496 Spark plug
 

Does anyone know what spark plug Merc put in the 496 mag. Changed my spark plugs and want to know the they are the originals. One looks like it has black engine paint on it

thank you

Please check these other posts.
https://www.offshoreonly.com/forums/...ark-plugs.html
I used NGK standard TR55 Stock # 3951 .060". NGK Iridium TR55IX

Take Care
Vince

IIRC early 496's were spec'd with a Denso plug. They were then replaced by AC Delco 41-983. I've had perfect results using the factory plugs.

Thanks for the reply, I used delco. That's what I thought...original plugs.

thank you all

I like the NGK TR55IX better. They handle long term low idling alot better. And seem a tad crisper when accelerating. Also NGK makes some of the AC delc spark plugs. I do know this - the Volvo 496 like the NGK better as well. The idle quality is improved with the NGK's.

And More info to come about the 496 spark plugs. Ill let the suspense kill ya for a day or 2.

Easily have changed lets see 8 X 1000 = 8000 spark plugs in 496's if not more than that. I think I know a bit about the 496's. Merc. Volvo, Indmar, Crusader. - 19 years seeing the 496's and running. The Merc winterizing 10 to 1 soup mix kills these plugs. Another reason so many plug changes. I do not do the 10 to 1 mix period. 50 to 1 maybe 40 to 1 in the wetter climates.

Ngk tr55ix
 

"NGK TR55IX "
-this spark plug is ok for 2005 496 HO?
-which is correct part # for this spark plug?-2885,3951 or 7164? (google search for TR55IX came back with multiply part #'s)

thank you

NGK are the fine wire so you really want to check the gap very gently / carefully. Checking and Changing the gap many offset the fine causing engine running misfires. See this so much especially with all the very fine wire spark plugs. Do not use any form of anti seize on the spark plugs period. Can careless less what ANYONE says especially the Joe tech whom thinks he knows. Seen misfires caused because of anti seize on the spark plugs threads plus NGK strongly recommends NO and Nothing on the threads upon install. I even talked to one of the NGK tech support face to face about the issues many years ago.

Also if one owns the round disc spark plug gap checker that needs to go in the trash. With current plugs apps today that is a tool that bends the fine wire slightly off to the side when forced to much to check spark plug gaps. Seen that many times as well. Also does a number on double platinum tip spark plugs as well ( the round disc spark plug gap checker ).

Actually when its comes to the 496, seen more jacked crap than good from whomever worked on them without true trained seasoned experience thru out the years. My experience in my day - averaged 200 -- 496 would come thru my hands for service and repairs and indepth repairs per year of Merc - Volvo some Indmar and few other manu;s. Merc by far the majority. With that said I seen the good -- the bad --- the ugly to the extreme ugly with the 496's. More times than not, it was not the perfectly good seeing them in person for attempted repairs.

Anyways NGK TR55IX Stock number is 7164

we will see how she goes on Saturday, might be heading back to autozone and cleaning anti-seize.

BUP is getting deep...

emmm anti seized the plugs. A huge mistake especially for DIS set ups. The 496 is a DIS app --- crank and cam sensor synced / ignition coil near plugs and so forth.

So I googled misfires DIS systems from anti seized spark plugs. Really not a huge googler especially for working on boats, do not need it. Way past that stage and correct deeply trained.

Anyways watch the video as it was dated in 2011 and old news, caused it was a known issue way before that with DIS systems or should say at least min 15 years ago for me.

Check out the not so much anti seize on the spark plug threads in the video and what it was causing and the fix plus indepth engineer diagnostics about why.. Hopefully this ends the anti seizers out dated practices.

And I will CONFIRM seen and fixed these almost exact same issues in the marine field not once or twice but handful of times.. Anyways passing on free info for the taking. But seriously watch the video - something to learn for whomever. FWIW.

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