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5.7L Starboard Manifold overheating?


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I first noticed this on launch day.  I smelled what I thought to be burning leaves, but when I opened the hatch I noticed a hint of smoke coming from the starboard Manifold.  I was able to put my hand on it for a couple seconds.  Anyways, today I took a nice long run and let everything come up to operating temperature.  Temp gauge was stable at about 165-170 under load and inched up a bit when coming back down to idle, then stabilizing back down to 165-170 again.  This was about the same temp that the boat has always run at in past seasons (even after a new impeller and T-stat).  But I felt a definite temperature difference between the starboard and port side manifold.

Should I be concerned with what seems to be a fairly higher temp on the starboard manifold vs the port side?  Or should I not worry about it since the operating temp is normal? It seems to be running perfectly fine, but I also want to be proactive and avoid something catastrophic.

Thanks in advance!

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I had the same issue last year.  I thought the manifold water jacket was starting to rust through.  I bought two new riser gaskets and took the starboard manifold riser off to inspect.  No major corrosion and the jackets looked fine, put it back together and ran it for the rest of the summer.  I don't know why the starboard is hotter either....

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  • 2 weeks later...

I read this on another forum.....

"The water coming out of the engine block exits only on the starboard side of the engine. Therefore the starboard exhaust manifolds and exhaust elbows will be warmer than the port exhaust manifolds and exhaust elbows. This is normal for your engine."

Can anybody confirm this to be correct? 

If so, I wonder if I just never noticed this in years past.  I think it's worth noting that this spring I did replace the oil lines that run to the remote oil filter, so there may have been some spilled oil that got on the manifold that caused the burning smell.  So maybe that's why I didn't notice it until this year. 

Edited by cbftbl87
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1 hour ago, cbftbl87 said:

I read this on another forum.....

"The water coming out of the engine block exits only on the starboard side of the engine. Therefore the starboard exhaust manifolds and exhaust elbows will be warmer than the port exhaust manifolds and exhaust elbows. This is normal for your engine."

Can anybody confirm this to be correct? 

If so, I wonder if I just never noticed this in years past.  I think it's worth noting that this spring I did replace the oil lines that run to the remote oil filter, so there may have been some spilled oil that got on the manifold that caused the burning smell.  So maybe that's why I didn't notice it until this year. 

I am 100% sure that is not correct.

  • Like 2
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Wellll, isn't it true that the circulation path through the engine starts on one side and then circulates through to the other side? One of my risers definately gets hotter than the other... anyone know for sure?  Larrry? Engine Nut?

Edited by DWhynot
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1 minute ago, DWhynot said:

Wellll, isn't it true that the circulation path through the engine starts on one side and then circulates through to the other side? One of my risers definately gets hotter than the other...

No, not true.  The water goes into the pump, thru the block and out thru the intake manifold at the front top of the engine.  Then thru a housing above the manifold that splits the water into both sides, so each side gets its own supply of water.  One of your risers may have an obstruction possibly?  Or do the spark plug indicate that both sides are burning equally?

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Thanks. I'll check the plugs first, but otherwise everything runs great, and water coming out the exhaust (on the trailer) seems balanced. Just one riser is hotter (and has been) to the touch than the other...sorry, didn't mean to hijack the thread...

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My problem is solved!  I took the hose off the trans cooler to check for pieces of impeller, and sure enough it was PACKED full of them.  This must have been like this since before I bought the boat, because I just replaced the impeller and it was not damaged.  After cleaning out the trans cooler, my manifold heat issue disappeared.  

Now I'm just curious how the motor did not overheat at any point over the last few years, given that the temp seemed to always be OK.  It was just the one manifold.  Fingers crossed that nothing was damaged.

  • Like 3
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This was my story when I first bought mine too. Guy said he replaced the impeller but I discovered later that he didn't bother to clean out the trans cooler from when the old one shredded (didn't mention this either). My temp gauge wasn't working at the time but the engine didn't overheat enough to trip the check engine light. I just knew it was running hot so after I got to digging around I discovered what happened. Mine has been running fine ever since and A LOT quieter. The boat basically had dry exhaust without enough water flow to quiet it. You should be fine.

 

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On 5/22/2018 at 7:14 PM, cbftbl87 said:

My problem is solved!  I took the hose off the trans cooler to check for pieces of impeller, and sure enough it was PACKED full of them.  This must have been like this since before I bought the boat, because I just replaced the impeller and it was not damaged.  After cleaning out the trans cooler, my manifold heat issue disappeared.  

Now I'm just curious how the motor did not overheat at any point over the last few years, given that the temp seemed to always be OK.  It was just the one manifold.  Fingers crossed that nothing was damaged.

So funny, because I found the exact same thing!  When I was winterizing this fall, I decided to be a little more thorough and sure enough there were bits and pieces of impeller and impeller housing on the screen.  I've had the boat for 7 years, must have happened with the previous owner as well.  I suppose my starboard riser will be cooler this season too.

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