Repair Manual for newer MerCruiser 4.5L 250hp

[phil chieco]

Hello I have the newer MerCruiser 2016 4.5L 250 HP V6 motor built by Mercury Marine that I'm looking for the engine repair manual. I'm also attaching a picture of the engine serial number. In addition, if anyone can tell me where the thermostat is on this engine that would be appreciated. The engine components layout is certainly much different than my last boat that had a mercruiser 2002 4.3L V6 GM.

 

[dubs283]

The only place to get an oem manual new is from mercury. You may try eBay.

Thermostat is located in the usual area for a v engine. Fwd end of the engine, top area for access

 

[alldodge]

Your parts break down
https://www.mercruiserparts.com/4-5l-mpi-200-alpha-bravo-2a441953-up

The thermostat (item 16) is in the crossover and is 140* F
https://www.mercruiserparts.com/bam/subassembly/31525/16591/140

Service manual is 8M0119305 and other manuals
https://www.mercruiserparts.com/bam/subassembly/31525/16591/0

 

[Bt Doctur]

SERVICE MANUAL 8M0178558

Mercury outboard parts source.

www.simmercury.com

 

[phil chieco]

Your parts break down
https://www.mercruiserparts.com/4-5l-mpi-200-alpha-bravo-2a441953-up

The thermostat (item 16) is in the crossover and is 140* F
https://www.mercruiserparts.com/bam/subassembly/31525/16591/140

Service manual is 8M0119305 and other manuals
https://www.mercruiserparts.com/bam/subassembly/31525/16591/0

Thank you. My engine has been running at ~120 degrees and I figured I would replace the thermostat first.

 

[Scott06]

Thank you. My engine has been running at ~120 degrees and I figured I would replace the thermostat first.

Wouldn’t hurt to check thermostat housing with IR temp gun to see if 120 indicated by gauge is accurate

 

[Cortes100]

Good luck changing the thermostat. Depending on your engine compartment, it may not be as simple as you think. On the 4.5L, the thermostat is at the back of engine. Behind/below the air intake screen.

 

[phil chieco]

Wouldn’t hurt to check thermostat housing with IR temp gun to see if 120 indicated by gauge is accurate

Thanks again for all your advice. I started up the boat this spring and I let it warm up to temperature on the gauge it was 120 and I did put a temp gun to it and it registered just about 120 to 123. The bottom of the risers were about 130 and the top of the risers were about 135. So I'm thinking it is the thermostat and the engine's been running much cooler than it should. Any additional thoughts on this topic. Thanks

 

[Bondo]

Thanks again for all your advice. I started up the boat this spring and I let it warm up to temperature on the gauge it was 120 and I did put a temp gun to it and it registered just about 120 to 123. The bottom of the risers were about 130 and the top of the risers were about 135. So I'm thinking it is the thermostat and the engine's been running much cooler than it should. Any additional thoughts on this topic. Thanks

Ayuh,..... How long ago, was the raw water pump impeller changed,..??

 

[phil chieco]

Ayuh,..... How long ago, was the raw water pump impeller changed,..??

I bought the boat two seasons ago with 75 hours on it. So I'm guessing it has the original impeller. I would imagine I would have to change it at about 300 hrs. It now has 130 hours. When I first picked up the boat when it had 75 hours it always ran at 120° temperature which I thought was low.

 

[Bondo]

Ayuh,...... Time kills impellers,.... not so much hours run,.....

 

[Scott Danforth]

Impellers and rubber bits go off calendar time. So doesn't matter if you don't use the boat or put 1000 hours a year on it

 

[tpenfield]

I have the big brothers to that engine . . . 2016 6.2L 350 HP. They do require a learning process vs. the old-school GM-based engines.

Anyway, I have not seen that the manuals are online (just parts lists and diagrams https://public-mercurymarine.sysonline.com/Login.aspx ), since the engines are the 'new' design, but maybe. I ordered a set of manuals for Mercury, so maybe bit the $$$ and order a set for your engine/outdrive.

The t-stat should be in the crossover assembly . . . (raw water cooled)



Is your engine the SeaCore version (closed cooling, Blue Decals) or the standard version (raw water cooling, Red Decals)? 120˚ F is a bit low, if that is what you are getting in the water. Does the temperature go up when at cruising speeds?

Is this an Alpha or Bravo outdrive?

 

[Scott Danforth]

Hello I have the newer MerCruiser 2016 4.5L 250 HP V6 motor built by Mercury Marine that I'm looking for the engine repair manual.

Mercury Marine Parts Accessories and Manuals

only legal place to buy a mercruiser manual is thru mercruiser dealers or direct.

you will want the engine manuals and the drive manual

 

[Scott06]

Thanks again for all your advice. I started up the boat this spring and I let it warm up to temperature on the gauge it was 120 and I did put a temp gun to it and it registered just about 120 to 123. The bottom of the risers were about 130 and the top of the risers were about 135. So I'm thinking it is the thermostat and the engine's been running much cooler than it should. Any additional thoughts on this topic. Thanks

Would agree thermostat seems to be not closing.
the guys mention impeller replacement, which is a good preventative item, cant see this making it run cool. Use oem merc impellers vs the cheaper aftermarket ones. I changed mine after six years was in perfect shape…

 

[Lou C]

With cast iron engines oftentimes it is a flake of rust keeping the stat from closing all the way & then the engine runs cool unless you have it up on plane....