'98 5.7 Mercruiser Timing Cover Material

Toyaddict71

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Jun 11, 2020
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I've had to pull hoses on my engine water circulating pump to prime the pump in order to get water flow before every use this season. So I am thinking of replacing the pump, but not sure what the timing cover material is in order to purchase correct pump. Composite or steel. Is there a way to tell while the old pump is still installed? Thanks for any help!
 

achris

More fish than mountain goat
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May 19, 2004
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27,468
We would need an engine serial number for that.

You could just touch it with a magnet...
 

Bt Doctur

Supreme Mariner
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Aug 29, 2004
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19,452
you should not have to pull any hoses.. the engine circ pump only circulates, needs no priming
 

76SeaRay

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Aug 24, 2017
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I am a bit confused. The water pump does not connect to the timing cover so the material of the timing cover shouldn't be an issue... Unless there is something I missed here on your engine, the water pump bolts to the two water jacket openings on the front of the engine block..
 

Bondo

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Apr 17, 2002
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So I am thinking of replacing the pump,

Ayuh,..... Welcome Aboard,..... I doubt the circulating water pump is the problem,.....

You don't understand how a boat's coolin' system works,......

Whatcha workin' on,..??..??
 

Lou C

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Nov 10, 2002
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13,398
One the block is full the only way that water leaves is by the control of the thermostat which opens as needed to maintain a set temp. So the circ pump should not need priming like the raw water impeller does (ie immersed in water). Does this engine have a thermostat installed?
if so then it seems that the impeller is not keeping the block full of water or maybe there are leaks at the drain plugs or core plugs letting water out...
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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I've had to pull hoses on my engine water circulating pump to prime the pump in order to get water flow before every use this season.

if you have to do this, you have a problem somewhere else. the circulating pump only circulates water that gets pumped in by the raw water pump.
 
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