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nwest
05-28-2011, 10:39 AM
my '97 maristar 200v overheats at an idle. As soon as I place it in neutral and increase the RPM's, the engine temp drops immediately. The engine has no problem staying cool when I'm crusing at any speed above idle. Any help on what might be causing this?

MattsCraft
05-28-2011, 10:52 AM
I would check these 3 things:
Impeller
Intake Scupper on the bottom of the boat
Trans Cooler Screen
Definitely sounds like a water flow issue

03geetee
05-28-2011, 10:56 AM
I would check these 3 things:
Impeller
Intake Scupper on the bottom of the boat
Trans Cooler Screen
Definitely sounds like a water flow issue

X2

That is exactly what I was thinking. Your flow potential at idle will be the lowest and if the impellar isnt up to the task it may work at higher RPMs if there is a blockage due to higher pressure generated. But at lower speeds a clogged intake screen or tranny cooler may not be enough flow with that small of a pump draw.

Keep us posted!

JTR

JohnnyB
05-28-2011, 10:56 AM
seems like you've got a restriction somewhere in your raw water coolant loop such that you're not moving water at idle. I would check several things:

1) Impeller - might be missing some of the vanes causing you not to move enough water at idle
2) Intake screens - both the one in the hull and the one where the raw water pump goes to the tranny cooler inlet. THe tranny cooler inlet screen is a common place for debris
3) T-stat -- 3rd item in the system. I suspect your problem is #1 or #2

JimN
05-28-2011, 12:49 PM
my '97 maristar 200v overheats at an idle. As soon as I place it in neutral and increase the RPM's, the engine temp drops immediately. The engine has no problem staying cool when I'm crusing at any speed above idle. Any help on what might be causing this?

Which engine? If it's the LT-1, it could be the bleeder tubes collecting air. If it's not that, I would look at the impeller. If you have an InfraRed thermometer, check the temperature of the exhaust risers and if one is significantly hotter than the other, change the impeller, even if it was new last fall.

nwest
05-28-2011, 01:06 PM
Thanks gents! I'll keep everyone posted.