[Beater Red]

I have develpoed a knock in the right side of my engine (looking in hood). It is really faint when I first start it, but as soon as I step on the gas it gets louder and faster. When the engine gets HOT it knocks harder too. I thought it might be a lifter or a bent rod, but I checked them both and I checked the springs and nothing was wrong. I was going to take the oil pan off and clean it out and replace the pump, and while I was there look around in there, but I can't do that without taking half of the stuff out from under the truck. Inside the valve covers was filthy and it looks like the guy who owned this truck before me didn't change the oil regularly. Could I just have one of my valves blocked open by crud and it be fixed with a good engine flush from good ol' Auto Zone or could it be something very serious that will take ripping the engine apart? It isn't missing or back firing, and it seems to be running normally for an old pickup. Please give me ideas.

 

[jebx]

More info would be nice, what motor, what year, how many miles?

give your best description of the knock it makes. Possible rod knock?

 

[Beater Red]

It has a 262 4.3. '90 model cheyenne. It was running a little hotter than normal like 220 or 230 when it started knocking. The best way I can describe the noise is you know when you were little and you put baseball cards in the spokes. It didn't make noise until you got going, but it got louder as you went faster. Mine doesn't make the noise right when I start it, but as soon as I hit the gas, even in park, it starts. It gets loud when I am going down the road and when it is hot it knocks even louder yet. I don't know if it is an oil related problem or f it is something else. Like I said in my other post, it drops oil pressure because it is overheating. The noise is to the right of the engine when you are looking in the hood. It isn't really high in the engine but a little higher than middle of it. It sounds like it is in the manifold but I checked all of the rods, and the rocker arms, and the springs. I don't have anymore description than that. I hope it is enough.

 

[jebx]

If the top end checks out OK, the bottom end is the next likely place. I would call a rod knock sound like a sledgehammer in the motor, it is a pretty heavy knock. It can start out faint, but usually knocks louder and louder. I have seen some that knocked somewhat intermettintly, but got worse and worse until it died. Pull the pan and inspect the bearings. Might want to plasti-guage them. If the engine is junk I might reccomend just getting a used motor put in, it is a slight gamble, but how much money do you want to sink into a '90 with 200K on it? I looked online and saw 4.3s ranging from $100-450 at local scrap yards here.

Also, the overheating until the oil pressure drops is not good. That is a recipe for disaster and most likely the root cause of failure. You should fix that before continuting any further.

 

[jebx]

One thing I forgot to mention, sometimes a small exhaust leak can sound like tick tick noise.

 

[coonbottom]

yuh, it can be exhaust leak, if it is higher up and is more of a slap kinda knock (did that make any sense?). Rod knocking it low and pretty loud.
Change your oil to see if you have any water in it. You could have a small amount of water running in due to the over heating. when you replace the oil run a quart of ATF thru your engine to clear up your valuves. Just dont run it too hard or too long with it in there.
If you cant find it..you might want to have it checked out. Oil pans dont hold rods in very well.

 

[dreamrr]

I had a 1991 Chevy Silverado 4WD. It developed a very similar knock. I sold it a few months later just to be safe. I would ditch the truck before the motor blows.

 

[Forklift]

that doesnt sound good, but without being there or seeing pics of it pulled apart , we cant tell