spark plug help
 

I have a 1998 mariah shabah 202 w/5.7 carb mercruiser alpha one outdrive.. I took the boat out yesterday and it was spitting and sputtering, upon looking into the motor i found that the spark plugs were in extremely bad shape. i need to replace them but i want to make sure these are the proper plugs. The plugs i just removed are ACDelco 41-993, but as i read online most ppl i see are using mr43t plugs? i have been researching for hours and am having no luck! could someone tell me which is the best plug?

Re: spark plug help
 

The 993 is an iridium plug vs the 43t, which is just a standard plug. The R43TS was the standard plug used in almost every small block Chevy for years so its really common. The iridium plug is definitely better, but probably a fair amount more expensive, but will last at least twice as long.

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Re: spark plug help
 

thanks so either one should be fine??

Re: spark plug help
 

Yep. Either will work fine.

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Re: spark plug help
 

Spitting and sputtering... Had that problem many times before in my personal boats and in friends boats. If you are going to do the plugs you may as well spend the extra $ on a new water separating fuel filter. I recall the WIX 33225 going for 14$ at the autoparts store and I run that filter in the 4.3 and the 7.4. I dont know if it is the ethanol that is the culprit for the contaminated filter but it has become an annual change for us and here in Colo. even though we are in a very dry climate. Last season I started running an "ethanol" treatment in my fuel. Plugs looked great out of the 4.3. Have not had the 7.4 long enough to notice. More on that later...
Here is a link for you of all the cross referenced filters if you are interested--->
FRAM - Part Details

Re: spark plug help
 

yes i plan on changing the water separator also.. i wish i could post a pic of the spark plugs, i have never seen any this bad

Re: spark plug help
 

What do you have going on with them? Rust? Black N wet? Roasted gold? Crispy white? Corrosion? Could be a carb adjustment as in electronic choke malfunction, plugged jet, etc. Maybe it came from sea level and you are at elevation making it run rich? Lots of things to consider. Can be a simple fix.

Are they original plugs?

Re: spark plug help
 

idk if they are original plugs but one of the the part where the center core sparks to is completely gone (like the thing you gap)the color looks good other than that, the boat has 346 hrs and has been rebuilt maybe 100 hrs ago so i would have thought they replaced sparks plugs... what could cause this?

Re: spark plug help
 

That's not normal for any amount of time they've been in. I'd check that cylinder for problems. At the least run a compression test, and best case a leakdown test. Sounds like there might be something funny going on in there. Only a super lean condition could burn that off, or mechanical failure could break it off.

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Re: spark plug help
 

Here's a chart..

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Re: spark plug help
 

Husker has the chart! I was contemplating google for that one!
Compression test would not hurt but like you said, 100 hrs is not much. Unless there is a problem waiting to be found.

Personally, Id put in the plugs and see how she ran. Id check each one after a run around the lake and go from there.

Make sure you have fresh fuel too...

Re: spark plug help
 

ok thanks for yalls help. i will check all tht, get the new spark plugs back in and let you all know how it goes..

Re: spark plug help
 

i finally got all the spark plugs changed and the rear spark plugs on either side were the same way as described!! what could be the deal?how can i post pics?

Re: spark plug help
 

Only the rear or all 8?

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Re: spark plug help
 

Almost sounds like water intrusion to me. Do a pressure test on the cooling system.

Re: spark plug help
 

Posting pics is quite simple. When you are replying to another post make sure you select "Advanced" and then enter your response. Once done & before you hit submit, scroll down the page a bit til you see "Manage Attachments" & click on it. The hit the button that says "choose file", select what file you want to upload from your computer and then hit upload. Once its done uploading the file then simply close the attachments window and hit submit on your reply.