Zackman
Petty Officer 1st Class
- Joined
- Dec 3, 2005
- Messages
- 376
I have a 1998 5.7 L with a Bravo 3 drive and seawater cooling. The other day while running the engine on the muffs, I noticed that the starboard side exhaust manifold and elbow was running at 115 F, while the port side was running around 95 F with the engine running at 160 F. On both the starboard and port sides the temperature was uniform all around the exhaust manifold and elbow. I have the captain?s call exhaust and as usual equal small streams of water was exiting from both sides of the thru hull exhaust, with the majority of the water exiting through the exhaust tube on the drive. The temperature difference appears to have occurred only after the thermostat opened.
I took the boat out for a short run yesterday and after running at about 3000 rpm for ten minutes I did another temperature survey. The starboard side was at 135 F and the port side was around 100 F. Again, on both the starboard and port sides the temperature was uniform all around the exhaust manifold and elbow.
I took the hose off the starboard exhaust manifold and checked the hose and connections for any blockage and all was clear.
Looking at the water flow diagram in the Mercruiser manual, it appears that the water enters the thermostat housing and gets diverted to both manifolds. But what happens after the thermostat opens and the warm engine water enters the housing? Does this warm water get equally distributed to both manifolds or does it tend to flow to the starboard side? Is my temperature difference a clear indication that I have blockage in the exhaust manifold? Or perhaps the thermostat housing?
I took the boat out for a short run yesterday and after running at about 3000 rpm for ten minutes I did another temperature survey. The starboard side was at 135 F and the port side was around 100 F. Again, on both the starboard and port sides the temperature was uniform all around the exhaust manifold and elbow.
I took the hose off the starboard exhaust manifold and checked the hose and connections for any blockage and all was clear.
Looking at the water flow diagram in the Mercruiser manual, it appears that the water enters the thermostat housing and gets diverted to both manifolds. But what happens after the thermostat opens and the warm engine water enters the housing? Does this warm water get equally distributed to both manifolds or does it tend to flow to the starboard side? Is my temperature difference a clear indication that I have blockage in the exhaust manifold? Or perhaps the thermostat housing?
