Dropping the oil pan will be the next thing I try. I hope it's nothing internal!!

 

With your ranger, did it rattle when the engine was cold and could you hear it at all at idle?

 

I forgot to add. I took the serpitine belt off and ran the engine and the rattle was still there.

Also, you can keep the rattle making its noise if you hold the rpms. If it starts rattling at 2000 rpms you can hold it steady and the rattle will continue until you either let up on it or increase the rpms. It will increase with the rpms until you can't hear it anymore. Also, it doesn't always start at the same rpms. One time it started at 1800 rpms, and the next time it didn't start until 2500rpms.

 

More information:

I noticed if there is a load on the engine it will not make the rattle. I put it in drive and held the brakes and put it around 2500 rpms and did not hear any rattle. Could this be rod bearings if there is no rattle while the engine is under load? Now if it is in park you can hear it rattle when holding the rpms.

 

I had what i thought was a vavle tick at around the same rpms, but since I had the water pump and T-Stat replaced the tick is gone (it was a short drive from the shop, I will be able to confirm tomorrow). What I have noticed that the temp gauge shows its running cooler. I had a total system flush as well, before when the truck was warmed up the temp needle was almost past the "2", now it doesn't even touch the "2". So, maybe mine was slowly over heating causing a valve to tick? The shop also said that it was a 195* Stat, I made sure of that.

 

My 87 5th ave. did that same thing. It was the timing chain slapping the cover. It was more what I call a knock though.The only time it would do it was when the engine was running free, not decelerating or accelerating.

 

My temperature range is fine, I do keep an eye on that. Also, I have just put a new chain on it (my first chain made the knocking sound Charlie was describing. I am going to pull the oil pan today and see if I can find anything wrong.

 

I dropped the oil pan and everything looked good. There was no metal flakes in the pan or oil. I checked all the bearings and they were all tight (with a little movement side-to-side which should be normal).

 

Maybe there's something loose in the bellhousing. TC to flexplate?

 

I checked that too while I had it tore down. I am just going to keep on driving it and see if it gets any worse. Sometimes these things are impossible to find. All I know for sure is that is does not do it while the engine is cold and the sound starts anywhere from 1800 to 2600 rpm. It doesn't do it under load and I can't hear it at idle. Oil pressure is good. It's more of a rattle sound, but it doesn't do it under load so it can't be spark knock.