496 backfire
Good to here that it was not a big problem, what did the old plugs look like??? thank's
09-04-2022, 01:38 PM
#24
Registered
Sorry to kick up an old and dead thread, but this post helped me solve my problem. I'm a long-time lurker but figured I'd give back to the community since this saved me so much time and money.
My boat (2012 Bryant 267 w/Mercruiser 496 Mag) started backfiring through the arrestor on Sunday. After reading this thread (and a few others) I opted to swap the plugs and the fuel filter. Long story short, one of my plugs was cracked. I installed new Denso Iridium IT16 (which advance auto pricematched Summit Racing at $7.00/plug) and the backfiring has stopped and the boat runs better than ever.
I do not understand why a backfire through the arrestor would be caused by a bad plug, so I was skeptical that this would work and was expecting that a valve job was in order. While swapping the plugs I did a compression test on every cylinder, all were good.
If you are backfiring through the arrestor on a Merc 496, start with the spark plugs first!
My boat (2012 Bryant 267 w/Mercruiser 496 Mag) started backfiring through the arrestor on Sunday. After reading this thread (and a few others) I opted to swap the plugs and the fuel filter. Long story short, one of my plugs was cracked. I installed new Denso Iridium IT16 (which advance auto pricematched Summit Racing at $7.00/plug) and the backfiring has stopped and the boat runs better than ever.
I do not understand why a backfire through the arrestor would be caused by a bad plug, so I was skeptical that this would work and was expecting that a valve job was in order. While swapping the plugs I did a compression test on every cylinder, all were good.
If you are backfiring through the arrestor on a Merc 496, start with the spark plugs first!
Last edited by Overtow; 09-04-2022 at 03:44 PM.
The following users liked this post:
Griff (09-08-2022)
07-05-2023, 02:09 PM
#26
496 back fire
Sorry to kick up an old and dead thread, but this post helped me solve my problem. I'm a long-time lurker but figured I'd give back to the community since this saved me so much time and money.
My boat (2012 Bryant 267 w/Mercruiser 496 Mag) started backfiring through the arrestor on Sunday. After reading this thread (and a few others) I opted to swap the plugs and the fuel filter. Long story short, one of my plugs was cracked. I installed new Denso Iridium IT16 (which advance auto pricematched Summit Racing at $7.00/plug) and the backfiring has stopped and the boat runs better than ever.
I do not understand why a backfire through the arrestor would be caused by a bad plug, so I was skeptical that this would work and was expecting that a valve job was in order. While swapping the plugs I did a compression test on every cylinder, all were good.
If you are backfiring through the arrestor on a Merc 496, start with the spark plugs first!
My boat (2012 Bryant 267 w/Mercruiser 496 Mag) started backfiring through the arrestor on Sunday. After reading this thread (and a few others) I opted to swap the plugs and the fuel filter. Long story short, one of my plugs was cracked. I installed new Denso Iridium IT16 (which advance auto pricematched Summit Racing at $7.00/plug) and the backfiring has stopped and the boat runs better than ever.
I do not understand why a backfire through the arrestor would be caused by a bad plug, so I was skeptical that this would work and was expecting that a valve job was in order. While swapping the plugs I did a compression test on every cylinder, all were good.
If you are backfiring through the arrestor on a Merc 496, start with the spark plugs first!
Just wanted to add that I also had this issue this week . Thought it was a bad valve spring but ended up being a bad plug ..
