Engine identification help needed

[Rick Rickoff]

I purchased a used 1988 Four Winns Freedom 160 boat having an inline 4 cylinder engine that is mated to a Cobra outdrive. This is not the original 3.0 litre engine that came with the boat, and I am having difficulty in determining exactly what this engine is. It does appear to be a GM marine engine, and I did find identifying numbers stamped into the block adjacent to the distributor, but so far haven't been able to find listings by GM, OMC, or even Mercruiser, which contain these numbers. There are two rows of numbers found on the block, and the top row reads "M11118RB" while the row below that reads "T1032416." I am assuming that the top number is the engine model number while the lower number is probably the engine serial number. From what I have been able to find out, it looks as though the last 3 numbers (8RB) of the model number are descriptive of the last digit of the model year followed by a two alpha character code designation which relates to the engine displacement and available options. So, this could be a 1988, a 1998, or a 2008 engine, which doesn't narrow things down very much, and I can't find the "RB" engine designation in any listings which I have been able to locate. I did find RA, RF, RJ, RM, RN, RP, and RX codes in a May 2002 Mercruiser service bulletin pdf, but no "RB" code, and the OMC engine code listings I have found don't match up either. I'm hoping that someone can point me to other possible listings where I can find a match. Thanks in advance for any help or suggestions.

 

[Scott Danforth]

look above the starter to see if the serial number tag is there.

 

[Rick Rickoff]

look above the starter to see if the serial number tag is there.

Scott, there is no id plate attached anywhere on the engine. I do see some engine casting numbers (raised lettering and numbers) on the side of the block near the starter. They read "GM" and "Hecho en Mexico" (Made in Mexico) and the numbers, found just above that appear to be "2770087 / 308 - 8"

 

[Scott Danforth]

All 3.0 liter motors are made in Mexico. for the most part, they are all the same when it comes to the long block. there are 1990 and older 3.0 motors and there are 1991 and newer 3.0 motors.

the intakes, exhaust, and electrical stuff comes from Mercruiser, Volvo, or when they were around, OMC.

take a picture of it.

 

[Rick Rickoff]

Here is a diagram of the 4 cylinder engine block showing the engine code location. That's precisely where I found the numbers I mentioned in my first post. There are two rows of numbers found on the block, and the top row reads "M11118RB" while the row below that reads "T1032416." I am assuming that the top number is the engine model number while the lower number is probably the engine serial number.

 

[Bondo]

and I am having difficulty in determining exactly what this engine is.

Ayuh,..... Welcome Aboard,...... What, Exactly are ya tryin' to figure out,....

The numbers yer listin' are irrelevant to buyin' parts or anything boat related,.....
'n I've never seen a GM database for the 3.0l motors,...
V8s, yes,... anything else, no,....

As Scott says, there's pre-91 motors, 'n post-90 motors,....

Any parts ya need will most likely be Merc or Volvo, or OMC stuff,.....

 

[Scott Danforth]

the only place that anything is stamped that boat people care about on the 3.0 is the OMC/Mercruiser/Volvo-Penta tag that is riveted on the side of the flywheel housing flange just above the starter.

the block numbers your reading off dont mean anything to anyone except maybe an assembly line worker in the GM plant in Mexico

 

[Rick Rickoff]

the only place that anything is stamped that boat people care about on the 3.0 is the OMC/Mercruiser/Volvo-Penta tag that is riveted on the side of the flywheel housing flange just above the starter.

I know that there should be a serial number plate at the location indicated in this diagram:


As I mentioned earlier, in post #3, there is no such i.d. plate above the starter. There are also no holes in the flange where a plate would ever have been riveted. Would this seem to indicate that this is not a marine engine? I'm wondering if this engine block could have been pulled from a used car and simply fitted with the necessary parts from the original marine engine which had failed. My prime concern is that I'd like to know exactly what I have (year of manufacture, actual engine displacement, and horsepower), and be able to find that in a reference table. I do know that the Cobra outdrive was originally mated to a 3.0 litre engine, as the Cobra i.d. tag says so, but the original engine was replaced at some point with whatever is in there now. I'm guessing that the current engine may have come from a Mercruiser setup, as the number that I found stamped next to the distributor starts with an 'M' and reads "M11118RB" which looks like a Mercruiser GM engine model number rather than an OMC number, which would normally start with the numbers "30" if a 3.0 litre engine. Problem is, as I stated earlier, I can't find any reference to the "RB" engine identifier in a Mercruiser manual. Here's what I do find:
Notice that these codes all start with the letter "R," which does seem to indicate that this is a 3.0 litre engine, as the "R" designation is not used on engines other than the 3.0L, but that no "RB" model is listed.

 

[Scott Danforth]

you have an OMC, not a mercruiser

as stated, there are two versions of 3.0 liter motors. 1990 and older, 1991 and newer. so base engine is the same no mater if mercruiser, volvo, omc, etc. the base engine comes from GM

the only thing that matters on parts for a 3.0 is 1-piece or 2-piece seal as this affects the flywheel and coupler. the rest of the stuff is bolt-on and interchangeable. most of the components have not changed since the 2.5 liter was introduced in 1963

here is a pic of the OMC 3.0 and where the serial numbers are located:

 

[Bondo]

Would this seem to indicate that this is not a marine engine? I'm wondering if this engine block could have been pulled from a used car and simply fitted with the necessary parts from the original marine engine which had failed.

Ayuh,.... The GM 3.0l has Never been used in a car or truck, it's a marine/ industrial motor,....

The numbers stamped in the block are GM numbers, not Merc, nor Volvo, nor OMC,....

There should be an aluminum tag from OMC, or Merc, or Volvo,.....

You can nail down the vintage of the accessory marine parts by usin' yer drive serial number,.....

 

[Rick Rickoff]

the block numbers your reading off don't mean anything to anyone except maybe an assembly line worker in the GM plant in Mexico

Actually, Scott, that's not quite so. Engine rebuilders use engine block casting numbers to positively identify engines, and so do automobile salvage yards. Knowing this, I started looking at marine engine rebuilder websites and lucked out by finding listings with block casting numbers as seen below:

You will notice that my block casting number (2770087) matches the 2nd and 3rd listings in the above chart, both of which are 3.0 litre GM engines manufactured in the 1975-1989 range. Thus, with this date range known, and knowing the "8RB" engine code stamped next to the distributor, this would be a 1988 engine, which is the same as the original. The only difference between these two matches is the cylinder head. The second 3.0L block number match uses the same cylinder head as the 2.5 liter engine. I haven't pulled the cylinder head cover off yet to check the head casting number, but that will be the final determining factor.