Whistling Bongo.......

[expresso bongo]

For information, I recently fitted a new (sections 3 & 4) exhaust system. Shortly after, I noticed that my Bongo was "whistling" when using high power. I repaired a broken exhaust manifold stud a couple of years ago so I feared either another manifold leak or impending turbo failure, but I need not have worried. Here's what I found:

I examined the exhaust manifold area and couldn't find a leak from the gasket. I examined the intercooler circuit and again, no leaks. I removed the exhaust manifold heat shield and air intake duct, examined the turbo impeller, found that the impeller is free to rotate and has no perceptible end or radial float. It spins when the engine is idling. With the intake duct in place, I revved the engine and noticed that the squeak/hiss/sizzle begins EXACTLY as the waste gate begins to close. I began to suspect that the noise is purely from the acoustic properties of the new exhaust (sections 3 and 4) I fitted a couple of weeks a go.

I then took the van to Hampshire Diesel Services where Eddie drove the van and repeated my inspections. He reached the same conclusion, but suggested I consult Universal Turbos in Fordingbridge for confirmation.

The next day I visited U.T. and Dale Spriggs checked my turbo, same points as before. His conclusion was the same (though expressed in more technical language-he's obviously an expert). Basically, he said there was nothing whatever to worry about, the turbo's fine, it's just the new exhaust. Indeed, almost all of the noise is emitted from the tailpipe-you can hardly hear it with the engine covers open. With the covers on and the doors and windows closed, I can't hear it at all. Dale said he could modify the turbo so that it wouldn't make a noise (on the rig) but I declined-I don't need any more expense and it tells me when the turbo is boosting (as long as I've got the window open!) which can be useful for economy!

Finally, I bought the new exhaust from United Automotive. No doubt it's a pattern part, it was fairly cheap (£170) but delivery was very quick.....perhaps it's a bit less restrictive than the original? We'll see how it performs.

[mikeonb4c]

An excellent post there expresso - could be v useful to another owner sooner or later.

Mike

[westonwarrior]

I remember driving bedford tm's in the army and they used to whistle when the turbo kicked in

[Richard D]

The turbo on my wifes trooper has been whisling for years now just satrted one day for no particular reason and hasnt stopped since . Only noticeable when revving high though. Man at garage said it is the shape of the impeller blades as they start to wear on some turbo,s (depends on how they have been driven) they start to whistle. would be more noticeable with a new exhaust that is not coated on the inside with sooty deposits acting as sound deadener.