turbo boost leak

[jackherer]

I've been left with my brother in laws 2.5TD 2wd Bongo while he goes on holiday so I can do some work on it for him.

Its had a pair of front droplinks and I'm fitting an immobiliser but there is a problem I am a bit stuck on. There is a loud whooshing noise that I am pretty certain is a boost leak, it builds up when the revs rise and only happens when the engine is loaded, it is fine when revved in neutral and worse when going up inclines.

Everything I've checked seems fine, I've loosened and retightened all the jubilee clips on the boost hoses and the intercooler doesn't look to be split or anything.

I tried driving it with the passenger seat tipped back but then I could only hear the engine, it drowned out the boost leak noise so I've not been able to pin it down.

Can anyone suggest any likely places boost can leak from? Its had a reconditioned cylinder head recently so a lot of things have been disturbed so it could be a number of things.

Performance seems quite good, but I think it has deteriorated a little while I've had it, and I think the noise has got louder too. I was following a friend of mine yesterday in his mx5 and he said he could only hear the whoosh noise, it drowned out the diesel clatter!

[Northern Bongolow]

could it be this.
http://www.igmaynard.co.uk/bongo/forum/ ... ifold+stud

they can sound similar.

[mikeonb4c]

I've been left with my brother in laws 2.5TD 2wd Bongo while he goes on holiday so I can do some work on it for him.

Its had a pair of front droplinks and I'm fitting an immobiliser but there is a problem I am a bit stuck on. There is a loud whooshing noise that I am pretty certain is a boost leak, it builds up when the revs rise and only happens when the engine is loaded, it is fine when revved in neutral and worse when going up inclines.

Everything I've checked seems fine, I've loosened and retightened all the jubilee clips on the boost hoses and the intercooler doesn't look to be split or anything.

I tried driving it with the passenger seat tipped back but then I could only hear the engine, it drowned out the boost leak noise so I've not been able to pin it down.

Can anyone suggest any likely places boost can leak from? Its had a reconditioned cylinder head recently so a lot of things have been disturbed so it could be a number of things.

Performance seems quite good, but I think it has deteriorated a little while I've had it, and I think the noise has got louder too. I was following a friend of mine yesterday in his mx5 and he said he could only hear the whoosh noise, it drowned out the diesel clatter!

...are you quite sure it isn't being caused by a broken manifold stud. Common problem and quite curable with the right tools

PS - typical, NB got in first

[Northern Bongolow]

great minds mike

[mikeonb4c]

great minds mike

some more tattered than others - you don't want to see inside mine at present

[jackherer]

Thanks for the replies.

I'm a mod on another car forum and I wouldn't dream of posting a thread like this without searching or reading the faq first, what I failed to say was that I did read about the exhaust manifold stud issue before I posted this thread and when I checked them they seemed fine, the head is still new looking around the exhaust ports, no sooty marks etc. I didn't fit the new cyl head but I imagine it was fitted with new studs as they look to be in very good condition.

I've taken a break from this issue for now, I just fixed the fuel gauge (thanks to your faq) and fog light so it feels like I'm getting somewhere again.

My next move might be to remove the intercooler so I can give it a proper check for splits.

[mikeonb4c]

I'm a mod on another car forum and I wouldn't dream of posting a thread like this without searching or reading the faq first

Well you're a rarity on here: Bongo owners tend to ask first and search second (I can't even think where the FAQs live myself, I'm so out of touch ). So we're used to popping off quick replies at least by way of reassurance, but tend to leave the enquirer to do a bit of homework searching for details themselves (not that the search facility on here is stunning, but they can always come back if they have no luck).

[Northern Bongolow]

try this then, unless you have already searched it .
follow the large pipe from the air filter housing towards the back of the head, there is a vac pipe with a green one way valve at the end just before its end where it goes into the large pipe, has this snapped off. this may allow air to be sucked in here rather than through the filter.
or.
on the drivers side, from the pump top to the steel pipe at the front of the inlet manifold there should be a small bore pipe, this can snap off and stops the pump from advancing when you press the loud peddle. it could also be blocked with crud,in the advance part of the pump top.

[rita]

Hi jackherer,
The easiest way to find a turbo boost leak is to pressure test the system(pipework).
You will hear the leak a lot easier without the engine running.

Cheers.

[jackherer]

Thanks for the suggestions.

The pipes you mentioned are present and correct, nothing snapped or loose.

I don't have a compressor here unfortunately so I can't pressurise the inlet.

There is a metal pipe towards the front of the inlet manifold (EGR?) that looks like it might be leaking, there is some staining and the gasket appears to be misaligned so maybe that could be the problem.

I have given the Bongo back to my brother in law now, he is going to take it back to the place that fitted the cyl head to see if they can find/cure it. I'll post the fix here if/when I find out what it was.

[Simon Jones]

The 'mis-aligned' gasket is quite standard. It's actually ok as is has an extra 'ear' which sits outside of the joint & serves no purpose. That joint is also well known for leaking an oily gunge which will also be inside all the pipework & the inlet manifold. In the past, I've removed the aluminium elbow, cleaned it out & then refitted with a drop of Hylomar gasket compount on the joint. I don't think it will make any difference to the apparent boost leak, but will be a bit less messy.