Mercruiser Alpha One Gen One Overheating

[Koa]

Just in time to ruin the 4th! Ok so quick run down, bought a 1984 wellcraft elite around this time last year. Engine was replaced over this winter and all the inboard stuff was gone over by an experienced boat mechanic so it was up to speed. Took it out in May and has been doing great since. This last trip out however it started over heating at WOT. So I backed off and crept to where I was going at first temps went down but now they creep up into 180-200 range even at idle. So my first guess was water pump tore off lower and upon my inexperienced look over appears fine (impeller wasn't visibly deteriorated). Both risers and manifolds are cool enough to touch while it's overheating, as are both T joints on top of intake. Only the hose going into crankshaft is hot. I pulled the hoses anyways and checked poppets. Im wondering if the problem could be not enough water flow from water pump still. Does any one have a solid reference as to how much water should be flowing through the first hose? Or maybe some more experienced insight as to where to look. Any help would be greatly appreciated

 

[kenny nunez]

Did you replace the water pump in the drive ? If not that has to be done to make sure there is enough water coming to the engine.

 

[alldodge]

Both risers and manifolds are cool enough to touch while it's overheating, as are both T joints on top of intake. Only the hose going into crankshaft is hot.

Need more info for clarification. The manifolds are cool to the touch but what is the hose going into the crankshaft? Is that the large hose going into the circulating water pump?

Get a IR temp gun and compare the temps at the thermostat housing with that of the gauge

 

[Koa]

Need more info for clarification. The manifolds are cool to the touch but what is the hose going into the crankshaft? Is that the large hose going into the circulating water pump?

Sorry yes I meant the one that went towards the crankshaft I will link some pictures, it is the one on the lower left.

The one on the lower left is where water comes in. It doesnt seem to be as big a stream of water as I would expect, but I have no idea to tell if thats the problem or not.

The only parts that feel hot are that larger hose and the place it drops down into

http://imgur.com/a/V7MUh

 

[alldodge]

It might be a gauge issue and not an overheat problem. Your temp gauge has a sender in the thermostat housing, suggest getting an IR temp gun and measure the temp at the housing and compare with the gauge

 

[Koa]

It might be a gauge issue and not an overheat problem. Your temp gauge has a sender in the thermostat housing, suggest getting an IR temp gun and measure the temp at the housing and compare with the gauge

I'm pretty new to all this you mean the thermostat housing, the thing between the two bolts on top? It will be cool enough to touch even when the gauge is saying the temp is 200-240. I will try with the IR gun though and let you know.

 

[Koa]

Here's a short video of water pressure at idle does it look sufficient?

https://youtu.be/TOTOgZeKo-c

 

[alldodge]

I'm pretty new to all this you mean the thermostat housing, the thing between the two bolts on top? It will be cool enough to touch even when the gauge is saying the temp is 200-240. I will try with the IR gun though and let you know.

Yes, check the area between the two bolts, that is the thermostat housing. The housing should show the same temp you boat gauge does

Here's a short video of water pressure at idle does it look sufficient?

If your on a hose then yes that is enough water, but if the boat was sitting in the water then doesn't look like enough

 

[Koa]

Ok i put the outdrive in a tub this time and now miraculously the overheating is gone. Went and bought a ir gun and this was the results after running at 1500RPM for 5 mins and then 3000 for 1 min. Risers-130, Manifold- 120, water circulator- 150, front of thermostat housing by first to hoses went from 70-100 from right to left TStat went from 90 up to 140 then back down. kinda frustrating because i feel like its gunna do it again soon as im out on the water. But maybe i loosened something stuck up with the back washing. who knows. will post again if problem returns.