Ok what should I do about this problem. I had a thread a while back on it and after replacing the valve cover that rusted out and check the heads I thought I had solved the issue. Well......... needless to say the noise is back and seems to me that it wants to do the ol' in. Ok so here are the symptoms.

1. Funny oil pressure. As in takes a couple seconds to build psi. after building psi the psi will vary. one time it may reach a cold start psi around the 60 mark or so. then at another time the psi will read like 45 to 50. Sounds odd.

2. The noise is only evident when traveling down the road at anywhere from 1800 rpm to 3000 rpm. Ok another curve ball. If you stand on it to pass a car a couple seconds of real bad knock then all quiet again for a little way. after returning to normal speed it will return.

so any ideas on where to start diagnosing this. I know of coarse i need a hughs plenum on it as i go through a quart of oil like its gas. (seriously) So that's on the list. I checked to see if the valve-train had any debris. all clean on the top of the heads. changed to winter oil. thinking bad oil. Still no change. I'll try to catch a vid or sound clip of it doing it. but I can't make it do it on demand that's the strange thing. the only thing that will remotely tell me when its going to happen is the oil pressure. Correct me if I'm wrong but i don't think the timing chain would be the cause because the rpms don't change when it happens?

Thanks for any help I can get. I love my baby and don't like to see her suffer.

 

Fix the plenum, a blown plenum will cause a knock.

 

sounds like spark knock (pinging) to me. what octane gas are you running ? if you're not already running high octane, switch over to it. see if it helps.

 

throw a bottle of octane booster in it and see if the knock disappears.

If it does, check plenum gasket and replace if necessary (take off Throttle Body and look for pooling oil anywhere in the intake manifold). By "pooling" we're not talking about a big puddle, but if you have any amount that would be thick enough to make a droplet, you have a leak, fix it.

Also swap the spark plugs and the cap and rotor. keep the number 5 and Number 7 spark plug wires away from each other as much as possible.

 

+1 on the plenum but also too maybe some debris in the oil or galleys causing some blockage causing the oil psi to fluctuate like that. Mine on a cold start i have about 80psi then at norm running temp im around 45 or so

 

whats with #5 and #7 plug wires squiurrel?

 

There on the same side of the block so they might be hitting.

 

Ok I'll check for the pooling oil. At the moment I am using 87octane. Is the knock going to cause any damage? I did replace the plugs that was the first thing I did when I got it in december. Haven't done cap and rotor cause im not looking forward to the tight spaces. Any tips to getting the cap off and back on easily?

 

Here:
http://dodgeram.info/tsb/1998/18-48-98/18-48-98-v8.htm

 

If you pull the intake to change the plenum gasket, drop the oil pan and pull the pump. Chances are that the oil passages are clogged or even the pump could have a blockage. If the lifter gallery looks like it has sludge build-up, you'd be better off pulling the engine and rebuilding it. No way can you remove clogs from the passageways unless the block is soaked in a cleaning solvent; otherwise, your work will be for naught.