My boat run slowly. 120HP,2.5L,1989

[Scott Danforth]

What did you set the timing to? What did you set the dwell to?

If your dwell and timing are in spec, the low compression and fuel system are the two other issues to address

Low compression means the motor comes out and goes to a machine shop to be rebuilt

Fuel system.
Start with the contents of the tank. Check your fuel pressure, inspect the anti-siphon valve, fuel vent, etc

 

[liusigou]

What did you set the timing to? What did you set the dwell to?

If your dwell and timing are in spec, the low compression and fuel system are the two other issues to address

Low compression means the motor comes out and goes to a machine shop to be rebuilt

Fuel system.
Start with the contents of the tank. Check your fuel pressure, inspect the anti-siphon valve, fuel vent, etc

I did set the timing according to the following video , 13,4,2 will be fired. Really I did not know anything about dwell. Could you please explain me how to set dwell? and I went Canadian Tire store and asked for dwell and nobody knew about it.

Also what is the cost rebuilt the cylinders?

 

[Scott Danforth]

You need a dwell meter to set dwell

How To: Troubleshoot a Points Ignition System

***Please read through ALL the information before attempting any procedure listed here and before asking ANY questions*** ***This tutorial is designed to explain step by step the proper procudures for troubleshooting a no spark issue for an engine with points ignition. If you are here, this...

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If you do the assembly labor yourself, about $1500 for a rebuild

If you pay for the labor to tear-down, clean, inspect, and reassemble. About $2500. However with you being in Canada, Call around

 

[dubs283]

I went Canadian Tire store and asked for dwell and nobody knew about it

lolz

 

[liusigou]

There is an thread to add some cleaner into cylinder and the compressures was up. Can I do so?

Mercruiser 120/2.5 compression readings

Did a cold and warm compression test today on my 120. What would you say about these numbers? Healthy? Cold: Cyl#1 (105psi) Cyl#2 (110psi) Cyl#3 (107psi) Cyl#4 (102psi) Warm: Cyl#1 (115psi) Cyl#2 (125psi) Cyl#3 (125psi) Cyl#4 (115psi)

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***†**†*%%*****†************†**
OK, here's the update: I soaked all cylinders with Yamaha combustion chamber cleaner for about an hour. Then I idled it up and down (gently) for a good 10-15 mins. Took a compression check (warm) and here's what I have now:

Cyl#1 (125)
Cyl#2 (130)
Cyl#3 (126)
Cyl#4 (116)

****†*****†***


Really I will give up to fix the old motor. A lot of time and money are needed.

Is there any simple way to add the cylinder compression?

 

[dubs283]

A lot of time and money are needed.

Yep.......

 

[alldodge]

Is there any simple way to add the cylinder compression?

You have done all that can be tried to get it up other then machine work

Could do a valve job but with all the oil seen on plugs it's time

 

[liusigou]

Can I apply Yamaha combustion chamber cleaner? How?

 

[Scott Danforth]

Find a 3.0 and Alpha 1 Gen 2 and drop in. Plenty in rotten Bayliners

Will be less than rebuilding what you have, even paying customs, VAT, etc

 

[liusigou]

Find a 3.0 and Alpha 1 Gen 2 and drop in. Plenty in rotten Bayliners

Will be less than rebuilding what you have, even paying customs, VAT, etc

Hi Scott, should I drop the Yamaha combustion chamber cleaner into the cylinders through the spark plug hole? Will it damage my engine?

 

[alldodge]

Can I apply Yamaha combustion chamber cleaner? How?

I understand your looking for like a mechanic in a can, and I don't see it helping.

It's sprayed down throat of carb when motor is running at high rpm. Need to boat in the water because garden hose may not supply enough to keep impeller safe from being damaged

Rev motor up and start spraying down the carb.

 

[liusigou]

I understand your looking for like a mechanic in a can, and I don't see it helping.

It's sprayed down throat of carb when motor is running at high rpm. Need to boat in the water because garden hose may not supply enough to keep impeller safe from being damaged

Rev motor up and start spraying down the carb.

What kind of product do you suggest to apply?

 

[alldodge]

What kind of product do you suggest to apply?

There is nothing that I know of that can be done to fix a wore out motor through spraying or pouring. Only way to fix a worn out motor is buy another or fix the one you have.

You could pull the head and have it rebuilt, normally isn't expensive. A couple 100 which would include valve job and gaskets.

This "should" increase compression, but if rings are weak/worn bad enough, then the motor will have more blow by

 

[dubs283]

At 3000 rpm under load pour a quart of distilled water down the carburetor

The water must be purchased locally, no cheating with tap water. If a spring is located nearby this water will suffice

Don't let the motor die when applying the water.

Boat motors run on water, who knew?

 

[liusigou]

Dangerous action. I prefer not trying doing so

 

[dubs283]

There's little difference between the combustion chamber cleaner you mentioned, power tune and water

Steam clean the engine

Another trick an ol boy told me once is to add a quart of atf to the crankcase a few hours prior to an oil/filter change. Frees up sticky lifters? Might just be a ford thing

 

[liusigou]

Could I do a cleaning for the carburator? I have bought a can of Sea Foam

 

[alldodge]

Dangerous action. I prefer not trying doing so

It's not dangerous so long as you don't put enough in to kill the motor. I use to do it as a youngen with a garden hose (we even drank from the hose)

IMO want to talk about junk and that's seafoam. Folks take good clean gas and dump seafoam in it. Snake oil so far as I see it

 

[dubs283]

I've always assumed oem marine engines are designed in house to run on fresh, clean, gasoline (where appropriate)

The engines will not run to top performance on anything but only the fuel they are designed to consume

 

[liusigou]

I pulled my boat into lake this morning and run the motor with gas mixed with the sea form about 20m. Then the boat can run with 33 miles. But later it shut off and failed to get fired. So I got back my my trolling. I checked the third cylinder's pressure is still 100. Battert's voltage is about 11.98. I will try to start it at my driveway after the batter is charged.