Finding the right starter for my 7.4 mercruiser

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Oct 10, 2021
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8
I ordered a starter, obviously not right or I wouldn't be here LOL. Somehow I ended up with a Sierra 18-6275-1. This starter has the extra post for red/purple which I don't have. I need a starter that just takes the orange and red on one post w/battery and yellow/red for switch. Can I work around this with this starter? Also if I need to send this back and get another what would the correct number be? The original is beat up and I don't see anything for numbers! Thanks!
 

achris

More fish than mountain goat
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May 19, 2004
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27,468
Merc started using 454 (7.4 litre) engines in 1977 and there's been about 5 different iterations of it. What is your engine serial number? With that we can get closer to getting you the right number.

If that starter motor will mount up correctly (it may not), then you can just ignore the extra post.

Chris.......
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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I ordered a starter, obviously not right or I wouldn't be here LOL. Somehow I ended up with a Sierra 18-6275-1. This starter has the extra post for red/purple which I don't have. I need a starter that just takes the orange and red on one post w/battery and yellow/red for switch. Can I work around this with this starter? Also if I need to send this back and get another what would the correct number be? The original is beat up and I don't see anything for numbers! Thanks!
some starters have the "I" or "R" terminal

some starters dont

if your starter has it and you dont need it, then dont use it (terminal).

BTW, there are 4 types of GM marine starters

direct drive for 153 tooth flywheels (straight pattern)
direct drive for 168 tooth flywheels (staggered pattern)
PMGR for 153 tooth flywheels (straight pattern)
PMGR for 168 tooth flywheels (staggered pattern)

the direct drive weighs about 35# and the PMGR is about 11# and has more power than the direct drive

DSC_0022sm.JPG
 

Bondo

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I ordered a starter, obviously not right or I wouldn't be here LOL. Somehow I ended up with a Sierra 18-6275-1. This starter has the extra post for red/purple which I don't have. I need a starter that just takes the orange and red on one post w/battery and yellow/red for switch. Can I work around this with this starter? Also if I need to send this back and get another what would the correct number be? The original is beat up and I don't see anything for numbers! Thanks!
Ayuh,..... Welcome Aboard,...... If you don;t need that terminal, just leave it empty,.....
 
Joined
Oct 10, 2021
Messages
8
some starters have the "I" or "R" terminal

some starters dont

if your starter has it and you dont need it, then dont use it (terminal).

BTW, there are 4 types of GM marine starters

direct drive for 153 tooth flywheels (straight pattern)
direct drive for 168 tooth flywheels (staggered pattern)
PMGR for 153 tooth flywheels (straight pattern)
PMGR for 168 tooth flywheels (staggered pattern)

the direct drive weighs about 35# and the PMGR is about 11# and has more power than the direct drive

DSC_0022sm.JPG
So I'm assuming I have a PMGR as the shipping weight comes in just under 11#. I would love to say the engine number would help but it's a 2005 in a 97 boat. I've wired it ignoring the extra post and nothing, Ive used the extra post and not the other and nothing, The starter does bolt up and does work on the motor just not with the key. I alligator clip jumped it right at the starter and everything spun fine but doesn't shut off unless i unhook the battery cable. The only post that seems to be marked is the one I thought was the extra post and has a circle with RX in it. I thought the same thinking there has to be a way for this thing to work. I'm kind of stumped at this point. I'm a staggered pattern I will try to get a picture or two later today maybe that will help IDK, I may have needed to just walk away and get fresh eyes and brain last night as the starter in my truck went out which I got fixed in about 15 minutes LOL
 
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Bt Doctur

Supreme Mariner
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Aug 29, 2004
Messages
19,445
The starter does bolt up and does work on the motor just not with the key. I alligator clip jumped it right at the starter and everything spun fine but doesn't shut off unless i unhook the battery cable.

Main lug has Red,system power, Orange, alt feed, and main battery cable. Yellow/red to the inboard post of the solenoid. Jumping from the small inboard post to the battery lug should operate the starter. If it locks on and constantly cranks the solenoid is bad. There usually is no Red/Purple. That appears at the main 50 a CB
 
Joined
Oct 10, 2021
Messages
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The starter does bolt up and does work on the motor just not with the key. I alligator clip jumped it right at the starter and everything spun fine but doesn't shut off unless i unhook the battery cable.

Main lug has Red,system power, Orange, alt feed, and main battery cable. Yellow/red to the inboard post of the solenoid. Jumping from the small inboard post to the battery lug should operate the starter. If it locks on and constantly cranks the solenoid is bad. There usually is no Red/Purple. That appears at the main 50 a CB
So maybe I have a bad solenoid, I have this drawing and it was correct, I looked at a couple other systems and Red/ purple wasn't right, I had meant to say yellow/purple which isn't in this harness at all. So you are correct on that. Might have been a newer harness I looked at trying to figure out what this other post was for. I have hooked it up just like this and nothing with the key. I looked at so much of this stuff last night I may have confused myself lmao. gonna dig into it again here in a bit, Thanks for the info!
 

Bondo

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I have hooked it up just like this and nothing with the key. I looked at so much of this stuff last night I may have confused myself lmao. gonna dig into it again here in a bit,

Ayuh,.... The inner post, the yellow/ red wires, is the power from the keyswitch, it goes key, neutral switch in the control, to the slave solenoid, probably on top of yer motor, to that post,....
Is the slave properly wired,..??
 
Joined
Oct 10, 2021
Messages
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Ayuh,.... The inner post, the yellow/ red wires, is the power from the keyswitch, it goes key, neutral switch in the control, to the slave solenoid, probably on top of yer motor, to that post,....
Is the slave properly wired,..??
As far as I know, it ran the old starter that smoked out on me lol
 
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