New 4Runner knock :/

[Trojan4x4]

So the 4Runner I recently bought developed a knock. It's apparent when it's warm, and very apparent after it's been ran a while( you can hear inside the cab). I can feel it in the transfer case shifter in any transfer case gear (besides Neutral). The knock seems to be amplified if I put the car in forward or reverse gear. If you turn the AC on the Rpms increase and so does the knocking.
The timing belt was done around 5-6 years ago, so I'm goin to attempt to take a look at the belt and pump tomorrow. I've also read that the flex plates are a common fairlure point. The car has 67k miles. Had a full syn oil change 200 miles ago. The serpentine belts have some cracking but I don't think that would affect it. I'm really hoping this not a rod knock, but this is very scary haha
Any suggestions? Thanks in advance



EDIT: 1 year update, after replacing my serpentine belts the knock basically disappeared

 

[AntleredRuin]

I have the same knock which I narrowed down to my AC compressor or clutch/idler pulley. No knock when cold, seems to mostly go away when in N and P (slightly raised RPMs), and seems to almost go away with AC off (not just turned down). When in D or R, the engine RPMs drop slightly, allowing you to really feel and hear the knock.
With the AC on, the knock increases when the compressor kicks on, and decreases when it turns off. You'll hear the click as the clutch grabs, and you can watch it happen if you open the hood. The engine RPMs will increase slightly when the compressor kicks on (this is normal). This just helps the engine not stall when the compressor is dragging on it.
This does not mean that the knock is directly related to engine RPM. Engine RPM is just a natural side effect.

I removed the AC drive belt and drove it for 2 days knock free to verify. Bought a new belt and installed even though the old belt looked fine and the knock was still there. Said **** it. Most likely compressor, and the AC blows great for now. With AC off, only the clutch is spinning, not the compressor, and with the belt off, neither are. Been 30k+ miles since. I'd really forgotten about it, but I may grab an idler pulley just to see. $25ish from AutoZone.
At least I know my engine isn't gonna blow anytime soon.

I can feel the knock in my tranny shifter (don't have 4wd for a t-case shifter).

Your case COULD be belt knock. A missing 'tooth' in the drive belts would slam (knock)

 

[thegipper]

Flex plates make more of a ticking noise when they crack and not a knock, unless they maybe outright break.

Any CEL?

Pull the oil dipstick and look closely at it. Do you see any shiny speckles in the oil? If you do, not good.....

 

[jgue467]

Start planning what to do.

....I'm really hoping this not a rod knock, but this is very scary haha
Any suggestions? Thanks in advance

True rod knock is very loud, like a 4lb hammer hitting a very solid piece of metal and can be heard a block away. It could be the beginning of it, difficult to say since it's deep in the engine. You are probably safe to drive around town and local areas but I wouldn't go cross country in it.

Mine started making a similar sound under similar conditions (very slight loping at low rpms then seems to dissappear after the 2-3 shift) but I've got nearly 284k on it so it's kinda expected eventually (sad anyway!).

Just start thinking of what you will do when the time comes. I'll probably go with a jasper engine, 3 year unlimited mileage warranty - the rest of the truck is worth it and I Really enjoy driving it. Luck and enjoy the runner! :cowboy:

 

[mtbtim]

Did you run a CarFax on this vehicle before you bought it? Something is not adding up. If it is a rod knock, this should not be happening at 67k if the vehicle was taken care of.

 

[Trojan4x4]

Did you run a CarFax on this vehicle before you bought it? Something is not adding up. If it is a rod knock, this should not be happening at 67k if the vehicle was taken care of.

The car does have 67k miles, according to carfax, and was driven consistently.
Did the fuel filter and spark plugs on it today, spark plugs looked almost brand new and all of them were NGK, which suggests the tune up was done before. That's good news since it seems like it was maintained at least some what.

I listened with a screw driver and I could hear it in the engine itself, not AC or transmission.
Going to prop the timing belt cover off and see what's going on there once the car cools down.

 

[mtbtim]

The car does have 67k miles, according to carfax, and was driven consistently.
Did the fuel filter and spark plugs on it today, spark plugs looked almost brand new and all of them were NGK, which suggests the tune up was done before. That's good news since it seems like it was maintained at least some what.

I listened with a screw driver and I could hear it in the engine itself, not AC or transmission.
Going to prop the timing belt cover off and see what's going on there once the car cools down.

Well, hate to say it but there's a very good chance the seller wasn't being exactly honest with you. Maybe they heard the knock, didn't want to deal with a potential costly repair and unloaded the vehicle. Maybe they even put a product in the engine like Motor Honey to quiet down the knock so they could sell it without the potential buyer knowing there was a problem with the engine.

I hope I'm wrong but you having an engine knock shortly after buying it is just a little too convenient.

 

[Tinigunner11]

There's got to be something wrong, someone may have run it out if oil before. Could you post up a video of it knocking?

 

[Moonbandit]

Never jump to conclusions.

Just take it one step at a time and see where it leads. All you can do.

 

[Scramble]

With only 67K I don't think it was driven consistently. Too many cold starts with gaskets & seals drying up. Hopefully the PO started it up every 2 weeks to keep the oil flowing through the engine. Good Luck.

 

[baja1]

:ybrick: you can't win....too many miles no bueno...too few miles no bueno. hope it turns out to be something simple!

 

[Trojan4x4]

Thanks for the replies !
Knowing my luck, it's probably a rod knock haha
I'll try posting a video sometime soon
Meanwhile, there's not much I can do besides driving it and saving up for a JDM swap

 

[2016 4Runner SR5]

You say the timing belt was done 5-6 years ago? Why would it have been done with such low mileage? What oil and filter did you use when you changed it recently?

 

[Trojan4x4]

You say the timing belt was done 5-6 years ago? Why would it have been done with such low mileage? What oil and filter did you use when you changed it recently?

Timing belt are made out of rubber, which detoriates over time, so it's like 90k or 5-7yr thing.
I used 10w30 Mobil 1.
The old oil that came out actually looked a little on the thin side, with a slight red tint.

 

[2016 4Runner SR5]

Timing belt are made out of rubber, which detoriates over time, so it's like 90k or 5-7yr thing.
I used 10w30 Mobil 1.
The old oil that came out actually looked a little on the thin side, with a slight red tint.

I wonder if they were using thinner oil to flow better and cover up the knock. Red could also be transmission fluid which is an old trick to flush engines. Hope it's not as bad as it could be.

 

[Trojan4x4]

I wonder if they were using thinner oil to flow better and cover up the knock. Red could also be transmission fluid which is an old trick to flush engines. Hope it's not as bad as it could be.

Next week I will change the oil, send a sample to black stone labs and also cut open my oil filter.
When I bought the car the oil cap looked clean (no sludge) and the dipstick was nice and shiny as well

 

[AntleredRuin]

Dude, try the drive belts, specifically the AC belt. Simple enough and you said they're cracking anyways. I can slightly hear my 'knock' on the engine too, but I know it's my AC. Start simple.

Sent from my SM-G900V using Tapatalk

 

[elazo1]

injectors

I wonder if they were using thinner oil to flow better and cover up the knock. Red could also be transmission fluid which is an old trick to flush engines. Hope it's not as bad as it could be.

i had a similar problem, i changed coils, plugs and wires and the problem was still there. ended up being the fuel injectors. number 2 cylinder was misfiring. i ended up installing (all 6) new injectors and now my truck runs like new. i have 380k miles on the truck. i would try new injectors

 

[Trojan4x4]

Dude, try the drive belts, specifically the AC belt. Simple enough and you said they're cracking anyways. I can slightly hear my 'knock' on the engine too, but I know it's my AC. Start simple.

Sent from my SM-G900V using Tapatalk

Doubt it's anything related as its after the car warms up. However I'll check that too tomorrow


Also it wouldn't be injectors, as that would make my idle rough and or throw a CEL.

Tomorrow at work I will scan for any old codes and post an update

 

[Brveagle]

If it were mine, i'd pull individual spark plug wires off and see if the "knock" goes away. Try and pinpoint a cylinder.