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Desperately trying to find year of Inboard Mercruiser 5.7 LX from it's number, please

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sitges-boats

New member
Sorry if this is wrong thread (cannot see one for Inboard Mercruiser)

Desperately trying to find year of Inboard Mercruiser 5.7 LX from it's number, please

Mercruiser have not replied to emails

Someone suggested it's around 1986, but need accurate year to source parts.
There is a plate with the number 0390717 (or 0690717) as below and attached. Along with a few photos of it.


Other than the Transcom (OC550452) and Drive Number (OC561587) of old boat, which we understand doesn't help...


Would really appreciate any help, as we are really stuck without a date.


Images attached

our-Mercruiser-5.7L-idno.jpgebay-version.jpg$_57 (2).jpg
 
Looks like a 1998 5.7 model a tag should be here
Untitled15_zps47380de6.jpg
 
Last edited:
Wow kghost....
so 0C390717 is the number and that link gives the correct parts for it??
I can hardly believe it, you are a star
(been struggling for weeks and Mercruiser weren't jumping to help!)

Thanks so much.
owe you a beer if ever in Sitges, near Barcelona
 
Another kind guy (who couldn't see the images) said:
Unable to see the pics
The outdrive comes up as a 1989 RH rotation 1.50
The block will have a casting number which should be able to be found in the link below. Sounds like the engine has been rebuilt and what your seeing is Merc's reman numbers. I have called before about the numbers and they know next to nothing about them other then when they were rebuilt.

http://outintheshop.com/faq/casting/heads.html
​

Cannot be certain the top/hood goes with this engine.
At best, the outdrive mentioned would be from the boat it came out of.
 
sitges-boats said:
Wow kghost....
so 0C390717 is the number and that link gives the correct parts for it??
I can hardly believe it, you are a star
(been struggling for weeks and Mercruiser weren't jumping to help!)

Thanks so much.
owe you a beer if ever in Sitges, near Barcelona
Click to expand...



Not so fast.......relooked at the motor, it is a pre one piece rear main seal motor.

a 1998 is definately a one piece rear main seal deign...........

so it is not a 1998.

there are three serial numbers on the plastic cover on top of the carb

What are they?????????


If you have a remote oil filter that is a sign of a 350 magnum, thus this is what I think it is.....

1986/1987 350 mag alpha one

http://www.marineengine.com/parts/m...pha-gm-350-v8-19861987/0a635178-thru-0b525981
 
Last edited:
Thanks kghost...

RE: three serial numbers on the plastic cover on top of the carb : What are they?????????

That is part of the saga! :)

The Transcom (OC550452) and Drive Number (OC561587) to do with old boat, came from the current Carb Cover (hood). In my possesion

But in the photos, as supplied, there is another Carb Cover (hood) on this motor (I think!)
So have asked the old owner for those numbers (and he has just replied, he will advise asap)
​

You determining it's a pre one piece rear main seal motor, so not a 1998, is helpful. Thanks
1986/1987 350 mag alpha one matches with numbers from current Carb Cover (hood).
I am told outdrive comes up as a 1989 RH rotation 1.50
Someone else also said... It is 1986 or earlier

I can ask my current mechanic whether it has a remote oil filter that is a sign of a 350 magnum
(but he is hard to get info/help from!)

But parts suppliers still need an exact year

Will pass on the numbers if I get them.

Thanks a million, so far. Very much needed and appreciated.
 
sitges-boats said:
Thanks kghost...

RE: three serial numbers on the plastic cover on top of the carb : What are they?????????

That is part of the saga! :)

The Transcom (OC550452) and Drive Number (OC561587) to do with old boat, came from the current Carb Cover (hood). In my possesion

But in the photos, as supplied, there is another Carb Cover (hood) on this motor (I think!)
So have asked the old owner for those numbers (and he has just replied, he will advise asap)
​

You determining it's a pre one piece rear main seal motor, so not a 1998, is helpful. Thanks
1986/1987 350 mag alpha one matches with numbers from current Carb Cover (hood).
I am told outdrive comes up as a 1989 RH rotation 1.50
Someone else also said... It is 1986 or earlier

I can ask my current mechanic whether it has a remote oil filter that is a sign of a 350 magnum
(but he is hard to get info/help from!)

But parts suppliers still need an exact year

Will pass on the numbers if I get them.

Thanks a million, so far. Very much needed and appreciated.
Click to expand...


I am saying that because it has a remote oil filter mounted off the right side exhaust elbow, this says it is a 350 mag.

Standard 350's or 305's did not have this unless it was installed after the boat was purchased. (not typical)

also 454's had this as a installed option.

Also it has to be pre one piece rear main seal.

so it is a 1987 or older two piece rear main seal motor. This 350 is a standard small block chevy motor and there are literaly millions available..

It wont matter exactly what year so the closer to 1986/1987 is all that you need.

I believe the second link I gave is the correct one regardless of the serial number.

One thing that is missing from that parts structure is the thremostat designs.

there were three different ones used.
I believe yours is design II as shown in this link for a 1987 350 which is the one piece rear main seal model. Most of the pariferals used are the same between two piece and one piece seal motors. The only difference would be the block, heads and intake manifold and flywheel, starter (maybe) and coupler style.

Link to 1987 350 one piece seal but has three different cooling systems designs
http://www.marineengine.com/parts/m...rts/260-gm-350-v8-1987/0b525982-thru-0b773304
EVERYTHING else should be the same
 
Last edited:
Bt Doctur said:
must be going blind with the small fonts, 1988 is the correct year
Click to expand...

By 1988 there were no more two piece rear main seal motor in production for GM or merc.....

in 1987 was the transinion year when both were being used so I believe that was the last year..........
 
Thanks Bt Doctur, fonts are getting smaller or my eyes are getting older :)
1988 looks close.

kghost...
thanks for studying the engine so closely. It is much more than I could have hoped for.

So, to re-cap
sounds like a 1987 350 (mag) alpha: thremostat design II (No. 0C390717)
(a standard small block chevy motor)
With a remote oil filter mounted off the right side exhaust elbow
A pre one piece rear main seal
For parts:
http://www.marineengine.com/parts/m...rts/260-gm-350-v8-1987/0b525982-thru-0b773304​

Not: http://www.marineengine.com/parts/mercury_marine_parts/sn/C390717

If the old owner comes back with numbers, it may help confirm all or they might not be from this engine. I will add once know

But, thanks again. In the meantime. Life saver.
And a credit to Northboro, Ma, USA
 
No......


Refer to first link for cooling system design II

http://www.marineengine.com/parts/m...rts/260-gm-350-v8-1987/0b525982-thru-0b773304

This link for parts.......1986/1987 350 mag........

http://www.marineengine.com/parts/m...pha-gm-350-v8-19861987/0a635178-thru-0b525981



The key to identifying your engine type (two piece rear main seal vs one piece rear main seal) is the valve cover design.

Two piece rear main seal motors use a valve cover that is held inplace by screws around the outside flange of the valve cover.
One piece rear main seal motors have screws that hold the valve cover down through the center of the valve cover.


To understand this click on both links (one at a time) and select the "CYLINDER HEAD AND ROCKER COVER" and review the picture difference.
if you look at your motor it has the vavle covers shown in second link.
 
Hi khhost,

Thanks so much, for clarifying. It is extremely appreciated.
And allows me to order parts with some amount of confidence.

It's been a struggle to source competent help in England (decent mechanics), as it's becoming increasingly inefficient. Let alone where we are in Spain. Which is renowned at being bad, for service and effort.
Making, buying a boat, the worst decision of my life.

And Mercruiser are of no assistance.

Thanks again.
You are a life saver.
 
I think that more needs to be considered here.

The cylinder heads suggest pre-1987, noted by the perimeter bolt valve covers.
However, this does not necessarily indicate that the cylinder block is also pre-1987.

The exhaust system appears to be of a later vintage.

You may have a mixture of engine components.
 
Thanks RicardoMarine

Whilst it would be nice, if it wasn't complicated.
It's better for me to know.

Then maybe I can order all parts conceivably buy able.
Rather than be stuck and not able to fix the horrible thing (0)
 
sitges-boats said:
Whilst it would be nice, if it wasn't complicated. It's better for me to know.

Then maybe I can order all parts conceivably buy able. Rather than be stuck and not able to fix the horrible thing (0)
Click to expand...
Perhaps you're over-thinking this! ;)
Just a thought here...... what are your concerns?

If you're concerned about having parts on board for on-the-water repairs, these are going to be parts that don't necessarily require engine tear-down or being on the hard.
If so, I'd identify your ignition system, your fuel delivery system, fuel filter cartridge, starter motor, alternator etc., and then keep these parts near you or on board.

Any parts needed for anything beyond on-the-water repairs, can be identified and purchased as needed.


Again.... just a thought!




.
 
Hi RicardoMarine... appreciate any thoughts and all help.
As mechanic has left me to source parts, in between delaying the fix constantly
(tried several mechanics over 3 seasons and the two that don't run away are no better!)

Need Starter motor, Belt(s) on front and Sump Gasket, to complete the fix and use the boat.
And the part suppliers demand to know the exact year, to be able to chose which ones/parts

They said
It is 1986 or earlier but I need which year

I have asked whether there is just a 'couple of versions' of all possible options.
As I will buy all of them!... just to be sure of having all the necessary parts, when my mechanic is finally gets round to completing the boat engine change/fix

Right now, kghost has been wonderful in suggesting why it might be a 1987 350 (mag) alpha: thremostat design II (No. 0C390717)
But your kind advice, is showing it may not be that easy!

The boat is actually in he middle of France. So I cannot roll up to a Mercruiser parts place, for a match.
(especially on the sump gasket, as it's deep in the boat :)

As said... buying a boat, is the worst decision of my life (especially when involving Spain or France)

It has a number plate on it, as in photo on previous messages, which I am told says 0C390717

Many thanks
 
Last edited:
RicardoMarine said:
I think that more needs to be considered here.

The cylinder heads suggest pre-1987, noted by the perimeter bolt valve covers.
However, this does not necessarily indicate that the cylinder block is also pre-1987.

The exhaust system appears to be of a later vintage.

You may have a mixture of engine components.
Click to expand...



The style exhaust manifold that is on his engine was used from 1982 to present.

Not the identifying issue.
 
My advice for you is to use this web sites parts sections That I have linked you to.

1. look additionally other years that have not been identified for specific parts and compare part numbers. see if they are the same or not.

If you are unable to identify exact parts then the part in question needs to be removed and visually identified before buying a replacement.

We all have had to do this in certain cases to be sure.............if you look at the master list of all the motors and years there is a lot of over lap of models and years

WHy you may ask????

It is because so many designs were created for so many different applications...........

in the end there is only a few different motors used from 1970's to 1990's.........in fact the only real motor change was the two piece rear seal to the one piece rear main seal.

into the 1990's they then went to a roller cammed motors and the vortex style heads and intake manifold.


So that being said yours is pre 1990's vortex so the only real question is, is it a two piece rear main seal or one piece.
So what we can tell from the pictures is due to the valve cover design it is a two piece design..................


Without being there or removing the motor I am not sure we can do much else from here.................
 
Thanks kghost, that's great advice.
As you say... precise year is not important if same part spans the mid to late 80's
Good mechanics might prepare for the effort, by identifying parts needed.
Mine doesn't!

Though on the sump, identification cannot happen until engine is back out.
(they only just put it in, before finding it has a leak/hole!)
That''s presuming it is usable/just a drain plug missing or something
Otherwise they plan to put the old one on it, which was a 1998, so I may not even fit!
(my partners relative, who is reportably an expert of 30+ years in mechanics)

But without the gasket waiting, they will want to delay for weeks again/re-book it it
(risking what's left of the summer).
So I hope to get one, several, if I can!

Thanks again...
I will look for the Starter motor, Belt(s) on front and Sump Gasket, for these years and order all conceivable options.

Everyone's help has been much appreciated.
 
Bt Doctur, RicardoMarine and especially KGhost

I wanted to thank you for your determination in helping me date the engine/find the right parts.
I think they may be on the way.

Will look at marineengine.com when ever I can for parts.

With all the pain of boat ownership and mechanics, you may have saved me an aneurysm!

Let us know if you ever get to Sitges/Barcelona, Spain.


Many thanks,

Scott
 
Scott
I cant speak for the others but I do not see myself traveling abroad seeing most of the world is on fire (at war)........
The United states is a very large country and many places to travel to and many places near the states where we are liked and is easy to travel to.

Not that I have a issue with spain but maybe if there was not so much turmoil in the european, african and middle eastern countries.

Besides I cant bring my harley-davison or my own boat.................haha
 
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