Mark VIII Spark Plug Repair

  • Thread starter Deleted member 20330
  • Start date
D

Deleted member 20330

Guest
I have a 1997 Lincoln Mark VIII where the piston impacted the underside of the spark plug, causing the threads to strip.

I'm looking into using a Helicoil Sav-A-Thread kit because I can't afford the Timesert kit.

Does anyone know the part number for the Sav-A-Thread kit ?

Is the kit below correct ?

http://www.toolsource.com/savathread-m14x125-p-72402.html

Is the type of spark plug used a factor (i.e., Motorcraft Double Platinum) ?
 
I know you say you can't afford the Timesert kit, but I'd really advise against the helicoil "fix". The helicoils almost always back out shortly after installing them, if they don't snag on the plug from the get-go and make contact with the piston. Timesert or Lock-N-Stitch are the two proven methods for fixing the spark plug threads on mod motors.
 
FYI your piston did not hit the plug pushing it out. Your plug just popped out from pulling the threads out of the head or they where stripped or messed up earlier. You can get the kit for like 25 dollars at auto parts store.
 
It could hit the piston, if the wrist pin was broken, or you installed the wrong plug that had a longer than specified electrode
 
Htrlman1 said:
+1
Click to expand...

If that would happen there would be alot of metal (alum) on the plug that blew out if it distroyed the piston. Also the piston cannot reach the spark plug because the deck on the head stops the piston flat with the deck where as the plug is up in the dome. Also come on, how many times have plugs "blown" out of 4.6 heads? (thousands) I have had the broken piston shut gap on plug in an Escort thou. Does she have the blown out plug and is the gap shut? If its gapped it blew out.
 
Right on the Mark said:
If that would happen there would be alot of metal (alum) on the plug that blew out if it distroyed the piston. Also the piston cannot reach the spark plug because the deck on the head stops the piston flat with the deck where as the plug is up in the dome. Also come on, how many times have plugs "blown" out of 4.6 heads? (thousands) I have had the broken piston shut gap on plug in an Escort thou. Does she have the blown out plug and is the gap shut? If its gapped it blew out.
Click to expand...

Nearly every one I've come across had a smashed gap from being pounded up and down from compression...at least when the plug is still there.


Fwiw i use the denlor tools inserts. Haven't done a dohc yet though.
 
Right on the Mark said:
If that would happen there would be alot of metal (alum) on the plug that blew out if it distroyed the piston. Also the piston cannot reach the spark plug because the deck on the head stops the piston flat with the deck where as the plug is up in the dome. Also come on, how many times have plugs "blown" out of 4.6 heads? (thousands) I have had the broken piston shut gap on plug in an Escort thou. Does she have the blown out plug and is the gap shut? If its gapped it blew out.
Click to expand...

+1

vr4 said:
Nearly every one I've come across had a smashed gap from being pounded up and down from compression...at least when the plug is still there.
Click to expand...

Compression can't close a spark plug gap, as it acts upon all sides of the electrode at the same time. :rolleyes:

Severe detonation? Possibly. Foreign objects? More likely.

However, I still agree with ROTM, the plug probably just blew out due to bad threads.
 
Blowing a plug is more likely, and a lot of that is due to improper plug installation. Some people don't know any better and try to do it with the engine still hot, or they over torque them, or cross thread them
 
Sapperfire said:
Blowing a plug is more likely, and a lot of that is due to improper plug installation. Some people don't know any better and try to do it with the engine still hot, or they over torque them, or cross thread them
Click to expand...

SATURN5 said:
I always put antiseize on any plug going into an aluminum head....
Click to expand...

Agreed.

Anyone who doesn't use anitseize and a torque wrench when installing spark plugs in aluminum cylinder heads is a fool living on borrowed time.
 
Thanks for all the replies.

Right now, the spark plug is still attached and when the engine is running, there's bits clanking about in the cylinder.

A mechanic said the threads were stripped and that I should replace the head ($2,000+) - presuming I could find one.

Whenever maintenance was done, it was done at a Ford/Lincoln service center and the plugs are Motorcraft Double Platinum.

I can't afford to do the Timesert repair because the money isn't there to do anything more than the Helicoil fix.

If I do the Helicoil fix, vacuum out the cylinder and replace the spark fix, is that an adequate fix ?
 
Denna said:
Thanks for all the replies.

Right now, the spark plug is still attached and when the engine is running, there's bits clanking about in the cylinder.

A mechanic said the threads were stripped and that I should replace the head ($2,000+) - presuming I could find one.

Whenever maintenance was done, it was done at a Ford/Lincoln service center and the plugs are Motorcraft Double Platinum.

I can't afford to do the Timesert repair because the money isn't there to do anything more than the Helicoil fix.

If I do the Helicoil fix, vacuum out the cylinder and replace the spark fix, is that an adequate fix ?
Click to expand...

The main problem comes down to what is "CLANGING" aroung in there. If anything is REALLY in there you have bigger problems like broken piston bent valves. I think your "guy" is kinda taking you. Pull the plug and look at it. You will know if stuff is rattling around in there by looking at end of plug that goes into engine. If its clean just do helicoil(any parts store has timecert for 25 dollars) and clean install new plug. If you find metal on plug FUBAR.
 
Like others have stated the piston did not hit the plug out. Mod motor heads usualy only have a few threads actualy holding the plug. Make sure when you do replace the plug that you put a motorcraft plug back in. they are slightly longer than aftermarket plugs so its less likely to happen again. I will get the helicoil repair kit # for you once I get to work.
 
Thanks for all the replies.

It took me a while to get someone at Emhart to respond to my pre-sales support questions.

The following Heli-coil kits were suggested by Emhart when using Autolite APP104 spark plugs. I'm not clear as to what the differences are between the kits and why you'd choose one over the other:

5411-14

5396-14

Emhart recommends removing the head to perform the repair. If this is an absolute requirement, I can forget the repair as I don't have the background to do so.

I should point out that this spark plug blowout problem has happened before and was repaired by a Ford dealership for $240 a few years ago. The dealership has always performed maintenance so I can't fault anyone else for improper installation. For $240, it doesn't sound like the dealership had to do an expensive or time consuming repair (especially removing the head).

I believe what's clanging about in the cylinder is the broken underside bits of the blown out spark plug.

I read somewhere on this site that running the engine for a few seconds with the top part of the spark plug removed would blow the bits out of the cylinder. Is this advisable ?
 
You don't have to remove the head to install a helicoil WTF, they are installed in same process as you would a spark plug, and you don't remove the head to install those.
If you've got pieces of spark plug loose in the combustion chamber, what would make you think you should run the engine at all? Remove the plug and get a magnet wand! Perhaps part of the issue could very well be that's it been serviced by the dealership. I've personally only known one guy that was worth his salt working at Lincoln, he has since retired

If for some reason you decide to start it with the plug removed, make sure youre no where near it or whatever comes out will be firmly lodged in your forehead .)
 
DLF said:
Agreed.

Anyone who doesn't use anitseize and a torque wrench when installing spark plugs in aluminum cylinder heads is a fool living on borrowed time.
Click to expand...

Hey guys, I've been researching on any Lincoln sites available for some time now. I have a 97 mark VIII, I changed my plugs about 10k ago. I have done many tune ups and know the game after 10 plus years being paid to work on cars and with little to no come backs. Now my mark not only spits a plug, but when I did the repair (drilled and re-tapped the head and inserted insert and plug after cleaning combustion chamber) I restarted motor to hear a large piece of metal bounce around for a second then disappear down into the exhaust and the car is missing badly and wont hold idle. I am hopping it didn't suck a valve. I looked and saw that the piston is marked up by coming into contact with the plug/ foreign object. You guys sound like you know something, let me know. PS anti-sieze is for removing plug not keeping it in place. Real techs reply pls
 
FordPro said:
Hey guys, I've been researching on any Lincoln sites available for some time now. I have a 97 mark VIII, I changed my plugs about 10k ago. I have done many tune ups and know the game after 10 plus years being paid to work on cars and with little to no come backs. Now my mark not only spits a plug, but when I did the repair (drilled and re-tapped the head and inserted insert and plug after cleaning combustion chamber) I restarted motor to hear a large piece of metal bounce around for a second then disappear down into the exhaust and the car is missing badly and wont hold idle. I am hopping it didn't suck a valve. I looked and saw that the piston is marked up by coming into contact with the plug/ foreign object. You guys sound like you know something, let me know. PS anti-sieze is for removing plug not keeping it in place. Real techs reply pls
Click to expand...

You most like bent a valve not dropped a valve. That piece you heard clanking around got stuck under closing exh valve bending head. Then it went on its not so merry way. Sounds like you didn't vacuum out the camber well enough. Also just do a "LEAK DOWN" on that cyl and you'll know if intake or exh valve. PS I'm not a tech but I did stay at a Holiday Inn. (not)
 
Right on the Mark said:
You most like bent a valve not dropped a valve. That piece you heard clanking around got stuck under closing exh valve bending head. Then it went on its not so merry way. Sounds like you didn't vacuum out the camber well enough. Also just do a "LEAK DOWN" on that cyl and you'll know if intake or exh valve.
Click to expand...

Thanks for the quick reply. I borescoped the c.chamber to make sure there were little to no debris left. Also, there was what I saw as a jagged crack in the lower crest of the piston, but my co-workers said it wasn't cracked. Either way, there was a seriously jagged edge at the lower end of the piston where it meets the cyl. wall. Have you heard of pistons cracking in these extreme circumstances, they aren't forged by any means. Due to the plug repair my compression gauge no longer fits in properly.
 
FordPro said:
Thanks for the quick reply. I borescoped the c.chamber to make sure there were little to no debris left. Also, there was what I saw as a jagged crack in the lower crest of the piston, but my co-workers said it wasn't cracked. Either way, there was a seriously jagged edge at the lower end of the piston where it meets the cyl. wall. Have you heard of pistons cracking in these extreme circumstances, they aren't forged by any means. Due to the plug repair my compression gauge no longer fits in properly.
Click to expand...

Don't do a compression test do a leak down test. Blowing out a plug is not a biggie and does no real damage most of the time. Plug just blows out. I have not heard of any real cases of piston problems in stock settings. On a side note why does your comp tester not fit now? Same thread went back into head. When you bore scoped was top of piston beat up or clean. And have you pulled new plug and bore scoped after you heard noise?
 
You must log in or register to reply here.

Members online

No members online now.
Total: 145 (members: 0, guests: 145)
Back
Top