Port manifold running hotter than the starboard manifod

Hi Everyone,

I have a 1999 Maxum 1900SR boat. It has a mercruiser 350, 5.7L engine. I just had the engine rebuild and installed new manifolds so from initial water entry into the manifolds to the output of the water there is not blockage. One of the manifolds seem to be running hooter than the other one and when the water come out out the back it seems like there is less water coming out the port side than the starboard side. Could it be the Thermostat?

Thanks,

Mark

I wonder if the gasket between the manifold and riser is incorrectly oriented and blocking the flow. It looks like there a couple options for the connection.

http://www.marineengine.com/parts/m...u-0m599999/exhaust-manifold-and-exhaust-elbow

No issue and is normal.....don't do anything unless engine temp goes above 180 as long as the rubber is not burning all is ok.

one always seems hotter than the other. it is the nature of the beast.


the port and starboard sides are fed from the SAME exit point of the exhaust they meet at the bottom of the "rams horns" as I call them. The exhaust tubes going from the rubber boots to the transom join and become one large exhaust and it is diverted thru the transom to two separate holes. does not matter which side it comes out of

To DJR nope. The issue existed before with the previous manifold. I'm 100% sure that the gasket is not blocking the flow

kghost said:

No issue and is normal.....don't do anything unless engine temp goes above 180 as long as the rubber is not burning all is ok.

one always seems hotter than the other. it is the nature of the beast.


the port and starboard sides are fed from the SAME exit point of the exhaust they meet at the bottom of the "rams horns" as I call them. The exhaust tubes going from the rubber boots to the transom join and become one large exhaust and it is diverted thru the transom to two separate holes. does not matter which side it comes out of

Click to expand...

Never thought about that. So I'm all good.

Thanks

MarkAA said:

................. One of the manifolds seem to be running hooter than the other one and when the water come out out the back it seems like there is less water coming out the port side than the starboard side. Could it be the Thermostat?

Click to expand...

Short answer.... NO!

I'm betting that you have an issue with the "spent" seawater not being divided equally just prior to the delivery to the manifolds.

Merc does this dividing/deversion/splitting several ways. Most common for a Raw Water cooled engine, will be within the T-stat housing ports.
Can you post a few photos of your cooling system for us???


DO NOT restrict the spent seawater flow at the cooler side!
Instead, find a way to open up the spent seawater flow at the hotter side.


Or...... you have a manifold, or an elbow "mixing" chamber that is restricted internally!
If both manifolds and elbows are identical, swap them.
It will cost you new gaskets only.



.

RicardoMarine said:

Merc does this dividing/deversion/splitting several ways. Most common for a Raw Water cooled engine, will be within the T-stat housing ports.
Can you post a few photos of your cooling system for us???
.

Click to expand...

I figure that since the thermostat housing is where the water splits then it was the thermostat. Could it be that the sleeve is not set right? That is what my cooling system looks like. With minor difference such as 3 inch risers but the front looks the same.

It's normal.