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350 MAG water temp issue

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Lucky13

New member
Not sure why, but my fuel injected 350 MAG will not come up to temp. I originally thought the gauge was bad and then sending unit. I checked the gauge and then replaced the sending unit and still the gauge doesn't move. I even bought a manual temp gauge and installed it in an extra 1/2" port right next to sending unit. Still no movement on either gauge. Changed thermostat thinking it was sticking open; still no change. Because the computer looks at temp for fuel curve, I am running rich at all times which is causing the engine to bog down. I look at the water flow diagram a cant make sense of it. the water has to come through the thermostat housing to exit through exhaust. Could there be another path the water can flow besides through thermostat? I guess it could be worst, I could be running hot. put 2 160 deg thermostats in and cant get the temp above 100 deg. The engine runs as cool as a cucumber. Has anybody seen this? Its probably simple. This is on a 01 Tige direct drive.
 
The only thing that controls temp is the thermostat.

Is this a salt water boat?

If not are you sure you assembled the thermostat and other components in the correct order?
 
I would tend to agree, but what could be wrong? If the thermostat was in upside down it would block water flow completely. Thats what has me confused, there is no way to get it wrong that I see. You put the thermostat in the intake, then gasket, then thermostat cover. It is operating as if I didn't have thermostat installed.
 
Not a salt water boat. The engine also has a Fuel cooler and transmission cooler as well as shower system run off of the water system, I am thinking something maybe plumed incorrectly giving a path to bypass the thermostat. I cant see a way whereby the thermostat assembly would be wrong. Although I wish that ere the case
 
Thanks Jack
Now we may be getting somewhere; I do no have the spacer piece labeled as #9. Do you think that is my problem? Would that cause the engine not to come to temperature? What exactly does that piece do? What is made of, brass? I just got the boat and there was not one included in the assembly when I changed the original thermostat.
 
I am not 100% sure exactly,

but if the thermostat is only sitting on the gasket and you put the top housing on the thermostat looks like it will just float around thus only cold water will be circulated all the time. No restriction.

Look into the top housing as it may have been installed incorrectly. The spacer may be there but the assembly of the parts are upside down.

if not get one...I think they are plastic and it should go the way the picture shows....it supposedly is keyed some how to it goes in one way.

Also the parts pick shows a two reliefs but the service manual shows one large relief.. don't think it matters as long as it is in there and facing the correct position.

Also thermostat should be 160 degrees. Stainless steel.
 
Thanks again Jack, you were right on. The piece was up in the thermostat housing as you stated. I figured it would be something simple, but in had me FUBARD. I am new to the site and really pleased the forum format. I am sure I will be back and thanks again.
Chris (Lucky13)
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