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Cars > redraif’s Garage > Blog > 1984 Pontiac Fiero (INDY #770) > 2005: Spark plug HELL!

 

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2005: Spark plug HELL!

By redraif

Filed under: 1984 Pontiac Fiero (INDY #770)

***EDIT***
To stop confusing folks: This happened back in 2005 when we were first getting the car going. Since then the car is doing fine. The repair held and compression was restored
***EDIT***


Ok we thought when we were doing the initial tune up that Joe, who leneded a hand with the once over on the fiero, swapped out he plugs. Though after looking at them he might not have. They look like they have more run time on them then 70 miles... and we sure did not install them in this condition...

Here is one that had no gap and its .025 partner.


The 3rd one had .040 gap (its not pictured)

Now here it the one that got beat up royally. What on earth could have caused this? The electrode is bent over and smushed sideways. The side of the plug is all knarled up... I hope the engine did not do this!




So they came out of the head like this:
Condition of plugs driver side to passenger side:
Smashed, no gap, .025, and lastly .040...

First thought was that this was the wrong plug and it was too long for this application....

Here is the number of the AC delco plug...verified to be correct from Advance Auto parts...

I even had them pull other plugs from other manufaturers to be sure there was not a part number mix up and this one is too long. Well all the other plugs are the same depth in the spark plug hole...

So believe it or not the car had been running with the plugs like this, not well, but it ran!

So I bought a new one... gapped them all to .060. Once installed the car finally purs instead up bucking and sputtering.

Well then the real fun began....

I heard a ticking and the car was not running right...

So we got to thinking maybe we need to further clean the air track on the car to be sure a carbon build up might not be the culprit for the sputtering under load. Plus the seafoam clean we planned to use could also point up to the exhaust leak. We had read that the 2.5s tended to crack the exhaust manifolds if water leaked on them when they were hot. So I was concerned was it that or had I blown a gasket???

So we started the car and ran the seafoam thru the Throttle body. Well I got smoke from an exhaust leak, but I was having trouble pin pointing it! So I looked closer and notice a plug wire was laying on the exhaust. It was all charred. I thought great the leak had toasted the wire. Well I got to looking further and saw the sparkplug was a mess as well. Thought great a big leak. Still was not pin pointing the leak. So I shut the car down & let it cool so I could check out the plug.

When I went to remove the plug it was horribly loose in the head. I thought WTF??? I know I tightened it down! Well when it came out I got my answer!







So over to the parts store I went, plug in hand. Well tom my parts guys was amazed. He is and older guy who has been working on cars as a hobby all his life. Well he took a look and said he had never seen this before. Well then a retired mechanic buddy came in and he also had not seen this before. So Tom figure what must have happened is the electrode in the spark plug got damaged somehow. (I'm thinking it was the one that the gap was closed on then we regapped) Well when it got damaged it started to spark out thru the side of the plug and ground on the head. Thus melting the plug....

My theory...This melting of the plug allowed for vapor to escape out beside the spark plug. This loosened it further in the head and allowed it to move arounf enought to damaged the threads, thus allowing even more vapor to escape.

So the plan was, get a new plug, obviously... Then compression test the car, to be sure the threads were not TOO damaged. So I did just that. A healthy cylinder tested around 120, this one... 50. Yep threads are bad! So it was off to Summit for a spark plug tap and heilicoil kit. Well I vasolined the tap per the guy at summit and tapped away! Then for further clean up I used a telescoping magnet to get any metal out of the cumbustion chamber. Next came instaling the heilicoil with high temp RTV per the instructions. SO I used Ultra Copper. Once installed I installed the plug per the directions and waited 24 hours for it to cure!

So then I fired up the car and poof, no exhaust leak! Go figure. Amazingly the plug wire was fine, but the boot was charred. Just to be sure I got all new ones that were swapped out.

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Read comments on this blog post 1 – 4 of 4

redraif’s Profile Photo
redraif
Aug 12, 2008 at 9:47 pm
Sorry for all the confusion. Yes this happened back in 05. I managed to fix it myself. Car ran great after, though its been an uphill battle with more set backs, but the fix held. First time I had to try a helicoil. That was nerve racking. Yeah, Im posting some of the past stuff here in case it can help someone. I had a cardomain site I got locked out of... too many ride pages. That was the same time the bird went down. I just thought I would pick up here.
 
JerryandMary’s Profile Photo
JerryandMary
Aug 12, 2008 at 4:12 pm
Darn, Sorry I just read your blog closer. Glad you got it fixed.

Jerry
 
BigNuttyPaul’s Profile Photo
BigNuttyPaul
Aug 12, 2008 at 1:31 pm
so how is it running now? it sounds like it has been one big mess
 
JerryandMary’s Profile Photo
JerryandMary
Aug 12, 2008 at 1:11 pm
Ok, first off what damaged the plug? Well it is likely not as bad as you think it may be. It is most often caused by a foreign object that has accidentally entered the combustion chamber. It is possible for small foreign objects to travel from one cylinder to another if there is enough valve overlap. This sounds weird but you might place a small hose on the vacuum and thoroughly vacuum each cylinder.

Good luck,
Jerry
 

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Cars > redraif’s Garage > Blog > 1984 Pontiac Fiero (INDY #770) > 2005: Spark plug HELL!

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