4.3 GL-J Spark Plug Gap--.045” or .060”? (and a couple other related questions)

[Aar0n]

4.3 GL-J Spark Plug Gap--.045” or .060”? (and a couple other related questions)

I apologize in advance for the "loaded" post.

I have a 2008 Four Winns H180 with a Volvo Penta 4.3 GL-J. The engine was manufactured in March 2008, according to this sticker on the motor itself:



When I bought the boat this past spring, the previous owner included a handful of new "maintenance parts" (oil filter, fuel filter, spark plugs, etc.) he had, Now that I'm getting to my post-season maintenance, I've used the new filters and am considering putting the new spark plugs in, too. My reasoning is that (a) it couldn't hurt, (b) obviously the previous (and original) owner was planning on doing it soon so it's probably time to do so based on the maintenance schedule, and (c) I noticed the engine tends to have a shake when it's at low RPMs (otherwise runs great). I'm not sure if the shake at low RPMs is normal for this engine or not, so while I know that if it's not normal a number of things could be the culprit (timing, idle speed, idle mixture, etc.), the spark plugs seem like the easiest place to start.

By the way, anyone on here have an opinion on if the shake is normal or not?

OK, so, as you can see, the sticker pictured above says the plug part number is 3851632 and the gap should be .060". However, my owner's manual differs by saying the plug number is 3858997, though it does agree on the .060" gap:



Well, neither of those plugs are what the VolvoPentaStore.com says to use (http://www.volvopentastore.com/Ignit...view_id.780607), though it does say that 21513423 supersedes 3858997. So, according to it, 21513423 is the way to go, and I can find these online. However, they’re of course pretty pricey.

The plugs the previous owner gave me and obviously intended to install are NGK BPR6EFS. I think, according to another thread here on the forum (http://forums.iboats.com/forum/engin...23-spark-plugs), even though it's about a GL-D engine, that these should be OK to replace the Volvo Penta parts outlined above, but there seems to be some disagreement on the gap. Where the sticker on my engine and my owner’s manual both call for a .060” gap (albeit on different plugs than the NGK BPR6EFS), Don S (whose knowledge and expertise I’m in awe of) suggests that all carbureted GLs should be at .045”.

So, if I do go with the NGK BPR6EFS plugs I already have, do you all have any concrete suggestions on what I should gap them at--.045” or .060”?

Also, either way, I am a little worried about the fact that the NGK BPR6EFS plugs come pre-gapped at around .030" (yes, I manually checked the ones I have in my possession) and that extending that to either .045” or .060” is going to put the ground electrodes on a pretty decent angle, making it hard to ensure either measurement (.045” or .060&#148 is where the plugs are truly gapped. This is also discussed in another thread (http://forums.iboats.com/forum/engin...ation-included), which is what got me thinking about it .

Does anyone think this'll actually present a problem, or should I just move forward with the plugs I’ve got gapped at whatever the recommendation here ends up being?

Thanks in advance for any insight and advice you can offer.

 

[evantful]

It definitely requires a .060" gap. The engine sticker and the manual both reference this.

I would not use the BPR6EFS due to the regapping amount needed.

 

[Aar0n]

Thanks. Any thoughts on the engine shake?

 

[bajaunderground]

Describe engine "shake"? My power steering system will shimmy when it's low on PSF causing a shake?

It could be the plugs? It could be cap and rotor? It's could be wires? It could be gimbal bearing? It could be propeller(s), if under power?

​Under what conditions do you get the shake (other than the stated "low RPM'S".

​~Brett

 

[Aar0n]

Describe engine "shake"? My power steering system will shimmy when it's low on PSF causing a shake?

It could be the plugs? It could be cap and rotor? It's could be wires? It could be gimbal bearing? It could be propeller(s), if under power?

​Under what conditions do you get the shake (other than the stated "low RPM'S".

​~Brett

Thanks for the reply.

By "shake" I mean the engine itself visibly shakes a decent amount when at low RPMs both in neutral and in gear. I've checked the motor mounts and they're all nice and tight, so I don't think it's a loose mount. The shake is strong enough that you can feel it while just sitting in the boat, you don't have to be staring at the motor to experience it. I don't know the exact RPM range it happens at (and the boat's winterized now so I won't be able to check on that until Spring), but I would say get up to maybe 1100-1200 RPMs and it's gone. For example, at one point this summer, some screws on the windshield came loose while out on the water allowing some play in the windshield, and at those low RPMs--I think we were moving through a no-wake zone when I noticed it--the engine shaking alone was strong enough to make that loose portion of the windshield bounce up and down.

Other than this "shake," I've haven't observed any other symptoms of something wrong (e.g. odd noises, which I would assume would be present if it were a bad gimbal bearing or u-joint). It's also got a brand new Volvo Penta prop.

 

[bajaunderground]

So then it's something engine related...unless your drive is out of alignment? The drive spins with the motor and engages the lower...so it could still be gimbal and/or u-joints. The most likely culprit might be the tune-up items (plugs/wires/cap...etc). When was the last time you had the drive off and were able to check alignment?

 

[Aar0n]

So then it's something engine related...unless your drive is out of alignment? The drive spins with the motor and engages the lower...so it could still be gimbal and/or u-joints. The most likely culprit might be the tune-up items (plugs/wires/cap...etc). When was the last time you had the drive off and were able to check alignment?

I haven't. I just bought the boat this past spring from a local dealer who told me that they had "checked everything" and it was all in good working order. So, we had a great time with it this summer and now that I'm getting into end of season maintenance I started thinking about everything and this has started weighing on my mind. Come Spring I may have to get it into a shop to have them look at the alignment. Thanks for the tip.

In the meantime, I'll probably replace the plugs, wires, cap and rotor for good measure, since I'm pretty sure they're all original (8 years old).

On that note, I think I've made progress on the plugs. I had a "duh" revelation and decided to pull one of the already installed plugs. From the looks of it (red paint on them), they are indeed the originals. I expected to see VP branding and was pleasantly surprised to see ACDelco 12607234/41-993. Apparently that number is no longer in use, though. As best I can tell ( https://www.amazon.com/ask/questions/Tx2ICY9SMUE36DI, http://forums.iboats.com/forum/engin...plugs-confused), it looks like that number was replaced with 19256067/41-993, which are available on Amazon for about $5. I think I'll pick these up as they seem to be the direct replacement for the OEM plugs that came with the engine originally. Oh, and gap them at .060.

 

[Aar0n]

Just to close the loop on the spark plugs, I have confirmed with GM that 19256067, which is GM's OEM part number, is indeed the direct replacement ACDelco plug for the 12607234 (also the OEM part number) plugs that came in the 4.3 GL-J engine from the factory, at least my 2008. The ACDelco part number for both is unchanged: 41-993.