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spark plug wiggle


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Some guy looking at my rig noticed a miss in the idle and pointed out to me that one of my plugs was actually wiggling while the engine ran. He claimed this is a common issue with Comanches and that It could blow out and shoot rigth through the hood like a rocket! I stopped the engine and sure enought the darn thing was loose and I could turn it by hand! This guy claimed thais was a serious deal and even if I put new plugs in and make sure they are tight it wil deteriorate to a condition where the plugs start blowing out of the head. I tried to determine what the !!!! he was talking about .I asked if he meant the threads in the head were shot or what but all I got was jibberish out of heim from then on.

So Is ther such an issue common to some engines? Or should I ignore this new threat of impending doom and just tighten my plugs and drive? :dunno:

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I would venture to say that calling it a common problem with Comanches is a large load of bovine excrement.

 

The Jeep engine has cast iron heads. It is extremely unlikely that the threads are stripped. Just tighten the plug and drive. IIRC the torque is 25 foot pounds, but after 50+ years of working on AMC and Jeep engines I just tighten to "right about there" and it's done.

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It could happen, yes. But as mentioned, it's unlikely. In any case, if you determine the threads are in fact stripped, you can get a "helicoil" or other brand insert to repair the thread, either by bumping up to the next size or using an insert to keep the stock thread size (best way to do it IMO). If you are slow and careful, you can do this without removing the head. Cheap, fast, easy! There are special inserts for sparkplug application so be sure to get one of those and not the regular thread repair!

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Saw a '58 Chevy 348 with the number 3 plug out and hanging by the wire. The last thread and half was stripped. Looked like it hadn't been put in properly in the first place. Cleaned the threads up and screwed the plug back in, all the way. Worked fine. The lady who owned the car had been driving it like that for over a week. Somebody casually suggested maybe she should take it to a mechanic and have him take a look at it.

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Saw a '58 Chevy 348 with the number 3 plug out and hanging by the wire. The last thread and half was stripped. Looked like it hadn't been put in properly in the first place. Cleaned the threads up and screwed the plug back in, all the way. Worked fine. The lady who owned the car had been driving it like that for over a week. Somebody casually suggested maybe she should take it to a mechanic and have him take a look at it.

 

 

Yep. I have had a mazda where the PO cross-threaded a plug into the block. I was NOT happy when I found that one.

 

@Brian.. I was saying a helicoil is cheaper (ie. fix the current threads) than replacing the block. Not that you would need to replace the block.

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bovine excrement.
:yes:

 

X 1,000,000. I haven't seen a single Comanche, or ANY other vehicle with spark plug holes thru the hood. If this guy tries to give you any more advice...just smile, nod and walk away.

 

I had a 78 Chevy Caprice with a 305 in it. Every few days the #3 spark plug would pop out of the head and put a new dent in my hood. It turned out to be the oil fouler in the head was stripped causing the plug and fouler to come out. I took the fouler off and just screwed the plug back in. Never had the problem again.

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RE: "It could blow out and shoot right through the hood like a rocket!"

 

Interesting visual. I had a 49 Chevy pickup that lost one fan blade, right

through the inner and outer fender, at waist height, not 10 inches outboard

of where I was standing. That was more than 40 years ago, and I still

shudder when I think of it.

 

Thank goodness Comanche hoods are stout. Flying spark plugs just

ricochet harmlessly back towards the ground.

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i wouldnt call a helicoil cheap lol. i bought one for my yamaha 4 wheeler when i stripped the fill plug for the front diff and it coast like 120 bucks

Cheaper than a new head -- but helicoils don't cost nearly that much, even in Canadian money. Youse wuz robbed.

 

For example: http://www.google.com/products/catalog? ... DoQ8wIwAw#

 

And that's for the tap, and six (6) coils. Enough to do an entire 6-cylinder engine, if necessary.

 

However, it's really difficult to strip the plug threads on a cast iron head. That problem usually only affect al-you-min-ee-um heads.

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i tightened my radiator cap to 90 pounds as the mechanic told me, it blew the hood up into the windshield and broke it. also had to replace the hood. have it painted etc. 1100 dollars later. at least it has a shiny new paint job on the hood.

now the rest of the body needs painting. maybe have to sell the truck to pay for the paint job. comanche.gif

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i guess the fact i upgraded to the newer radiator caused the pressure to go up not down.

 

you learn something new every day.

 

if i hadn't upgraded it would of been cheaper to fix.

 

so what i'm learning is all the upgrades i read on the site might not be smart to do?

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