I have a '95 E150 Clubwagon with a 5.0 in it. I have owned the vehicle since it had 18,000 miles on it and it now has 240,000. It has been well maintained and runs flawlessly holding good oil pressure.

In the last few months I have noticed a slight knocking sound at idle that was difficult to identify. Sometimes it was worse than others but always there. It seems to have gotten worse in the last few weeks.

This van is used almost exclusively for towing and I recently returned from a 4200 mile round trip tow to deliver one car and pickup another. It seemed to me that the noise was worse when the weather was cold during the trip. It didn't seem to matter if the motor was cold or warm.

I have been a racer for 20+ years and know intimately the sound of a rod or wrist pin knock and this isn't. It appears to be coming from the harmonic balancer on the front of the motor but I have little experience with the OE harmonic balancer.

Can an OE balancer cause a knock? I know its not any of the accessories and the fan clutch is fine. It almost sounds as if the fan blade is just touching the shroud but I checked it and its not. Other than the harmonic balancer I was figuring it might me the timing chain hitting the cover? With that many miles perhaps the chain has stretched and the sprockets are worn?

I have lots of experience building racing engines and know them well. I have even build 5 liters for racing but the ins and outs of very high mileage street engines is not where my experience lies. Race engines don't see that kind of mileage so this stuff just doesn't happen.

Steve
'95 Clubwagon XLT