Spark plugs for 2006 mercruiser MPI 4.3 engine 215 tahoe deckboat.

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shackle101

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Just wondering what would be the best option here, and what gap do I need. I got a 215 Tahoe deckboat and it's really cramped in there, any tool suggestions or should I be able to get them out with a standard swivel spark plug socket? I remember the last time I did them on a old 5.0L volvo deckboat and it was a nightmare so I guess I'm hesitant.
 
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Bt Doctur

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AC Delco MR43LTS b. The recommended service replacement spark plugs for these engines are
non-platinum AC MR43LTS (P/N 33-884019) or NGK BPR6EFS (P/N 33-816336).
 
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shackle101

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I went to a parts store and they said it's calling for AC Delco 41-993 or NGK ITR4A15. I searched based on my SN and got the same online. Are they incorrect? I got the NGK, but I haven't installed them yet.

Engine SN (my engine year might be different than the boat): 0w349749
 
Bt Doctur

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I cant see spending all that money for a spark plug when a standard plug does the same thing an 1/3 the price.
boats are not like cars where you can leave a plug in the engine for 100,000 hours
 
Bondo

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Bt Doctur said:
I cant see spending all that money for a spark plug when a standard plug does the same thing an 1/3 the price.
boats are not like cars where you can leave a plug in the engine for 100,000 hours
Click to expand...

Ayuh,.... A Big Ditto,..... Don't waste yer fuel money on spark plugs that work exactly the same, 'n offer No advantages,.....
 
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shackle101

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Oh so you guys are suggesting the non-platinum due to cost, but what I have is recommended and will work, right? Yeah these ran about 8.49 a piece.
 
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shackle101

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Just took off the plugs and I noticed the old ones are oily this surely is not a good sign right? I know my old 2 stroke would leave them sorta oily. I don't know when they where last replaced. Would this be expected if not replaced in awhile or if the oil is too high? I know when I filled the oil I wasn't on perfectly leveled.
 
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shackle101

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Well most the oil is on the threads of the sparkplugs. It's hard to tell in these pics but they is wet oil around the threads. There doesn't seem to much on the firing ends. compression Tested 1-3 cylinders and so far 152 PSI or so on all of them. Will report back when I test all of them.
 

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shackle101

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All Cylinders tested about the same with 158-160 PSI range. My gauge is actually 4 PSI per notch.
 
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Bondo

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Ayuh,.... The plugs ya took out are AC Delco, MR43LTS, with perfectly square sharp electrodes,...

I'd put 'em back in, 'n go Boatin',..... Nothin' at All wrong with 'em,....

Oily threads ain't a bad thing,... yer compression is Fine,...

'n so are the spark plugs,.....

When the center electrode starts to round over the sharp corners, then think 'bout buyin' a fresh set,.....

fetch
 
Fun Times

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shackle101 said:
I went to a parts store and they said it's calling for AC Delco 41-993 or NGK ITR4A15. I searched based on my SN and got the same online. Are they incorrect? I got the NGK, but I haven't installed them yet.

Engine SN (my engine year might be different than the boat): 0w349749
Click to expand...
shackle101 said:
Oh so you guys are suggesting the non-platinum due to cost, but what I have is recommended and will work, right? Yeah these ran about 8.49 a piece.
Click to expand...
The NGK ITR4A15 plug is the newest/latest plug that Mercruiser is just using as a service replacement over the original AC 41-993 plug now as both are really good plugs. So yes being that your engine model is an MPI engine, the plugs you already bought are just fine to use.

Since there were AC Delco, MR43LTS in there, someone has already replaced them at one point. Where they loose fitting or seemed tight when removing?

shackle101 said:
Well most the oil is on the threads of the sparkplugs. It's hard to tell in these pics but they is wet oil around the threads. There doesn't seem to much on the firing ends. compression Tested 1-3 cylinders and so far 152 PSI or so on all of them. Will report back when I test all of them.
Click to expand...
Though the threads may appear to be oily, chances are it's actually just unburnt fuel being pushed back up by the cylinder compression. It's not all that uncommon to see that black colored look on the threads.

While it may look like dirty oil, it isn't, this is unburnt fuel that all the lighter elements in the fuel have boiled off leaving the heavier hydrocarbon components behind. This is not unusual to find even on race engines. I wouldn't have known this myself if I hadn't run acrossed the explanation from a very respected pro engine builder on another site. This "fuel" is here because the seal(tapered seat or gasket) is above the threads but the threads themselves are shielded from the actual combustion process
Click to expand...

http://motogymkhana.pl/katana/wp-con...lugs-guide.jpg
spark-plugs-guide.jpg
 
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