Thoughts on this knock? (1 Viewer)

[Phares]

pulled into my driveway tonight and heard this knock. It appears to be coming from the top of the motor. Front. I’m gonna pull the valve cover this weekend to investigate. Any thoughts on the noise? I need to drive it tomorrow but then I can tear into it. I’m leaning towards a broke valve but I’m no expert. May be time to pull the head and go ahead with all that maintenance. Mileage 171000

 

[BILT4ME]

Who's there?

 

[inkpot]

How old is your oil, and what are you running? Is if low? Your probably not going to find much under the valve cover. 2 cams and a chain. No rockers, and you cant see the valves. If you had a busted valve, it would be miss firing. Probably enough to code. I drove about 6 months on 2 burned valves and there was nothing to hear except an occasional cold miss.

 

[DBTLC]

Sounds like a rod knock to me. What does it sound like under the engine?

 

[ppc]

It is hard to tell from a video but that sounds more external than internal. Have you closely checked all the belts making sure there is not a missing chunk? what happens when you slowly rev the engine?

 

[Phares]

I will check all of this today. Oil is 1000 miles old. Good level. Belts looked clear. It definitely sounds like it is coming from the top.
I’ll be calling @beno on Monday either way.
Thanks for yalls input. More to follow once it’s light out

 

[musthave]

Does the knock increase as engine rpm increases? Hot or cold, same knock? It does sound like it is exterior but that’s just me.

 

[elhombre]

Pull one spark plug wire off at a time while it is running. See if you can tell if one cylinder is responsible for the noise. If it is a rod bearing, it will get much quieter without the piston being hammered down by the fuel explosion. Beware, this can be a SHOCKING experience.

May even be a spark plug has come loose.

 

[Phares]

Just fired up the truck. Noise is there hot or cold though it sounds quieter when cold but no data to back this up. It is definitely coming from the top of the motor half of the motor. Almost can’t hear it when underneath. With the engine cold I was better to ascertain that it seems to be coming from the middle of the motor. Also it DOES trend with engine rpm. Fan area is clear and belts are all SAT. It does not seem to be an exterior noise. Time to get into it?

 

[Proven]

Get a really long screw driver and put one end on the engine and the other end to your ear or one of these Mechanic's Stethoscope. Probe around the engine while it is running.

If it is internal it will increase repetition with rpm and very likely get louder.

To me it sounds like your fan blade is scuffing something. A stethoscope will help you pin point where it is coming from.

 

[musthave]

This means down crazy but check The two bolts that hold the top of the fan shroud. Also make sure that the bottom of the fan shroud is on the two tabs correctly. I agree after listening to it further it sounds like the fan is hitting something.

 

[Phares]

I can spin the fan by hand without any interference. It is definitely coming from the middle of the top half of the engine. I'm gonna have some local cruiser heads take a listen today.

 

[Tedward]

The bottom handle, screw driver, length of hose to the ear can work. It's not easy to tell the difference from one spot to another, it it's free and may help. Shot in the dark but worth the nothing you'll pay...

 

[LandCruisinMy93]

Check you timing chain tensioner. That doesn't sound like rod knock, maybe piston slap, but not rod knock. Honestly it sounds hollow. Like something is beating up against the valve cover...or the timing cover. The tensioner runs up against a tensioning shoe that is nylon coated metal. It almost sounds like your tensioner is either stuck or weak and that shoe is bouncing around. I don't know, more description of when it does it and if ignition increases with idle and if sound worsens etc.. is needed. An funky noise at idle tells us little.

 

[Phares]

I've listened to it all weekend and had some fellow cruiser heads take a listen. It is just off sync with the engine idle but does speed up and down with engine rpms. It sounds more like an air puff than a metal clank and I am not throwing any codes or noticing any change in performance. It is coming from the middle of the motor, top half, passenger side.
We have determined it is actually an exhaust leak at the gasket. I will order all new studs, nuts, and gaskets and get to work. I will continue this discussion in my build thread. Thank you everyone for your input and thoughts. Noises are never easy to diagnose through a video. To those that were convinced it is an external noise you were probably right. I will update as I tear into the exhaust manifold.
Thanks again to the community.

 

[Proven]

I appreciate the video and the diagnosis, because now I know what "That sounds like" on a cruiser.

 

[stu8319]

This means down crazy but check The two bolts that hold the top of the fan shroud. Also make sure that the bottom of the fan shroud is on the two tabs correctly. I agree after listening to it further it sounds like the fan is hitting something.

Doesn't sound crazy to me. I thought I was going to need a new engine mine sounded so bad the other day. It ended up being the bottom of the shroud rubbing on the fan. I just broke that part off for now.

 

[TheAmerican]

Put your hand around the manifold/ downpipe gasket. I had a similar sound and it was a tiny exhaust leak there

 

[Phares]

So the noise is still present but now it goes away once the truck warms up when I shift into Park or Nuetral and is present in all the drive gears. When the truck is cold it is present in all gears. I still believe it is an exhaust leak but the fact it changes based on the gear I'm in is super strange. Any new ideas?

 

[baldilocks]

While you are focused on exhaust leaks, check that small rubber hose that connects the egr modulator to the egr pipe. That one can create a hell off a racket.