Spark plug issues

[dadgeff]

Here's a new one and i tried to find an answer with Google, but no luck. We went out on our boat yesterday and it ran great, until we slowed down and then we lost thrust. By the Grace of God we were able to limp back to the ramp. I ran through all the possible causes i could think of, gas mixture, blown seal etc and narrowed it down to pistons/ rings or compression.

Checked compression on both cylinders and they were fine, but then looked at spark plugs and this is what I see. Can anyone please advise the cause for this?

Thank you.

 

[jerryjerry05]

Pull the head and check for damage.
Looks like maybe melted aluminum???

 

[dadgeff]

noooooooo. That's going to suck. Thank you for the reply.

 

[Tassie 1]

What motor/ hp/ year is it?

 

[Redbarron%%]

Back when we were running leaded aviation fuel some times lead fouling would look similar, but with no lead the most likely thing is aluminum from pistons and detonation from either bad fuel or timing advanced too far. Perhaps aggravated by high temps.
Sometimes you can see with one of those cell phone creepy peepie small usb cameras, . Perhaps you have not yet destroyed the piston, but you should take a look.
I had a similar problem when I had a timing issue with a CDM conversion and bad gas I lost one of three pistons and had to replace it. Luckily I did not damage the cylinder bore.

 

[dadgeff]

1975 Chrysler 45 HP model 455HH

 

[emoney]

Some WalMarts carry that inexpensive diagnostic snake cameras that would allow you to look through the removed plug. I bought one and it was like $29.00.. Believe it or not, it works pretty well. May not last 6 months, but time will tell.

 

[jerryjerry05]

I bought the "snake camera" 11$ Ebay
Get the one with the stiff/firm cable.
Just get the right one for your phone.
The Android needs a special connector.

https://www.ebay.com/itm/Borescope-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649