1991 Mariner/ Mercury 200 2.5 offshore

Buddy gave me a 21 seaway with a 1991 mariner/Mercury 200 2.5 offshore (Carbureted)Says it’s an Xr4 magnum. The stator and the water pump were changed 8 years ago before he winterized and then it sat in his yard. The motor started right up after 8 years and the only thing I had to do was change the thermostats repaint the motor and put mercury decals on cause I couldn’t find the Mariner ones anywhere. The motor ran perfect from what I can tell was just wondering if anyone has info on these motors, can’t find much on them anywhere, any good or bad with these motors or what to look out for. Thanks Andy


https://www.screamandfly.com/blob:ht...0-386ab3dc9bad

https://www.screamandfly.com/blob:ht...c-d0ace105d5fb

https://www.screamandfly.com/blob:ht...e-7bef3c51188e

Welcome to the site. 2.5 and xr4 do not match as the xr4 is a 2.4 litre motor. Likewise xr4 and 200 do not match up as the xr4 was a 150. Show a couple pics of motor with cowling off. This was around the time Mercury switched from 2.4 to 2.5 and there were some fat blocks, 2.5 based block with 2.4 sleeves, but I am not sure of the years. I would definitely change out the water pump impeller. I know you said it was new 8 years ago but without it being in use the impeller has taken a set and cannot function correctly and could easily self destruct ruining an otherwise good motor. The xr4 and the 2.5 200 are both good motors.

Rock

Go ahead and see if u cant get us serial # off block , behind throttle arm or on Welch plug in between heads. if it's a 91 2.5 they kinda rare didnt make many
And what says xr4? Mid plate?

Here are some pics of the motor. Think I found the serial number says 59103 looks like they stamped 44 right under the 59. Also found another number that said 03 16 90 which seems like it would be manufacture date

What bout freeze plug lookin thing between heads top of block?

Looks can b deceiving but looks like 2.5

Looks pretty much exactly like mine - which is a 1992 Mercury 2.5 / 200.

Attachment 451310

Says C291631. This is my first time dealing with a mercury, I don’t know these motors for sh*t. All my other motors are Yamaha’s lol

Attachment 451313
Kinda confusing but u have a 91 200 but it dont say 2.4 or 2.5. They swapped that yr from 2.4 to 2.5. Can u take air box cover off and get good pic of intake? That yr 2.5 200 had 7 pedal intake (big intake) only made the 91 2.5 200 with that front half for 1 yr in fishin motor

After lookin again the 2.5 is in parentheses ( ) my guess 2.5 since block looks just like mine. But still curious bout reed set up

Pretty sure they only made the water cooled reg in 90 therefore your build date is correct. I also thought the only motors hat had the water cooled reg were 2.4 but not 100% sure about that. They used that regulator on all sized v6 motors so either the serial # or remove a head and see what size the holes are. 3.38 is 2.4 and 3.5 is 2.5 and just in case the 2.0 is 3.125. Good luck.

Rock

thanks for the help guys, really appreciate it. when i get some time off of work, weather permitting, ill pull it all apart and take a look. keep ya posted

My 91 14 petal powerhead had the big water cooled regulator in the divider plate

reg was '89 ta '91... tha only 200 built in '91 was a 2.5.. only 2.4 in '91 was XR4... coulda had some kinda oddball 175 in there but don't remember... '91 was a stupid year for tha merc imo… was kinda of a "redo" of '80/'81 seems ta me..