1995 Mariner 225's Overheating

[rpmrpm1]

Engines(twins)both show temp normal at idle to 3000 rpm. Engines overheat at rpm 3000 and over. Port worse than starbd. Usually takes 5-10 min. Changed impellers, thermostats, waterpump. Considering replacing water deflectors in cylinder head or removing powerhead entirely to check for carbon debris or other clogs. Engine carefully maintained and has less than 350 hrs. Both procedures costly. Which is more likely cause? Any other suggestions? <br /><br />Any service bulletins on this outboard overheating?

 

[jdkzrt]

Re: 1995 Mariner 225's Overheating

Sounds like your rigging. Are the engine water pick ups coming out of the water once your boat hits a certain speed??? Have you got set back brackets, and are you usings lots of positive trim? (water pressure gauges would probably help answer these questions)

 

[rpmrpm1]

Re: 1995 Mariner 225's Overheating

We just started considering rigging problems but motors have never been off boat. Motors mounted as low as possible. However we recently made a steering adjustment to align motors closer to perpendicular with transom (visually they seemed splayed outward.) Boat ran smoother and it took longer to overheat - modest improvement. I guess it's possible that they were installed wrong from day one. We will probably adjust steering some more but we don't see how boat ran well from day one with rigging problems from the beginning.

 

[rpmrpm1]

Re: 1995 Mariner 225's Overheating

I should have mentioned that we tested water pressure (temporary gauge) and found 6 psi with some falloff as temperature increased on the port engine (which has more of a problem than stbd.) I thought pressure was low but I don't know what's normal for these engines.<br /><br />BTW port engine model number is 7225425dd and stbd# is 7225422dd. We were hoping someone might have a line on service bulletins for overheating on these models.