i was driving down the freeway and the truck surged and a loud flapping/knocking sound started. i had it towed to the dealer. the tech listened to it and said it sounded like a spun rod bearing. he told me i need to swap the engine out. so i towed it home last night and pulled out my spark plugs and found one of the coil pack plugs was missing its center electrode, and the plug well was full of carbon (see picture). i replaced that plug with a brand new one, hoping the flapping/knocking sound would go away, but it hasn't. i have a video, but it is too big to upload. (i will work on getting it posted so you can hear/see the sound.) my rig is a 5vzfe with only 190,000 miles on it. thank you for reading my post, and I appreciate any advice/comments because I don't know what to do at this point.

 

Disassemble the engine and see what happen if you have another vehicle.

 

You can pull the oil pan and inspect the crank bearings on some motors. But loud knocking sounds that are not in the head are generally in the crank/rod department. Might be a swap. Might be a rebuild. You can do it or pay someone else to do it. All up to you. Mostly depends on your checkbook skill level and time to work on it. Did the motor trip any codes?

 

It doesn't sound good but the noise could be coming from any number of places. Some could be very minor like maybe a loose starter or something to what is described by your mechanic. I would get a mechanics stethoscope and see what is actually the problem. Just because it was a Toyota mechanic doesn't mean he is right.

If by chance it is a major problem, I would suggest buying a rebuilt motor. Used motors or salvage motors is a risky gamble. Rebuilding it yourself is an option but you need an extremely long amount of time. I would suggest having at least month. May sound long but with machine work, ordering parts, and doing it on your own free time, it takes awhile.

A rebuilt motor can be dropped in a day or so. Just my suggestion. Find the noise first, it may just be a minor problem.

 

Best advise on the problem yet. Nice work Terry

 

Don't sound good. I spun a connecting rod and could change the sound of knock by advancing and retarding timing while listening with a stethoscope. Wouldn't have changed if a crank bearing. But in the end it I still had to swap out motors.

 

Thanks for the replies everyone. My wife was driving when it happened, but she said check engine light didn't come on and didn't notice anything happening on the gauges. Just mild lurching while at interstate speeds, then the knock/tap started.

Great idea on the stethoscope, thanks, I'll definitely give that a try.

People have said to pull the oil pan and inspect for shiny metal (to help know for sure whether spun rod bearing), but w/4WD, not so sure about getting that pan off. So instead, I drained the oil before work this morning and plan to inspect it closely tonight. Some mechanics have said maybe center electrode broke on that spark plug due to piston coming up and hitting it - thoughts? Would the plug have metallic specks on the porcelain if that was happening? A neighbor's going to bring his borescope over to see if we can see where that electrode wound up. Anybody think it's possible that piece is rattling around causing the noise, and maybe did little to no damage? Wishful thinking? The plug was an NGK BKR5EKB-11 Standard Plug, center electrode was nickel, and I always gap 'em to specs. Thought about pulling the replacement spark plug then starting it, to see if the noise went away - thoughts on that?

Someone mentioned revving the engine, and if it WAS a spun rod bearing, the knock frequency would increase - sound right? At this point I'm just trying to find simple ways to be sure if it's a spun rod bearing or not, before having it towed somewhere to get the engine rebuilt (because I couldn't agree more - just because it's a Toyota mechanic doesn't mean he was right!). Would love to rebuild it myself and save some $$$, but with no garage plus limited tools and time, not so sure about heading down that road. With nearly 200,000, I tried to convince myself to replace taco, but just can't do it.....and wife def. wants to keep......so might be an engine for xmas this year.

Advice on places to go in Portland, OR area for this? Been talking with B & M engines and NW Team Yota - anyone heard good/bad things about either, or know of someone else around here they'd recommend? Advice on specifics to ask about when choosing who to take it to? Thanks for any additional input.

 

I find this diagnosis suspect. Why? Simply, the outer electrodes would be mashed before the center electrode is hit by the piston as the center electrode is not out beyond the outer electrodes.

IMHO, the plug just failed somehow and spit out the center electrode.

Pulling the replacement spark plug would not cause the sound to go away if it's the missing center electrode causing all that noise since it would still be bouncing around in the cylinder.

Have you probed around with a mechanics stethoscope to try a finding where the sound is the loudest?

Can you post a short video of varied engine speeds?

 

I used sunwest on east side of washington. I've liked their engine but I'm a 22RE guy.

 

just examined the oil can't tell if i'm seeing gold dust or not. it kinda looks normal. gonna try the bore camera next.

 

Bummer. Run a clean magnet through the oil.

 

The thing I don`t understand when the electrode broke off in theory the plug should not have been able to fire.

Which should have tripped the Mil with the misfire code .For whatever cylinder

Did the rod break and piston hit the plug??

I can`t think a little electrode can sound anything like a rod bearing knock.

One of those things you really won`tknow to you open it up and look.

 

I ran the camera down the spark plug hole (number 3), and it appears like there is a hole on the top of the piston? I'm not exactly sure what I am talking about (newbie), but does that look normal? Should I scope the other spark plug holes to see if they have holes on top also? Thank you for all of your replies.

 

Looks like a hole in the piston at the end to my eye.
I agree with wyoming, it's going to have to be opened up to fully diagnose.

What I thought was a missing valve was just going down the spark tube.

 

thanks rw for your response. so are you thinking my camera went down through a blown valve to get a view of the top of the piston? i have been trolling the internet for a similar scenario, and i stumbled upon this guy:

http://www.tacomaworld.com/forum/1st...-part-2-a.html

it looks like his electrode danced around inside the cylinder and eventually cracked the head, and left out the exhaust. so having said that, do think that hole (on mine) goes all the way through the top of my piston? i really appreciate all of your help. i realize i need to just start dissecting, but all i have for a work space is a short unlevel gravel driveway, and i am considering hiring a mechanic to do the work, but i kinda wanted to know what happened to it before i open my wallet.

 

Going in through the spark plug hole, you are in the cylinder that is bounded by the piston which is a solid surface below and the cylinder head and valves above. It looked like to me initially the scope was looking up and the cylinder and then later flipped down toward the piston.

Yes, ate in the video appears to have put a quarter sized hole in the top of the piston to my eye. However, the dark spot may not be a hole, but just the appearance of one due to the shiny area around it. Once the head comes off the issue(s) will become apparent.

 

This thread from another site will show you what the top of the pistons look like, page 6
http://www.ultimateyota.com/showthre...ght=overheated

and the bottom of the head with the spark plug in the center of the 4 valves, page 8:
http://www.ultimateyota.com/showthre...ght=overheated

 

Has a compression test been ran on that and the other cylinders? A cylinder with a hole will not make compression.

 

Thanks thefishguy77... These motors are 20 plus years old and most of the Toyota mechanics today most likely dont know the older ones. 99% of the work they do is new to 4 year old trucks. The ones that worked on these most likely retired. I know the 22r but would not consider myself a Toyota mechanic.

Oregon taco... A compression test will tell you quick. If you dont have a tester, what about trying to bring that cylinder to top dead center and with a thin wooden dowel, poke thru the spark plug hole and getting an idea of how high the piston is and make a mark on your dowel. Then best guessing try and hit the hole or the dark spot and see if it goes a little deeper. With some poking and proding, you might go way deep or even hit the risk pin. A clothes hanger or metal wire of similar type might work better.

Since you may have a mechanic to do the job, I feel it is cheaper to buy a motor instead of rebuilding one. I can buy them cheaper then rebuilding them. I can rebuild one a nickel at a time and is easier and slower to do, but in the long run cost more. Really shop around and I dont know a goood source for the 3.4, if you buy a used motor, strip all of the sensors off of it as they will add up if needed in the future.

 

i am finally realizing i need to do a new engine. have you guys ever heard of this place that sells jdm's:

http://www.japanpowerinc.com/home

if not, do you know a decent source? are the jdm's wired the same as the domestic engines? or would i be better off installing a reman?