Wanted to share another "learning curve" experience when I replaced injector o-rings and reinstalled my injectors about three months ago. At first everything was fine, and then recently I lost power while towing during a long pull, and had large amounts of white smoke. I pulled the injectors and found three of them were scorched, see pic



Comparison between proper and improper injector installation. These o-rings have approximately 2000 miles on them.



Close up with damaged o-ring / copper washer



After asking many boring questions on this forum, and many phone calls I bascially determined this was a self inflicted wound. There are several issues which may have caused this, if not a combination of them all:

1) Injector's not fully seated
2) Injector bolts improperly torqued due to a poor seating
3) Debris, oil, in the injector cups interfering with copper washer during seating.

I spoke with a diesel tech who stated ensure you clean, clean, clean, and clean again the injector cups prior to install. If there is anything small interfering with the copper washer, it provides a path for combustion gases to follow and eventually deteriorates the washer. This is why the symptoms aren't noticed for several months.

Secondly, when seating, smack the solenid of the injector with a rubber mallet and get a good seat. I was timid smacking the solenoid because I didn't want to cause damage. When torqing the injector bolts, tighten them as tight as you can by hand. You will not break the injector brackets or deform the copper washer. He stated this results in about 30-40 ft lbs of torque. Bascially, don't be afraid to tighten it.

On a good note, the scorched injectors are most likely OK and just look worse for the wear. Just need new o-rings and clean up a fine abrasive. I think I'm going to upgrade to Stage 1's now.

 

thanks for the info. never done injectors, but its in my future, i'm sure. i'm all for all the second-hand know-how i can get!

good luck with the re-install!

 

Thanks - I plan to do injectors this fall and this is really helpful. But, what do you mean by "tighten by hand". To me that sounds like just your fingers or something. Did you torque it with a torque wrench? Wouldn't that be critical with something like injectors? I'm usually a little lax about getting out the torque wrench, but it seems to me for injectors that would be one where you would want to torque it with a well-calibrated wrench to the exact factory specs.

 

Good question, and this wasn't very clear. This means use a wrench/socket and tighten very tight. Don't be afraid to yarf on it. I got this information from Matt at "Full Force Deisel.com". He reassured me several times I damage anything. He stated this will generally result in about 30-40ft lbs of torque. Spec for these bolts is 120 in lbs which is equivalent to 9.9 ft lbs. Granted the 30-40 ft lbs is substantially more. Just to clarify I'm no expert here, so if anyone else has an opinion regarding this tightening procedure please chime in.

 

Those bolts aren't that big, you will stretch them at 30-40lbs, weakening them, failure is right around the corner imo. I'd think they'd know what they are saying, but I wouldn't go that tight.

 

Oil the crap out of the injector the push it in as far as you can by hand and hit it with a mallet. You'll hear a distinctive "Ping" when it seats

 

Probably right. I think the gist of what he was saying is don't be afraid to get those bolts tight, after you seat the injector with a mallet.

 

Id question your "diesel tech" guy. Injector hold down bolts get torqued to 10 ft pnds or so, which equates to 110 in pounds. Maybe he mispoke, but I would sure hate to see what happens trying to torque them to 30 ft pounds.

 

I haven't messed with my 7.3's injectors but aren't the hold down's similar style to the 6.0l? I would imagine the hold down bolts are similar size too.

6.0l injectors get torqued to 20 ft lbs.

 

7.3 injectors are 120 in lbs or 14nm

 

 

Right, but isn't is a very similar setup to the 6.0l injectors which call for 240 in lbs of torque? I'm just speculating that if the bolts are similar shouldn't the 7.3l bolts be safe at least up to 240 in lbs?

 

I took the advice of a super moderator here (cookie) and mixed Vaseline with oil and coated the injectors with that before putting them in. Worked good, when hit with a rubber mallet, like Mike said, you could hear them seat.

 

I'll give the vaseline a try this time as well. Just ordered my Stage 1's! I definately want to hear them seat this time. I won't be using 30-40 ft lbs of torque either as I'm not in the mood to stretch any bolts, or end up with another improperly seated injector. If I go over 120 nm/10ft lbs a tiny bit though, I'm not going to worry about it.

 

You want a 120 in lbs. or 14nm
If you go 120nm you'll need new bolts