1977 Mercury 1150 need help!

[tavacska]

Hi, everyone, New to the forum.
One guy I met today for craigslist happened to work on the 1978 1150 before. He recommended me to this forum and he appreciate the help from here.

So thanks for any advice in advance.




My story:

Last week I bought a Boston Whaler 17 and Mercury outboard 1977 1150. The boat is good but all the wires to the outboard were dissembled. I was told by the first owner that it was supposed to be rewired. And the compression were all around 110-120. I am happy with the boat so I bought them anyway. Just a boat, an outboard and a bunch of lines. No tanks, no battery, no other things.

Tonight, I was following some instructions and did the compression test by my self.
Here following is exactly what I am doing.
1. dis attach the spark lines.
2. remove the sparkles.
3. Check inside through holes with naked eyes and flash light, there seems to be some rust, which make me feel not good.
4. Spray some WD 40 through the holes.
5. Attach battery positive to starter motor positive.
6. attach the compression tester to the sparkles holes.
7. attach the battery negative to starter motor negative.
8. Read the number.

I did this for the first 4 or 6 cylinders, the readings are 90, 60, 90, 120.


My question is:

1. Is there anything wrong with the above procedures?
2. Is it still worthy to keep working on the motor?
3. Do I need to call a technician to help to check this again?


Please help.

Thanks.

 

[racerone]

remove bypass covers on starboard side of the block for a look at the pistons.

 

[tavacska]

remove bypass covers on starboard side of the block for a look at the pistons.

Do you think it is ok?
This is the one with 60 psi reading. the side and the rings looks smooth to me. Only the face in the combustion room is rusted.

 

[tallcanadian]

I'm not a mechanic but do my own compression testing. Why the WD-40? I take out one plug at time, starting at the top. Make sure your tester is in snug, no air leaking around the rubber gasket. Turn engine over a few times. Check reading, release, then check one more time. Repeat for each cylinder. If you see some rust, try using Sea Foam after ward. If compression is all over the place, you may need new rings.

 

[tavacska]

I'm not a mechanic but do my own compression testing. Why the WD-40? I take out one plug at time, starting at the top. Make sure your tester is in snug, no air leaking around the rubber gasket. Turn engine over a few times. Check reading, release, then check one more time. Repeat for each cylinder. If you see some rust, try using Sea Foam after ward. If compression is all over the place, you may need new rings.

Thanks for the hint.
I watched the youtube channel of DangerMarine, he used some WD40 on an outboard long time sit. So I think maybe it is a routine to do so.

I checked the compression again today. Several times for each cylinder.
The reading is 120,80,125,140,135,?bottom can't be reached.

I tried and was sure there should be no leak on 2nd cylinder.
What should I do next?

 

[tallcanadian]

Numbers like that you will never get that motor to idle right it may run but at its potential. Again, I'm not a mechanic. I just know that my motor has the same issue. I do know that it needs to be rebuilt. It runs, and sounds fine wide open. But I'm lacking speed and it idles rough. I used sea foam and it got me through last year.

 

[tavacska]

By rebuilt, do you mean change the piston ring, or have the cylinders bored?

 

[Faztbullet]

Rebuild is returning to factory spec's(new pistons ,boring) re-ring is waste of time and money in my opinion, only for display,show or restore and short usage.Inlines are bad about cylinder wearing around transfer port from piston side thrust and have only seen a handful in 40+ years that wasn't worn.

 

[tavacska]

So any suggestions now?
1. Trash can
2. Sea foam treating
3. 2nd piston re ring
4. All pistons re ring
5. 2nd cynlinder bored
6. All cynlinders bored

Thanks.

 

[racerone]

You can only make those decisions after taking it apart and inspecting the parts.----If you have to pay a shop for all the work you might be shocked at the total cost.----And do not forget inspection / sealing of the lower unit on a 40 year old motor.

 

[tavacska]

Ok. I will take apart it this weekend.
Thank you.

 

[mr 88]

Really can't bore those out at a normal engine shop
The block is one piece,no separate cylinder head.

 

[tavacska]

The compression test is done again and the results are:

No. Cyclesx4 Cycles x 8
#1 110 117
#2 62 63
#3 117 125
#4 126 133
#5 130 140
#6 122 125


I opened the crankcase today and checked the pistons and cylinders.
the #2 piston turns out to have a broken ring of 1/2 inch missing.
All the cylinders and pistons look good to me.

This is really a good news.

My questions are:

1. Do I need to replace all the rings or just #1-3 rings? which is better?
2. Do I have to clean the pistons and cylinders? with what chemicals?
3. To clean carburetors, which is a better way? The cleaner spray or the big cleaner gallon?

Thanks.

 

[Chris1956]

Gee, I had that motor and never broke a ring, despite overheating it twice and severely damaging cylinder #1 and #3 and then #1 again. You need to find out why that ring broke. Maybe it sucked in a reed petal or rock?

 

[Faztbullet]

All the cylinders and pistons look good to me.

This means nothing till you take a inside mike and rigid hone(no spring hone) to cylinder and measure wear and measure pistons.

 

[tavacska]

I am trying to rebuild everything.
Fortunately, the cylinders and lower unit are good.

The #2 piston has 1/4" worn groove one side and 1/2" broken ring.
All the grooves of pistons have thick carbons and the rings got stuck inside.

So I cleared the pistons up and replaced all the rings. Not yet install the crankshaft yet.

I was planning to replace all the gaskets for exhaust part. But I dare not to do so.
Because the old gasket cleaning of intake part and base part is a nightmare.
I was using carbon cleaner and a small razor to bite it off very carefully but still can not have the work done.

Is there a solvent there in home depot can help do this efficiently?