350 MAG MPI Horizon Thermostat Housing

grouch0jr · August 6

I'd like to change the thermostat in my 2006 350 MAG MPI Horizon. When I use the parts lookup, it shows 3 different housings: single point drain, 3 point drain, and 7 point drain. The thermostat looks the same, but the gaskets etc are different. Does anybody know how to figure out which housing I have?

rasbury · August 6

Are you shopping with your engine serial number? I have the same motor with closed cooling- if their are that many variations then your going to have to look at what you have on your motor...I'd think.

grouch0jr · August 6

The parts lookup I used is for a given range of serial numbers, that's why I'm surprised it's not telling me what I need. I guess I don't even know what to look for on the engine itself.

rasbury · August 6

I'm right there with you...did it crack? No expert but unless you have something really special I'd think they don't break? There may be a p/n on it- or, take a picture of it and ask chat gbt- you'd be surprised if you have not tried that. It's seeing what you have and do some searching outside the catalogs. I find parts on ebay and/Amazon that look like mine and then go to the parts book for fitment. Usually those sites will have the part number- it's a process for sure. I have no friends with boats other than here- good luck ! Throw some pictures and what is wrong with it? And I don't see that suppliers have access to how the engine was built by vin- if you call a merc dealer with your serial# they would probably have an accurate parts list of your motor.