5.7 mercruiser running hotter than normal with steam from exhaust

beech2000

Petty Officer 2nd Class
Joined
Jul 5, 2009
Messages
110
Hi all,
So I notice several weeks ago that my fresh water bow rider started running about 20-30 degrees hotter. It usually stays around 170F but noticed on a hard lake run it creeped up to 200-210 with steam noted from right exhaust. I changed the water pump impeller but found in like new condition. Next I pulled the thermostat out and boiled it in a pot of water. It never opened even when hitting 212 (boiling). I changed out the thermostat and now it runs at 175-185. I haven't noted any steam since. To make sure all is well, I decided to pull riser and inspect. They look ok to me. See pictures.
Question 1: Does the 5 year riser and exhaust manifold replacement apply to fresh water boats?
Question 2: Could the faulty thermostat have cause the steam from the starboard exhaust port?
 

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Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,465
Hi all,
So I notice several weeks ago that my fresh water bow rider started running about 20-30 degrees hotter. It usually stays around 170F but noticed on a hard lake run it creeped up to 200-210 with steam noted from right exhaust. I changed the water pump impeller but found in like new condition. Next I pulled the thermostat out and boiled it in a pot of water. It never opened even when hitting 212 (boiling). I changed out the thermostat and now it runs at 175-185. I haven't noted any steam since. To make sure all is well, I decided to pull riser and inspect. They look ok to me. See pictures.
Question 1: Does the 5 year riser and exhaust manifold replacement apply to fresh water boats?
Question 2: Could the faulty thermostat have cause the steam from the starboard exhaust port?

Ayuh,...... #1, Nope, 'n #2, Sure,.....

In sweetwater manifolds, 'n risers will last a lifetime,....

The guys in the brine like to buy our used iron,.... nearly new after decades,...
 
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