Injector Re-torque
Laughing Gas
Joined: Oct 2016
Posts: 1,074
Likes: 91
From: DFW, Texas
I worked on a truck today for a customer. While doing glow plugs, I checked the injector hold down bolts. The passenger side bolts were much looser than the driver's side. I did not get an exact torque value, but they were more than 80 and less than 100. I do not believe they have ever been touched. Totally stock '00 F350 dually. 168k miles.
Veteran/Sheepdog
Joined: Feb 2012
Posts: 6,047
Likes: 110
From: Western AR
I dove into my truck today to check the injector hold-down bolts. Curiosity was killing me...
Engine was not warmed up, and block was around 58*. Injectors were installed 123k miles ago, and I have not touched them since.
Driver side were all between 110-120.
Passenger side were between 100-120 with exception of #3, which was between 95-100.
I cold torqued them all back to 120, and when I started the truck I thought it sounded quieter. I have single shots, so "stock quiet" really isn't in my future. My passenger side exhaust manifold is also leaking at #5 (maybe more). so I have a nice "ping" when #5 fires on a cold engine/manifold.
Engine was not warmed up, and block was around 58*. Injectors were installed 123k miles ago, and I have not touched them since.
Driver side were all between 110-120.
Passenger side were between 100-120 with exception of #3, which was between 95-100.
I cold torqued them all back to 120, and when I started the truck I thought it sounded quieter. I have single shots, so "stock quiet" really isn't in my future. My passenger side exhaust manifold is also leaking at #5 (maybe more). so I have a nice "ping" when #5 fires on a cold engine/manifold.
Fleet Mechanic
Joined: Jul 2010
Posts: 1,753
Likes: 34
From: Los Angeles, Ca.
Are you opposed to the hot torque idea or just didn't feel like doing it? I think I will next time I go in there, haven't seen anyone saying not to and lots indicating it's a good idea.
Hotshot
Joined: Jul 2008
Posts: 12,782
Likes: 2,142
From: N.GA Mountains
I am curious though, at what point does the temp change the torque spec? Like wet vs dry torque? I wonder what the guys who ‘hot retorque’ are actually just tightening the bolts more??
Lead Driver
Joined: Jun 2013
Posts: 5,648
Likes: 893
From: north of Minneapolis, MN
"For example, if the original temperature was 70 degrees Fahrenheit and the final temperature was 75 degrees Fahrenheit, you would have a temperature increase of five degrees.
Multiply the temperature change by 7.2 x 10-6, which is the expansion coefficient for steel. Continuing the example, you would multiply 0.0000072 by 5 to get 0.000036.""
That is on a 5 degree rise. Let's say you installed the bolts at 70 degrees. What is the operating temp of the material surrounding the bolt? 200? So, that would be a 130 degree rise.
.0000072 (the expansion of steel) x 130 (the degree rise) = .0009 per inch of length.
I have maintained the whole time during the cold vs hot torque....that variable is the crush washer....not the bolt.
More Turbo
Joined: May 2018
Posts: 729
Likes: 147
From: Butler, OK
This has been been quite the read, so far. And ive learned something. That i have been using my fancy fat handled torque wrench from china exactly right....
taking my serpentine belt off and on....
On the other hand... sounds like i need to hunt down one of you guys with a good wrench, one of these days....
taking my serpentine belt off and on....On the other hand... sounds like i need to hunt down one of you guys with a good wrench, one of these days....
Hotshot
Joined: Jul 2008
Posts: 12,782
Likes: 2,142
From: N.GA Mountains
I used my googlefoo and found this.
"For example, if the original temperature was 70 degrees Fahrenheit and the final temperature was 75 degrees Fahrenheit, you would have a temperature increase of five degrees.
Multiply the temperature change by 7.2 x 10-6, which is the expansion coefficient for steel. Continuing the example, you would multiply 0.0000072 by 5 to get 0.000036.""
That is on a 5 degree rise. Let's say you installed the bolts at 70 degrees. What is the operating temp of the material surrounding the bolt? 200? So, that would be a 130 degree rise.
.0000072 (the expansion of steel) x 130 (the degree rise) = .0009 per inch of length.
I have maintained the whole time during the cold vs hot torque....that variable is the crush washer....not the bolt.
"For example, if the original temperature was 70 degrees Fahrenheit and the final temperature was 75 degrees Fahrenheit, you would have a temperature increase of five degrees.
Multiply the temperature change by 7.2 x 10-6, which is the expansion coefficient for steel. Continuing the example, you would multiply 0.0000072 by 5 to get 0.000036.""
That is on a 5 degree rise. Let's say you installed the bolts at 70 degrees. What is the operating temp of the material surrounding the bolt? 200? So, that would be a 130 degree rise.
.0000072 (the expansion of steel) x 130 (the degree rise) = .0009 per inch of length.
I have maintained the whole time during the cold vs hot torque....that variable is the crush washer....not the bolt.
I deeply miss this type of discussion!!!
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Hotshot
Joined: Jul 2008
Posts: 12,782
Likes: 2,142
From: N.GA Mountains
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
When I had my game of whack-A-mole in full swing, nothing would get a few of my injectors to sit still... no matter how many times I went back in on the same injectors. So no, I don't think it's exclusively the "crush" washer or the copper washer. It's a see-saw, and holding the see-saw more firmly on both ends reduces/eliminates the jump at the pivot - thereby greatly reducing the vibration and noise that can loosen a bolt or a nerve.
Veteran/Sheepdog
Joined: Feb 2012
Posts: 6,047
Likes: 110
From: Western AR
So, I deduce from the discussion that:
If you have an injector that is not staying snug and comfy in its hole, then you need to visit the hold down bolt on the top side to ensure it has not backed out or is still bottomed out.
If you have an injector that is not staying snug and comfy in its hole, then you need to visit the hold down bolt on the top side to ensure it has not backed out or is still bottomed out.
