2003 f350 spark plugs blowing out, why?


Asked by Jan 10, 2013 at 01:52 PM about the 2003 Ford F-350 Super Duty XL LB

Question type: Maintenance & Repair

I have had three different  spark plugs come loose and blow out destroying the coil. Why would they do that?

12 Answers


The only is I can think of is that they were not tightened down using torque specs. Another cause could be the threads are stripped or worn. Can't tell with out looking at them.

1 people found this helpful.

what should the torque be on the plugs? I did have a tune up done nine months ago before this started happening.

There has been many original Ford spark plugs that have blown out that were in the engine when the vehicles were new. I don't believe that the spark plugs were installed incorrectly from the factory. I know that Ford has had a problem with spark plugs blowing out of their 4.6, 5.4 and 6.8 Triton engines, I think it is a design issue (4 aluminum threads holding the plugs). The heads are aluminum as well as the spark plug


David H hit the nail on the head.


Thanks for the ideas, however this is not a new truck. It is not a matter here of being installed incorrectly from the factory. The truck is ten years old, I got it with 15,000 miles on it and have had at least ten changes of spark plugs in the nine years I have had it and never had this situation before. The truck has 187,000 miles on it now and this issue just recently began happening. What do I need to do, put "NEW" heads on it to keep this from continuing? I picked it up today at the shop. They did not charge me for the work, as it was one of cylinders that they replaced the spark plug and Coil on just two weeks ago. However they did say that I needed to put NEW heads on it, not rebuilt ones if it happened again. They assured me that their Mechanic was a valued and Certified Mechanic and he tightened down the spark plugs to the correct specifications. The shop also said, that they would not be responsible for any further repairs for the plugs blowing out and destroying the coils. It seems that FORD did not have a better IDEA on this design. I have a 1972 Ford F250 that has over 800,000 miles on it. Sure I have replaced the motor three times as well as the transmission two times. I never had a spark plug blow out on any of the motors. I only remember replacing the coil once for all three motors. How stupid to put eight coils on one motor, and over the spark plugs! So can one of you fine fellows advise me on what to do next time the plugs blow out and breaks a $100 coil. I am a small one man tow operator and cannot afford to have new heads put on my truck. Thanks, Joe


I would helicoil inserts a try before buying new heads. That could give you more thread area.

1 people found this helpful.

This is a know problem on these fords. Sorry its came to bite you in the a$$.

tenspeed has the right idea, a helicoil would indeed give you more threads to have screwed in, but the problem with that is you would then have different threads that the plugs would not accept..that is unless you use the type of helicoil that you have to drill out the hole in the head, and that is opening up a real can of worms with shavings dropping in to combustion chamber, and other things like that..you will need a set of numbered bits to have the EXACT precise size, and I don't know if you can even get a drill in the right position with the heads on...and yeah, I can fully understand the financial aspect of the whole ordeal. $600 or so a month for a new truck would be out of my league too..I test drove a 2013 Ford and just about shit when the saleswoman brought out the paperwork....it would have been $612 a month for 60 months, that's at 3.99% and my credit was only 20 points from being able to get that rate, so it went to 6.9%...$700 a month...screw THAT I will keep my '78

PS I am not going to give out my credit score, but just say you have to have VERY good credit to get 4% on a new vehicle..


David, they tap the spark plug hole all the time. The helicoils come in a kit with the exact sized drill and tap. They put grease on the tap and the drill bit to catch the shavings. You end with the same sized threads that you originally had.

Thanks tenspeend I didn't know they came in kits like that, I have only seen the packs, I learned something.


Well, thanks for the great ideas. I am going to start looking at the local tow company auctions for another Ford Pickup the same year range that has my motor. If I can find one wrecket or a bad transmission I will buy it and see how it runs. IF it has motor problems, I will pull the heads and get them rebuilt and put Heli Coils into the cylinders. As soon as the next plug blows out, I will have the heads swalped. In the meantime I am working on another pickup a bit older one ton dually and it is a 6.9 L Diesel that I built and installed a HYDROGEN GAS GENERATOR on it. It was one of my earlier tow trucks that I put out of service and sold the tow lift. I am installing a SNEEKER LIFT on it under the back. Hopefully it will be ready to put into service when I have to take my 2003 down to replace the heads. I will check back in as my project proceeds. Thanks for all your ideas and help. Joe

1 people found this helpful.

Your Answer:

F-350 Super Duty

Looking for a Used F-350 Super Duty in your area?

CarGurus has 23,350 nationwide F-350 Super Duty listings starting at $3,249.


Ford F-350 Super Duty Experts

  • #1
    Bigbob Reece
  • #2
  • #3
View All

Related Models For Sale

Used Ford F-250 Super Duty
493 Great Deals out of 40,207 listings starting at $2,800
Used Ford F-450 Super Duty
41 Great Deals out of 2,295 listings starting at $6,700
Used Chevrolet Silverado 2500HD
383 Great Deals out of 30,073 listings starting at $3,395
Used Ford F-150
2,280 Great Deals out of 208,575 listings starting at $1,300
Used Dodge Ram 3500
73 Great Deals out of 2,093 listings starting at $4,990
Used GMC Sierra 2500HD
150 Great Deals out of 17,365 listings starting at $2,999
Used Dodge Ram 2500
154 Great Deals out of 4,835 listings starting at $2,200
Used Chevrolet Silverado 1500
1,780 Great Deals out of 153,003 listings starting at $1,000
Used Chevrolet Corvette
91 Great Deals out of 15,032 listings starting at $3,620
Used Toyota Tundra
455 Great Deals out of 39,170 listings starting at $2,700

Used Cars For Sale

2017 Ford F-350 Super Duty XL LB For Sale
20 listings starting at $26,988
2015 Ford F-350 Super Duty XL LB For Sale
1 listings starting at $30,950

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.