Long story short, I can hear some kind of ticking noise that speeds up with engine RPM, and I'm fairly certain it's a fuel injector.

I'd like to replace it but I'm not sure which fuel injectors from which makes/models are compatible with my 4.7L engine.

Can anyone give me a range of vehicles for which an injector will fit/work on my truck so I know what I'm looking for from the wreckers?

 

Not a very good idea, unless you plan on pulling ALL of the injectors out of the truck at the wreckers but even then they might be clogged/non-functional and might even be of different resistance which will NOT work very well and may cause more problems.

I do not know what other injectors will or will not fit aside from the exact same model and flow-rate from identical vehicles and/or vehicles with the same motor.

So you should be looking for any truck that Dodge/Chrysler/Jeep put the same 4.7L engine in, but you'll want to make sure the flow rates and resistances are the same, and you'll probably want to get them flow tested to make sure they aren't clogged, which can be very expensive, you'll also want to set them up in your truck so that the cylinders that are furthest from the inlet on the fuel rails get the highest flow rated injectors, so you don't run into lean conditions. You will also need to buy new injector o-rings for them as well, which isn't too costly but can be a pain to get them to sit right sometimes.

My suggestion to you would be buy brand new injectors that come with flow ratings so you can do the job right the first time.

Injector tick is actually pretty normal, and new injectors may not make them any quieter... so if that is the only reason you are changing them then you might be very disappointed, especially if the ticking isn't actually injector tick and is instead lifter/valve tick...

 

This is fairly loud, and I'm a little concerned that it could be something more serious, like valve train related issues which scare the $#%@ out of me.

I could probably get a video with the noise and post it which is likely what I'll end up doing.

I touched an injector or COP though and even though I didn't move it or anything the noise seemed to subside for some reason, then became quieter but came back.

I'm a little confused about that one, but if it's repeatable then there is a good bet it ISN'T a problem with valves or rockers.

 

well you can do a compression and leak down test to check the valves... if you dropped a valve or have a broken push-rod then the leak down test should pick up on it...

Only other way to look is to get the valve covers off and start poking around in there...

If an injector is "that broken" it would be leaking gas outside of the engine which you would likely smell.

I would also suggest pulling the plugs and see if they are damaged or burnt in anyway you would be surprised how much the spark plugs can tell you, they can tell you if you are getting an uneven burn or if the fuel mixture is too lean/rich.

Pull the plugs and see what you've got there first.

Does the sound increase in volume if you rev the engine?

You can also pull each injector out of the fuel rail and give a good look, you can usually see most major clogs and what-not, but not always...... go download the OEM service manual and follow the steps to take those out, but be sure to replace the o-rings on them when you take them out.

 

Take a screwdriver and put the point end on the valve cover and your ear on the other, Repeat with the other valve cover. This will help pinpoint the noise. You can also do each injector if you want. It's cheaper than a mechanics stethoscope.

 

You might try starting the truck and then disconnecting the electrical connector to the injector one at a time to determine if it is the actual injector or not. You will most likely get fault codes, but they can be removed after you're done with the checks.

It would be a VERY good idea (as mentioned above) to carefully check the valves and springs as the era 4.7's have had broken springs, and if caught early enough, replaced without notable damage, where if you drop a valve or bend anything, get out your check book and a very FAT wallet!

It could lead to a full top to bottom rebuild depending on the damage

 

I have a stethoscope


It speeds up with RPM but does not get louder.

Now here is an interesting thing, I recently treated the engine with seafoam, and the sound has now become almost intermittent, where its barely audible at idle for the most part (or non-existent at idle) and can be heard when the engine speeds up.

Is there a possibility that the engine is gunked up and oil isn't getting to the rockers properly?

 

yes,

All the more reason to pull the valve cover on that side and check out the overall condition of the upper internals. If the engine is sludged up, you really do need to address it, and the 4.7's are very prone to it if you are using dino oil, and/or you are doing anything like extended oil changes.

Good Luck!