Meltdown

[maddad]

Over the weekend, while on the way back from a local soda shack, I noticed the temp. gauge fly up just as the smoke/steam cloud came from under the dash on my 18' with my new 413ci SBC. By the time the smoke cleared and the bilge emptied, I could see I'd be needing a tow home.
All the plastic fittings on the stainless marine exhaust had melted, both rubber flappers were well done salisbury's and the 3 or 4 inches of exhaust hose I do have under the hatch were pretty crunchy.
I think it was the old plastic bag over the water inlet trick because on a restart it started pumping a ton of water into the bilge.
The stainless risers have a bit of a tan, and the powder coating at the connection of the riser/manifold seems to be a bit flakey and there's melted plastic in all the threaded holes.
Any ideas on what happened and suggestions on how to best clean it up are welcome and needed.

[Rootsy]

had to be pretty toasty to degredate powder coating...

ouch... I hope you didn't tweak the mouse....

[MOP]

Mike much as I hate to say it pull it apart check the heads, fair chance they may have warped aslo I would trust them if it got that hot.

Phil

[gcarter]

A through transom water pickup might eliminate this happening in the furure.
Sorry to hear it happened though.

[maddad]

I know good advise when I hear it, so I'm off to get all the new gaskets I'll need to put it right back together after I check and find nothing happened.
:crossfing::crossfing::crossfing:

[ITTLFLI]

Ouch!! Sorry to hear this!

I would do a compression test at least.....

[MOP]

Mike the discoloration is the spooky part, it was way hot. Got my:crossfing: for you!

Phil

[yeller]

That hurts! Hate to say it, but there's a good chance you cracked the block. When you get the heads off, pay particular attention to the top edges of the lifter valley. They will usually crack between the two middle cylinders.
Let's hope not. :crossfing:

[maddad]

The tanning on the stainless is what worried me too Phil.
As it's comming apart I've noticed no damage to the rubber valve cover gaskets, spark plug boots or wires that run near and in some spots on the block. The oil at the top of the heads is dark, but not black or burnt smelling. All the plugs look normal also. I'm going to do a compression test as it sits and check all the head bolts for torque before I take it all the way apart. The guys at the engine shop showed me what the black death looks like on the pistons and described what to look for on the cylinder walls. I've got this dream that the motor, which still had water in it after the cool down, didn't really go above 260/280, but the manifolds with no water in them once the lower fittings melted, got up there in temp. None of the hoses are burnt to the point of failure and the flappers are still semi flexable but drop cinders as they are bent.
I described the damage to Brownie when I ordered the replacment parts and he said they may look odd, but should still work after a super heating.
How the heck to get the plastic out of the threaded holes???

[Donziweasel]

As someone who has had their own issues over the last 8 months, I definetly feel for you. At least you are doing a thourogh checking of the engine before heading out again so you don't do more damage. A lot of people would just fix the fittings and, if the engine still ran, be done with it. An ounce of prevention (or compression:bonk:) is worth a pound of cure (or a pound of new pistons:bonk:).

As far as getting the plastic out of the threaded holes, if it got hot to get it in there, you may have to get it hot to get it out. Perhaps a small butane torch could heat the plastic till it is plyable and then use a pick and pick it out of the threads. I know this is a PITA, but if it melted and cooled in the threaded holes, I am not sure you have many other options. If there is another option, I am sure someone on these boards will eventually think of it. Good luck.

[MOP]

Mike those 400's were not happy when you got them hot, do a real good look see!

[BigGrizzly]

Napa sells a thread file that will work on the plastic.