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Older Mercruiser 1976

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gps

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"Have a question about a 1976

"Have a question about a 1976 Mercruiser. 233 hp. 351 cid. v-8, with I think a Type 1 outdrive. Well before the Alpha series. The water pump is on the front of the engine. Is there a pump in the outdrive or only a pick-up hose to supply the front eng. water pump? Thanks in advance GPS. LET SEAT BELTS AND LIFE JACKETS DO THERE JOB>"
 
"Thanks Guy for the quick resp

"Thanks Guy for the quick response. I'm currently helping a buddy with this older unit and am only familiar with my Alpha1. So am I correct in assuming that an older v-8 has an engine water pump AND an outdrive pump, or do they all? Thanks GPS."
 
All engines have circulating p

All engines have circulating pumps. Bravo drives have seawater pumps vs. OD pumps.
 
Thanks Guy but I'm still c

Thanks Guy but I'm still confused. Where would I look to see a seawater pump. Is the belt driven w. pump on this 76 engine a sea water or the engine circ pump. Sorry for being such a pest. GPS
 
"There is a shaft driven water

"There is a shaft driven water impeller pump in every Alpha and pre-Alpha drive leg. It is accessible once the upper and lower gear cases are separated.

The Bravo's do not use a leg impeller; as in neutral the vertical shaft in a Bravo does not turn. They have a belt driven seawater pump that takes suction either thru the drive leg ports, or thru a hull pickup.

All Merc engines also have a so called circulation pump driven by the front belt(s). Its job is to circulate water thru the block and heads. The impeller seawater pump is only to pump water from the lake up into the engine.

Rod"
 
If the motor has a closed cool

If the motor has a closed cooling system (evidenced by a cylindrical tank with a pressure
cap like a car) it could also have a thru hull pickup with a belt driven water pump. Back then
it was required for V-8's 'cause the drive pump did not supply sufficient water flow. I believe
those old FWC's were "complete" systems
 
"You are totally confused!

"You are totally confused!

Look at the front of the engine..........What do you see..........

Power steering pump?
Altenator?
Harmonic balancer?
Engine Water pump/pully?

If you see any other belt driven assembly and it has 1 to 1/12 inch diameter hoses going to it then you have a motor driven RAW water (pump) impeller.

If you do not then you have an outdrive driven IMPELLER just like the alpha's.

Are you sure this is a pre alpha drive ( 1,I,R )and not a TRS drive. TRS drives are very big, bigger than a Bravo and use a engine mounted impeller pump. Closed cooling does not have anything to do with the way the water is mechanically drawn from the water source only how it is distributed on its way to the manifold elbows or heat exchanger."
 
Thank you all for being patien

Thank you all for being patient with me. We dropped the lower unit from the rest of the outdrive and Lo and Behold a totally fried impeller pump. Housing and all will be replaced as the hot exhaust ruined everything. Any thing else we should look at before putting it back together.Thanks again. GPS
 
Look at the bottom of the uppe

Look at the bottom of the upper OD and see what the water pocket looks like? It's where the copper pipe goes into. They tend to get fried from hot exhaust when water flow is low.
 
"Ayuh,...

And don't for

"Ayuh,...

And don't forget to check All the Rubber parts in the Exhaust system,...
Flappers are the 1st to Smoke,... Then the rubber pipes...

Btw,....
"I'm currently helping a buddy with this older unit and am only familiar with my Alpha1."

For all intents,+ purposes,...
The Pre-Alphas,+ Alpha 1s are pretty much the Same units,+ can be interchanged between them..."
 
"Be very very carefull and loo

"Be very very carefull and look everywhere for any of the impeller pieces. If you can not reconstruct the old, bad impeller completely on a bench you MUST find ALL the pieces or it will cause you a ton of grief..........."
 
"Thanks Ghost and everyone, th

"Thanks Ghost and everyone, the impellar is still intact, just melted into the housing. It is now back together and the owner has left for the lake to do an on trailer , in gear test . Thanks again. Hope that I can help someone back someday or PASS IT ON as they say. Safe boating GPS."
 
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