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NGK CR9EB spark plugs

FSH 210 Sport

Jetboaters Fleet Admiral
Messages
7,248
Reaction score
8,965
Points
502
Location
Tranquility Base
Boat Make
Yamaha
Year
2020
Boat Model
FSH Sport
Boat Length
21
I recently posted about pulling my plugs at 250 hours and I replaced them with plugs I had on hand, I used a super thin coat of anti seize and the service manual torque of 9.6’ pounds or in my case, 115” pounds since I have 1/4” drive inch pound torque wrench for small things. When I woke up in the morning I didn’t have a good feeling about that, even though its what I had done in the past, and I’ve learned not to ignore my intuition as it were. Which resulted in a big dive, Aka fell down the rabbit hole on spark plugs.

NGK is now Niterra

The TR-1 engines take the long skinny CR9EB plugs, a 10MM thread.

The service manual states to tighten the plugs to 9.6 ft lb. Period.

The NGK pack of four plugs box states 1/2 turn after crush washer contacts the head or 7.2-8.7ft lbs.

On the individual plug box it says 1/4 turn after the crush washer hits the head and that's it. This was on those plugs I got from @drewkaree suggesting from overstock dot com off of Amazon.

Of the numerous boxes of plugs I bought from Amazon all but the last two had close fitting translucent plastic sheaths for the plug threads and tip. The last couple of boxes had loose fitting card board protectors. This got my spidey sense tingling about counterfeit plugs.

I called NGK corporate to get some clarification, the first question I asked was why there were two different tightening specs in a box of four plugs. She told me it should be 1/4 turn or 7.2-8.7 ft lbs with no anti seize. I said okay, which one rules the day? The 1/4 turn or the torque, she said torque of course but not everyone has a torque wrench.

I recently bought another set of six from an auto parts store in town and those had the new Niterra box, still says NGK on the front, basically the same except there is no tightening information on the back of the box of 4 plugs, but, the individual boxes stated 1/4 turn or 10-12Nm which is 7.37-8.85 ft lbs or 92.4-106.2 inch pounds and I have that 150 inch pound 1/4” drive torque wrench for small stuff.

Next I asked her about the plugs having the translucent or cardboard protectors. She told me that the plugs with the plastic covers are made in the USA, and the ones with the cardboard are made in Thailand or one of the other countries that makes them.

I then asked what about counterfeit plugs? First thing she said was the low end plugs like the CR9EB are generally not the ones getting counterfeited, it's usually the iridium plug or the high end ones. I said okay I saw that the new parent company Niterra had an app where you could check the QR code, she said the only company that puts the QR code on the box is overstock dot com which is who sells them on amazon. Last question, is overstock dot com a reputable place to get your products from? She said they are one of our sellers.

So I head out to the shop, gap the new plugs to .028”, which were all at .030” out of the box, pop the recently installed plugs loose and the break free feels just like the 250 hour plugs I just pulled out did. Once popped free they spun out freely.

In go the new plugs, dry, and hand tighten until crush washer contacts the head. Torque wrench set at 96" pounds or 8 ft lbs, all of them take 3/8 of a turn before the torque wrench clicks and all had the same feel. I increased the torque setting to 102" pounds or 8.5' pounds, hit the plugs again and no movement. This torque setting is 1' pound or 12" pounds below what the service manual states.

The main reason I pulled the plugs was that I was not comfortable with how I'd done it the night before thinking I may have overtightened them, I couldn’t change that but I didn't want to heat cycle the engines with the possibly over tightened plugs. Chances are they would have been fine but I wasn't comfortable so I swapped them out. I come from a work culture of sharing experiences so that others may benefit, I don’t like conflicting information so that is why I took the deep dive into this and made notes in my shop manual.

While I was doing all of this I went back through and looked at the plugs I have changed out in the past, I have them all, and the plugs that I had from the lower hours did not have anti seize on them, nor was there any sigh of corrosion and that is why I went to not using anti seize on them. If I was boating in salt or brackish water then I’d probably be using anti seize or that wacker paste that JBP sells, but I think it is important to note to use a very thin layer of whatever on the plug threads so you don’t end up with a lot of excess anti seize / wacker paste down in the plug well, I don’t know how you’d clean that out without the risk of that materiel falling into the cylinders. I thought I had read somewhere that there was a stainless steel insert in the plug holes but I can’t confirm that maybe @lazergeek can chime in on that since he had a stuck plug a while back.
 
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