Questions about checking and maintaining MC-1 drive

cecho

Petty Officer 1st Class
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Jan 29, 2013
Messages
367
I'm about to go through a 1979 MC-1 attached to a Mercruiser 898 Chevy 305. I'm planning on replacing the impeller, pressure and vacuum testing the drive, checking the bellows, checking the alignment and checking the u-joint and bearings.

Other than the alignment tool, what other special tools will I need?

What else should I replace other than the impeller?

Do the MC-1s use the same impeller as the alphas?

Should I get a complete water pump repair kit or just an impeller?

What kind of grease do I need for the grease fittings I'll run into?

What order should I do the work in? I was considering pressure checking the drive before and after I replace the impeller.

What kind of gear oil does the MC-1 use. I have a manual that tells me... But I have a feeling there might have been changes in oil after over 30 years. :)
 

Augie56

Seaman
Joined
Feb 26, 2012
Messages
73
Re: Questions about checking and maintaining MC-1 drive

I just completed the same service on my '79 MC-1 outdrive (Mercruiser 228).

Take the whole outdrive off the boat to service the impeller, u-joints, inspect bellows, etc. I made a lower unit stand that made installing the water pump kit a breeze...it was also easy to re-join the upper and lower units on the stand I made. Also, measure how high up the BOTTOMS of the anti-cavitation plates need to be off the ground when you re-install the assembled outdrive to the boat and make your stand this tall....this way, you can slide it off the stand and back onto the bellhousing on your boat without having to lift it up!

Buy either Sierra Impeller kit #18-3017 or Mallory kit #9-45306. The kit has everything you'll need, plus some extras. Use the whole kit, don't risk only replacing the impeller. Check the 'net for videos and the Mercruiser manual for how everything goes back together if you need to.

Buy spline grease for re-installing your lower to upper unit, installing your prop, and installing the assembled outdrive back onto boat. Clean and coat the splines gratuitously. Use the same grease to LIGHTLY coat your gaskets if you like, but don't goop them up as this can cause them to slide during re-assembly. I used Mallory High Pressure Spline grease...the stuff was awesome.

You can top off the grease in your u-joints if they have zirc fitting with standard grease that's already in your grease gun.

Buy another outdrive-to-bellhousing gasket, #18-2820. If the water jacket passage o-ring isn't good after you clean it up and inspect it, buy another one of those, too. And also buy another Bell Housing gasket (big rubber o-ring) 18-2840 if the old one is beat up.

Re-fill the outdrive with marine outdrive lube, it should be 80W-90. Unless you plan on neglecting it, or pulling a waterski team all summer, the standard (non-synthetic) will do well for one season. Buy the pump that fits on the bottle, it will have the fitting to screw into the lower unit fill hole and make it easy. Fill from the bottom up, until it starts coming out of the vent hole. You'll need 2 qts, the outdrive will take about 1.5 qts.

Pressure test the assembled outdrive (before filling) on your stand....pressurize one of the fill/vent ports and monitor the other with a pressure gage. A good outdrive will hold 10-15 psi no problem. Don't pressurize over 15 psi, though.

Remember to clean and grease the gear shifting mechanism inside the outdrive (the square shaft that's hanging on the end of the shift cable in the bellhousing), too. Good sliding action there helps to ensure good shifting.

That's about all....good luck!
 

ktbarrentine

Lieutenant
Joined
Dec 12, 2011
Messages
1,296
Re: Questions about checking and maintaining MC-1 drive

In addition to the above (great) post, get a pot of coffee going (or a six pack of your favorite brew) and go to the "adults only" stickys at the top of this (mercruiser) forum. There you will find more than enough of the answers you look for. Up to date manuals there, too. Good luck and keep us posted on your efforts.
 

cecho

Petty Officer 1st Class
Joined
Jan 29, 2013
Messages
367
Re: Questions about checking and maintaining MC-1 drive

Thanks for the great info Augie56! Those part numbers are going to be a great help.

Thanks for the suggestion, ktbarrentine. I've been reading through that section on and off since 2008. I'm just not sure what "gotchyas" might exist since I have an MC-1 and not an "Alpha."

Thanks!
 

wrench 3

Commander
Joined
Aug 12, 2012
Messages
2,108
Re: Questions about checking and maintaining MC-1 drive

The 18-2820 and 18-2840 can be purchased as 18-2614 kit, witch also has the water passage "O" ring and the drive shaft "O" rings. The gear lube will most likely be a straight 90 grade.
 

Augie56

Seaman
Joined
Feb 26, 2012
Messages
73
Re: Questions about checking and maintaining MC-1 drive

Cool, great catch Wrench! I wish I would've found that kit two weeks ago..would've saved me a couple of bucks and made ordering things easier! That's definitely the way to go.
 

cecho

Petty Officer 1st Class
Joined
Jan 29, 2013
Messages
367
Re: Questions about checking and maintaining MC-1 drive

Thanks, I'll make sure to get that. Do you know which water pump repair kit I should get? There are dozens to choose from.
 

wrench 3

Commander
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Aug 12, 2012
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2,108
Re: Questions about checking and maintaining MC-1 drive

I double checked Augie's numbers. It seems he got the impeller number instead of the kit. The kit is 18-3217, but make sure your housing is in good shape before ordering.
 

cecho

Petty Officer 1st Class
Joined
Jan 29, 2013
Messages
367
Re: Questions about checking and maintaining MC-1 drive

Thanks, I'm not sure why I'm having so much trouble searching the iboats parts database. It seems to be bringing everything but what I'm trying to find. I'll take the drive apart tomorrow and see what I need to order.
 

Cresco750

Petty Officer 2nd Class
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Jul 7, 2012
Messages
192
Re: Questions about checking and maintaining MC-1 drive

Just did my MC-1 at the end of last year. Follow Augies advice! On top of his suggestion, I replaced the gear shift shaft bush and seal (because they were leaking water not the u/j bellows). Also, have a good look at your trim position senders; it is fairly common for the insulation to break down and fall off. I replaced mine, as well as the lower shift cable. Best to invest in a hinge pin tool, too.
 

cecho

Petty Officer 1st Class
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Jan 29, 2013
Messages
367
Re: Questions about checking and maintaining MC-1 drive

I'll be getting the hinge pin tool and the alignment tool. Anything else I should get while I'm at it?
 

dubs283

Vice Admiral
Joined
Jul 27, 2005
Messages
5,058
Re: Questions about checking and maintaining MC-1 drive

unless all the bellows, senders, shift cable, etc. haved been replaced recently, you may as well do everything back there

then you know everything is good before boating this next season

get a water pump base assy too, it has the seals in it already and lower gasket which is a fail point for allowing exhuast gases to enter the cooling water flow

quicksilver high performance gear lube is what merc recommends and it is the best
 

cecho

Petty Officer 1st Class
Joined
Jan 29, 2013
Messages
367
Re: Questions about checking and maintaining MC-1 drive

unless all the bellows, senders, shift cable, etc. haved been replaced recently, you may as well do everything back there

then you know everything is good before boating this next season

get a water pump base assy too, it has the seals in it already and lower gasket which is a fail point for allowing exhuast gases to enter the cooling water flow

quicksilver high performance gear lube is what merc recommends and it is the best

So something like this?
Complete Pump Housing Kit for Mercruiser, GLM 12130 - Sierra 18-3321 - iboats
 

MarkSee

Lieutenant Junior Grade
Joined
Sep 10, 2010
Messages
1,172
Re: Questions about checking and maintaining MC-1 drive

... checking the bellows, checking the alignment and checking the u-joint and bearings....
Other than the alignment tool, what other special tools will I need?
What kind of grease do I need for the grease fittings I'll run into?
I have a manual that tells me...

Since it seems you are going to be doing your own maintenance, the "manual" you refer to, is it the official Merc. service manual or one of the others that you should not be using?

The Merc. service manual will show various procedures relating to the bellows and gimbal bearing replacement that will list some tools you will need. Some places sell "sets" of the needed tools where you can save some money buying it all at once.
Of course some guys make their own that you can view in the sticky section posted at the top of the forum; lots of great information Don has compiled in that section.

Regarding grease: that's always a "various opinions" topic as some guys (like me) use the different kinds of grease as recommended in the Merc. service manual and other guys might use a single type of grease for everything and others have a mixture.

Mark
 

cecho

Petty Officer 1st Class
Joined
Jan 29, 2013
Messages
367
Re: Questions about checking and maintaining MC-1 drive

I have two manuals.

Mercury Marine Service Manual Volume I and Mercury Marine Service Manual Volume II both show part number C-90-71707. Both seem to be from January of 1978.

What "Single type of grease" do most people end up using?
 

Augie56

Seaman
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Feb 26, 2012
Messages
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Re: Questions about checking and maintaining MC-1 drive

All right, here's your shopping list....

From iBoats.com....order :

Sierra Impeller kit #18-3217 - replace the whole pump with this kit

Sierra gasket kit #18-2614 - necessary gaskets to re-install outdrive

Sierra Upper Unit seal kit #18-2648 - this kit will give you a new vertical shaft oil seal for the upper unit, a new gasket for the water pocket cover, and two new gear oil drain screw gaskets.

1 tube of Mallory High Pressure Spline grease # 9-82700

2 qts of Sierra Outdrive Lower Unit Lube #18-9680-2

1 Gear Lube Pump # 50091461 - fits 1 qt bottle and has fitting that screws into outdrive lower unit fill hole

Clean shop towels, standard bearing grease in a grease gun to lube u-joints, good scraper to clean gasketed surfaces before re-installing everything, maybe some grease cutter to further clean things up.

Also, remember to NOT re-install a new o-ring into the o-ring groove at the top of the lower unit vertical shaft. This o-ring isn't necessary to the design and causes home mechanics more harm than good during re-assembly.

That's about all I can remember.
 

cecho

Petty Officer 1st Class
Joined
Jan 29, 2013
Messages
367
Re: Questions about checking and maintaining MC-1 drive

Thanks! I've got all that in my cart ready to go. The only question I have is what about using part 18-3320 instead of 18-3217?

I'll pull the drive in just a bit to see if the pump housing is bad or not. I'll also take a look at the bellows before I place my order.
 

Augie56

Seaman
Joined
Feb 26, 2012
Messages
73
Re: Questions about checking and maintaining MC-1 drive

Sierra 18-3320 is for Mercruiser R/MR outrdrive, NOT the MC-1 outdrive you indicated you have.

Sierra 18-3217 is the correct complete kit for a Mercruiser MC-1 outdrive, most likely your 1979 MC-1 s/n will fall between 2763442-6854392.

Mercruiser Water Pump Repair Kits - iboats
 

wrench 3

Commander
Joined
Aug 12, 2012
Messages
2,108
Re: Questions about checking and maintaining MC-1 drive

get a water pump base assy too, it has the seals in it already and lower gasket which is a fail point for allowing exhuast gases to enter the cooling water flow
quicksilver high performance gear lube is what merc recommends and it is the best

The 18-3217 kit has the water pump base gasket and "O" ring. Pry the water pump base put carefully (it's Fragile) and inspect it.
I also use Sierra standard gear lube for everything that doesn't have cone clutches.
 
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