STARBOARD HOT MANIFOLD Port OK 1998 Searay 240DA 300 hours 305 E.F.I. alpha 1 gen 2

[ESekelsky]

1998 Sea Ray 240 DA E.F.I. fuel inj. alpha 1 gen 2 one manifold hotter than other by 60-80 degrees
New lower unit water pump
New fresh water hose
New thermostat
This spring I had the bellows and outdrive water pump and trim limit switch wires and fresh water hose between transom and outdrive replaced.
The mechanic that installed the fresh water between transom and outdrive kinked the hose kinked it. Boat was run with kinked hose. Boat was getting some water but would throw temp alarm and gauge would rise under full throttle. Alarm and gauge would immediately settle down when speed reduced to idle and stick was placed in neutral.
I have replaced the fresh water hose between transom and outdrive, btw this can be done without pulling alpha 1 gen 2 outdrive.
I now have a secondary issue the starboard manifold is 60-80 degrees hotter than the port manifold. When I run it hard for a mile the starboard got to 210 degrees and the port was 110 degrees with an infrared temperature gun
I have read allot of the posts regarding one manifold hotter than the other I still have a few questions / ideas
Does my 1998 have check valves in the thermostat housing?
, or is it possible the newer thermostat housing are designed better.
Starboard manifold is consistently 60-80 degrees hotter.
Starboard elbow was pulled and it looks great for 10 year old boat.
On muffs very little water comes out of the prop
Port side 1 inch water hole next to boat drain plug has good flow and is cool
Starboard 1 inch water hole next to boat drain plug has very little water some steam and low flow
Here are my theories.
? Stuck check wave in my thermostat housing (if applicable) if my thermostat housing has check valves.
? Possibly the exhaust flapper melted due to previously getting hot with kinked water hose?

Where should the flapper be and what should I remove to find it the exhaust tube after the exhaust elbow going down to the rear of boat? I realize it may be all the way down to where the exhausts combine and even out in the exhaust bellows or even down in the drive
I may have to pull the drive to inspect for the broken or melted flapper correct?
How do I repair the broken or missing exhaust flapper? Do I purchase just a new flapper and place it on the hangers or hooks inside the exhaust?
If all of the above gets tested and correct then I guess I will be R & R manifolds followed by head gasket.
Thank you for the replies in advance.
Eddie

 

[mylesm260]

Re: STARBOARD HOT MANIFOLD Port OK 1998 Searay 240DA 300 hours 305 E.F.I. alpha 1 gen

You mentioned very little water from the prop, what about your water flow from the upper outlets?


My understanding of how the manifolds are cooled is that the cold water is pumped up from the pump to the bottom of the manifolds, and then the hot water leaving the thermostat housing is pumped into the tops of the manifolds (risers).

Usually one manifold runs a little hotter, because the hoses running from the thermostat housing are never level (one side vs the other), and therefore, one manifold is getting more hot water from the engine than the other.

It sounds like there isn't enough water flow getting to the bottom of the manifold on one side, try taking off the house clamps, and then with the engine running on the muffs, remove one side, then try the other, see if one side is flowing more than the other.


As the engine load increase, the water gets "diverted" from the manifolds to the engine, so under low load, the manifolds may be getting 75% of the flow and only 25% will be going to the engine. As load increase, the thermostat opens and more and more water goes through the engine and less goes through the manifolds. This is offset somewhat by the increase in RPMS at the impeller.


I would check 2 things.

#1 the flow to both manifolds (lower hoses) left vs right
#2 Over-all flow from the lower leg pump. IF you don't have much flow to work with to begin with, there may simply be not enough water to cool everything that's needed. Double check that you're leg pump is installed properly, gaskets, etc, and make sure there isn't any obstruction, be it a kinked hose or otherwise.

In terms of flappers, I have no idea, I run without them.

 

[ESekelsky]

Re: STARBOARD HOT MANIFOLD Port OK 1998 Searay 240DA 300 hours 305 E.F.I. alpha 1 gen

THANK YOU! Mylesm260 you hit the nail on the head. I disconnected lower hoses from manifolds. Btw I only have raw water feeds to the bottoms of each center rise manifold. These hoses come from the Thermostat housing. I placed a 5 gallon pail on each side. The Hot side (Starboard) had 1/2 inch. The port side (cool side) filled the pail in the same amount of time. I removed and inspected the TSTAT housing. My TSTAT housing does not have check valves "1998" vintage.
I was told to get the TSTAT housing back on and place my finger over the port side hose to see if the water will flow out the starboard side of the TSTAT housing with the same force it comes out of the port side.
Where were going with this is that based on the fact that this 5.0 E.F.I. or fuel injected 1998 throttle body motor uses restrictor gaskets. We think the cold side or port side restrictor gasket may have failed.
Again in other words I was chasing the hot side - starboard side, I removed and inspected the hot starboard side elbow which looked clear and fine.
I will remove and inspect the port side elbow. If the restrictor gasket failed this may account for why a higher percentage of the raw water is going to Port.
I still don?t know but I hope it?s the gasket.
Again thanks for your help!
Eddie

 

[ESekelsky]

Re: STARBOARD HOT MANIFOLD Port OK 1998 Searay 240DA 300 hours 305 E.F.I. alpha 1 gen

Hi One more thing Do I require Restrictor gaskets or not for this application
1998 Searay 240 DA 305 Mercruiser E.F.I. I found another post with a link (below) and maybe I am rading it right or not but it looks like i should have 4 slot or max flow gaskets if I am reading this link correct.

Link = http://www.boatfix.com/merc/Bullet/99/99_10.pdf

Previous post = Below:


March 30th, 2009, 09:14 PM
Don S
Moderator
Join Date: Aug 2004
Location: Ocean Shores, WA.
Posts: 25,310

Re: Over Heating and Confused..

--------------------------------------------------------------------------------

Read this service bulletin about the type of riser/manifold gaskets that you need with the new tstat housing.
http://www.boatfix.com/merc/Bullet/99/99_10.pdf
Since it's already installed, no since going back at this point.

Are you sure the raw water pump and impeller are ok? if not, you can change thermostat housings forevery and still overheat.