I have a 2007 Dodge Ram 1500 SLT with the 4.7. The plugs for the 4.7 have a reach of 3/4". I believe my mechanic may have installed the plugs for the 5.7 hemi which are 1" in reach. My truck went into the shop perfectly fine and came out with the engine knocking. Is it possible that the 1/4" difference in length caused the pistons to strike the longer, incorrect plugs hence, that caused the knock? The shop admitted to me that the wrong plugs had been ordered. When asked if it was possible that they may have installed the incorrect ones, they told me that the thread size wasn't the same. Well, truth be told, it is the same size thread. Thanks for any input!

Asked by bluefish935 Mar 23, 2014 at 09:25 AM about the 2007 Dodge RAM 1500 SLT RWD

Question type: Maintenance & Repair

The plugs for the 4.7 have a reach of 3/4". I believe my mechanic may have installed
the plugs for the 5.7 hemi which are 1" in reach. My truck went into the shop perfectly
fine and came out with the engine knocking. Is it possible that the 1/4" difference in
length caused the pistons to strike the longer, incorrect plugs hence, that caused the
knock? The shop admitted to me that the wrong plugs had been ordered. When asked
if it was possible that they may have installed the incorrect ones, they told me that the
thread size wasn't the same. Well, truth be told, it is the same size thread. Thanks for
any input!

2 Answers

12,585

yes, it is entirely possible. only way to know for sure is to tear it down.

1 people found this helpful.
10

Is it a knocking or a pinging sound, if the pistons struck the plugs it would not be running however incorrect reach will cause inadequate combustion thus causing the valves to chatter, have you replaced with the correct plugs?

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