GMC Sierra 1500 How often should I change my spark plug wires?

[Brenden Burnham]

2 minutes ago, txab said:

You may end up regretting that choice later on, hopefully not. Bosch and a few other aftermarket plugs haven't always performed well. AC Delco, NGK, or Denso. All are OEM

Hopefully not but only time will tell.  

[Brenden Burnham]

5 minutes ago, txab said:

You may end up regretting that choice later on, hopefully not. Bosch and a few other aftermarket plugs haven't always performed well. AC Delco, NGK, or Denso. All are OEM

Do you happen to know the deal on the spark plug wires?  Sites show that the Bosch Platinum Spark Plug 6704 are suppose to fit but side by side with my old ones they were about a half inch too short.  I have a GMC Sierra 1500 4x4 4.8l.

[Supreme Pizza]

If you bought the plug wires on Amazon, they will often refund you without even wanting the parts back. Where ever you got them - I would ask for a refund or replacement.  You could always test your old plug wires. You use a digital volt meter to check the resistance on each wire. They are all the same length, so all the values should be about the same. If one wire has a lot more resistance, or the numbers are all over the place on every wire - then its time for a new set. The exact resistance value may be different with different types or brands of wires, but they should always be consistent when compared to each other - like cylinder compression.

 

5.3L Plug wire prices:

eBay $22

Amazon $25

OEM on Amazon $42

 

I recently bought a cheap set of plug wires on eBay just to get the heat shields. Who ever had the rig before me put new plug wires on it, but the heat shields were missing. I could not find a lower price for just the heat shields themselves. So after taking the heat shields off, I gave the plug wires away because my current ones were of higher quality - and will likely last longer than I need.  As far as the busted plugs go, I have found that as long as I have the rubber insert in the plug socket, and I place one hand one the ratchet head to stabilize it, I never accidentally break plugs. Sometimes they are already cracked though and just fall apart no matter what. As for gap, I have read that too large of gap will put extra strain on the coil, and can cause misfires - especially if the plug wires are not in good condition. A large gap makes it harder for the spark to make the jump.

[txab]

18 minutes ago, Brenden Burnham said:

Do you happen to know the deal on the spark plug wires?  Sites show that the Bosch Platinum Spark Plug 6704 are suppose to fit but side by side with my old ones they were about a half inch too short.  I have a GMC Sierra 1500 4x4 4.8l.

You need AC Delco 9748HH, They are 3/4" - 1" longer.

 

Parts catalog will often reference square coil or round coil or provide a coil number to look for. Length is the only difference between the wires

Edited December 16, 2021 by txab

[Black02Silverado]

If you get stuff at a parts store, it is best to take in the old one to make sure it looks and measures the same.  I do this with my air filters, cabin filters and such.

[Brenden Burnham]

2 hours ago, txab said:

You need AC Delco 9748HH, They are 3/4" - 1" longer.

 

Parts catalog will often reference square coil or round coil or provide a coil number to look for. Length is the only difference between the wires

And we have a winner.  Autozone has the AC Delco 9748GG and the AC Delco 9748HH both fitting my truck and the hard part is on their site it does not even show the length.  The guys there were also confused, he said typically it will show the length but in these cases they did not.  The funny thing is when I went into Autozone there was someone else with a 2006 Silverado with the same exact set I had(GG) and was returning that set saying they were too short also, we both laughed.  He was able to get the last set of HH they had before I could so had to go to another Autozone a few miles down the road that had one last set as well.

 

Not sure why Autozone shows the GG fitting I told them to correct it that it ABSOLUTELY does not fit.  The HH were the exact fit that I needed like you said about 3/4" longer.  

 

There was about a $20 price increase for the extra 3/4" it seems but he said for my troubles he gave me an additional 10% off.

 

Installed and happy as all is good to go(for now

Edited December 17, 2021 by Brenden Burnham

[Brenden Burnham]

2 hours ago, Black02Silverado said:

If you get stuff at a parts store, it is best to take in the old one to make sure it looks and measures the same.  I do this with my air filters, cabin filters and such.

Problem was in this case(due to promotions) I bought online.  And unfortunately it did not state the length.  That was the issue I had.  And yes I agree that is typically what I will do when possible.

[Brenden Burnham]

2 hours ago, Supreme Pizza said:

If you bought the plug wires on Amazon, they will often refund you without even wanting the parts back. Where ever you got them - I would ask for a refund or replacement.  You could always test your old plug wires. You use a digital volt meter to check the resistance on each wire. They are all the same length, so all the values should be about the same. If one wire has a lot more resistance, or the numbers are all over the place on every wire - then its time for a new set. The exact resistance value may be different with different types or brands of wires, but they should always be consistent when compared to each other - like cylinder compression.

 

5.3L Plug wire prices:

eBay $22

Amazon $25

OEM on Amazon $42

 

I recently bought a cheap set of plug wires on eBay just to get the heat shields. Who ever had the rig before me put new plug wires on it, but the heat shields were missing. I could not find a lower price for just the heat shields themselves. So after taking the heat shields off, I gave the plug wires away because my current ones were of higher quality - and will likely last longer than I need.  As far as the busted plugs go, I have found that as long as I have the rubber insert in the plug socket, and I place one hand one the ratchet head to stabilize it, I never accidentally break plugs. Sometimes they are already cracked though and just fall apart no matter what. As for gap, I have read that too large of gap will put extra strain on the coil, and can cause misfires - especially if the plug wires are not in good condition. A large gap makes it harder for the spark to make the jump.

Most excellent information and feedback.  I swapped out the old wires with the new since I figured those old plugs were very old can only assume the wires as well.  Easy enough to do, once I got the right length that is lol.

 

Thanks for the information 

[Brenden Burnham]

So for those that do the same thing as me and go into Autozone DO NOT get the GG set get the HH set.(Shown below)

 

[Brenden Burnham]

Ok a quick search and looking at a review on Amazon for these AC Delco 9748HH wires now it makes complete sense at the two sizes.  You can search for these wires( on Amazon and a top review with an image comes up and explains.  Basically It comes down to the coils your truck has.  Some have the Melco Coils(like me)(coils stamped 19005218) where the wires attach to the side(not below) therefore you need the longer wires the HH kit gives you.  For those that have the Delphi coils((coils stamped 19005218) the wires attach to the bottom therefore the length of wires is a little shorter therefore needing the GG wires.  

[Supreme Pizza]

Sounds like it all worked out well.

[txab]

Always buy the longer wire set.

[Grumpy Bear]

Old school but works. 

 

https://www.instructables.com/How-to-Test-a-Spark-Plug-Wire/

[Supreme Pizza]

That is an incredibly thorough, informative and LONG video. It has pretty much everything there is to know about... Spark plug wires....

 

I guess every mechanic should watch that video all the way through, at least once in their life.

 

Kinda reminded me of the Auto Shop 101 classes, back in the day.

[Grumpy Bear]

A couple more you may like:

 

Electricity, DC, is simple. If the circuit completes it works. If not, it doesn't. The reasons for an incomplete circuit (misfire) however can be a bit more complicated and misfires come in two categories. Those caused by an incomplete circuit and those caused by a short circuited circuit. A device may test perfectly on the bench and still fail in service for a number of reasons. Some explained in these two links. Enjoy.  

 

https://www.briskusa.com/spark_plugs_electrical_properties

 

http://www.dragonfly75.com/motorbike/gapvoltage.html