TOPIC: New 2 Me 1957 Mercury Mark75 Where should I start?

Hi all!

I have a 1957 Mercury Mark 75 Marathon Six that came with a Tomahawk boat that I purchased last week. The boat and motor have been in storage for the last 20 or so years, but, according to the previous owner, ran well before put in to storage. I was wondering where should I start this restoration? I went out and bought a new battery and spark plugs today. I am waiting on a friend to sell me his gas tank. My plan was to pour some mystery oil down the spark plug holes and try to fire it up.

Can I use muffs to run this out of water or do I have to put it in a barrel of water? I didn't see any inlets so I'm assuming barrel.

Also, what are some essentials for working on this motor? I've only worked on cars before so I'm a complete novice on marine motors.

Any help and tips are welcome! Thank you!

The first thing everyone told me to do on my engine which had only been sitting for four years was to change the water pump impeller. That's where I started. If it's seized up I've freed bike motors by shooting WD-40 into the plug holes and let it sit for a couple days. If that doesn't do it there's gonna be some pain. Good luck with it.

It's definitely not seized. I can turn the propeller with ease and see the pistons moving up and down. Putting the mystery oil in it only made that easier. The impeller is located in the lower unit, correct? I think I found one for sale on oldmerc.com; would you recommend anywhere else I can look to buy one? Thanks for your reply.

And by the pics, how bad does it look? I was super excited to see how clean it looked for its age. I'm crossing my fingers that she fires right up. lol

I'm in the same boat with a different boat. lol. This is my "new2me" 1960 Humber. It hasn't been started in at least four years but it's really clean and was well prepped. I just learned what I told you about that impeller a week ago I'm not sure if you can use the mufflers they have to cool yours or if you'll need a barrel. By looks it ain't bad. Those spark plug boots are shot and should be replaced. I really don't see anything else that would worry me. Nice find ! I hope it does fire right up for you but you might want to rebuild the carb(s). I'd imagine all the rubber bits are hardened up by now including that impeller. You'll have more and better answers before the day is out I'm sure. Good luck, I'll cross my fingers for you.

marineengines.com seems to have everything I've looked for plus manuals for a lot of motors which are like bibles (small b) for old iron. My Merc Buddy says yes it's in the lower unit. Did I mention change the plugs ? Steve says NGK works great in his 1150. He also said to check the gear oil quality and levels. 20 years is a while. Others will have more no doubt, I'm just coming back to outboards and don't know as much as I should but I've gotten right answers to every question I've asked so far and I've asked a LOT. LOL.

water intake is under the cav plate just ahead of the exhaust snout. smack screen.

Welcome to the magic that is Mercury motors; the best designed and built motors on the water. Your motor is a beauty, very clean. Here is what I and most guys do when they get a motor like this.
A) Remove and clean the carbs. Check out the floats for damage, you may need to replace Look for cracks in hoses.
Clean and replace the diaphragms and gaskets in the fuel pump, after all this time they will be tired and won't do the job.
C) Replace spark plugs.
D) Replace impeller (instructions online).
E) Replace lower-end fluid
F) How are the controls? They may need attention, check for cracks in the battery leads.
Add Seafoam to your gas.
I get all my parts from Joe Poole at fergusonpoolemarine.com/
He either has or can get every part you need. He will also add his considerable experience to help you with your project. I am restoring a '63 Merc 1000 and I just said, Joe, what am I going to need? He came back with a long list. He is very reasonable and nobody has more parts.
Joe spent an hour and a half on the phone with me over 2 years to help diagnose a persistent problem with my '81 150hp Merc. He called me on his dime at 9pm Atlantic time, he is an amazing fellow.
Good Luck, let us know how else we can help you
Headley

What is the first thing to do with this engine? Understand it. Get a genuine Mercury manual, no clones, and read it from cover to cover. Understand the layout and the systems before you even touch a screw on that thing, they do not suffer fools gladly, and get a digital camera to photograph everything as you take it apart. They are not rocket science but they are not your fathers Oldsmobile either.

BOY, gfgarland speak's the truth. It's "NOT" your fathers Oldsmobile. You can get hooked on them though. All three of my boats now have Merc's on them plus a rolling stand with 4 more.

Thanks for all the advice!

I ordered a service manual from amazon for $60. Yesterday I cleaned the boat and motor and replaced the spark plugs. After I get the manual I'll start taking out the carbs and clean/rebuild those.

I think this thing is going to surprise me and fire up when I try it. Getting excited...!

check for spark while you wait for the manual.

How in the world did you post such large pictures??
What is your secret???

Once you get the cylinders lubed up, and before you spend much time and money on the beast, check the compressions, and post the results.
I encourage you to remove the propeller before doing anything else.

doc Frankenmerc

Haha! I uploaded them to imgur.com then linked to them on here using the [ img ] tag. What is a good way to check the compression? I'm assuming there is a tool...?

Available at just about any auto supply shop. Just screws into the spark plug hole of each cylinder. Makes me think of checking mine while I'm changing plugs. Good tip Dr.Frankenmerc

Cool! I think on my day off I'll go swing by a shop and get the spark and compression testers.

Side question: I was browsing paint for the boat the other day and was wondering how those of you who have refurbished your Mark engines got fresh paint down in the hard to reach areas. There is a lot of red in between the chrome. I'm assuming with a small brush? Are there any threads regarding refurbishing or painting?

Painting with a brush will not look good unless you are a pro. I am and I couldn't do it.
You have a nice engine there, you should do a nice repaint. I get all my decals, medallions and paint from Peter at NY Marine: www.nymarine.ca/ . His site is down right now but he has all the stuff you will need. You can get a rattle can of the paint to match your motor and decals for the proper model. I buy his Urethane by the pint and use a detail gun to paint all parts.
It is tough to get to all those little areas. I am a freak and clean, prime and paint them all. It is all how far you want to go. I like factory fresh.

Yes there are. And lots of tips. Check out " Member's Projects ". You'll find pictures of every step you'll be taking.

The best thing you can do right now? Your book is on the way, so while waiting for that, troll. Go through this site, especially the MERC page. go way back. keep going. Chances are, your issues and questions have already been covered. Good bet, things you never thought of are also answered.
If after all that, you dont understand something, ask. The guys here love to share their love of all things Merc.
We were all new at one point (I'm still at the new point)

Will

Headley, what is that bright red color on the far right called? Thanks for the site!

sunset orange I think

Cool that's what I thought. Thanks!

The Sunset Orange is really a beautiful paint color.

Wow, those older Mercury's are some really nice looking machines.

Will

Metallhed,

Excellent Choice Mark75 DR AKA "DockBuster"!!!

One of my all time favorites. Above a lot of good information. Make sure you do your homework on this one not to scare you but to fore warn these are tricky to get set up but lots of fun when you have it tuned in. Couple sites I have listed for you and others also many others out there.

1. www.michiganboatandengine.com for Mercury Medallions Bob has the best.
2. www.johnsmcintoshvintagemercuryoutboard.com John great for parts,tools,decals also cool T-Shirts
3. www.vintageoutboard.com Doug is a great source for parts.

Send me a pm or email if you ever want to chat old mercs I'm in Michigan and into the 4cyl Mark series.
Sunset Orange & Sand Tan great choice.

Travis

Thanks for the sites and encouragement!

I ordered some stuff from a site that was mentioned earlier, Ferguson-Poole Inc.:

44.97 (3) carburetor kits

11.58 (2) fuel pump diaphragm kits

17.16 (4) fuel pump check valves

20.93 (7) fuel hose rubber compression sleeves

That should get me started on this beast. I haven't had a day off yet so I haven't been able to get the spark and compression tests. My plan is getting those tomorrow! I'll post the results.

I've been searching the forum but I can't find anyone else that has refurbished a 75. Motoscotty99 is the only other member that came up. Maybe I'm not searching hard enough.

I want to expand on that last part and say I haven't found another member that has documented their refurbished 75; I know, obviously, that it's been done.

Ok quick question:

I bought the spark and compression testers today. It's probably obvious but am I supposed to have the motor hooked up to a battery and gassed up for these? Basically this will be a test to see if it fires up too, correct?

Sorry...as you can tell..I'm a total noob.

no you should check both without running it.

To check compression, remove all spark plugs. Stick 'em back in their boots and ground them on the block/cowling/etc.

Screw the compression gage in the 1st cylinder, crank over the engine until the needle on the gauge stops rising; record reading, remove gauge, reset to zero, install in next cylinder; Rinse, Lather, Repeat until all (6) are tested.

To check spark, crank over the engine with the plugs grounded and see if each plug sparks properly.

Note this is just a basic test, if you really want to get down in the weeds, take a spare good plug and cut/grind the ground electrode off. A really good, strong spark should jump this gap. Meaning that the ign will also fire a plug under compression. Use this "test plug" on each plug wire, one-at-a-time.

Now, if your regular spark plugs fire with a nice purplish/whitish spark, the ign system is likely healthy. If the spark is weak/yellowish/orangish, it's probably not gonna fire under load.

Compression-wise, ideally the readings would be even across the board. However, if they are all within about 5 psi of each other, that's OK for an initial check. If they're 10-15 psi apart, especially on a Mercury, I'd start worrying about the condition of the innards.

After the engine has been tuned, you can run it on the boat at speed with some decarbonizing additive (Seafoam, Gumout Regane, etc), then check compression again. Sometimes it'll improve due to carbon being cleaned off the rings.

BTW when you're cranking the engine over out-of-the-water, always have water supplied to the pump, even if you don't intend on running the engine. Otherwise the impeller could be damaged.

An easy way to do this is to pull the prop and stick the L/U in a big bucket, such that will completely cover the L/U with water.

HTH.......ed

Awesome. Thank you Dave an Ed!

Ok..well.. I tried to do the spark and compression tests today. Hooked up the brand new battery, turned the key, and nothing. So... I now need to figure that out. I guess I should start with a voltage meter to see where there isn't power?

if it ends up a bad starter I have a few good ones.

Thanks Dave!

On the controls, there is a red light. Do you know if that's supposed to light up when I'm trying to turn it over. I was just thinking about this at work.

Thanks!

yes it is on when in running position. the light reminds you to turn the key off so you don't burn the points

Ok, because there was no light when I tried it yesterday. Maybe I'll start there.

bulb could be burn't out.

Figured it out.

I'm an idiot and didn't know the Quicksilver controls use a push button starter on top of the lever. Was messing around with it and it kicked up immediately. This sucker would fire up if I had the gas hooked up.

BTW the bulb is burnt out.

OK!

Thanks to a vasectomy and some percocets I have some time off! Lol.

I did the compression tests while I'm waiting my order from Poole-Ferguson. I did NOT test the sixth cylinder because I could not reach it and didn't want to take the lower cowl off. That looked like a lot of work. The other cylinders are as follows:

1st: 121
2nd: 124
3rd: 151 (2nd test: 149)
4th: 122
5th: 126

Is the 3rd cylinder a concern because it's so much higher? I wasn't concerned about the 6th cylinder because everything else seemed to go smoothly and I am assuming the same with the 6th.

Video:

start here
with this