85' Sundancer 250 temp question

[odin210]

Hello everybody,
new to this so bare with me. I just purchased a 1985, 250 Sundancer with a alpha I drive. I had the boat surveyed and everything check out ok.
I have taken her out three times so far and noticed that this last time the temperature gauge was about to go into the red. (no alarms so far) So I back off throttle and kept a close eye on the temperature gage. The temp went down and went back up and then down again and stayed below running temp. It has done just the opposite also and stayed hot. Not really sure what it could be but I'm thinking thermostat or water pump/ pump impeller? The 260 hp merc is orginal. If anybody has any ideas of what should be looked at first feel free.

 

[Nehalennia]

It sounds like your impeller is due for replacement.
If you're not sure how long it's been since replaced, and the PO didn't tell you....it's probably due.
Welcome to the board.

 

[eddiezuskin]

Welcome. I have a 1987 250 And had odd temp fluctuations my first season. Biggest issue was that I couldn't idle below 1200rpms without temp steadily climbing. Rev the engine a bit and temp would come back down. I diagnosed it to needing to replace the whole thermostat housing assembly. When I did my first winterizing and pulled the hoses to check things out the metal under the hose literally disintegrated, as in nothing left to reconnect hose. I replaced the housing, was around $150 online. The old one also had significant internal rust.

The DPO(Damn Previous Owner) had replaced the manifolds and risers but not the thermo housing.
Did the survey include a sampling of outdrive fluid? Did documentation show last time impeller in outdrive was replaced? If you aren't sure then its probably best to start fresh and know where you are in your maintenance schedule.
Oil Change
Outrive oil and impellor
water seperator filter
Little filter going into the Carb
Hopefully the surveyor carefully checked the various bellow going through the transom to the outdrive.

Enjoy the boat, keep ahead of the maintenance, focus on safety equipment(not just minimum)and learn to replace a prop hanging over the swim platform if you are in areas with debris and shallows.
Eddie

 

[Maritime Matt]

Welcome to the forum. Seems like we have a good amount of Classic owner's on here. I myself just purchased a 85 260 da. 260 Merc/Alpha power. Besides what was mentioned, if you don't have any previous records when the manifolds and risers were replaced, I would do it. Then you know its been done and you have no issues with those. These power packages are so common. You don't want to injest water into a cylinder. How about postin some pics of your boat for us? Matt.

 

[odin210]

Hi all,
thanks for the help, you guys are great! The Manifolds and risers were redon roughly two years ago. Even though I had it surveyed and went threw the boat top and bottom. It's still the org powerplant so I do expect some extra maintenance here and there. I just needed some advice as to where to start with this temp issue. This is my first boat over 19" and I'm new to inboard motors (I've always had outboards) Anyway I'll check the thermo housing and I will replace the impeller as soon as I can.
I have been busy cleaning up the teak, fixing some minor wiring issues (Dam salt creep) and I can't belive it's 20 years old and WOW! It looks as good and some of the newer boats on the water.
Thanks again for the tips.
I'll get some photos up as I get them.

 

[KRB64]

Welcome, where are you?

When you winterize its no extra trouble to put in a new thermo. While she's out have the impeller changed to like they've said.

Also the posibility of accumulated gunk inside. If the hoses weren't replaced with the risers that would be a good idea now.

 

[84 SR268]

same problem , raw water cooled thermastat of mine was salted close ,, ( cheap fix)