Mercruiser 5.7 rust in cylinder bore

[Julz1]

Hi,
I'm new to to this forum and I am new to engine repair... I have done basic services but have never done anything to this extent. Im working on a mercruiser 5.7 fuel injected from a 2001 calabria ski boat. The boat was submerged with rain water because he unfortunately left the plug in. It was frozen until I soaked it with a 50/50 mix of atf and acetone mix. It broke free after removing the heads and hitting the pistons with a piece of wood and hammer. Eventually through time and hitting the piston and putting a pry bar on the fly wheel it moved. It moves pretty freely now however there are a few bores have rust pitting and buildup on the bore wall. Any information on what I should do would be great. Im trying to keep the budget low so hopefully I don't have to strip down the motor and rebuild it.

Thanks ahead of time.


Here is a link to see the pictures of the bore..

https://julz1.imgbb.com

 

[Scott Danforth]

welcome aboard

from you description alone, you either need to rebuild or get a different motor (I wont click on your links - I generally dont click on links)

any pitting is bad, any time you need to beat on the pistons to get them to move is bad

if you would have caught the motor maybe a day or two after it was submerged....

you also need to replace the rotating electrics on the motor and the steering cable and most anything that was under water including wiring harnesses, etc.

Also suggest you weigh the boat. if water got that high in the bilge, guarantee there is water in places that it should not have been. and its going to take lots of work to get it out.......and depending on how long the water was in contact with the foam, you may need to re-foam.

 

[Bondo]

Im trying to keep the budget low so hopefully I don't have to strip down the motor and rebuild it.

Ayuh,...... Welcome Aboard,........ I see a rebuildable core motor, not a runner,......

A .030 overbore might clean it up enough to rebuild,.....

 

[achris]

.... I'm trying to keep the budget low ...

This ^^^ and boats don't go together. Doing the job right isn't cheap, doing it cheap isn't right.

Chris........

 

[jws123]

Tear it down you cant avoid that your rings are most likely stuck hone cylinders and see how they come out ya might get away with it cylinders look pre nasty but I have had worse:lol: my first boat had water in cylinders just like this from bad risers it was locked solid. I pulled it out cleaned it up new rings,lifters,pump, ect and she ran great. But as said above boats and cheap dont go together.

 

[Rick Stephens]

As noted above, a rebuild is the way to gain a trustworthy motor. Before doing that, go through everything else and come up with a cost analyses on all the other stuff. Write it up. Only way to know whether the price is in your wheelhouse and whether the boat is cost effective to repair. Hull restorations can be spendy in $$ and certainly time.

 

[Julz1]

Hi,
Thanks for everyones feedback so far... I've gone through the other parts on the boat (electrical, steering, hull integrity, cables etc) and luckily with help from these forums and youtube lol, Ive gotten a lot taken care of. My main concern is definitely the motor. I know the more reliable choice would be to rebuild the motor. However, I've heard of people having similar situation as mine that had success with good cleaning and other tricks. Would doing a leak down test and compression test, of course after I put the heads back on and cleaning, be a reliable source for motor performance.If the results are good could I use it or would the pitting cause excessive wear.

I know pitting isn't good because it could cause blow back potentially and if I'm correct consume more oil? Also Since the rust is on top of the cylinder , would that affect anything or does the compression ring not go that high?

 

[Scott Danforth]

first, stop playing with the font

second, your motor needs a rebuild. you cant fix that with a band-aid. rust pitting will take out the rings and probably break the rings, taking out the piston and cylinder wall

if you want reliability, either rebuild your long block for about $1500 or buy a new long block for about a bit over $3k

since you have had water in the bilge, unless you replaced the rotating electrics, wiring harness, and the steering cable. expect the steering cable to freeze up within a year, the wiring harness will start to corrode from the inside out and the starter will fail, most likely when you are out on the water.

 

[tank1949]

Tear it down and take parts to reliable machine shop to be "mic'ed." Then, you will have a better understanding of $$$$.

 

[racerone]

And how much water leaked into the oil pan ??-------How long did it sit with water during this event ?---------Yes the motor may " run " for you.----There is more to it than a motor just running.

 

[Rick Stephens]

I know pitting isn't good because it could cause blow back potentially and if I'm correct consume more oil? Also Since the rust is on top of the cylinder , would that affect anything or does the compression ring not go that high?

I know you want to hear from someone that it's just fine to take the shortcut and hope it all works out. Ain't gonna happen. Several things different about boat motors and car motors. First, boat motors are at 100% load 100% of the time. Talk about a stress test. You will find any weakness in the motor quickly and then it will cost you what you thought saved plus a bunch more. Second, walking back sucks when they break down. Third, safety on the water comes from being prepared. All of us have safety in mind when we make a recommendation to do everything as right as possible.

Only thing more expensive than a boat is an airplane.

 

[Lou C]

Looking at your pix, that pitting is going to cause high oil consumption and blow by. I was able to avoid pulling the block when I had water in 2 cyls because I got the water out right away and fogged the cyls multiple times. I had no rust or pitting in mine. In the end if you put it all back together and to do a comp test even if comp test results are OK, it is likely to still burn oil, foul plugs, etc. Do it right the first time you will have more confidence in your boat. When I did mine it was really an experiment, I was fully prepared to put in a reman or new long block if it burned oil like crazy or had other problems. I decided I'll run it as long as I can, when starts to act up again, new engine time.

 

[Scott Danforth]

Only thing more expensive than a boat is an airplane.

Racing is cheaper than owning a boat.

 

[Scott06]

Your call, but last time I did a quickie re ring & valve job on an old engine (1965 Pontiac 389 with no water damage like u have), it never ran right didn’t idle smooth and had low idle vacuum ( yes it was tuned properly). I was in a rush to get it back together but I always regretted not doing it right.

other option not mentioned her is used marine engine or marinizing a running truck 5.7 from a wrecking yard. I think running 5.7 s from a place like LKQ are $350-500. Strip it to long block put the marine externals after changing head gasketsand core plugs.