Help with Tapping Noise!!

New member here! I will post up a new pic soon, just wanted to get this out there. So my truck started making this noise and I wanted to see if you guys think it could possibly be an injector.
See video below.

A bit of background on the noise. I bought the vehicle last Wednesday, drove it 200 miles to the coast the following day. Truck drove awesome when i test drove it and it drove great again on the way to the coast. At about the 200 mile mark, the truck stalled when coming to a stop, i started it back up and it started making the clacking sound in the video, which was shot in the gas station i pulled into.

I decided to drive it to our destination since I was already so far from home and the sound went completely away when I drove off as if nothing happened. Stayed this way for about another 100 miles. I replaced the spark plugs when I got to the hotel with new NGKs, gapped them to .043 which is what the manual says. When I pulled the old plugs, they looked like they could be changed but cylinder 2 plug was pinched shut. I put the new ones in and the loud clacking went away but now its more of a loud ticking that increases with RPMs. The truck drives okay, but I its throwing a P0302 code which is a misfire in cylinder #2. I tested the coils too, pulled #2 and put in on another cylinder to see if a code gets thrown in that cylinder however it does not change.

at this point im hoping its just an injector, seafoam in the brake booster and gas tank seemed to help a little, but the tick and misfire are still there. any words of encouragement or ideas what it could be? There is a loss of power, I can tell, when you give it gas and the truck down shifts, things tend to smooth out a bit.

 

I'm gonna take a shot with all bad news. But I'm wrong 82% of the time so others will post after me with a better answer. Assuming a high mileage, old timing belt, i think your belt stretched/jumped a tooth causing your cam valve timing to get out of time. The #2 piston slammed into a valve and bent the valve into the spark plug. That was the original clacking. When you removed the bad plug it allowed the valve to recess into it's seat to eliminate the valve to piston impact. But I think you have a bent valve in #2. You're getting a misfire code in #2 cause the leaking valve won't hold compression. A compression test on #2 and a manifold vacuum test will help confirm. Or, just turn the radio up till the ticking goes away.

 

^^^^^^This is logical.

 

Would that be a direct short on the plug and blow a fuse?

 

No. Sparkplugs....well...your ignition system in general works by shorting out a circuit to create the spark.

Something bent that sparkplug.

Likely, the head is coming off and your getting a valve job and new timing belt. It sucks but its not fatal.

A compression test I think is the next step. It will confirm or rule out valve damage.

 

For OP's sake, I really hope this isn't what happened....

 

Man that is a really logical outcome, appreciate the educated guess remington351. I did forget to mention that the previous owner had paperwork that the timing belt and water pump was just done. It’s also noted on the cam cover. Although I guess it can’t be confirmed since I didn’t do the work myself. It does have about 137,000 on the odometer. I’ll try to do a compression test this weekend and update you guys. I have all the tools for it, just need the time to pull off all the plugs.

 

Who did the work? It almost sounds like someone screwed up. We had another member that recently went through 2 timing belts because he was using some aftermarket brand. You should really go with the OEM(Aisan) kit on this.

 

I’m not sure exactly who did the work. The paperwork he had was for a local shop that has a decent reputation. Here is an update. I was able to do the compression test.

 

That test tells the tale.

Put a tablespoon or so of oil i. Cyl 2 and try the compression test again. If it goes up its rings. If it stays the same its valves.

I'm assuming that the new plug gap remained good?

Worst case, #2 bearing is going which let the piston go too far up, kissing a valve and the plug. Best case is a valve is jacked and you need to pull that head.

 

Shit. Just listening to that video. Rod knock.

 

Yes, the plug gap in cylinder 2 is good now.

 

Drop the oil and see how metallic it is. It may be gray.

 

Damn... hate to see this, definitely going to be interesting seeing what happens from here forward.

 

The spark plug at the top of a convex combustion chamber so I cant see a piston top making contact directly with the spark plug. I'm thinking your rods and crank are in ok shape. Maybe your issue is confined to the head and not the lower end. Hopefully.

 

Yeah. In theory if the pistons are flat tops the squish area would have kissed.

Borescope

 

Sounds like a rod bearing is on its way out..

 

Looks like the pistons are dished. Borescope is a good idea.

 

I borescoped it. Can’t tell if there is damage to the piston or not. Maybe someone with a better trained eye can take a look.


Here is a comparison of the other pistons. The pics at the top of my post are of the dead cylinder. This one below was fine

 

Nice pics. I always enjoy when posters give us updates so we can follow the repair. The piston looks fine to me. If there was significant impact it would be apparent. I still think we are dealing with valve issue. The extra oil buildup on the dead cylinder supports a bent valve that has ruined the valve guide/seal and is allowing oil to leak into the combustion chamber.

I rotated your images so to compare.


The jagged area in red seems to show some type of impact.


Your good cylinder pistons have smooth curves and recesses which is what you would expect to see.


Google of a new piston.



If you pull the valve cover, rotate the #2 cylinder to TDC, apply compressed air to the chamber, you should be able to confirm which valve is leaking up through the lifter and bucket. The bucket lifter design does not allow much visibility of the valve stem, if any. A vacuum test should also confirm a valve leak as well I believe. Keep us posted.

 

Dang! Remington has some mad skills!

 

You can see something was hitting the piston.

 

I don’t have an air compressor so that might be a challenge to do the next steps. I guess what’s yalls opinion from here? I have a reputable Toyota/Lexus mechanic that I trust to help with the work. I asked to quote a used motor swap with low miles. I don’t want to have to go down that route but would it be worth fixing the parts that need it in the top end assuming the bottom end is okay? I don’t think any noise is coming from the rod bearings and my guy said he’s never really seen them go bad in all the 4.7ls he’s had which I believe, these engines are rock solid! I just don’t know what caused the valve to get bent. I think the previous owner must just have drove it like he stole it.

 

The previous owner may have had the timing belt break on him, and had it changed,and noticed the noise and that may be the reason he sold it.
Or something fell in the intake or cylinder and caused the damage.
I wonder if the top of the head has damage as well

 

I think since the piston is not mutilated or punctured, and the knocking sound has diminished to a clicking, your bottom end is good to go. Get an estimate from your Toyota guy to replace the head, vs an entire engine, which I'm thinking has to be 3-4k even for a used engine with no knowledge of the top or bottom end.

Let us know what he says if he tears down the head. I'm most interested in knowing the possible issues that caused your stall, restart, clanking noise. And based on your original post, I don't think the previous owner was trying to deceive you.

A bit of background on the noise. I bought the vehicle last Wednesday, drove it 200 miles to the coast the following day. Truck drove awesome when i test drove it and it drove great again on the way to the coast. At about the 200 mile mark, the truck stalled when coming to a stop, i started it back up and it started making the clacking sound in the video, which was shot in the gas station i pulled into.

Did a valve keeper fail? Valve spring? Valve stem shear or get stripped off? I've seen an example of each but on Ford and GM products. Hoping to avoid those types of failures is why I migrated to a Tundra.

I've read that belt replacements that are one or two teeth off will still run the motor, albeit poorly. Did your belt jump a tooth or two, cause the stall, then on restart you were just unlucky with the interface of the valve and piston at that exact moment? Maybe, but it seems odd that only one valve would be affected by a jumped belt, you would think if one valve cycle was mistimed that others would be as well since they are all driven by the same camshaft. But the counter point is the impact, those noisy, does not appear to have done much damage to the piston. There is evidence of piston to valve contact, but not exceptionally severe. A steel valve can do much more damage to an aluminum piston if it gets angry at it.

Please ask your mechanic to do a detailed post mortem for us weekend hackers.

 

BTW, you asked your mechanic to quote you a used motor with low miles. For a 1st gen your 137k is a used motor with low miles. I doubt there are many under 100k used motors lying around and would not be surprised if the used sellers wanted close to the price of a reman like this one.

https://www.jegs.com/i/ATK-Engines/059/853A/10002/-1

 

The 4.7l is an interference engine, right?

 

It looks a reman head is $400-600. New Toyota head sub assembly is $950 at Mcgeorge Toyota Parts online but I'm not sure if that includes the valvetrain components or is just the head casting. You can email them with your vin and they will tell you exactly what your getting. You didn't say what you bought it for, or the overall condition, but if it's in good shape I'd make the investment for a 06 with only 137k.

 

def loosing compression in #2, Rings or valves just have to figure which one.
Bent spark plug has a concern. either the piston is hitting it or someone bent it to keep it from firing hiding an existing issue (Not my first choice)
As others said, it may have jumped timing but that would cause the valve to hit the piston (please correct me if I'm wrong) could be a wrist pin or rod bearing.
I stretched out an old 1971 351C and popped 3 pistons and rings just by getting into the cylinder ring ridge (that damn thing would fly until I blew it up) and oil blow back looked like a freight train or mosquito duster until I rebuilt it (yes, a few mods went into it for over 500HP)

 

That's a nice looking truck! Worth fixing.
Have you asked the seller about your findings