This is topic Spark Plug keeps getting pushed to no gap in forum Tech Talk at Northern California Ford Owners  .


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Posted by mrovai (Member # 8657) on :
 
Wussup guys. I got a 98 GT manual trans. 2 year old Remanufactured Motor. So i have had this problem for a couple weeks now. After pushing my car to about 4500 RPMs, the car will die or want to die unless you give it gas and keep the RPMs higher than idle. The car then has a misfire on cylinder 3. I pull the plug to find that tip has been pushed up against the center leaving no gap. I replaced the plug, and the same thing happened 2 weeks later at about the same power range of 4500 RPMs in 3rd gear. It was the same cylinder #3. Obviously the plug is being pushed in. I have heard from a muscle car mechanic that you can buy washer/spacer type things so that the spark plug can sit a little higher. I thought about trying those, but i want to know if i have a more SERIOUS problem? Any thoughtful brainstorming is greatly appreciated from the community.
 

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Posted by Adam5.0 (Member # 6995) on :
 
Are you sure you have correct plugs in there?
 

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Posted by 98 Black GT Concord (Member # 8657) on :
 
Yes. Its definetly the right plug.
 

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Posted by LXjames (Member # 10791) on :
 
Detonation. Heard this happens a lot when you use poor fuels
 

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Posted by SteveL (Member # 1241) on :
 
One of those scopes would help if you can borrow one. Pull the plug and look at the top of the piston. If there's a mark on the piston top, it's mechanical. No mark and it could be detonation.
 

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Posted by 98 Black GT Concord (Member # 8657) on :
 
Great thanks guys. Im gonna borrow a scope and take a closer look. If its just detonation then i will replace some fuel components and get my timing readjusted. Any ideas on what my timing should be set to?
 

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Posted by LXjames (Member # 10791) on :
 
Stock is 10 degrees advanced
 

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Posted by Brokn Nx (Member # 8526) on :
 
I had this happen when I first swapped a new motor in a 98 GT. It actually broke the ceramic plug electrode on one of the plugs. When I first fired up the car it ran poorly and had a harsh knocking sound at idle. After awhile the sound went away and the motor ran much better but the check engine light said I had a misfire in one of the cylinders. I pulled all the plugs and found damage to 1,5, 4 and 8 plugs. After replacing all the plugs its been fine and hasn't had any problems in about 3k miles. Never did figure out why it happened, but since it seems fine now I chalked it up to low oil or fuel pressure at startup.
 

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Posted by SETONKILL (Member # 7277) on :
 
good luc set your timing on your 98 gt.an if want some to look at that knows what there doing pm
 

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Posted by Duncan Motors (Member # 7045) on :
 
lol what he said is u cant set your timing on that car lol. crank and cam triggers dont move and if u want to trust him to work on your car, pm him.

the plug could be carbon build up, could be a loose rod coming up, i never heard of detonation doing that before. get a boroscope and see if it is hitting your piston. like said earlier above i think is your best bet.
 

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Posted by SLOWSN95 (Member # 8269) on :
 
There is no distributor on a 98
 

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Posted by 98 Black GT Concord (Member # 8657) on :
 
So what if it is the piston hitting the plug?? Wat are my options? Do i have to pull the motor
 

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Posted by JohnB (Member # 969) on :
 
You have internal damage of some sort. Plug gaps do not close due to detonation, they close because either the piston is coming apart...the piston/rod assembly is traveling farther than it should (rod bearing or wrist pin is shot)...or combo of the two.

As stated, the timing isn't adjustable unless you've had major engine and computer mods done.
 

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Posted by SETONKILL (Member # 7277) on :
 
has the been any spark plug insterts installed in the heads?
 

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Posted by Ricks Hot Rod Lincoln (Member # 7637) on :
 
Any luck?
You said it was a rebuild. The rebuilder may not have done a good job...
The spark plug shims are a bandaid fix, But they will get you by for a while. Do you have any old spark plugs to compare the ones that are in the engine right now? it is possible they were mis-labeled at the factory. Or you can look for a shorter length plug. Check out Plug #11
http://autolite.com/sites/default/a/uploads/en/plugtips.pdf
Any warranty? It is possible that the pistons are rocking in their bores so much they are coming up and hitting the plug just enough. Do you have any piston slapping sound? Has your oil pressure dropped lower than it used to be before the plug/s went bad?

I don't buy the; Detonation is causing plugs to close up theory.
 

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Posted by Ricks Hot Rod Lincoln (Member # 7637) on :
 
Check out what Autolight has to say.http://autolite.com/sites/default/a/uploads/en/understandingspsizes.pdf

http://autolite.com/learn_more/technical_documents/tech_specs

This might be a possible cause too.
http://autolite.com/sites/default/a/uploads/en/half_fullthread.pdf
 

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Posted by 98 Black GT Concord (Member # 8657) on :
 
I still havent figured it out. Im pretty sure i still have the problem but i havent blown any plugs since that last time. Obviously i still have a problem but i have been choosing to ignore it and just not race. The car runs fine right now since i havent put it under any racing stress. My oil pressure is normal. No check engine light. I dont feel like the car is making any noise out of the ordinary except for idles kinda funny sometimes. Probably just need to replace my idle air control valve or whatever its called. I was talking to a few ford mechanics and they mentioned that ford 4.6 has a common problem with blowing spark plugs because of something to do with the spark plug threads. Does this sounds familiar to anyone?
 

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Posted by 98 Black GT Concord (Member # 8657) on :
 
Also about the engine... I bought it as a remanufactured engine straight from detroit. The engine is stamped remanufactured in 2010. As far as the spark plugs, i am using NGK iridium from my local auto parts store.
 

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Posted by Ricks Hot Rod Lincoln (Member # 7637) on :
 
The blowing plugs out problem is related to the threads failing in the cylinder heads due to Ford's bad machining/castings... It is different then what your problem is.
Go buy 1 Motorcraft/Autolite/Champion plug for your car and pull one of your plugs out and compare them and check the plug length, threads, tip length, ETC... (Check out the links from Autolite)
On a side note, do you use anti-seize compound on the threads on your plugs?
 

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Posted by 98 Black GT Concord (Member # 8657) on :
 
Im planning on doing a head swap after the winter. I want to convert to trickflow twisted wedge heads. Will this solve my problem? Will the bottom end of my engine be negatively affected by my current problem?
 

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Posted by Greasy (Member # 5258) on :
 

quote:

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Originally posted by 98 Black GT Concord:
Im planning on doing a head swap after the winter. I want to convert to trickflow twisted wedge heads. Will this solve my problem? Will the bottom end of my engine be negatively affected by my current problem?

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