99 WRANGLER "KNOCKING"

I'm the proud owner of a 1999 4.0 Sahara with an I6, which I bought last year . Shortly after I bought it it started making a low knocking sound at low speed when the engine was under load (most notably when I'm releasing the clutch when moving from a stop--especially starting up a hill).

A friend gauranteed that it was an exhaust manifold problem, and when I took it in, sure enough it was cracked. They replaced it for me and now my wallet is lighter, my baby drives a lot better and gets great gas mileage--but it STILL makes the same knocking under load!!

The only possibility that I hadn't thought about was spark knock, but I thought that was more of a ping, and this is a low rattle (but I have been putting cheap gas in). Besides if it was spark knock I assume that it would happen when I revved the engine, right? but this noise only happens when it's under load.

Sorry about the long explanation--but I'm p!ssed that I can't diagnose this . Someone help me. Any ideas???

Thanks,
Jon

Spark knock and pinging are just different words for the same thing.

The only time you will notice this happening is when the engine is under load. That is when the cylinder pressures are the highest and the fuel will self ignite.

This can be caused by a carbon buildup in the cylinders or by poor gas.

Try using a higher octane fuel to start with and if that doesn't help enough, investigate the carbon buildup problem

JD

At my dealership we shipped a Jeep I6 with only one quart of oil in it. The guy who owned it made it 20 miles before he shut it off. After filling the jeep up with oil it would only knock under load. Some of the I6 jeeps suffer from "crank walk", so you might have that or the jeep at one time may have been without oil, depends on how bad the knock is.