My truck is currently stock and recently started making a knocking noise louder than it usually does. I researched and have found the injectors can make a knocking noise when not performing correctly. I took it to a local shop who hooked it up to a snap on scan tool and ran some tests. It passed the Buzz test but continually failed the contribution test on cylinder 8. I'm going to go home and remove valve cover and unclip the injector to see if the noise goes away. I'm sure hoping it does as an injector by the looks of things is definitely the cheaper option. I'm scared because if I was listening to a gas powered truck and heard the sound my trucks making I would assume it was a lower end noise. Wish me luck and if you have any advice please pass it on. My truck only has 148,000 miles

 

While you are under there check the torque on the injector hold down bolts. They should be 120 in/lbs. If it is much below 100, you could have a knock related to a loose injector. Let us know what you find. INCH pounds, not foot pounds, just for clarification.

 

My truck has an audibule knock as well. Cylinder con test points at 8 always

Checked y torque values and all are fine. 220k on mine but no lack of performance.

I wouldn't be alarmed if your gauges read good.


Denny

 

It's common for 8 to fail the CCT. Nothing to worry about.

Many of us know the knocking noise of which you speak. Some have spent thousands trying to fix it. Some have done nothing and just let it be to no ill effect. When you rev the engine, does the noise go away? If so, then just stick to your normal maintenance schedule and drive the truck as you normally would. Turn up the radio if the noise bothers you. It's not uncommon for these engines to knock a little louder at times....it comes and goes. If something was wrong, then the knock would increase with the RPM and you would have other symptoms as well....such as reduced fuel mileage etc.

Welcome to FTE!

 

I pulled the cover and had no luck with getting the knock to go away after unplugging any of the injectors on the drivers side. I will check the torque values on the bolts as stated above and see what that does. The guys I had scan it kinda had the same attitude as others as they are noise motors and sometimes you just have to live with it. I'm ok with that if I have to but it sure is hard to sleep good knowing it could cost a bunch of cash if it goes BOOM. Thanks for the help.....im going to pull the other cover tomorrow and check that side out.

 

You can always do compression test since your in there. Might also be fuel knock (note it does not have many miles for the year, diesel contains alot of moisture if not used it goes bad and you end up with moisture and even water in your fuel tank) leaving you with worn out injectors even if they passed, they tend to get noisier with time due to wear .

 

I am the self-proclaimed knock master. Here are the common causes:

• As the truck ages, there are components in the fuel tank and picukup line that leak, break, or clog. This can starve the fuel or introduce air in fuel. Search "Hutch mod".
• I am learning loose injectors are far more common than many realized before. As HKusp stated, they don't have to be very loose to get a knock. Ideally, you want a torque wrench that has 120 inch/pounds near the middle of the range for the best accuracy. My first attempt was with a ft/lb wrench with 10 ft/lb at the bottom of the scale. That was a total and utter fail.
• Tired oil will aerate more than fresh oil. Air in oil is a noisy bugger, and it make the idle a little lopey.

In order for an injector to truly fail a CCT, you would have a big miss at idle. Most CPS sensors make #8 look bad when it's fine.

 

Welcome to FTE !! First of all I agree with everything these guys said. I myself have a E99 also and had the same problem back when I got my truck. Back then you were able to still buy the black IH cps which in my case helped some. The hutch mod also helped quiet all of them alittle bit. But still not a good CCT.
And if I recall correctly on my E99 I had all AB injectors.
So what injector do you have in #8?
Once again if I recall correctly the Late99-03 they used a AD injector to help with this issue.
Someone please correct me if I am wrong.

I cured my problem by installing new speakers and just turned up the radio!
The knock is still there and it hasn't gotten worse and hasn't gotten better.
All I can say it's a stock E99 with a 7.3 and "It is what it is"

 

Ed, I THINK it was an AE long lead (LL) injector for the cure. I BELIEVE all the later injectors are AD except for the LL ones, but I may be mistaken.

 

Jason thank you for the correction.
I knew it had something to do with AD's....Daaa..... One more cup of coffee PLEASE LOL
With a stock E99 with stock AB's I wonder what would happen if you put a AE in #8 ??

 

Do they even sell LL injectors anymore? I'm gonna put stock AD injectors with Clay's FRX fuel crossover in my E99 in early March.

 

My #8 went bad and it idled fine. I have e99 also. I would notice mine most after it warmed up, or a long drive. Not so much on the freeway but when you stopped and went to park it. In a parking garage you really noticed it. If you fit. I changed it out and that noise went a way. Clay's frx also helps a lot. But if it's not really loud, it is probably just the beast of the motor. They always fail the test.

 

Ok...I got off work early today and decided to do some more investigating. Si ce the first time I crawled under the truck I thought it sounded to be possibly coming from the front of the auto trans area. I took the inspection cover off and the sound got alot louder. I had my son run the gear selector thru the gears. When you go from park to "r" the knock goes away put in "n" and the knock comes back put in "drive" and it goes away again...No cracks visible in flywheel no wobble of the torque converter.....any ideas...drives normal

 

Finally some good news. I went back out and decided to check the nuts on the torque converter/flexplate. Damn things where loose, I got almost a full turn on all the nuts...the knock is now GONE......so my next question is reuse the nuts and tighten with blue locktite or red locktite?. I'm really glad that it was a labor only repair as I'm in the process of finalizing building a garage and is all I could think about was the cash I have saved was going to a new motor and not my shop...Thanks for your help and I hope this thread helps others find there KNOCK in the old 7.3. Thanks guys.

 

Also...reuse the nuts or get new?. Ford or auto parts store?