Hi guys thanks for any help in advance. I have a 2000 Dodge Ram 5.9 360 with about 120,000 miles on the bottom end and brand new heads. I put the heads on about 2 months ago and left the bottom end alone other than timing chain thinking that I should be okay with that low of miles on the motor. It ran great for the past 2 months. It was quiet and had good oil pressure response with RPMs. I thought I was in the clear and could focus on other things, but a couple days ago I started hearing a rapping that I couldn't really determine if it was a loud tap or a light knock. I only heard it on hard acceleration under load. But it got worse and now its everytime the motor accelerates. It sounds much more like a knock now too. I was hoping it was just a collapsed lifter but now I'm thinking it's a bearing. I would like to have someone elses opinion who has more experience with these sorts of problems though. I did some Google searing but couldn't find and definitive answers for this peticular problem. Like the title says, the truck only knocks when it warms up, quiet as a mouse when it's cold. And it only knocks when the motor is accelerating. It doesn't knock at idle or even when holding steady RPMs. Also the oil pressure sits at about 35 when idling and 40 going down the road but does not increase more than a few pounds over 40 at higher RPMs. When I first put the heads on though, the oil pressure responded nicely with RPMs going up to about 50 at higher RPM and 35 at idle. I pulled injector plugs one by one and found that when I pull cylinder number 4 injector wire the knock is gone completely. I am assuming that the problem is a rod bearing but I'm hoping there is a chance that it could be an issue in the valvetrain like a lifter. I have another complete bottom end that I am planning on swapping in if the problem is a rod bearing or wrist pin but I would like to hear someone elses input in case it is a valvetrain issue or something other problem. It would save me some time and money. Thanks for any help!

 

Is it a double knock or single knock?


I guess it doesn't matter, the bottom has to come out anyway.

 

Got a mechanics stethoscope?


Use it to determine where the sounds is coming from. It's really hard to describe sounds on the internet and everyone hears things different.



What kind of head gaskets did you use and what was the reason for replacing heads?

 

Do you hear it as soon as you start it? If it's rod bearing they will usually make noise before the oil starts pumping. You will hear it at a certain rpm when accelerating depending on how much load is on it and how bad it is.

 

For what it's worth, valvetrain noise is affected by engine RPM but not engine load. So, if your perception is accurate, the bottom end is badly wounded.

 

sounds more like a single knock to me. and yes i used a stethoscope and it does sound loudest in the oil pan. i dont hear it at all until engine warms up to temp. and youre right that valvetrain noise wouldnt be affected by load. i guess it might have been a waste of everyones time writing this post because the symptoms do fit bottom end knock. i was just hoping for a different answer. so do you guys think that its rod knock or wrist pin?

 

What's your oil pressure look like as the engine warms?

 

I think you may have a spun bearing. Need to drop the pan and investigate.

 

Personally, I can't blame a guy for wanting additional input when looking at that much bother and expense ahead.

And that's why. We'd all be hoping for a different answer!

Can't tell from here... No matter what it is, you'll want to tear down the entire rotating assembly anyway, so you'll see it when you get to it.