Seized 787 question

[willkere]

I have a 98 Challenger 1800 with a seized right rear piston.

The story:
First time out this season I couldn't get the right engine to rev past 4500 rpms. When I would try, it would feel like it bog down and quit. I could restart it fine though. I pulled the spark plugs and the rear spark plug gap was gone. Not from build up but from something hitting it. I replaced the spark plugs and took it out again. After letting the engine warm up for 5 mins I got the right engine up to 6500 rpms before it quit and would not restart.

I pulled the cylinders and found the rear piston in bad shape. It looks like serious pitting, a large chunk missing, and a four corner seizure.









My questions:
What do you think caused this? Especially the spark plug gap issue?

I bought an SBT top end kit but don't want to put the engine back together without finding out the original problem. I'm assuming it was fuel starvation. I was thinking about rebuilding the carbs and replacing the fuel and oil lines. Any thoughts on anything else I should/shouldn't do?

Do you think I should replace the whole engine based on the severity of the seizure, ie is there a big chance of bottom end problems as a result?

Thanks in advance for any advice.

[dsolie]

Re: Seized 787 question

Looks a little more than starvation. Something let loose in the motor and wreaked havoc on that piston.

You will need to pull the motor and split the cases... You will have debris in there that will need to be cleaned and flushed out.

How are the wrist pin bearings? Still in tact? How about the big end bearings, how much play is in there?

[willkere]

Re: Seized 787 question

If I'm thinking of the wrist pin bearings correctly they are in between the connecting rod and piston? They came apart as I took the piston off the rod, but from what I remember each of them looked to be fine. I can take a look when I get home later. I didn't feel much side to side play before I pulled the pistons though.

Not sure how to check the play of the big end bearings? I'll take a look at my manual and check it out when I get home.

[dsolie]

Re: Seized 787 question

Snipe...

The high speed screw is supposed to be closed... That had nothing to do with your failure.