Starter for 1984 5.7L I/O Mercruiserl

tfret

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So I’m experiencing some weak cranking after the boat is hot. Like after swapping skiers. All connections are tight, and my alternator is producing 13.5 volts at idle, and my battery is only a year or two old. I’m thinking it’s the starter or starter solenoid. But I’m having the darndest time finding the part I need. I really hate the iboats part finder interface. I can find it on Amazon but it’s all cheesy brands I’ve never heard of. Do you think my diagnosis is right, and if so, can someone please help me find the correct part?
 

Scott Danforth

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for Chevy V8's there are 2 types of starters - the direct drive you have and the new PMGR starters. and there are two types of bolt patterns, straight across and staggered.

so, what type of starter are you looking for?

and what bolt pattern do you need?

beyond that, I would go back to the connections and make sure each battery cable connection is clean and shiny as well as being tight.

also, if this happens only when you key off, make sure you dont have run-on (dieseling) if so, you could be hydrolocking
 

tfret

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I guess I was hoping to find a parts look up web page that would tell me what starter I need if I enter 1984 5.7L Merc. GM.
No, engine doesn't diesel or anything like that. All terminals are clean and tight.
 

Scott Danforth

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i would look at your starter at the bolt pattern, then order a PMGR that has that bolt pattern. otherwise you need to know what flywheel size is on your boat, and for that you would need to put your serial number into a Mercruiser parts breakdown search engine.
 

tfret

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I did try the serial number in the parts search on more than one website, and they still list more than one starter, leaving me with the same question. I guess between 1982 - 1986 there are two different fly wheel sizes. How the heck do I know which one I have? That's frustrating!
 
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Scott Danforth

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both flywheels were offered well before '82 and well after '86

you stick your head in the bilge and you look at the starter (or better yet, pull the starter and look)

if the bolts are staggered you buy a starter with staggered bolts
if the bolts are straight across you buy a starter with straight across bolts.

your block has both patterns.

then you simply google search for GM marine staggered starter or GM marine straight starter
 

tfret

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Thanks again Scott. Yes, I can do that no problem. I was just hoping to have the new starter with me when I drive back to the lake to repair the boat. Looks like it's going to require two trips. One to positively ID the starter, and another to make repairs. I'm not brave enough to order one on the chance it will be right. My luck never goes that way!
 

tfret

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Ok, I have the starter out of the boat. It is the straight across bolt pattern. One long one short bolt. BUT, I'm still not sure which starter to order. Apparently I also need to know the fly wheel diameter? How is measuring this even possible? I've got the starter on the bench and my serial # is 6685266. With this info can someone help direct me to the right starter?
 

Bt Doctur

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Sierra 18-5911 if you want the full size or 18-5919 for the PMGR smaller one
 

tfret

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Yes, I've been online and on the phone to parts dealers for over 3 hours. The last person I talked to was a rep at Sierra who told me the same thing. One of the parts store guys actually told me that the starter for the 14" flywheel mounts with two bolts the same size, and the 12 3/4" fly wheel starter uses one short and one long bolt. That bit of information is what put me onto these Sierra part numbers to begin with. Wow, what a pain!
I'm going with the PMGR which people say is a better starter. And has the added bonus of being lighter so maybe easier to install. It is in a nearly impossible position to get to. So maybe that will help. Thanks as always for the pointers!
 
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tfret

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One last question; What should I do with my old starter? I hate to throw it away when it could be recycled. Usually the auto parts stores take the old ones when you buy a new starter. But I don’t know if they’d take it or not.
 

Scott Danforth

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One last question; What should I do with my old starter? I hate to throw it away when it could be recycled. Usually the auto parts stores take the old ones when you buy a new starter. But I don’t know if they’d take it or not.

take it to a scrap yard for recycling then. I take mine to work and toss in the mixed metals scrap bin.
 
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