Running a little warm

F

frosh coach

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I have a 94 #0' Sea Ray Sundancer with Twin 350/260 Mercruiser FWC Alpha's. Last season I noticed the port engine was running around 170В°F in August. The starboard runs about 160В°F. Fast forward to this season. When I launched in Mid-May they both run at around 160В°F. This past weekend I noticed the starboard at 170В°f again.
Any Ideas? Could this be due to the water warming up? I'm thinking about changing the impellers on the circ pumps. I'm not sure when the risers and manifolds were done last. I'm hoping to get through the rest of this season and change them at the beginning of next season.
Thanks
Chris
 
If your engines are a full FWC system, there should be no reason to replace the manifolds as most likely, they will last the life of the engine. Risers are a different story.
What is your T-stat temperature?
 
Those temps are nothing to worry about. If you want, test the thermostats in a pan of water as you bring it to boil. Mostly you're testing the opening rate between them and the full open.

I don't see a problem that would prevent you from using the boat. Just be aware...Do you have an infra-red temp gun? You can get them on sale at harbor freight for $25-$30.
 
Charlie:
Thats my plan (gun rb2@gr5t HF). Gotta love that place......
I'm going to do the risers and Manifolds next season since the exhaust is RWC (I think).
 
Everybody has RWC exhaust unless they have dry exhaust. the question is, do you have a half or whole FWC system? If whole, then you don't need to change the exhaust manifolds because they are part of the FWC system. If you have a half system, then they are not and should be changed with the risers.
 
As Gregory said, before wasting money replacing manifolds, confirm whether your system is a full or half FWC system. If a full system, the manifolds should last the life of the engine.
 
i'll double check, but I about 99% sure it's a half system. If thats the case, can you change to a full if i'm going to replace everything?
 
It could be done since the engine has not seen salt water, but you would want to make sure all cooling parts (heat exch, etc.) then matched those of the original full FWC systems.

Your 170* on the gauge is certainly no cause at all for alarm in terms of engine cooling with a 160* thermostat, but sometimes a small rise in gauge temp may be a hint of greater rise in RWC system temp and restriction , since the FWC system thermostat helps overcome and mask RWC issues up to a point. So IMO it's a good idea to put your palm on the top of the riser/elbows regularly to see if you can still keep it there indefinitely at cruise speed without undue pain . Ideally it should feel cool with fully-flowing RW components, but fairly warm is still OK as long as you keep checking for increase.

It can also be wise to make a reality check with an IR temp gun aimed near the thermostat housing to compare to the gauges, and on RW exhaust parts to compare between the warmer engine and the still cooler one.
 
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