Chrysler 75 hp gear box lubrication

rkinross

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Jan 23, 2017
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I am preparing to change the gear lubricant in my 1982 75 hp Chrysler outboard model # 756h2h. My owner's guide does not list the capacity for this gear box so I do not know how much to purchase. Also are there o-rings, washers, or gaskets I need to buy to seal up the three screws that will drain and fill the lube? The owners manual also suggest using e.p.90 outboard gear lube. Does anyone have a recommendation on a good manufacturer (crc mercury 24c)? I have never done this before so if there are any other procedures I should follow I would like to know about them. It seems straight forward in owners manual (basically drain and fill) - no special pump required.
 

Yegboats

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Feb 20, 2016
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508
I would go with a gear lube pump and a quart bottle of gear lube. I don't know the exact capacity of yours but I would assume around half a quart. You can use Mercury/Quicksilver premium gear lube. Sierra also makes a premium gear lube. lower unit gear lube pumps are cheap enough too. These thread onto the gear lube bottle and pump it in. It's Easier than the hassle of squeeze bottles. You can purchase those as well if you want. The seal# is gonna be the same as mercs
19183 3 You can puchase all of this right here on iboats or any local marine dealer should have in stock.
 

Nordin

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Jun 12, 2010
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You can use any marine grade SAE 80-90W gearlube.
I am in Sweden so I do not know what to get in the US, but Wallmart do have cheap marine grade gear lube.

jerryjerry might chime in and give a good answer.

The capacity of oil in the gearcase is about 26 ounces (0,8 liter in metric)
I would suggest new seals at the three screws that fill and drain .
 

jerryjerry05

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May 7, 2008
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My manual says. Capacity is 28 oz.
​The lower has an allen headed set screw for the bottom drain.
​It needs pipe tape or some kind of sealer.(probably gonna weep there anyway???)
​The slotted screw is a pivot pin for the shift linkage do NOT remove unless it's leaking(I never saw one leak)

The vent and fill(if you have that) the washers need to be replaced each time with new.
In a pinch you can turn them over and reuse.
Yegboats gave you the part# for the seal.
​They might sell them here.
And suggested a pump.
Get the pump and a gallon of the lube.
​You will be changing it enough to warrant the expense.

I use 80/90 gear oil from Wally World.
But the more you spend?? the better the oil.

​IF??? you drain it and the oil is off colored?? then you need to do a pressure test and re-seal the bad seal.
 

rkinross

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Jan 23, 2017
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29
Thanks to yegboats, nordin, and jerryjerry05 for the quick replies. I am really not understanding the slotted shift linkage screw jerryjerry05 mentioned in the reply. The lower unit has 3 screws (drain, fill, and vent). The shift linkage also comes up in the impeller replacement instructions on another post. It states: Below the engine mounting clamps (actually, below the lower engine pivot mount--a plate with 4 bolts holding it) you will see a cylindical shift linkage connector. It will be held with a small pin through it and a smaller cotter pin through the small pin. Pull out the cotter and slip out the pin. The shift linkage is now disconnected.

Since the impeller is a replacement part that is critical for the engine to run properly I feel I need to understand how to change it properly. I can not find a youtube video on how to do this on a Chrysler 75 hp outboard. The best I can come up with is Frank's detailed instructions http://forums.iboats.com/forum/engi...outboards/237589-step-by-step-impeller-change. After reading them 4 times I still do not feel confident I can do this myself. The shift linkage is the biggest concern.
 

jerryjerry05

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May 7, 2008
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The pin/cotter pin is on the tip of the shift rod that goes into the lower unit.
The pin connects to the lower shift rod that extends through the mid section.
​In the pic, about 10" above the pic is the connector for the lower shift rod and the shift rod through the mid section.
Get a parts diagram(boatsdotnet) has good ones.
​The Force/Chrysler is listed under Mercury.

​I don't know what the 4 bolts and plate is??

The pic again: that spot is where the slotted screw for the bottom of the shift rod is.
No need to EVER take that screw out.

​Changing the impeller , no need to worry about the shift rod (pin/cotter pin)other than it needs to be unhooked to drop the lower unit.

​The one piece and two piece lower unit, the pin and shift rods both come apart the same way.

The job isn't hard.
​The toughest part is putting the lower back on.

​The screw/bolts if they are hard to undo then you might need to heat them to loosen??
The corrosion can lock them in place.
PB Blaster and a small torch can help with the harder ones.
The 4 screws holding the impeller housing can be real tricky.
​There is one that extends through the housing through the water passage.
It might be harder to get out.


 

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rkinross

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Jan 23, 2017
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29
Thanks jerryjerry05 for more information on the impeller replacement and lower unit shift linkage. I'm going to have to compare your photo 1 to my lower unit to see where this is on mine. I can't tell from the photo where this is on the lower unit due to the zoom on the bolt. I'm thinking it must be near the prop.
 

jerryjerry05

Supreme Mariner
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May 7, 2008
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Shouldn't be any drains or screws near the prop.
Unless you have the 2 piece gear housing, then the bearing carrier has 2 screws on the rear of the housing.
But that should have the screw for the pivot pin about the same spot as I showed on the 1 piece housing.
Your 82/75 should have a 1 piece housing.
 

Isa4325

Petty Officer 2nd Class
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Oct 7, 2017
Messages
121
I used Lucas 80-90 weight gear oil, one bottle on my Chrysler Magnapower 70 HP 707HE.
 
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