1985 Mercury 25hp XD No Thermostat

[Judgie05]

Hi guys i just bought a 1985 merc 25 xd (A194385) a few weeks ago and when it was in the water recently (to test it) it had some trouble idling. Once i got on it, it ran fine but it seemed as if it never got a chance to warm up. Upon further inspection we found that cold water was coming out of the tell tale so we figued it needed a new thermostat. When we ckecked there was no housing for it. Also the water jacket is not the same as what the parts say it should be.My engine doesn't have a thermostat at all. The line goes straight from the waterjacket to the tell-tale. My dad has a 2006 merc 25 and we checked that and the water jacket is different. Any suggestions? Thanks, Brian

 

[Dukedog]

Re: 1985 Mercury 25hp XD No Thermostat

Yours falls into Group I catagory for that motor. It has no t-stat. You Dad's is Group II (several changes, including t-stat)...................

 

[Judgie05]

Re: 1985 Mercury 25hp XD No Thermostat

So there is just no thermostat? Is it made to run cooler or should i let it warm up longer before i use it?

 

[Dukedog]

Re: 1985 Mercury 25hp XD No Thermostat

No t-stat. So yeah, that would be tha only option. Don't know what Merc was thinkin'
Maybe someone else that knows these smaller motors more than I (which wouldn't take much) has some suggestions. But on tha motor blow-ups and parts listings there is no t-stat in tha Group I range...............D