As many already know, I just got bit by one injector lifting during the compression stroke... and this may have caused a variety of other symptoms (fix not confirmed 100% yet). Did I miss a chapter in the book replacing the injectors? Are we supposed to hot-torque them? Re-torque after xyz miles? Hot-torque after xyz miles? Is there mention of this? Is this a "trick" experienced mechanics know, but it's not documented? Is there anything else post-install (in addition to oil change) that I could have overlooked?

 

Good question.....
I don't know the answer but I'll throw out some of my own observations.

An injector that was so loose that it was lifting out of the bore would sound like a hammer. Under those conditions the copper washer is usually consumed by the combustion event....at least they were totally gone on the few cases that I know about.

So far to date (knock on wood), I have never had to go back and re-tighten the hold down bolts after a certain amount of miles. The OE engines didn't have to be re-tightened so I presume the initial sequence should suffice.

Keep in mind that it's very hard to accurately torque a smaller fastener, things like tool calibration, method of operation, lubrication of threads all come into play. 10 foot lbs/sq inch is a very fine setting. My torque wrench won't even fit on those bolts without some sort of extension and once you add an extension then the torque setting is invalid. You would have to increase the setting on the tool to account for the deflection in the extension piece.

So, for the injector hold down bolts....I just tighten them by hand with a small 8mm wrench. The smaller the wrench, the less chance you have of breaking the fastener because your leverage is less when compared to something like a ratchet that has a longer handle. Just my $0.02....

 

I used a 1/4 drive ratchet to tighten my injectors. No torque wrench used, just choke up on the ratchet... Like Greg said to lessen the leverage.

 

I havent had to retorque mine, however the last time I checked was a couple of months after install. Honestly I think its a fluke rich. A hot retorque might have helped, but I highly doubt it would have caught that. I think it was a freak accident. However it fits all the problems presented.

 

the ones i have put it i torqued the 1 time and there still holding.

 

Me too!

Just Stinky luck??

 

That is actually a myth. Tested up to 15 feet of extensions and the torque was still dead accurate. Torque doesn't disappear in the extension however you have to hold the head of the torque wrench while torquing with an extension.

 

you will have deflection in the extension but the torque will be transmitted to the bolt.

 

Have you checked the threads on that hold down bolt? Did they maybe stretch ?

 

IF...one was to strip, say, one of those 120in lb bolts, then re-tighten it, hand tight with no loctite, what "could" be the outcome...

 

Use a new bolt if it striped. Never reuse it.

 

Loctite? Are we using this? How would I check for stretch? Would there be an excess of friction when spinning in the long bolt? I have been down for two days, so the VCs are off and it's not too late to install new bolts.

 

Personally I doubt those bolts stretch at 10ft lbs. I also really doubt they are designed to be stretched like a head bolt.

But I could see how they could get stripped out. Yes any sort of debris will throw off the torque value.

I noticed while doing my injectors that the hold down clamp on the injector can get ****-eyed a bit when tightening it down and possibly give a false seating/torque.

Maybe it was just a flawed copper washer? Maybe it had a gouge or deep enough scratch in it to have a very very minuet leak right off the bat that constantly just got worse over the miles.

I seem to remember you saying something weird while doing your fuel filter that you saw more air bubbles coming back from the motor than what was flowing to the motor. Does that sound familiar?

Possibly some debris down in the injector bore when installing the injector. The smallest little anything under the copper washer can cause problems. Especially carbon coming off the tip of the old injector when pulling it out.

 

Close. I had a temporary clear filter before my fuel pump during the Hutch mod... and that's where I saw a ton of air being introduced into the fuel system. I ultimately removed all the QDs to prevent air introduction before the pump. I have confidence in the fuel delivery system, but I installed a FP gauge to verify everything. Stinky is still apart (but in running condition) in the garage because I've been in bed with a bug the last couple of days. I'm ambulatory today, so I hope to get everything buttoned up after work in time to drive to work tomorrow. The fuel pressure gauge will let me know if everything is OK there.


Crooked injector hold-down bracket.... great tip!

 

I now think it may be a good idea to torque down an injector, loosen the bolt, jiggle the bracket a bit and torque the bolt a second time. Just to make sure everything is seating right and all. If when you are torquing down an injector and the injector moves down in the bore even a tiny bit I wonder if that can compromise the injector to bracket contact area. Like when you pry on something with a pry bar, when going threw the arch motion the part being pried on has to slip on the pry bar some.
With the injector bracket, if the bracket doesn't slip on the injector while torquing it down it may push the bracket over to the side a bit causing a false torque value. Then over time and heat cycles the bracket slips on the injector back to its centered position thus loosening the torque on the bolt causing problems.

Many critical parts call for double torquing. Torque the part down, then loosen the bolt and torque again. I have seen it more than a couple times.