4.3 mercruiser tune up question??

paczowski123

Petty Officer 2nd Class
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Mar 20, 2011
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I'm about to do a tune up on my mercruiser 4.3 as I never got around to doing it when I first dewinterized. My question is do I need to use mercruiser specific plugs, wires, cap and rotor, or can normal OEM chevy 4.3 vortec parts be used such as blazer or s10? I know in most cases parts are marine specific like alternators, starters etc. but wasn't sure about simple ignition parts?
 

Maclin

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May 27, 2007
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Re: 4.3 mercruiser tune up question??

I could be wrong, but (assuming your boat still has factory original engine components) I would bet that the igniton systems are not the same between your boat and a Blazer, especially in the Distributor area. And typically marine engines call for longer plug wires due to routing around bulkier exhaust configurations. The spark plugs are usually a different heat range as well.
 

Don S

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Re: 4.3 mercruiser tune up question??

I don't know why everyone thinks because they have an IO that parts can come from an auto parts store. The only thing automotive is the long block (except for cam and core plugs), everything else is marine and should be treated as such.
 

Volphin

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Re: 4.3 mercruiser tune up question??

I'm about to do a tune up on my mercruiser 4.3 as I never got around to doing it when I first dewinterized. My question is do I need to use mercruiser specific plugs, wires, cap and rotor, or can normal OEM chevy 4.3 vortec parts be used such as blazer or s10? I know in most cases parts are marine specific like alternators, starters etc. but wasn't sure about simple ignition parts?

Check with NAPA. They have the correct marine dist cap, rotor, AC plugs and wires for your engine. They are pretty inexpensive. As I recall, there is a longer reach plug for the Vortec heads that works well. I'm running them on my 4.3. I'll post the number tonight after work.
 

paczowski123

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Re: 4.3 mercruiser tune up question??

I figured so I was just curious. I do have one more question though and it relates to the drive/motor. I've had this boat a year and a half and it's always seemed to have a sort of "wobbling" noise is best I can describe it. It's not a knock necessarily, or a roaring. It may slightly change as I turn at low speed I'm thinking it may be a gimbal symptom, but its always done it since I've had the boat and I'm having trouble telling whether its normal drive line noise from all the direction changes and what not or other noise. It does it idling in neutral as well and makes no noise if I go above anything other than idling in gear or neutral. I know just about everything moves in the lower unit in gear or not in gear and I didn't know if it should be totally silent in relation to engine running and exhaust bubbling or if its normal to hear slight drivetrain noise as this is my first I/O?
 

Bondo

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Re: 4.3 mercruiser tune up question??

Bump. Thoughts anyone?

Ayuh,.... You've had it a year, 'm 1/2,... Yer overdue for pullin' the drive for service, 'n Inspection,...

That'll answer yer question,...
 

paczowski123

Petty Officer 2nd Class
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Mar 20, 2011
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Re: 4.3 mercruiser tune up question??

Yeah I know, and even worse last year I bought the gasket kit to do it and didn't as I'm good at getting things apart and not getting them back together. However, I did the WP/impeller job with ease so I figure ill pull it and check it. I guess it was also a little bit of being scared of what I'd find wrong as well.
 

bonzoscott

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Jul 26, 2008
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Re: 4.3 mercruiser tune up question??

I'd enjoy the boat for now and set up for a fall/winter project.!
 

paczowski123

Petty Officer 2nd Class
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Mar 20, 2011
Messages
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Re: 4.3 mercruiser tune up question??

That's my thinking, but I'd hate for something to go catastrophically wrong and ruin the gimbal housing and such.
 

bonzoscott

Senior Chief Petty Officer
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Jul 26, 2008
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745
Re: 4.3 mercruiser tune up question??

Well, go ahead and pull the drive for inspection. This is first time I heard of a noise described as a "wobbling" but first thing comes to mind is U-joints. Especially how you describe "changes slightly when turning". But a good time to inspect gimbal and check alignment too.
 

NHGuy

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May 21, 2009
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Re: 4.3 mercruiser tune up question??

If you can get it to go away by putting the drive exactly straight behind the boat and at an exact 90 degree angle with the trim adjustment that would point toward a noise or bind in the double u joint. Or possibly the gimbal bearing. They are inside the big bellows, and spin whenever the engine runs.
I would run it for now and just keep paying attention. If it gets bad and you are listening you will notice it before it causes catastrophe.
When you open it, check to see what it needs and then decide what to get. You are going to want an alignment bar because the engine alignment has to be checked each year. But if you need a gimbal bearing there are bearing drivers that attach to the alignment bar. Buying together can be a cost savings. There are resellers that sell service kits too. A little time in research can save you some money and I like to do it to try to beat the big guys.
 
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