Engine swap Water temp question

[Flyinb]

Finally got my engine back in my 1983 Sea Ray 260. I opted to find a used engine for the replacement, the engine i got was a few years newer (88~89 350 magnum). Engine started and ran great but as i ran it on the muffs at about 1000 rpms the coolant temp gauge just keeps climbing to the red line then i shut it off. My observations are...There is lots of water flow out the back of the transom but none out of the prop hub, i can hold my hand under it and its really warm but not super hot. I took out the thermostat and tested it in boiling water, its fine. Is it possible that the sending unit is different from my old motor and maybe not compatible with my gauge? Thanks

 

[Don S]

Re: Engine swap Water temp question

Is it possible that the sending unit is different from my old motor and maybe not compatible with my gauge?

Sure, it's possible. Did the engine feel hot? One of those IR temp guns is the best way to check the engine.

I have also run into several engine swaps like this where the coolings systems were combined and plumbed all wrong. Might want to post a picture showing your hose routing and thermostat housing.

 

[Flyinb]

Re: Engine swap Water temp question

Thanks Don, The replacement engine had the entire cooling system on it as it came out of the boat including manifolds, the only connection i made was the supply hose to the transom and the exhaust manifold bellows. One thing i noticed different, my old engine has a temp sender on the intake manifold, the new engine has a sender in the same place and also a sender on the water pump on the starboard side??

 

[Flyinb]

Re: Engine swap Water temp question

After reading your post no the engine diden't feel that hot so i did what i should have in the first place and took the sender from the old engine and put it in the new engine...problem solved...Doh. thanks for your help again Don.