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oldjeep

Platinum vs iridium plugs 2012 Monsoon 350

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oldjeep

As part of my winterizing this year I decided to replace the plugs - engine has 200 hours on it but just ended its 4th season.

The indmar manual for 2012 states plug number 41-993 gapped at .045 which is a delco double platinum tipped plug

Pulled one out today and the original factory plugs are 41-101 (Have some black paint on them so I know they are original), which is an iridium tipped plug and actually has a slightly deeper reach

Little internet research says that they are used interchangeably, but it seems odd that Indmar would spec one and then use the other.

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oldjeep

Another oddity, the new plugs 41-993 came gapped at around .060 and the plugs I just pulled out also appear to be gapped at around .060. Manual says .045 and there is no way that the old plugs opened up .015 from use - the electrode is no shorter, looks new.

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oldjeep

And to further complicate things - the 2015 Indmar manual says 41-101 with a .060 gap for the Monsoon 350. I think that is what I'll go with - might be worth a call to the dealer to verify.

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Fman

200 hours and new plugs? I was thinking at least 500 before this was even a concern. Was your engine running poorly?

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foiler1

200 hours on a three year old boat?

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oldjeep

200 hours and new plugs? I was thinking at least 500 before this was even a concern. Was your engine running poorly?

Manual says 300 hours or annually, figured I would do them this year since it has had 4 seasons on it. The concern with plugs is typically the threaded part that extends into the cylinder getting all carboned up and not wanting to come out.

Edited by oldjeep

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oldjeep

200 hours on a three year old boat?

4 season old - 40-50 run hours is pretty average for us a season since we go out and get our skiing/boarding done first thing and then anchor out for a few hours. The LXI that we use in the course goes out around 5 days a week for 6 months and that one only got 30 hours on it this season. (2004 with around 900 hours)

Edited by oldjeep

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JeffK

If it were me, I'd call Indmar. They will readily take your calls and offer great advice. You might even try their facebook page.

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oldjeep

If it were me, I'd call Indmar. They will readily take your calls and offer great advice. You might even try their facebook page.

Yes, I'll have to . To further muck this up - the Indmar Manual that I downloaded from this site:

http://www.themalibucrew.com/forums/images/files/indmar_2012_2015.pdf

Actually says 2 different things in 2 different places 41-101 with a .040 gap on one page and 41-993 with a .045 gap on another

The paper manual says 41-101 in both spots and lists a gap of .040 in one place

Edited by oldjeep

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MadMan

There always seems to be discrepancies in the Indmar documentation. I believe it's just cut and pasted from General Motors information and things get mixed up.

If it were me, since you know what GM installed originally, I would just go with that.

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oldjeep

From the horses mouth

"Sorry for the confusion. 41-101 plugs gapped at .060 are correct for your engine.

Larry Engelbert

Indmar Marine Engines

"

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ahopkinsVTX

From the horses mouth

"Sorry for the confusion. 41-101 plugs gapped at .060 are correct for your engine.

Larry Engelbert

Indmar Marine Engines

"

Thanks for the leg work OJ. I want to replace mine as well. 460 hours on our boat now.

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oldjeep

Thanks for the leg work OJ. I want to replace mine as well. 460 hours on our boat now.

$6 at amazon with a $2 rebate.

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ahopkinsVTX

$6 at amazon with a $2 rebate.

Awesome, just ordered. Again, thank you!

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Bturner

In the old days we'd change out plugs every other year or 100 hours whichever came first but those were the days of carburetors and points (yeah I know I'm getting old). Since I did a lot of boating on the great lakes I always did points and plugs every year regardless of hours and kept two sets of the previous years plugs/points on board just in case. The reality these days with electronic ignition, variably valve timing and fuel injection is that the need to change plugs just isn't there like it used to be. If it make you feel safe or like you're hitting all the maintenance points it certainly isn't going to hurt and is cheap insurance but in most cases it isn't necessary.

As with any maintenance item a lot is going to depend on use. If you idling a lot changing your oil and plugs sooner is probably going to be a good idea. But if you're doing a lot of cruising you're probably going to be fine going longer between maintenance cycles on your plugs. Remember these same plugs go 100K in cars. A lot of people are going to argue that the duty cycle on a marine engine is going to be much different and that is certainly true but if you pulled that plug and it looked like new you're not changing it because you needed to.

Edited by Bturner

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itznowonder

OK IDK a thing about this stuff, but every year I ask my dealer what would be the suggested maintenance on my boat. This year I was told to do points / plugs / dist cap. They did a compression test, said everything looks really good. It is bad that these things haven't been done and I am just south of 1000 hours on a 2007 boat?

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oldjeep

I'd be interested to see what plugs/cap/ rotor look like after 1000 hours. Have them save the parts and take a picture.

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oldjeep

Just for grins, this is what a set of 4 year old plugs with about 200 hours on them looks like. The gap was still pretty tight on 7 of them - the 8th was a little looser but not by much. For around $50 I don't feel bad about changing them every few years.

WP_20151105_11_45_13_Pro.jpg

WP_20151105_11_46_54_Pro.jpg

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MadMan

Just for grins, this is what a set of 4 year old plugs with about 200 hours on them looks like. The gap was still pretty tight on 7 of them - the 8th was a little looser but not by much. For around $50 I don't feel bad about changing them every few years.

Those plugs look pretty close to new. Were they the originals (paint over-spray)?

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oldjeep

Those plugs look pretty close to new. Were they the originals (paint over-spray)?

I'm sure they were original. I bought boat from original owner who had it 2 seasons (93 hours) and the only maint that had been done on it was the initial break service and the oil change at the end of season 1.

Edited by oldjeep

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Rednucleus

When you think about the environment those plugs live in, they really are quite a remarkable piece of work!

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