Exhaust Noise

[danboy99]

A couple of weeks ago, while driving along in my 2.5 TD 2WD I suddenly became aware of a throaty exhaust sound which I had never heard before. I assumed the exhaust had sprung a leak (newish import so no idea how old it was) and as my intention should this happen was to go down the stainless steel route I booked it in at my local Long Life branch. When I went there yesterday I went under the vehicle with the fitter prior to anything being done to verify the leak, but the old exhaust was fine - no leaks at all! But the noise is there all the same, particularly noticeable at around 2,300 - 2,500 RPM - a sort of throaty spitting noise. Not a squeak - and I can see that Manifold no 1 stud is present and correct but haven't looked further.

I had the new exhaust fitted anyway having gone to the trouble of booking in and taking day off etc - very lovely it looks too. Inevitably though the problem persists.

The guy who fitted the exhaust suggested maybe a turbo bearing being on the way out - but I don't think this would show this symptom would it? The vehicle drives perfectly by the way.

When he said this I must confess to some paranoia as shortly before all this happened I changed engine oil from the standard local garage 10W40 to Fuchs fully synthetic 5W30 (suitable for Turbo Diesels, and actually listed at the motor Factors as the oil to pour into a Ford Ranger Diesel), after much deliberation and checking on here what others have done. This wouldn't harm the turbo would it folks?

I haven't had a good look at the exhaust manifold yet, but I am wondering if the manifold could crack, or if the manifold gasket could just go, or if maybe another manifold stud has gone but is not presenting as a squeak, but as described above?

Any ideas Peeps?

Thanks,

Dan

[Simon Jones]

Have you checked the air filter & associated ducting is all in good order? The induction noise can sound very similar to that of the exhaust.

[danboy99]

Thanks for that Simon. I will check that next. I guess I have asked a difficult question as noone else has suggested anything yet.

What I have done this evening is remove the heat shield and have a good look with the engine running. All studs are present, there is no evidence of sooting anywhere on the manifold, the turbo or anywhere else and I certainly can't feel any escaping gas at all while revving with one hand and feeling with t'other, so certainly I will check the inductgion side as you suggest - just seems a little odd that it wasn't there at all in nearly a year, and suddenly one day recently it appeared and is still there.

How would a worn out turbo present itself - what would it sound like? I repeat the Bongo still drives perfectly...

[missfixit70]

I wonder if you've lost some of the exhaust baffles in one of the silencer boxes or they've come loose if you're sure there are no exhaust leaks?

[mister munkey]

Strange one this.

A Bongo will run quite quietly even without a back box on, Mike can vouch for that too.

The 2300 rpm mark is where the turbo kicks in. Could be worth exploring that avenue . . . .

[danboy99]

Thanks Kirsty - I was hoping that yesterday when old exhaust came off and shiny SS one went on but noise persists even with brand new exhaust. New exhaust is straight through so no baffles...

[missfixit70]

Worth checking out the EGR side to see if that's got any leaks in the pipework? Comes of the back of the turbo, goes around the back of the engine to the EGR valve itself & then on to the air intake. Bottom bit of pipework on the drawing - http://www.lushprojects.com/bongopartsm ... mgno=.html

[danboy99]

Thanks Kirsty - you mean the 20-310 part I take it? I will try to find it tomorrow. If this had a split would it lead to a throaty exhaust noise then?

As an aside - you run on 5W30 synth don't you - the turbo would be happy with this wouldn't it? Probably just a coincidence that in my case moving to this grade was so close to my noise starting...

[missfixit70]

I don't think the different oil'd make any difference, I've been running mine on 5w 30 since its first oil change (just done another) as long as you didn't overfill?