I just spent the last couple hours going trough the posts that came up under "rod knock" when I did a search.

My engine knocks for a second maybe every morning. It has a deep knock that knocks maybe 4-5 times then it goes away. I was thinking.... rod bearing. The engine has about 4000 miles on it and was built by me. From past posts I hear it can also be a bad lifter. The lifters do have about 90+ something miles on them and they looked worn when I put them in. I do however have another set. A rod knock is supposed to always knock or get worse as the engine gets warmer and the oil gets thinner. Not the case with me engine. When I start it up and it's already warm it doesnt knock. Only when it's really cold or it's been sitting overnight. What does it sound like... lifter or rod bearing ?

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92 Z28 5.7
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Trick Flow 23° heads, XR270HR-10 cam, Accel intake base + ported TPI, TES headers, Flowmaster catback, MSD ignition
#24 SVO injectors, 1LE aluminum driveshaft.


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Lifter.....a rod bearing will always knock. When the car sits, the oil is drained down into the pan so when you go to start, the lifter is "dry" until oil is run through it, and the noise dissappears.

 

yea sounds like a rod bearing, a friend of mine had a dodge p/u and he had the knocking for about 2 weeks and threw the rod right into the oil pan

 

If it's going away, lifter. You may be able to tell which one by letting the car sit overnight, and then pulling the valve covers, and checking pressure on the push rods (see if you can push any down) and see if one is bleeding down. You can try to run a quart of trans fluid or marvel mystery oil through the oil and maybe free up a stuck lifter...

-Rich

 

Weird... this morning it didnt do it at all. No knocking! I think I'll replace all the lifters when I swap my heads and intake next week.

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92 Z28 5.7
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Trick Flow 23° heads, Comp Cams XR270HR-10 cam, Accel intake base + ported TPI,
TES headers, Flowmaster catback, MSD ignition, #24 SVO injectors, 1LE aluminum driveshaft.

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sounds just like piston slap to me. I wouldn't worry as long as it goes away.

 

Your Knock really sounds like it is either a rod or main bearing is not coverd with oil after sitting awhile. lifters make a tapping noise not a knocking noise. try some slick 50
or teflon+, that might take care of the problem. If you took the engine apart you shuold changed the lifters if you installed a new cam or put them back in the same hole they came from if you left the old cam in.
Ps it just might be the valve train a lifter or two bleeding when sitting but that would make the engine tick but only if it does it warm as well as cold.

 

Well I listened to it this morning. It did tick for like 3 times then it quit. My engine takes a split second of cranking to start. If I crank it longer on purpose it doesnt tick at all. But this morning it sounded a lot more like a lifter then a deep knock like a rod would sound. I'm "relieved" ! I have a new set of roller lifters ligned up for the engine when I swap the heads and intake. I'm sure it will go away.

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92 Z28 5.7
------------------
Trick Flow 23° heads, Comp Cams XR270HR-10 cam, Accel intake base + ported TPI,
TES headers, Flowmaster catback, MSD ignition, #24 SVO injectors, 1LE aluminum driveshaft.

Click here to see pics of my car.
Check out our car club Truspeed
Check out the Bin Archive for all your .bin needs