20/21 The year of the engine knock (2F in this story) (1 Viewer)

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My issue has been going on since November but it seems as if in the time since there have been a lot of threads of 2F and 3FE owners asking about engine knocks.

In my case it started as a strange rattle while I was heading out to pick up a table for the house. I turned around and went home to swap cars. I've pulled the valve cover and inspected the pushrods, valve springs, and valve movement. I've listened to through the screwdriver to each bolt on the rocker assembly. I've pulled one spark plug wire at a time and listened for noise change. Lastly just now I loosened all my belts so as to take the load off the harmonic balancer (which isn't wobbling or showing any sign of failure.)

I've checked the oil and the coolant both of which look like the liquids they are supposed to be as opposed to some mixture revealing bad things. I've checked motor mounts and brackets and nothing revealed itself.

its 30 Deg F here in Vermont and I just did the belt test and the truck started up no problem and runs smoothly but still a deep rpm dependent noise from within and low. I had to move the truck around the driveway and oil PSI is fine as is engine power. This I understand to indicate that the pistons sealing and all moving.


So the next step is to either pull the oil pan and have a look or just pull the engine. I'm not exactly racing to do either at the moment because I don't enjoy working on my back in the driveway in the winter. I'll eventually tow the truck over to my friends shop and get it up on the lift. In the mean time I'm researching swap options should I find something expensive inside the bottom end.
 

Gretsch

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Any video of how this sounds anywhere? I agree it seems as though there has been a slew of Engine knock threads lately. Mine has always had a bit of what I would classify as more of a rattle and have always assumed its how these 2F's generally sound. But with all these knock threads its got me thinking maybe I am mistaken about what I am hearing on mine. So was a bit curious about what the knock you describe on yours sounds like. Sub'ed.
 

Dr. John

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I have an obvious knock that goes way as soon as the engine warms up a bit. After lots of investigation, including replacing all the bottom end bearings, I've written it off as piston slap and learned to live with it.
 
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In my case the knock just happened one day and got louder. Bad enough to not run it. Sounds like a piston slap but bad enough to warrant attention. I think it’s a bearing problem though. Hoping that I can do new bearings and a reseal and be good to go.
 

Apagee83

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You have helped so many on here that i hope someone will be able to assist you with figuring this out. if in the lower end your gut feeling that it is a bearing is probably correct. crankshaft bearings or connecting rod bearings would fit rpm dependent deep sound from the bottom. drop that pan and lets see how much metal you find. can you see metal reflection in dipstick oil?
 

MoaByte

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Stethoscope didn't narrow it down? It's ever-present? (Throw out bearings can make funny noises.)
You are a better mechanic than me, but sometimes when it's your own, it's good to hear from others.
 

OSS

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If the compression in each cylinder isn't sort of the same, the imbalance during idle can set up a loud banging sound in the transmission at idle as the engine shakes the gears. The idle may feel pretty smooth, but the shock of a laggy piston can make stuff bang together. Probably not your issue but thought I'd mention it again
 
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If the compression in each cylinder isn't sort of the same, the imbalance during idle can set up a loud banging sound in the transmission at idle as the engine shakes the gears. The idle may feel pretty smooth, but the shock of a laggy piston can make stuff bang together. Probably not your issue but thought I'd mention it again

yeah that’s a good point. I can do a compression test. Some times it’s sound like the clatter you get when you get power pulses in a set of meshed gears. I can play with the throttle and quiet it down around 1k rpms. I’ll do the comp check and shoot another video.

this was from a month or so ago. No air leaks and no exhausts as I just redid the whole manifold system.

 
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Stethoscope didn't narrow it down? It's ever-present? (Throw out bearings can make funny noises.)
You are a better mechanic than me, but sometimes when it's your own, it's good to hear from others.
I thought about the throw out bearing and tried various shifting and clutching tricks but no change in the sound.

definitely appreciate the input. I’m being careful to not fall into the diagnostic traps I try to warn others about. 😉
 
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You have helped so many on here that i hope someone will be able to assist you with figuring this out. if in the lower end your gut feeling that it is a bearing is probably correct. crankshaft bearings or connecting rod bearings would fit rpm dependent deep sound from the bottom. drop that pan and lets see how much metal you find. can you see metal reflection in dipstick oil?

the dipstick was nice clean oil. Very few miles since I changed the oil and Toyota filter. My gut says bearing and @OSS has a good point with the compression check pointing to a weak cylinder like if a rod bearing failed.
 

Apagee83

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Just a thought before you dig too deep. Pull the plugs add a little oil turn over four or five times. Reinstall the plugs fire her up to see if the noise is the same. Maybe this will help in finding out the true source of your issue.
 
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X2 on the compression test. Also compare the spark plugs. In the video, the knock doesn't sound rhythmic like a bearing. If nothing shows up on the compression test I would borescope the cylinders. Something wants to get out of that engine.
SimS
 

BGarcia88FJ62

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I'd forget about compression testing for now. Drop the oil pan and take a hard look at your bottom end that knock sounds like a loose rod cap bolt or something
trying to free itself from your block. :beer: ✌️
 
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Ok. I’ll get motivated and drain the oil and drop the pan. I think this is also the logical next step.
 
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Time to pull the pan...

Oil analysis is good to show you an increasing wear metal trend, and potentially save you from a problem, but you're past that - at the "i have a problem" stage.

time to pull some bearing caps and see what's what
 

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