Mercury 402 questions

[spamn]

I purchased a boat last summer with a 40hp 2 cylinder 2 stroke 402 Merc on it. I have never owner a boat and know nothing about outboards. I am decent with a wrench though.

The engine had some overheating problems and sputtering.

This winter I have been trying to fix everything so it's ready for the Spring. I popped the cover and saw a blown gasket between the block and plate that holds the spark plugs. The plate was cracked and repaired with JB Weld apparently too. I removed the old plate and of course some of the bolts broke.

I finally have all bolts removed and new gasket and plate on. However, the bottom cowl restricts me from inserting the bottom bolt and properly tightening it. I cannot see a way to just remove the bottom cowl. Any idea?

I removed the lower unit and found the impeller to be trashed. Ordering a new one. Anything else I should look for in the lower?

Removed the transfer port cover and found the poppet and all related grommets to be melted. Ordering all new components and t-stat.

What other suggestions do you have that I should look for? When running, the telltale had water flowing from it. I am a little apprehensive about taking apart the carb to clean it properly as I have no idea how to adjust it when done. I was thinking of just cleaning it the best I could while together and using some carb cleaner. Any advice on this as well?

Lastly, I'm thinking that this motor is too old and won't support an onboard battery charger, is this correct?

My serial number leads me to believe that this is a 1973 model.

Final question is that when I look up parts, there is always multiple categories that my serial number falls under.. not sure which to choose. Also, there is a "cylinder block and coil mounting bracket" category for Serial group #3 and serial group #5. Noone can tell me what that means.

(My serial number is 3727480)
http://www.boats.net/parts/search/Merc2/Mercury/402/parts.html

Hoping to get this engine fixed up quickly and I also have a 1978 Mercury 500 that appears to be in awesome shape, but I have never seen it run so it's a big mystery for now. Once the 402 is good, I would like to try out the 500 and hope that it's in good condition. Any suggestions on things to look at before I attempt to fire it up?

Sorry for all of the questions and thanks in advance

 

[carholme]

Re: Mercury 402 questions

Lots of questions to answer here but to start you off, here is the parts breakdown for your engine which does show up as a 1973:

http://www.crowleymarine.com/mercury-outboard/489.cfm

Scroll down to the serial number chart and you will see that yours belongs to Serial Group # 1.

carholme

 

[jerryjerry05]

Re: Mercury 402 questions

As far as the bolt that won't go in.Try taking off the head and then install the bolts in the head and then put the head back in.With the bolts already in place.
If the impeller is trashed then check for missing pieces in the tube to the head.
Rebuild the fuel pump about $15-$20. The carb is easy to clean.There is an air screw usually on the front/top of the carb.Screw it in,counting the turns till it bottoms out.REMEMBER the #.
When you re-assemble re set it to the beginning settings.
Replace all hoses.Even the squeezie.Change the oil in the lower.
The water jacket,you might be able to find a new one if not there are lots of salvage yards.
Good luck,J

 

[spamn]

Re: Mercury 402 questions

Thanks for the suggestions, guys.

Excuse my ignorance but what is the water jacket? As well as the squeezie?

I wil try your suggestion for removing the head, just need to order another gasket for when I reinstall it. What do you mean by rebuild the fuel pump? Is there some sort of kit or do you mean to just replace certain pieces of it?

Lastly, where exactly should I look for the missing impeller pieces?

Thanks again

 

[bktheking]

Re: Mercury 402 questions

By plate that holds the plugs i'm assuming you mean the cylinder head. If it was JB welded (the head) did compression check out ok?

 

[Faztbullet]

Re: Mercury 402 questions

I agree with Bk as that motor has been really hot. Check compression before spending any more time and $$$ on it. The water jacket is what your replacing and squeezie is fuel line bulb(primer)...

 

[backyard mechanic]

Re: Mercury 402 questions

Older Mercs don't have a removable head like many of the new do. The water jacket cover often leaks and appears to be worse than it looks. The posts here remain true... This one got hot and that will pose some BIG trouble. Here's my two cent opinion/comments:

Check Compression- is there any, is it good?
Is the lower unit good; holds pressure not full of water?
The reeds are held in place with plastic locater pins on this old 402. If the engine got hot enough to smoke the water jacket you most likely have damage to those plastic locater pins. That is going to cause you grief eventually unless you fix it.
The water jacket cover might be able to be welded if you can't get a new or used one. It will not seal well unless you file it flat. Silicone will help you with minor warping but I think the reed locate pin issues are bigger issues.

Check out the info on the reed pins to make sure. I hate to bring doom and gloom but knowing all the bad is sometimes worth knowing before you spend a lot of dollars to find out the engine is trash.