modern spark plugs/engines

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Bob Bancroft

Well-known Member

Location

Aurora NY

• Feb 22, 2014

• #1

One of the well below zero mornings my pickup was hesitant, and was skipping briefly after it started. 2004 Chev. 5.3L 106000 miles. I assume original plugs.
So, maybe it's time for new plugs! I get the recommended ones (GM/Delco) from the local parts house. They are a different number than what's in my op. manual, and different from what's in the engine! Parts house says the numbers are changing constantly. So, I replace them. The plugs that were in the engine had a GM number as well as an NGK number printed on them! They look OK. Don't even look worn. But the gap is about .060". Aftermarket repair manual says .040" gap, years 2004 and later. The new plugs were .040". I'm wondering if the plugs in the truck were the wrong ones? Truck had about 40000 miles on it when I bought it.

 

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rick1

Member

• Feb 22, 2014

• #1

your lucky i have a 07 with the 5.3 must have a bad set of rings on one cylinder it will foul that plug about every 5000 miles or so.
RICK

 

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jimg.allentown

Well-known Member

• Feb 22, 2014

• #1

More likely a loose valve guide or leaking valve stem seal on that cylinder.

 

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Aaron Ford

Well-known Member

• Feb 22, 2014

• #1

I did a search to see what the recommended gap was for your truck It looks like it was originally .060 and later there was an update to the 0.040. There should be a sticker under your hood that designates what the original spec was. This seems to be a pretty common question on the forums. Which setting did you go with?

Aaron

 

MarkB_MI

Well-known Member

Location

Motown USA

• Feb 22, 2014

• #1

Your missing problem might be bad plug wires. Even if the plugs have been changed, the wires probably haven't.

 

Geo-TH,In

Well-known Member

• Feb 22, 2014

• #1

I have a friend with 2004 malibu, 96000 oem plugs. Doesn't skip a beat.

I have a 2007 GMC 6 cylinder truck. Weak link is the rotor/distributor. OEM distributor lasted 30,000. Auto zone lasted 30,000. Auto zone gave me a free replacement. GM didn't give me a free one. Truck plugs went south at about 40,000. So much for GM's OEM plugs and distributor.

 

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Dean

Well-known Member

• Feb 22, 2014

• #1

I agree.

Inspect the plug wires with the engine running at night.

Dean

 

OP

OP

B

Bob Bancroft

Well-known Member

Location

Aurora NY

• Feb 22, 2014

• #1

Didn't even think to look at that sticker!
Went with .040"

 

John M

Well-known Member

Location

Nunyafn business

• Feb 22, 2014

• #1

Brother has an 01, same engine. Has a little ove 200000 on it, and its still on the same factory plugs. At least it was, having some other work done to it andtold the guy to give it a tune up while hes got it, I don't know if the guy will change them of not. It runs like a top.

 

S

Sprint 6

Well-known Member

• Feb 22, 2014

• #1

The gap spec and part number did indeed change, the. 040 is correct. Side note, Delco platinum and iridium plugs should only have the gap inspected, not adjusted. You can damage the tips by adjusting.

Your truck likely needs intake gaskets, they shrink and allow a vacuum leak when very cold. They then seal back after the engine warms for a few minutes. See them a lot in my shop. Not a bad job on that engine, no coolant or distributor to deal with.

 

OP

OP

B

Bob Bancroft

Well-known Member

Location

Aurora NY

• Feb 22, 2014

• #1

Thank you.
I suspected the part number difference had something to do with the gap. As you indicate- you don't go changing from .040" to .060" without some serious bending.

 

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Bryan inIowa

Member

• Feb 22, 2014

• #1

It"s not the rings. Gm decided the drain back holes behind the rings needed to be smaller in their pistons. End result , hole plug up , cylinder pumps oil . I see a lot of this . Jasper engine rep showed me some bulletins and redesigned pistons to correct the issue . I have used Motor Vac injector cleaner along with top engine cleaning to help. But once they plug ,pretty hard to get them to clean out . Real common on 5.3 and 4.2 .

 

Gambles

Well-known Member

• Feb 22, 2014

• #1

Wife and I visited her sister and her sister's hubby last weekend. They took us out to eat and we rode there in their Toyota Sequoia. They bought it brand new in 2007 and it now has 275,000 miles on it. (Yes, that is two hundred seventy five thousand miles. The lady drives a long way to work each day) They asked me why their gas mileage had suddenly dropped from 17 to 14.5 MPG. When I asked them about any maintenance that had been done to it, they told me that the spark plugs were original on it. When I told them that they should start there, they then told me that they were probably going to trade it off. I was rolling my eyes in the dark, but I finally told them that some of it might be the reformulation of winter/summer gas and I just switched the subject to something else.
A couple of years ago, a Ford Winstar came into the shop that threw a check-engine code with 250,000 miles that had the original plugs in it. It turns out the light came on because a rodent had chewed into a vacuum line, not because the plugs were bad. We put new plugs in the vehicle before it left though.
I don't let plugs in any of my vehicles go over 60K, but that's just me.

 

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Mark-Mi

Well-known Member

Location

S.E. Mi.

• Feb 22, 2014

• #1

Just changed the original spark plugs in the wife's 3.8 liter Dodge Caravan. 207,000 miles and was still running fine. Gap was real wide. Wish I would of checked the gap on the old ones. Dreaded that job for a long time.

 

showcrop

Well-known Member

• Feb 22, 2014

• #1

my '04 Explorer with about 190,000 at the time was hesitating and it had to go in for two or three things. The plugs were original and had worn to the point that the gap was about three times what it should have been. New plugs made a big difference.

 

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MARK ROBKE

Well-known Member

• Feb 22, 2014

• #1

I heard there is / was gm extended warranty on the 5.3s using oil : someone I know got a new short block in his '06(?)from gm. He did document his oil consumption. Mark

 

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Brian Jasper co. Ia

Well-known Member

• Feb 23, 2014

• #1

There's a bulletin from GM that that the original plugs were .060, but the new plugs are .045.

 

4

4play

Well-known Member

• Feb 23, 2014

• #1

Like already said, the service bulletin for spark plugs was because they started using iridium instead of platinum, the .060 was platinum, .040 for iridium. The service message date was from late Oct 2003, so the complete phase in was probably 2004. Also as spark plugs age and wear, they erode at the tips which will also increase the gap.

Just a tid bit of info here which I think is ridiculous. GM specs for oil consumption per warranty guidelines for acceptable consumption are 1qt per 2,000 miles, and if over 8600 GVW 1qt per 100 gallons. Its not just GM, these specs are par with all manufacturers too, at least the ones I checked on.

 

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Hal/ Eastern WA

Member

• Feb 23, 2014

• #1

I have a 2006 Pontiac Vibe that we bought new. At about 100K, I realized that I had never changed the spark plugs, so I bought a new set. I was worried that after all those miles, the plugs might be hard to remove from the aluminum head, but they came out with no problems at all. I was surprised that the plugs looked so good: no buildup on the insulator tips and the gap was very close to specifications. I put the new plugs in, but it didn"t run any better (or worse). After about 20K more on the new plugs, I am starting to get a little hesitation when I take off and my gas mileage has gone down several mpg. The new plugs were standard resistor plugs and the plugs I changed were Iridium plugs. I think I will replace the standard plugs with the much more expensive Iridium plugs this spring. I think they are worth it.