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Port and Starboard Exhaust temps

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wes910

Member
I have a 02 5.0 mericruiser with a alpha one gen 2. I noticed that when running in the drive way the port side manifold is complety cool to the touch while tarboard side is hot, can only keep hand one there for 10-20 secs. The boat temp gauge never runs above half way. Also when I look at the transom exhaust ports seems to be more water coming out of the port side. is this normal? this is my first stern drive boat.
 
Slightly different temps. between the manifolds is normal but you should always be able to lay your hand upon either one w/o getting burned. Is the engine fresh water (no heat exchanger w/antifreeze) cooled? The manifold could have rust scale blocking the water flow. A weak impeller could contribute to the issue...when was it last replaced?

Loosen the clamps on the manifold hoses, start the engine and pull one hose off at a time to check the water outflow for a few seconds and reconnect. Compare the two...if they are similar then suspect a blockage in the manifold. Pull the riser off to see if the blockage is between the two pieces. Let us know what you find.
 
The hose doesn't supply enough water to cool both sides. Your impeller can outpump a hose anyday. Water will go to the path of least resistance. Like guyjg said possible clog? Profile? Location? Salt water?Fresh water? In salt water 12 years old? Possible the riser's shot?
 
I agree with both Jerry and guyjg.
A slight temperature differential is quite common, but an excessive differential would not be acceptable.

None of our systems, whether closed cooling or raw water cooling, divert the "spent" sea water equally. Under normal circumstances, this is not a deal breaker.

There are sea water transfer ports between the manifold and elbow, as suggested.
The fact that you are seeing more spent sea water at the Port side exhaust relief, would suggest that the Stdb side is restricted.

This is not your model.... but it demonstrates just how rusted and clogged up these transfer ports can become.
These can be cleared and the mating surfaces can be renewed if the manifolds and elbows are salvageable.






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10 - 20 seconds is PERFECTLY ok

Dont worry about it..................................

if it were 3-5 seconds and it was very hot that might indicate an issue.
 
kghost said:
10 - 20 seconds is PERFECTLY ok

Dont worry about it..................................

if it were 3-5 seconds and it was very hot that might indicate an issue.
Click to expand...
I'd agree if this occurs at low speed only.
At planing speeds, I believe that we should expect manifolds/elbows to be more equal in temperature.
If not.... then something is wrong, IMO.



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RicardoMarine said:
I'd agree if this occurs at low speed only.
At planing speeds, I believe that we should expect manifolds/elbows to be more equal in temperature.
If not.... then something is wrong, IMO.



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""""""""""""""""""""""""I have a 02 5.0 mericruiser with a alpha one gen 2. I noticed that when running in the drive way""""""""""""""""""""""""""""""""
 
Understood, and I agree.
But Wes goes on to say;
Also when I look at the transom exhaust ports seems to be more water coming out of the port side. is this normal?
Click to expand...

What I'm suggesting.... is that to a degree (pun intended), this would be considered "normal".... meaning that while on the garden hose and water muffs.

I figured that he would want to understand the difference.


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his driveway isn't level.. the water falls to the lower side
Let the air out of 1 trailer tire and it will switch sides.
 
Its been a fresh water only boat. Im assuming the manifolds are orginal ive only had the boat a few months. Im going to get a ir temp gun and see what the degree split is.
 
Wes, the boat is approx 11 years old but is new to you!
Don't take the previous owner's word on any of this regarding what's good, what's been replaced, etc.

Pull it apart and examine these components for yourself.


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Wes, look at the division between the Port and Starboard banks regarding the Y-pipe relief ports.
These relief ports are lowest in the casting, and gravity plays a role in this.

Even if the hull was substantially un-level on the trailer, this alone does not explain the un-equal exhaust relief water, nor does it explain the un-equal temperatures of the exhaust manifolds and elbows.

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IMO, you have a restriction somewhere that is preventing an equal division of spent sea water.
Find this restriction, and correct it, and I'll bet you that the problem goes away.




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IMO, you have a restriction somewhere that is preventing an equal division of spent sea water.
Click to expand...
Just a thought; you might want to look at the exhaust shutter...it may have fallen into the Y pipe restricting hot water outflow.
 
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