Merc 402 40hp?

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user 20022

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Your motor looks just like my 1973 402. The serial number will give you the year it was built.
 
lckstckn2smknbrls said:
Your motor looks just like my 1973 402. The serial number will give you the year it was built.
Hey would you mind posting some pictures of your 402 so I's can compare mine to yours? Mostly engine pics would help. Mine is missing the controls. Does yours have controls or is it a tiller?

Sent from the dust in front of you!
 
Anyhoo looks like the motor will be getting a rebuild. I figured so once i saw how bad the power wires to the ignition coils were corroded. Bottom cylinder reads 110psi top reads 40psi 60 when wet. I'm looking at the cost of parts vs paying a shop to rebuild the short block. This will set things back but make for a more reliable maiden voyage later...

Sent from the dust in front of you!
 
Would you guys just replace the rings and call it good or go in with more parts?

Sent from the dust in front of you!
 
Texas Prowler said:
lckstckn2smknbrls said:
Your motor looks just like my 1973 402. The serial number will give you the year it was built.
Hey would you mind posting some pictures of your 402 so I's can compare mine to yours? Mostly engine pics would help. Mine is missing the controls. Does yours have controls or is it a tiller?

Sent from the dust in front of you!

It uses remote controls.
I can't do pictures at this time.
 
Yea mine does to. I found a parts motor with controls that I can put on mine. This thanks though

Sent from the dust in front of you!
 
Pappy can you give me some advice please? Thanks!

Sent from the dust in front of you!
 
Anyhoo no help needed... I'll just start reading this manual and dive into rebuilding the outboard. Guess no one rebuilds motors around here.

Sent from the dust in front of you!
 
Texas Prowler said:
Guess no one rebuilds motors around here.

Sent from the dust in front of you!
There just aren't many of them that work on or have mercs. If you can't get the answers you need on a mercury here, you might want to try asking the mercury guys over at Iboats. https://forums.iboats.com/forum/engine-repair-and-maintenance/mercury-mariner-outboards
 
Sorry - the work you're getting into involves a machine shop unless you have the tooling yourself - which I do not. Living in CT once you get a professional involved in a project the cost skyrockets to the point it's likely not viable from a financial perspective. It's just easier to find a lazy idiot with a dirty carb that wants to sell his "non-running" motor for $50 than it is to dump that kind of time into a motor.

Power to you though, if you go that route you'll have a motor that you know inside & out which should be bullet proof for a long, long time.
 
Yep reliable is what I'm going for I have a service manual and I've read through it. Guys I'm really into rebuilding things auto engines, electrical, hvac, plumbing, so I feel this would not be to difficult to take it apart and rebuild. I'm thinking of having a shop clean,bore and clearance the piston bores. This way I'll have a solid foundation to build from. This will also give me a better idea of what size pistons and rings to buy. I'm positive that I can rebuild this motor.

Sent from the dust in front of you!
 
Just found a shop (Texas Machine Works) that will bore the cylinders for $45 a piece. Not bad at all. He even offered to supply the parts if need be. I'll start tearing down the motor this weekend after buying some big Ziploc bags. Since he is going to bore the cylinders over I'll have to get a complete power head rebuild kit. I've found one on https://www.maxrules.com/fixphead_merc.html#mmu40

Sent from the dust in front of you!
 
Are you sure this is worth it though? Why this motor?

Points I see against it:

1.) It's a crank-rated 40hp motor, meaning it makes less power at the prop than a more modern 40hp motor whose power output is measured at the prop.
2.) Its age - maintenance parts will become scarce for it at some point
3.) Total cost to build it up - if you're going deep into the motor you should be putting more than $140 into it - you should be replacing the bearings & seals & just about anything else that moves so that you get the end result you're after - an engine with as close to brand-new reliability as possible.
4.) Value when you're done - what will the realistic sale value of that motor be? I'm willing to guess it won't be more than $500 which is likely below your total project cost by the time you're done.

Points for it:

1.) You own the motor already
2.) ???
 
1.) I just want to get out on the water and have fun. Buying a newer motor just cause the prop hp isn't justifiable in my case.
2.) maintenance parts will be bought along the way little bit by little.
3.) The total cost has gone up because I've found a complete rebuild kit for $308. So motor$125, shop machine work $90, paint $30 for a total cost of $553 so far which could go up. I'm willing to pay that for a reliable motor that I can say I know what's going on internally.
4.) I'm not really concerned with the value because I don't plan on selling the motor as it will stay in the family.
Thanks for your input and please don't take what I've said negatively.

Sent from the dust in front of you!
 

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