Newbie in need of some help and advice

[davids_1718]

Well I finally got me a nice birthday present. I bought me a used Pelican Scorpion with a 7.5 HP outboard for a nice price. The issue is the gentleman I purchased it from told me that it was working last year and it was stored in the garage. No problem, it seems that there is very liitle sand inside the cowl cover that I am looking to blow out with an air compressor. The starter handle is gone. I am in the construction field and I know that the handles on most of these power tools spartically brake from time to time. Next thing is he told me that he cleaned out the carb before storing it and never put it back. The carb is in the cowl but it's not connected. Doesnt seem like much work just 2 bolts.

My thing is this is my first real motor. I previously had a 30lb thrust minkota with a sevylor 8' inflatable.

Can someone guide me in the right direction on what should I look for and things I should do. Also am I correct by assuming that my serial # is 3933654 that my motor is a Merc 75 somewhere between 74-76. If so Dam this motor was well taken care of cause the factory paint is still immaculate.

Sorry for the narrative but I know how forums are and just want to be a lil clear on things before I post another question. I'll save the parts question for later. Thanks to all.

 

[SeaKaye12]

Re: Newbie in need of some help and advice

Hi David,

Well; it's a little worrysome that the seller chose to present the motor with the carb un-installed and the starter handle missing....it wouldn't be the first time where the situation was that there was something wrong with the engine and he was trying to avoid a situation where he would have to demonstrate it.

But hey; people are generally honest; we're gonna assume your guy was as well.

You seem pretty savvy...but I'll remind you that the fuel for that is a 50:1 mix of gasoline with two stroke oil (TWC-3). And, most people here would suggest replacing the impeller before the first run if you're not certain of its condition.

At the point you're at now; I would remove the plugs to inspect them and do a compression test. Maybe a squirt of 2 stroke oil in the cylinders would be a good idea just to insure that you have some cylinder wall lubricant in there for the initial run.

Then...if the compression test turns out good...hook up the carb and give it a go.

Let us know what happens!

Thanks for reading, Chuck

 

[davids_1718]

Re: Newbie in need of some help and advice

I would think that he would be kind of honest being that he drove from Syracuse to Queens NY for $700. Please pardon me but as I said this is my first real motor so I will have to start learning the language. Where would the impeller be? I am in the process of buying a repair manual but I need to confirm that this is the right motor before anything. Mercury 7.5 Thunderbolt Ignition serial # 3933654. Can anyone help me out with a confirmation. This will help me with not asking simple ridiculous questions.

 

[Hackamore]

Re: Newbie in need of some help and advice

the impeller is in the lower unit just above the prop. You have to drop the lower unit to get to it. It is the mechanism that pumps water through the motor to keep it from over heating. The other post is correct, if the motor has sat as it seems it has, you need to replace the impeller. Never thrust that it is good after storage. It needs to be replaced ever year or so all time. It is easier if you wait for your manuel to do that. It would take to long to explain on here. Good luck. Just a thought but seems might be a high price for a that model motor.

 

[davids_1718]

Re: Newbie in need of some help and advice

Is working on an outboard easier or harder than a car engine? I ask because I do my own work on my truck and learn as each day goes on. I am just skeptical on working on this motor cause I need to see how it functions. Also I see that they are pretty expensive. Would anyone happen to have a detailed parts list with pics to help me identify the motor. Cause as of now it seems that cosmetically i need to replace the hood release lever and the pull start handle. If I can see a picture or pictures of the same motor than I can explore and look for things that may need replacement.

 

[ctoshack]

Re: Newbie in need of some help and advice

Fee things I would do for starters.

1. Get your handle fixed your going to need it before anything.

2. Before you change anything on the motor other then the handle and spend more money, get a compression tester and pull one spark plug at a time testing the compression in each cylinder. Also disconnect your spark wires before doing this you don't want the motor to fire at all. Checking the compression is easy. Screw your tester into the plug hole and pull over the motor 4 or 5 times. Read the gage should be in the green at least around 120 psi and I'm pretty sure that each side should be within 10% of each other.

If compression is good Proceed.

4. Hook ears with a garden hose to the motor and try to start it see if she starts. If it does then your good to go onto other repairs if not we need to figure out why.

5. Change the impeller for the watter pump in the bottom end as suggested it's not to hard and you can find info hear on how to do it.

6. Change the foot oil with new fresh gear lube you will need special pump to get it in not expensive.

7. New plugs can never hurt.

Try that for starters.

 

[davids_1718]

Re: Newbie in need of some help and advice

I really do appreciate all the info. I guess no luck on the pictured parts huh. Also would anyone be able to tell me what does the thunderbolt ignition stand for?

 

[Titanty]

Re: Newbie in need of some help and advice

Fee things I would do for starters.

1. Get your handle fixed your going to need it before anything.

2. Before you change anything on the motor other then the handle and spend more money, get a compression tester and pull one spark plug at a time testing the compression in each cylinder. Also disconnect your spark wires before doing this you don't want the motor to fire at all. Checking the compression is easy. Screw your tester into the plug hole and pull over the motor 4 or 5 times. Read the gage should be in the green at least around 120 psi and I'm pretty sure that each side should be within 10% of each other.

If compression is good Proceed.

4. Hook ears with a garden hose to the motor and try to start it see if she starts. If it does then your good to go onto other repairs if not we need to figure out why.

5. Change the impeller for the watter pump in the bottom end as suggested it's not to hard and you can find info hear on how to do it.

6. Change the foot oil with new fresh gear lube you will need special pump to get it in not expensive.

7. New plugs can never hurt.

Try that for starters.

This is not my thread but thanks...your response was nicely worded and comprehensive.

 

[SeaKaye12]

Re: Newbie in need of some help and advice

David,

For one of many sites that give part numbers and diagrams...you can try dougrussell.com.

The below link may well take you to the page that lists the starter ***'y for your motor:

http://www.dougrussell.com/partscat...,6,5,16,10,9,14,19,3,18,17,4,1,11,7,12,15,8,2

Thanks for reading,

Chuck

 

[Jacket4life]

Re: Newbie in need of some help and advice

the impeller is in the lower unit just above the prop. You have to drop the lower unit to get to it. It is the mechanism that pumps water through the motor to keep it from over heating. The other post is correct, if the motor has sat as it seems it has, you need to replace the impeller. Never thrust that it is good after storage. It needs to be replaced ever year or so all time. It is easier if you wait for your manuel to do that. It would take to long to explain on here. Good luck. Just a thought but seems might be a high price for a that model motor.

I think he bought a boat and motor.

 

[Jacket4life]

Re: Newbie in need of some help and advice

CTO is right, every old-timer in here will telll you to check compression first. Without that, you got a paper weight or a LOT of work. The numbers he said are right too. In the neighborhood of 120 and within 10% of each other.

Simplest answer for me---it is more similar to working on motorcycles or lawnmowers than to cars. But that may be a generational thing for me, I'm not yet 40, and so I wasn't around so much for the older distributor, points, gapping, etc. that ppl. did a lot of when I was a kid.

Also, it is a two stroke. Don't know if you have any experience with them at all. You can search two stroke anywhere and see a basic diagram of the difference. There's a thread somewhere on here that has a pictorial version. Long story short on that, if you have a running motor, the MOST important thing in dealing with it is properly lubricating it through the use of the proper oil in FRESH gasoline. (This is the hard part b/c you don't always run all the gas out of your boat everytime out, and if you aren't careful, you'll forget.) This is even more important now that ethanol is everywhere. I'm not positive on all the reasons why ethanol is bad, but I DO know that it separates over time, and that the alcohol won't transport the oil. Second most important, the cooling system MUST work properly, or the engine will suffer serious damage fairly quickly. That's why everyone was talking about replacing the impeller. This is usually signified by three major symptoms: the cowling is hot to the touch while running, there is no water coming from the tell tale (some ppl cal it the pee hole), and the motor begins running very choppily, sputters, and dies often. If you have any of these three symptoms, shut the motor down and fix the problem, or you can destroy it quickly.

You are one of the few of us who are new that has one excellent idea right up front: buying the manual. The one thing I would add there, buy the mercury manual, it is much better than the aftermarket ones. I didn't, and now I'm getting one. The Clymer will go on the shelf or on EBay, or in the trash, or something else. Also about twice the price (of course). Everyone has opinions of that too, but there are two things I always buy from Mercury: Fuel Oil and lower unit lubricant. I have used aftermarket products for lots of other things, but not these two items. That's just my .02, though.

 

[davids_1718]

Re: Newbie in need of some help and advice

Real quick question because as I said before I want to make sure I am looking for the correct information can someone help me out. How do I identify my motor. What I have is a Mercury Thunderbolt Ignition 7.5 HP Outboard Motor serial # is 3933654. Reason I am reiterating this is because that is what I am typing in but I do not get any good results.

 

[SeaKaye12]

Re: Newbie in need of some help and advice

Hi David,

Well; if by identifying it you mean you want to know what year it is...you can look here:

http://www.maxrules.com/Merc_model_files/7p5-9p9.html

Your engine appears to ne a 1974 Rope Start,
Does that check out?

Thunderbolt Ignition in and of itself doesn't mean much. Mercury used that designation for years and years and doesn't really indicate any specific design of ignition system.

This is fun; ain't it?

Chuck

 

[davids_1718]

Re: Newbie in need of some help and advice

Fun isnt even the word. You would think with technology nowaday searching would be easy. At least I found a seller on ebay with parts for my motor. Now it's just a matter of finding the exact factory manual.

 

[lncoop]

Re: Newbie in need of some help and advice

Long story short on that, if you have a running motor, the MOST important thing in dealing with it is properly lubricating it through the use of the proper oil in FRESH gasoline. (This is the hard part b/c you don't always run all the gas out of your boat everytime out, and if you aren't careful, you'll forget.) This is even more important now that ethanol is everywhere. I'm not positive on all the reasons why ethanol is bad, but I DO know that it separates over time, and that the alcohol won't transport the oil.

I think the consensus is it begins to break down after a couple of weeks or so. I decided to start using Stabil because I see it as cheap insurance against fuel breakdown related issues, any one of which can cost more than many years' worth of the stuff. I run it in my big motor and my small one. That way I don't have to run the gas out if I think it will be a little while before I run either of them again. There are still a few scoffers, but I highly recommend it and I bet if you asked a marine mechanic he or she would as well.

 

[davids_1718]

Re: Newbie in need of some help and advice

Well to my suprise I came across an honest entrepenuer that works on outboards. The man ran a compression test for me and told me that the outboard seems to be in exceelent condition. ! cylinder had a 154 compression as the other ran a 146. The only concern he had was the water pump. I did not want to take too much of his time nor leave it with him because he is very busy and said it might take him 2 weeks to work on it. The other great thing was he had a 9.8 HP where I was able to get a carb n fuel pump off him. Overall for everything I ended up spending 85 bucks and left him a $40 tip just because of his honesty. All I need now is to get this pull rope to retact and I can finally hit the water.

* Would anyone be able to help me with this. The inner spring appears to be tight. I'm guessing that I reassembled it wrong.

 

[CV16]

Re: Newbie in need of some help and advice

When you find a manual for your motor, it'll show you how it goes together. Til then, try this manual. I know it's not for your motor, but the impeller and pull start shouldn't be much different.

http://forums.iboats.com/showthread.php?t=410338