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OMC overheating

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kpg7121

Member
Hi all, ist post here. Boat is an '87 with a 3.0 Cobra. Engine is overheating & I can't figure out why. I have completely rebuilt the water pump with a new impeller, new impeller housing, o-ring, new adaptor, etc., etc. I have changed every part in the lower unit pump, including new seals on the pickup tube in the lower half. I have a clear hose to the t-stat housing but it's sucking air as I can see air bubbles in the hose. The pump is working as I'm getting a good pee stream from the impeller housing, but when I launch the boat it overheats. What gives? I can't figure this one out & am hoping someone here can tell me why it's sucking air. Thanx.
 
chiefalen said:
cause you didn't seal it right or the housing has pits in it.
Click to expand...
It's a new housing if you're referring to the impeller housing. And every surface on every part in the water pump that calls for a gasket or an 0-ring has a new one. And the pump has totally new parts from the water pump shaft back to the impeller housing. Got me what the hell's wrong with it.
 
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You got good water to the t-stat ? If yes you say bubbles in a clear hose, the drive is submerged or is the mciky ears on the drive.

If you have the mickey ears on the drive then bubbles are normal, if the drive is submerged then it's not normal.

Say the drive is submerged, and you have bubbles then the fitting that goes thru the hull that connects the long hose to the t-stat housing is cracked. You say everything to that fitting on the drive side is good.

The t-stat is good ? If good then maybe the riser is clogged up, or the flapper fell down and is blocking the exhaust # 84 in the link.

You have to pull the riser and check in the exhaust tube for the remains of the flapper.

http://www.marineengine.com/parts/o...=OMC+Stern+Drive&section=Cooling+&+Oiling
 
The t-stat is new. I pulled the impeller housing & the plate. When I match up the plate with the housing there's a gap on the bottom of about a 16th of an inch. I put a straight edge across it & found that's it's concave. So, I ordered a new plate which sucks cuz it's new. Thanx, Sierra. I'm hoping it was sucking air thru this gap, causing the pump not to prime. I won't get the plate till Wed., so we'll see what happens next. By the way Chief. The manifold & riser are 8 yrs. old so I'm hoping that's not the issue. Thanx again.
 
87' has a flapper, if that fell down will cause you to overheat, the riser also.

really the riser should be pulled if still good just a gasket is all you need. check the freekin flapper my boat never had one. Your waiting for the part right?

You didn't put up where your located?
 
i have a house near monticello go on swinging bridge res.

look on a symatic of your drive you will see i think # 81 the flapper, it shows it for your model year the flapper.

http://www.dougrussell.com/partscat...6,347,348,349,352,353,354,355,356,362,358,359

That stinkin flapper is really not needed if you never beach your boat and if you allow the motor to idle 3-4 minutes after run then water can't shoot up your rear with the motor running and the wake hits you.

I always try to turn left or right after i come off plane then let it idle. So the wake very rarely hits my rear.
 
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