210 5.0 EFI Repower Advice

[SeaRay]

I have a 1999 210 BR with a 5.0L EFI engine (SN OL380364). From the drivers seat, I have noticed she has gradually been losing power the last couple of years. The engine has just over 600 hours on it. The engine (and entire boat) has had regular maintenance, with the exception there was one year where we had enough hours on it that we could have done a mid year oil change but it just didn't happen.

We do a lot of towing - wake boards, tubes, etc - so I am sure that adds to the engine wear.

I just did a compression check and with the engine cold the difference from high to low was 180 to 120. When warm it was 180 to 130. When it was cold I added oil to the three lowest cylinders (120, 135 and 140) they all went up to 150 - 160. So I am well out of the 10% difference and seems like the rings are getting worn (since the oil increased the pressure).

I am considering a re-power. If I do, I'd like to upgrade to at least a 5.7L.

I have been doing some research on engines but I have never replaced an engine, so I have lots of questions....

1) I have been shopping online but would like to hear recommendations on where to buy a new engine. There was a place I found a couple of years ago that seemed to have a great reputation but I wasn't able to find it and I don't recall the name.

2) A complete new engine is out of my budget. So I am looking at a new base engine or a remanufactured engine. What is the advantage or disadvantage of these? Do I need to send my old engine back if I get a remanufactured engine? If so, I need to add the shipping cost into the price difference.

3) What are my options on the replacement engine size? If I have to swap parts off of my engine, what will work on the new engine? Can I go to a 6.2L? Do I even want a 6.2L? I think a 5.7L is an easy swap but I have EFI and not MPI, does that matter? What about the ECU?

4) Can I keep running the boat as it is?

FWIW - The pressure readings when warm were 175, 142, 153, 180, 174, 130, 160, 170.
The order of the cylinder readings start with starboard side rear plug to front plug, then port side rear plug to front plug. (sorry I am not sure of the correct cylinder numbering)

Thanks

 

[Chip S]

Mercury recommends a remanufactured 4.3L (225 hp) to replace a 5.0L ( https://www.mercurymarine.com/en/us...emanufacturing/plus-series-alpha-sterndrives/ ). It will have all new parts but is not fuel injected. I don't know the cost and I don't know your budget. A 5.0L long block would be the least expensive option, but then all of the parts (starter, alternator, etc.) are still old.

With the 4.3L you would have more room in your engine room. I'm not sure what modifications would need to be made to the engine mounts, however.

 

[Espos4]

If you are not replacing the computer, then I believe that you need to go with the same size motor if you wish to retain the current fuel injection system.

 

[ColoSR]

What kind of drive do you have? Merc limited the alphas to 300hp, so you don't see them paired with anything bigger than the 5.7.

There usually isn't much cost difference between a 5.0 and 5.7 longblock, although you will have to reflash or buy a used computer. The injectors and the rest of the stuff will move over.

Mercury remanufacturing, Michigan Motors, and Jasper are mentioned most often here. The 5.7 longblock didn't change much from 1996 to present, although you will want to verify the interchange with your serial number. Make sure they put 0 not O in the first digit.

 

[SeaRay]

I have the Bravo 3 drive. Yea, if I replaced it I didn't see the benefit in going back to the 5.0, the 5.7 long block prices are so close. But I wasn't sure what else I would need. So, I could just reuse the EFI (2 throttle body injectors) system from my existing engine? But I would need to reflash or get a new ECU? What would that run?

On a side note - when you compare compression readings, you are supposed to use the DRY compression readings to check for the delta 10% - correct? I mean after I added the oil to the 120 cylinder it went to 155ish, but I would still use the 120 number to compare to the high cylinder which was 180 - correct?

I ask this because I replaced all the plugs after doing the compression check and the boat ran MUCH better. I also ordered a new distributor cap, rotor and plug wires but haven't gotten them yet. If the boat continues to run like it is, I think I can hold off on the engine replacement. It is running that much better.


Thanks

 

[ColoSR]

With the bravo you could go straight to the 383 stroker, that’s the 6.2L bored 0.030 over. Mercury is still remanufacturing those so you might have better OEM support, but the merc 383 longblocks are a lot pricier than the aftermarket 350's.

Reflashing the computer isn't terribly expensive, these guys say that they do an ECU for $400.
https://www.hardin-marine.com/c-2250-ecu-upgrades-and-tuning.aspx

 

[El Capitan]

Here’s my question. Why did it get blow-by w only 600 hours?
That’s roughly half it’s life expectancy. Even if you ran at WOT most of the time you should have gotten close to 900-1000 hours runtime.

Secondly, I believe the 5.0 is the same block as the 350 block which I would recommend.

First figure out why it list comp then determine most suitable power.

 

[SeaRay]

The only thing I can think of that hurt the life of the engine was the first summer we got the boat we probably put 100 hours on it (second owners, bought it with about 150 hours on it). In retrospect, I should have changed the oil halfway through the season. The oil broke down and I had, what I think was, a slight lifter noise when we ran the boat hard. This only happened once or twice at the end of the season. I'd shut the boat down and let it cool off when I heard it. I did an oil change and the noise never came back. Other than this, the engine and the entire boat has had very good service.
As I mentioned above, I just changed the plugs and the boat is running WAYYYY better. This doesn't explain the difference in compression but maybe I need to check it again. It was running so bad before that I would not be surprised if it was running on 7 cylinders for some reason...Stupid question...But would this cause some carbon build up on the valves or some other temporary issue that would have affected the compression????