Engine Noises - What Are Some Causes?

[84Toyota4x4]

So, lets say you have a 22RE motor, and it makes some interesting knocking noises, but only at certain times, what would your diagnosis be? Its been running strong with no other problems, just auditory noise.

When the truck was bought, it had a "rebuilt" motor in it. Nice and clean, painted, etc. It had some nasty timing chain problems (bolt hit the tensioner) which I fixed with a new timing chain set. This obviously puts my doubts in the quality of the rebuild. It then was in an accident which broke the front cover, so it got a new front cover, timing chain, tensoner, head gasket, etc again. I also recently replaced the power steering pully bearing which was making some noise.

Since replacing the PS pully bearing, I noticed a new noise (I suspect its been there all along), which Im not sure what it could be. Its almost a knocking sound, but only when the engine is coming down from RPMs, or idling. For instance, you rev it to 2K, hold it for a second, then let off. It will knock a number of times, then quiet up for the most part with a very faint knock in the background as it runs. Its hard to locate it in the engine with the screwdriver handle trick (no stethescope), but it doesnt sound valve train. It MIGHT be timing chain area, but its hard to tell. I was thinking it might be excess slack on the chain when the pressure drops causing noise, but the tensioner should hold it tight with spring pressure.

So, any ideas? Im starting to wonder about wrist pins, or that sort of thing, but I have little to no experience as to what that sounds like. Or, could it just be a poorly sized bearing from the rebuild thats eventually going to go? I have no idea really, enlighten me oh great ones

~T.J.

 

[PUO-BANNED]

possibly a piston pin. take it up to about 6 grand and hold it till it blows. problem solved :redneck:

 

[junkyard jim]

A connecting rod has grown up and wants to leave home!

 

[JThompson]

possibly a piston pin. take it up to about 6 grand and hold it till it blows. problem solved :redneck:

This occurs every time I drive my truck... It's a 4 cylinder!

 

[84Toyota4x4]

Im pretty sure its not valve train, and since I've already replaced all the timing chain stuff plus oil pump and so on, that there isnt anything I can do short of a rebuild anyway. Im just curious what things it COULD be that would be causing it.

I basically have accepted that its just gonna have to run until it dies. I have another 22RE thats fresh from the machine shop just waiting to be assembled, so I can go that route if I have to. Im just curious if anyone has had a similar sound, and found it to be a broken pin, worn thrust washer, or something like that for sure after they tore it down.

~T.J.

EDIT: After some reading and searching, it seems that piston slap is pretty common on these things too. It has a pretty rattly startup then goes away quick, which I had chalked up to timing chain slack, then the only noises it makes after that are the knocks as described above. Im starting to wonder if maybe its just piston slap? I figure Ill pull the valve cover and check everything in there (spacers, adjusters, clearance, etc), and get a stethoscope to mess with, but its just aggravating when I have no real direction of how to diagnose or narrow it down. I read about people pulling plug wires one at a time as a diagnostic "tool", what does this accomplish or tell me if I were to do that? Is it simply that there will be no combustion force on the piston/rod so any noise should be quieter? It doesnt really determine what is making noise, just narrows it down to a single cylinder (if its a piston/rod problem)?

 

[Toyotanut]

it is just a 4 cylinder toy motor. Run it till it dies and then throw your other one in there. Then repeat

 

[skrause]

It has a pretty rattly startup then goes away quick

If your timing set is good then that's your valvetrain. Use an oil filter that has a good antidrainback valve and that should stop. The other noise, probably a rod knock or spun bearing. Hold it at 6k as mentioned until the problem surfaces through the side of the block. :redneck:

 

[84Toyota4x4]

Just did an oil change not even 500 miles ago with a Napa gold filter which has the silicone anti drainback valve. No matter what kind of filter is on it, its made that noise. From the cheap one that was on it when we bought it, to the decent one we put on after I did all the work, which got changed to a nice one after a couple hundred miles, its always done it. I had the same thoughts about it. I was thinking timing chain slack there too, because its way louder than valve train IMO, but there again, the spring tension should keep it tight. I dont want to rule out a bad tensioner, but its done the same thing with TWO new tensioners that have been put in it. Is it possible the block or head were machined too much when it was rebuilt so the chain has a little too much slack? It was tight when it was installed, but if it stretches at all, I could see how if it stretches farther than the range of the tensioner, it could cause rattling. Then again, if that were the case, the oil pressure part of the tensioner shouldnt be able to quiet it because it would be out of the range for that as well.

~T.J.

 

[84Toyota4x4]

:corn:

~T.J.

 

[ljtoy]

Toyota oil filters are cheap - try one.

 

[84Toyota4x4]

Been there, done that. Like I said, DOESNT MATTER what oil filter is on it.

~T.J.

 

[84Toyota4x4]

Other opinions?

~T.J.

 

[TigTorch]

A lot of 4cyl and especially 6 cyls have a harmonic point where they make a brief rattle at a specific RPM when you blip the throttle and release it. Mostly valve train noise I think.

To ease your mind do this:

Warm up the motor. Pull the dipstick and look at the oil on it real close. If the oil has big silver flakes or especially copper flakes in it, motors shot.

Next change the oil. Look at the oil for metal flakes and to see what settled to the bottom of the drain pan. Cut the filter open and look. The stuff your hoping not to find will be at the base of the pleats and near the top and bottom edge of the filter. Your looking for too much metal. All motors will have a few specks (The oil always flows from the outside of the filter inward so contamination will be on the outside of the element.) Post photos if you can!

If no metal then your motor should be sound.

 

[84Toyota4x4]

Like I said, it just got an oil change less than 500 miles ago. Oil looked fine. I still have the filter though, I could cut it open and have a look.

I guess my main thought is that Im 90% sure this sound has been there for the entire time she's owned the truck (years). I would think that if it were a connecting rod bearing, it would have been gone by now. I was wondering how long it would run with a bad wrist pin bushing or something I guess, or what else could even make such noises. In my experience, a bad rod bearing is kind of a "working or not" kinda thing. They dont "slowly" go bad from what Ive seen in my short time. The last one I killed in my truck went from working, to shot in about 5 minutes.

Im kind of leaning towards piston slap, and a little excessive valve train noise (which I will look into)...

~T.J.

 

[Pat]

The trick of pulling the plug wires helped me diagnose my blown head gasket. I don't know if it will tell you anything about your problem but its easy enough may as well try it. Just don't shock yourself like I did, it freakin hurt!

One thing those toyota motors are known for is not having much adjustment in the timing chain, I'd check there again too.

But if you've got a new motor I'd put that in, tear the old one down and the source of the noise will probably present itself.

 

[84Toyota4x4]

The REAL trick to pulling the plug wires, is NOT pulling the plug wires, haha.

Just use a circuit tester probe, clamp to ground, then probe the plug. It will short to ground without ever taking the boot off.

~T.J.