Compression readings good or bad 1989 60HP Mariner

[armentroutkt]

Hey Guys,

After replacing the impeller, I finally did a compression check. Should of done this to begin with.

I have a 1989 Mariner 60HP 2 stroke

1st Cylinder 115
2nd Cylinder 140
3rd Cylinder 140

I'm assuming this isn't good for the first cylinder? Is there anything I can do for it?

 

[Clams Canino]

Re: Compression readings good or bad 1989 60HP Mariner

You can try decarbing it with Marcury Power Tune. If that don't help you outta rip it down and do a ring-job. If the waterpump failed, #1 is the cylider that will get damaged first.

-W

 

[armentroutkt]

Re: Compression readings good or bad 1989 60HP Mariner

Hey Clams,

Thanks for the quick reply. Where exactly do I dump the stuff. I bought some Seafoam. Do I put it down in the number one cylinder?

 

[armentroutkt]

Re: Compression readings good or bad 1989 60HP Mariner

Also the water pump never actually failed. I just thought it was definately time to replace it. Water wasn't coming out full stream when idling. After I replaced it, It was shooting out pretty good.

I'm trying to troubleshoot a problem with process of elimination.

It boggs down when in the water only. When I first fire it up in the water it will idle and go full steam until about 100yrds, it acts like it just has no power and goes up and down up and down.

replaced the impeller
replaced spark plugs
coils have spark
replaced some corroded wiring
new fuel line....(bulb always stays solid when driving)
Took carbs off and cleaned.

Havn't tried rebulding the fuel pump (replacing the diaphram in it)

What else could it be. Or do you thing the whole problem is that no. 1 cylinder?

Thanks alot for the help. Learned a couple things from my repair manual last night.

 

[jebeebe]

Re: Compression readings good or bad 1989 60HP Mariner

It always seems to be the #1 cyl that goes bad on that model. I had an '89 merc 60 that had the top cyl toasted. It can be from lack of water or lack of oil. usualy water. Mine was so bad broken rings were completely gone out the exaust and the remainder stuck in the ring groves. Not a pretty sight. I replaced all three pistons and honed the block. Good luck.

 

[Clams Canino]

Re: Compression readings good or bad 1989 60HP Mariner

Hey Clams,

Thanks for the quick reply. Where exactly do I dump the stuff. I bought some Seafoam. Do I put it down in the number one cylinder?

You can put it in #1 cylinder and also spray it in the top carb while it's running until it stalls - then let it soak for a good while.

Extended running "full steam" is not a good idea. They cruise best at 4200 RPM. But it sounds like a fuel delivery issue to me, have someone pump the ball during a test run.

-W

 

[armentroutkt]

Re: Compression readings good or bad 1989 60HP Mariner

Thanks a bunch guys...

So start the engine with the no. 1 spark plug out and spray some stuff in there and also in the top carb?

Jebeebe - How bad was it replacing the pistons. I have rebuild a Chevy 350 before but havn't touched an outboard. What would it run to have someone rebuild it for me? Just a round a bout.

I'll try the suggested tonight when I get home.... Otherwise, don't really know what direction to go. Always something. Does anyone know anyone in fredericksburg, VA or roundabout area who does motorwork?

Thanks again

 

[jebeebe]

Re: Compression readings good or bad 1989 60HP Mariner

I did it myself with the help of my brother in law who was a chev mechanic at one time. It takes patience and care but it wasn't too bad. I made some special tools as I am a toolmaker by trade and have a machine shop, but we could have done it without. There are needle berrings on both ends of the connecting rods that have to be kept in place while you press in the wrist pins...................not too bad. I had 500.00 in the job doing it myself. That includes fuel pump , water pump carb cleaning, starter selenoid, starter gear, and anything else that looked like it needed it. Good luck..............Jerry

 

[armentroutkt]

Re: Compression readings good or bad 1989 60HP Mariner

$500 is right up my alley. I might tackle this with my dad. Take lots of pics and dive in. I put some more Seafoam in it yesterday and let it sit. I think I need the stuff Clams was talking about made by mercury.

I did how ever fire it up yesterday without the no. 1 plug in looked to be white smoke coming out for a while. Is this the carbon burning up from the seafoam? It stopped after a while. Did another compression check:
115
136
136

I'll hit the marine shop on the way home today.

 

[AMD Rules]

Re: Compression readings good or bad 1989 60HP Mariner

So start the engine with the no. 1 spark plug out and spray some stuff in there and also in the top carb?

Nope..

If you start the motor with a plug out, then try to spray something into the spark plug hole... you'll end up covered in fuel, oil, and decarb as it spits it back in your face.

Start the motor normally, with all plugs in. While running spray the decarb in the carb throat keeping it running for a bit, then increase the amount to stall the motor. Remove spark plug and spray decarb into the cylinder(s). Let it to soak overnight, or longer. Run it to test. If not successful, try repeating the process.

 

[j_martin]

Re: Compression readings good or bad 1989 60HP Mariner

If an outboard balks when you're trying to run WOT, never push it. If it's lean on fuel, you'll roast a piston. Chances are that is what's going on with your #1 cylinder.

Try decarboning. If it doesn't bring up the compression, it needs fixin'.

Get the fuel problem resolved before you do any more damage.

hope it helps
John

 

[armentroutkt]

Re: Compression readings good or bad 1989 60HP Mariner

Hey Guys,

Been pondering what to do. I did try decarbing it. It did bring the psi back up.

The first cylinder is at 126, 2nd at 149, and 3rd at 149....

I think I will tackle the fuel problem. I had another thread about gas leaking from the exhaust.

Filled up a trash can full of water and ran the motor at idle for a half an hour. The water in the can after the half hour smelled like raw fuel. Laddies suggested maybe a pinhole in the fuel pump diaphragm. I think I'll get one of those and rebuild the carbs. I guess it won't be a loss doing this, even if I have to get a ring job done, at least the carbs will be like new right? This hobby is turning into a money pit!!

Thanks again for the help......