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post #1 of (permalink) Old 10-21-2002, 07:41 PM
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Smashed Plugs, What went wrong?

So I bought a 79 CJ7 with the 258 2 months ago and have had a fun 2,000 miles or so with it. Ran like a dream on a remanufactured engine with 25k miles (5 years old). (Installed by previous owner.) Last week it suddenly started running really rough, then wouldn't start for more than 15 seconds.

After alot of looking around and friends blaming the carburetor, it turns out the plugs in cylinders 1, 3, 4, and 5 are bent, with #1 looking pretty bad and #4 severly mangled. I attached a pic of #4 so you can all get a good laugh out of this. I know that this means trouble... Now all the symptoms make sense. I wish it was the carb.

1) What the heck happened? My mechanic friend says he has never heard of this happening in that many cylinders all at once. Could I have avoided this, or can I avoid it in the future?

2) More importantly, can it be fixed affordably, or am I now in the market for another reman engine? If so, what are good companies to deal with? This one was bought at SuperTrak... Again, how can I avoid this problem?

Thanks in advance to any of you out there willing to help me out. I planned to run this thing until it died, but didn't plan for it to die so soon.

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post #2 of (permalink) Old 10-21-2002, 07:51 PM
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Re: Smashed Plugs, What went wrong?

Well your pistons are hitting your plugs now. [img]images/graemlins/smirk.gif[/img]
post #3 of (permalink) Old 10-21-2002, 08:22 PM
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Re: Smashed Plugs, What went wrong?

I'll give you the abbreviated RRich answer (I can almost see it now [img]images/graemlins/shocked.gif[/img])...........throw those pansey plugs away and put in a set specified by the manufacturer! The one size fits all deal DOES NOT hold true when it comes to condoms, socks, & especially Sparkplugs.
Seriously, it looks as if those plugs were the wrong length for your engine and came in contact with the pistons (not to mention probably the wrong temp also). Check your thread length againest a set of Champion, Autolite, or AC plugs of the correct spec for your I6. Did I miss anything RR? [img]images/graemlins/grin.gif[/img]
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post #4 of (permalink) Old 10-21-2002, 08:31 PM
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Re: Smashed Plugs, What went wrong?

Thanks. I realize that the pistons are hitting, but what would cause this to happen?
post #5 of (permalink) Old 10-21-2002, 08:33 PM
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Re: Smashed Plugs, What went wrong?

I don't think that your connecting rods in cyl's 1, 3, 4, & 5 ALL stretched at the same time (althought I have seen it with aluminum have steel) so my bet would be with Carver Dave. The plugs are probably wrong for your motor...why your motor took 2000 miles to figure it out is the next question [img]images/graemlins/tongue.gif[/img]
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post #6 of (permalink) Old 10-21-2002, 08:43 PM
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Re: Smashed Plugs, What went wrong?

Too long was the first thing I thought of, but there are a couple things that contradict that... First, they worked fine for the first 1000 miles. Second, not all cylinders hit. I went on down to the local Autozone that sold me these plugs right after I found the problem. Yes, these are cheap plugs, but they are the ones that their computer picked for me. They looked like the same size as the ones I took out when I replaced them. They confirmed that they were the "right" plugs when I went back with them. They are Bosch FR9HC. Are these wrong?

Thanks for replying.
post #7 of (permalink) Old 10-21-2002, 08:58 PM
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Re: Smashed Plugs, What went wrong?

something that just occured to me, maybe the rod bearings/caps/bolts( all the stuff that bolts around the crank) broke or came loose. my ford once spun 4 rod bearings, and although they didnt hit the plugs, it did knock, make it run bad, and it happend after about 2k miles. my problem was a clogged oil pump. worked fine until one day it just didnt get enough oil. as i said, i doubt this is your problem, or anywhere near it, but its possible that something caused rod bolts to come loose, which in turn would cause your pistons to be effectivly longer. just my thoughts. sparky
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post #8 of (permalink) Old 10-21-2002, 10:12 PM
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Re: Smashed Plugs, What went wrong?

From what I can tell with some internet searching and Haynes manual help, these are the right plugs. So, next step... Fix or replace? Does anyone have any experience with any engine reman shops? Any to seek out or avoid?

Thanks for reading this.

post #9 of (permalink) Old 10-21-2002, 11:52 PM
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Re: Smashed Plugs, What went wrong?

As far as the plugs go, books may say that Bosch Plugs will
fit, maybe even work.
But - is your engine made in Germany? Do you think the
engineers that designed that engine used German plugs?

Use what they designed it around.

The reason Bosch is promoted by parts houses is they cost
them nearly nothing compared with real plugs.

Now look closely at them with a magnifying glass.
Are they melted and burned? Or beat to death.

I'll bet what happened is at least one was running too hot,
the tip melted off of one, then the pieces bounced around
from cylinder to cylinder through the intake manifold.

Yes, trash can jump from cylinder to cylinder through the
intake valves, I've seen it several times - even happened
on my 225 oddfire (I was trying out Splitfires.)
Looking close may reveal one melted, the pieces beat the
others to death.

Use the correct AC plugs, or Champion, toss those Bosch
engine killers out.
Don't use yellow, pink, blue, platinum, split fire,
fire rings, Mexican, Jap, Argentina, rebuilt, "gas savers,"
or any of the other gimmick plugs that are "made to sell,
not to use."

Every month there's another "miricle" plug introduced, at
the same time, last year's gimmick goes away.

Look at the Champion or AC book. Why do they call out so
many numbers when yellow or Bosch plugs only have a few?
Ask your wife how she likes "One size fits all clothes."

If you are lucky you didn't hurt anything. Valves can get
bent like that, pistons can be collapsed (rings lands get
crushed,) holes poked in pistons etc, but if you are lucky
it'll be OK. Hopefully when it melted the hunk off you
shut it down soon.

Try a new set of "real" plugs before crying too much. Before
installing them, squirt a few shots of oil in each cylinder
and spin the starter quite a bit. Hopefully anything left
in there will clear out harmlessly. You may even want to
poke a magnet around in each cyl too.

I know I'll get arguments about using "magik" plugs, but
the proof is in the results, and you proved it.

Let us know on this thread how you fare.

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post #10 of (permalink) Old 10-22-2002, 06:41 AM
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Re: Smashed Plugs, What went wrong?

Thanks. Hopefully your theory will pan out and maybe I didn't damage anything. I would much rather not buy another engine. Although I was trying to start it here and there for a week, never considering the plugs because they were new. Maybe I will get lucky, but if something messed up the plugs so badly bouncing around, and it travelled between 4 cylinders, the other parts in there can't be too pretty.

In the mean time, does anybody have any advice on remanufactured engines?


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