1988 Merc 5.0XL with alpha drives engine replacement suggestions

[crazy charlie]

One of my extremely low hour twins is gonna need replacing.Water in oil that i was not aware of.Gonna get a few quotes this week for an "off season" job.Anyone done the same?? Charlie

 

[Bondo]

Ayuh,...... Drop in a pair of 5.7ls Charlie,.....

There's no replacement for displacement,.....
'n All the bolt holes are in the same places,.....

 

[Scott06]

One of my extremely low hour twins is gonna need replacing.Water in oil that i was not aware of.Gonna get a few quotes this week for an "off season" job.Anyone done the same?? Charlie

not sure exactly what question you are asking. Are u trying to determine what you should pay off season for a turn key? Are you asking who you should look to for engines?
also agree swap in a pair of 5.7s

 

[crazy charlie]

Thanks guys but I am only replacing one of them.How whacked out would it be if I replaced it with a 5.7 and had mismatched motors until other needs replacement and then finish the pair?? Charlie

 

[Scott06]

Thanks guys but I am only replacing one of them.How whacked out would it be if I replaced it with a 5.7 and had mismatched motors until other needs replacement and then finish the pair?? Charlie

I think that would be pretty goofy to run. I would think They would need to run different rpms to match power so it doesnt push the boat into a turn.
still not sure what your original question was. If you are looking for pricing on the engine michigan motorz has reman and new options

 

[matt167]

Get it going cheap. Buy a good used truck motor, swap gaskets and cam, freeze plugs in your garage. Your engine should have the '87-'95 intake pattern. If it does not, then just re use your heads as well..

Prepare to upgrade to 5.7's when you can

 

[Lou C]

Charlie why not do some diagnostics and see if you can figure out the source of water intrusion. If the water has not been in the oil a long time you might be able to do repairs depending on the situation. If your boat is not covered with 6-12” of snow that is!
4 years ago I had water in a cyl and water in the oil at the end of the ‘16 season. I pickled the engine changing the oil several times fogging it and draining all the water out. Then in Feb of ‘17 we had a warm spell and I started taking it apart. I found blown head gaskets and had the heads checked at SK Speed shop in Lindenhurst. They found cracks in the center cyls exhaust valve seats. This was all likely from an overheat 3 years before in ‘13. So they advised replacing the cyl heads which I did. I think they got them from a place called Machine World nearby to them. Put it back together with new Fel/Pro gaskets and new exhaust and it’s still fine 3 years later. Did the work without pulling the engine. Used an electric impact gun to get the head bolts out and replaced them with ARP head bolts. Not a hard job really. The cleaning of the block deck and intake manifold sealing surfaces took the most time. Just find a way to keep all the parts organized.

 

[crazy charlie]

Thanks again guys.I think I am gonna go over the options with a local reliable marine mechanic.Unfortunately my capabilities and experience are non existant when it comes to tearing down a motor.I am more of an exhaust manifold/riser,outdrive waterpump service type of guy.Just the basics sorry to admit.Charlie

 

[Lou C]

Hey Charlie my first tearing down of an engine was this job. I figured I had nothing to lose. I used SK Speed's machine shop, I know you're in Long Island correct?
The hard part is keeping dirt out of the engine keeping all the parts labeled and clean and organized. I didn't lose or break one bolt even! Surprised myself. If you have a good local guy let me know, might need in the future.

 

[crazy charlie]

Hey Charlie my first tearing down of an engine was this job. I figured I had nothing to lose. I used SK Speed's machine shop, I know you're in Long Island correct?
The hard part is keeping dirt out of the engine keeping all the parts labeled and clean and organized. I didn't lose or break one bolt even! Surprised myself. If you have a good local guy let me know, might need in the future.

That must have been a pretty good feeling when you got it all done.Yes I am on LI .Bummer as I used to have a few GM old time mechanics as friends that have since moved south.These guys could take apart a motor while holding a full blown conversation and put it back together so effortlessly.I never realized how valuable these old timers were.Will let u know what i wind up doing.Wish I could have caught this sooner but I was under the impression I had a carb issue which stopped the motor from starting so I didnt check into anything until it was way too late in the season.Charlie

 

[matt167]

My old bossman made me fix a mid 1990's Chevy 2500 w/ 5.7. The intake gasket had blown and dumped the contents of the radiator into the oil pan several times over. Owner ran it as a wood truck till it got hot, and then filled it up again with straight water over and over again never checking to see where the coolant was going. This was in the dead of winter..

I told bossman the engine was wasted as I drained out a few gallons of water and a few quarts of oil, but he insisted we fix it so I put intake gaskets on it and sent it out the door. It actually ran pretty good considering the bearings were probably smoked. It ticked and rattled but held decent oil pressure

 

[crazy charlie]

thanks Matt,guess its worth a try fixing first

 

[Lou C]

If you do:
figure a way to organize the parts first and take lots of pics. Label stuff as you take it off.
the intake manifold can be tough to get off, what I wound up having to do was heat the manifold with a heat gun around the joint with the cyl heads (be careful) and then use a couple of padded screwdrivers (duct tape) to carefully pry in between the manifold and the edges of the block. Be careful with this you don't want to scar the sealing surface. The intake gaskets on mine were baked on like Kryptonite.
getting the head bolts out can be difficult esp if the engine was raw water cooled, I used an electric 1/2" De Walt impact gun. Lucky I did not break any bolts.
I would up replacing the head bolts (got a set of ARP bolts) and spent a lot of time cleaning up the block deck surface, the intake sealing surfaces and the cyl head bolt holes in the block. That took the most time.
After that, the tricky parts were setting the hydraulic valve lifters and getting the distributor in right. Just take your time. These engines are stone age technology very easy to take apart and repair, if all you are doing is pulling off the manifold and heads.

the risk is the bearings can be damaged by water in the oil. I got the water out fast and my bearings are still good, no noises and same oil pressure as I had before the head gaskets blew.