going to buy a used mercruiser

[liusigou]

I am going to buy a used 1989 2.5L mercruiser. He said the fuel pump is weak. But the cylinder pressure are about 140~145psi. I will run it with water to check if there is any water leaking into oil or not.

What other should I pay attention?

Does pressure good mean good motor or not?


Thank you

 

[rolmops]

Go with a musical tuner or a magnifying glass over the block to hear or see any cracks in the block. There can be good compression in spite of a crack in the block. I found that out the hard way. Make sure that your lower unit is an Alpha 1 so things fit not just size wise but also gear wise. Weak fuel pump? It's a mechanical pump so just rebuild it or replace it. No big deal there. If it has an electrical pump for some reason, I would beware.

 

[Lou C]

What about the rest of the boat? That era of a ‘glass/wood boat will have plenty of places for rot to have developed, be very careful!

 

[liusigou]

What about the rest of the boat? That era of a ‘glass/wood boat will have plenty of places for rot to have developed, be very careful!

I just buy a motor to replace my old low cylinder pressure motor.

 

[Scott06]

I am going to buy a used 1989 2.5L mercruiser. He said the fuel pump is weak. But the cylinder pressure are about 140~145psi. I will run it with water to check if there is any water leaking into oil or not.

What other should I pay attention?

Does pressure good mean good motor or not?


Thank you

new the engine will have about 150 psi compression pressure so 140-145 on all cylinders indicates the pistons, rings and valves are in good shape. I would ask to see this my self don't just take the sellers word for it.

Additionally you want to look at what the oil pressure is normal rule of thumb is 10 psi /1000 rpm engine is running when the oil is hot. So at hot idle you should have 10 -15 psi minimum, 45 psi at WOT 4500 rpm or so. if oil pressure is good when it is hot it is indicative that the bearing clearances are still good and not worn.

Also look for evidence of water in the oil any milkyness or oil residue baked on engine that may be indicative of poor maintenance.

I would look ate the spark plugs for evidence of oil fouling or carbon build up, or water in combustion chambers.

Listen for ticks and tapping noises, but the 2.5 and 3.0 are not the smoothest running or quietest engines out there. If some one has kept up with the oil and maintained it they are tough engines and will last for years.

 

[liusigou]

A few ago I tested 1989 mecruiser motor and first and second are about 110 psi. So I quit continue to test the rest. He sent me his testing reading are more than 150. Is it possible?

 

[rolmops]

You should test all four cylinders after warming up the engine.
The pictures show an even 175 psi which is good, but what about the 4th one?

 

[liusigou]

You should test all four cylinders after warming up the engine.
The pictures show an even 175 psi which is good, but what about the 4th one?

the fourth is an video. So I did not upload it. but it showed more than 150 psi. I remembered he batter was not charged regularly and only cranked it two time's when I tested it and they were 110， 110 PSI. then I gave up because the third and the fourth are blocked by tbe riser. now he tested it again by himself.

 

[liusigou]

How come the pressure are more 150 PSI for the year of 1989 3.0L mecruiser motor? is it rebuilt? Can I buy the boat. should I test in the water. what should I pay attention ?

 

[rolmops]

175 is great. It can be this high, no worries Can you buy the boat?. That is up to you.

 

[matt167]

Just so you are aware that is not a 2.5L. That is a 3.7L 165hp ( 470, 488, 165 are all 3.7L.

Not a direct swap to a 3.7L from a 2.5L but can be made to work if you need to ( 3.7L is littered with problems though)

 

[liusigou]

i

Just so you are aware that is not a 2.5L. That is a 3.7L 165hp ( 470, 488, 165 are all 3.7L.

Not a direct swap to a 3.7L from a 2.5L but can be made to work if you need to ( 3.7L is littered with problems though)

I will buy the boat and the motor

 

[liusigou]

175 is great. It can be this high, no worries Can you buy the boat?. That is up to you.

Yes. I am going to upgrade the boat

 

[nola mike]

Just so you are aware that is not a 2.5L. That is a 3.7L 165hp ( 470, 488, 165 are all 3.7L.

Not a direct swap to a 3.7L from a 2.5L but can be made to work if you need to ( 3.7L is littered with problems though)

Nice catch. Although I'll go to my grave singing the praises of a 3.7.

 

[matt167]

Nice catch. Although I'll go to my grave singing the praises of a 3.7.

I love a good running 3.7L too. But there is no denying it has bugs that Merc never worked out before pulling the plug on the project

 

[liusigou]

I just cannot believe that the pressure are more than 150 PSI for thr 1987 Mercruiser motor. sure I will do the pressure testing again even water running testing

 

[airshot]

Pay close attention to the #2 and 3 cylinder. It has been my experience that the head gaskets blow out between those two cylinders from an overheat and a head warp. Be sure your comp gage works properly !

 

[tank1949]

I am going to buy a used 1989 2.5L mercruiser. He said the fuel pump is weak. But the cylinder pressure are about 140~145psi. I will run it with water to check if there is any water leaking into oil or not.

What other should I pay attention?

Does pressure good mean good motor or not?


Thank you

If salt water used motor, walk away! Also check boat for rot. I'd be more concern with that potential. You might be sinking too much money into yo hole.

 

[Scott Danforth]

I just cannot believe that the pressure are more than 150 PSI for thr 1987 Mercruiser motor. sure I will do the pressure testing again even water running testing

it cant be, it wasnt above 150 when new. your gauge is most likely off