Rod vs. Valve knock
- Thread starter eboutin88
- Start date
eboutin88;1441269 said:
I personally think, valves noise sound like clicking pens, just sometimes a little louder. (my valves make noise too)
Rod knock sounds like somebody knocking on a counter top.
At least thats what i think it sounds like.
Use a long screw driver, put the handle up to your ear. Touch different parts of the head and cam covers. Listen for where the noise is loudest or at all. Then do the same for the block if ya can, maybe from under the car. You should be able to pick up a cheep mechanics stethoscope at your local auto parts store. This will give you a general idea of where the noise is coming from.
PLEASE use extreme caution when doing this as you have to lean over a running engine. Have someone else watch out while you work. NO loose clothing
Rod knock is usually pretty loud compared to valve tic.
PLEASE use extreme caution when doing this as you have to lean over a running engine. Have someone else watch out while you work. NO loose clothing
Rod knock is usually pretty loud compared to valve tic.
If you are going to remove the engine, why worry now? Just pull the oilpan, the main caps, and check the bearings. If one is roasted, it'll be rather obvious.
My rod knock sounded like a piston was hitting the head at 3,500 rpm - not something I could ignore day after day.
valves - sewing machine when in clearance. Valve noise should be .5 : 1 with rpms and starts at idle and just gets louder with higher revs. Other noises will drown this out in higher rpms though. When mine were out of clearance, it made quite the racket/ clatter from 1000-2500rpms or so. I could easily make the noise with the slightest blip of the throttle when at idle.
rk should be 1:1 with rpms and should be most obvious from 2000-3000rpms. Should not come and go, should be louder when the motors at operating temp (early on set).
I should add that like the post above, there is no "mold" rk follows. Some have lost oil psi, others say they never saw a drop in psi. Some have it start at 1800rpms and others higher up. A lot of things can knock with so much metal under the hood, grimjacks advice is simplest at this point.
or IJ's if your not pulling it
rk should be 1:1 with rpms and should be most obvious from 2000-3000rpms. Should not come and go, should be louder when the motors at operating temp (early on set).
I should add that like the post above, there is no "mold" rk follows. Some have lost oil psi, others say they never saw a drop in psi. Some have it start at 1800rpms and others higher up. A lot of things can knock with so much metal under the hood, grimjacks advice is simplest at this point.
or IJ's if your not pulling it
Get a helper to hold the throttle at the knocking rpm then unplug injectors one at a time, if it's RK it should stop.
IJ's advice is probably one of the easiest ways to to verify, another way would be to ground out each plug wire with a test light (hooked to ground) and slightly pierce the wires be careful to not create a hole this will cause the spark to jump. This takes the load off the selected cylinder due to no fire, as with removing the injector clip, there is no forcing of the piston down. Dont quote me but i do believe when you do this and there is still the knocking noise you would have a lifter issue, being that the lifter movement is mechanical and the rod/piston movement is based around ignition in the cylinder.
If you've got a mechanic's stethescope (or long screwdriver/baseball bat/broomstick to ear), you should be able to hear very easily whether it's in the top end or bottom end even if you don't know what you're listening for. Put the stethescope (or whatever you're using) to different places on the top end of the engine (valve covers, injectors, etc.), see where the noise is louder. Then go to the bottom end and listen from the oil pan. You should be able to hear where it's louder and where it's quieter at the very least. If it's loudest on top, it's definitely not rod knock. Shouldn't be too hard to tell what you are closest to while testing, and that should give you a good idea of what could be making the noise.
IJ's injector clip trick is another good way of ruling out rod knock.
IJ's injector clip trick is another good way of ruling out rod knock.
From the first second I start the car you can hear the knocking. At idle you hear it and when you rev it up it is ridiculously loud. The reason why I thought it was a rod knock is because of how loud it is. I may be wrong, How loud could a lifter or a valve noise be.
.Took IJ's advice "Get a helper to hold the throttle at the knocking rpm then pull and replace each injector clip, if it's RK it should stop"
Found that Cylinder number one and Four were the noise makers. One a little, Four, huge difference when unplugged. I guess, it is officially the death of the just rebuilt 7M. Stock too, thats the part that pisses me off. Now I am building one with ACL bearings, eagles H Beam Rods and Wiseco Pistons. Hopefully this will last.
Thanks IJ for the advise.
Found that Cylinder number one and Four were the noise makers. One a little, Four, huge difference when unplugged. I guess, it is officially the death of the just rebuilt 7M. Stock too, thats the part that pisses me off. Now I am building one with ACL bearings, eagles H Beam Rods and Wiseco Pistons. Hopefully this will last.
Thanks IJ for the advise.
Too bad they werent companion cylinders, just kill the plugs and fuel and make it a four cylinder lol!!!!!! Did you rebuild it or have it rebuilt?
what kind of repairs would happen if it WAS from the head/valves? i'm having this issue now - i'll be doing IJs method tomorrow but interested in both possibilities for knowledge.
GrimJack;1441328 said:
I'm with Grim Jack, even if it was a rod knock you would still have to replace the bearings and/or do machine work. If it was the valve would still have to replace the valve and/or the piston, if youv'e gone that far, then I would just do the whole engine. From my experience from the past, if you did the valve job, the presure would just blow your rings out. Then you end up losing progress, then all the money, effort, parts, would just be a waste of time, money.