poop. If you can not get hold of the yellow grease use old fashioned automotive water pump grease.

If the bolts were difficult to remove, clean the threads in the alloy and the bolt threads before commencing reassembly.

Reassembly

Slide the new impellor down the shaft and align the slot with the drive pin.
Do not lose the pump drive pin (item 8 in the diagram) or you will cook the motor.

Smear plenty of grease inside the pump housing and over the impellor to provide lubrication until it fills with water. Dry running is the prime cause of impellor wear.

When installing the pump housing, the impellor fingers have to be folded to allow the housing to fit over them. The fingers must be folded in the trailing position. If you are unsure about this, take the cover off the motor, pull the start rope a few inches to observe the direction of motor rotation, then mark an arrow on the lower unit showing shaft rotation. With one hand twist the driveshaft in normal direction of rotation while with the other hand gently push the pump housing over the impellor at the same time.

Smear all bolt threads with grease before reinstalling to give the next person servicing the unit a chance to remove them. Do not fill the threaded holes with grease, some are blind holes and the grease will burst the alloy when the bolts are tightened.

Remember you are tightening bolts threaded into a soft material and a heavy hand will strip the thread.

When refitting the lower unit to the main housing another pair of hands makes things much simpler.

Feed the driveshaft up the leg then reconnect the gear shift rod. You may need the other person to wiggle the gear lever at the top of the motor to hold the rod in the lowest position. Do not over tighten the clamp pinch bolt or you will strip the thread.

Push the driveshaft upwards until it hits the bottom of the crankshaft and holds the lower unit housing about 1-1/2 inches away from the leg housing. Engage either gear, hold the prop from turning, then slowly pull the start rope to align the splines which will allow the driveshaft to enter the end of the crankshaft. The lower unit housing will then come up to the leg housing and the bolts can be refitted.

This is another time an assistant can really help otherwise you have to hold the weight of the lower unit with one hand while wiggling to align the bolt holes, then fit the bolts with the other hand. Again, do not over tighten the bolts.

Select neutral then slowly pull the start rope to ensure the motor turns freely, then repeat in both gears.

Refit the spark plug lead. :oops:

Start the motor in water and watch for the water telltale spray.

chopped · May 28, 2009, 12:52:55 PM

Make sure the gasket has the proper holes for water flow, you may get one for more than one application.

wayne petty · May 28, 2009, 06:10:07 PM

i was looking at some of the parts lists... the thrust plate and the pump housing are no longer listed on the parts list i saw from Evenrude... if a dealer has it..

the impeller was used on the 4 horse power motors up to 72... so that is an easier thing to get...

you might really want to snap a picture of it .. if it is new.. along with the part number... and measurements ... before you put it in the motor.. and please.. lay any gaskets on the scanner.. along with a ruler... scan them in...

that way... you have something you can run a piece of gasket material through the printer or printed onto paper... measure the thickness also...