Unusual noise

Question

i have a 2007 BT cruiser on a Ford E450 V8 diesel.
if i lift off the gas pedal suddenly (especially in the low gears) there is an unusual loud noise coming from under the hood, this noise is not easy to describe but maybe a relief valve opening and closing two to three times.
Also when i am coasting, usually up to a traffic light, i can hear a screeching noise like a loose fan belt, i have replaced the fan belt on the front of the engine, the spring adjuster pulley seems fine, but i still have the same noise.
Good to hear from anyone that might be having the same noises.

midnightsadie · Answer

I had that engine on a truck, one of the support bolts holding the alternator broke.

bucky · Answer

The noise letting off quickly under load is probably the turbo waste gate opening to relieve pressure. The cure is to ease off the throttle. The screeching may be your brake wear indicators trying to tell you something. Lightly apply the brakes when the screeching is happening on roll up. If it goes away check the brakes and the hubs bearings.

kneal44 · Answer

mine still sqeeks when i back off. found that the engine drops rpm faster than the fan .... the inerita makes the fan rotate some and hence a squeel. replaced the tensioner and belt.
for me not a probem since i know where the noise is comming from.

jack_flynn · Answer

Thanks to all,
look as i am not the only one these problems
The turbo boost relieving pressure, I think this is correct for the noise I am hearing.
The screeching pulley belt i think is also correct,
now i am happy that these noises are not serious and i will have a peace of mind on the road

Forum Discussion

Unusual noise

4 Replies

About Technical Issues

Related Content

Generator noise reduction

Unusual tire wear

Unusual Rental Motorhomes

Unusual Occurrence

Unusual propane plumbing???