Hey, I have a 1997 Mercury Grand Marquis with the 4.6 V8 engine. For a while now, the engine has been making a fairly loud rattling/knocking noise when the engine is warm and under a load, especially when the transmission is in third gear and vehicle speed is around 30MPH. Also, the sound is considerably louder with the Air Conditioning on. I tried using 10W40 oil instead of 10W30, but this didn't help any. The owner's manual recommends 5W30, but Haynes Repair Manual recommends 10W30. I've heard that this sound can be caused by detonation/preignition. I'm going to try some fuel injector cleaners, as well as switch to a higher octane fuel. In the meantime, anybody know exactly what's going on? What's causing that noise? Thanks!1997 Mercury Grand Marquis 4.6 V8 Engine makes a knocking/rattling noise when warm and under load?
Ok, First go with the 5W-30 oil, Next I think you have preignition problems, There is a gray plug that has 2 wires going to it on the fender well under the hood, one wire green the other I think is gray, unplug the grey connector it is called a octane shorting bar, it adjusts the octane level in the PCM, Go drive it if it is better and or gone leave it out and put in the glove box, next start using a better brand of fuel.1997 Mercury Grand Marquis 4.6 V8 Engine makes a knocking/rattling noise when warm and under load?
remove the fan belt and start it. do not let it run more than a minute or two because it will have no water pump. it is likely the bearing in the air conditioner clutch pully on the end of the compressor
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment