Cross threaded plug - how bad is it?

Further to my previous thread about the tight spark plug, I've now got it out but this is what I found..



All the plugs were supposed to have been changed last year when we first got the boat, but this one is def not just 12 months old so I'll be speaking to the service guys about that - but of more concern is the fact that the thread seems to be crossed right at the beginning. Do I need to do anything about this, should I be concerned, or should I just put a new plug in and make sure it's got anti-seize on it?

I'm no expert, but it seems to me if one of your other plugs will go into that cylinder nice and smooth then you have no problems. However, if the threads seem buggered up it would probably be good to run a tap in and out a couple of times to clean up the threads. possibly using a shop vac and bringing the tap out frequently to avoid putting metal fragments into the cylinder.

On a friends truck it was so bad he had to install a helicoil to fix the issue. Hopefully your still in good shape, but that is always an option if your threads are trashed.

Your dealer will have seen this more than once.--------------Will have the correct tools to chase the thread.------------Plugs are to be installed using fingers and a gentle touch , final tightening is done with a torque wrench.

I've tried one of the other plugs and it won't go in using just finger-power (well it not easily). I've been reading about the 'back tap' that cleans the threads from the inside out so that any bits do not go into the cylinder.
My dealer is >100 miles away and I'd rather get this done at home so I may speak to my local garage and see what they can do - it's just an engine after all!

I'm exceptionally pee'd off at the company that did the service last year though. They said everything was 'just fine' but the lower unit lunched itself within 4 hours (needed a new unit) and now this. B*stards.

Something like this is what you need. If you back tap it, the shaving are much less likely to get inside the cylinder, not to mention that you do not have to worry about starting a regular tap at just the right spot.

https://www.amazon.com/Powerbuilt-640811-Back-Tap-Thread-Repair/dp/B0014FGVVW

Mike

hondadude said:

Something like this is what you need. If you back tap it, the shaving are much less likely to get inside the cylinder, not to mention that you do not have to worry about starting a regular tap at just the right spot

Click to expand...

Thanks Mike, I'll speak to my local motor mechanic tomorrow and see what he can do.
I'll keep the thread updated.