Worn vacuum hoses

[3narf]

Hi, I've spotted several worn vacuum hoses (it's a 1.9 TDI PD engine), any one of which could be the cause of the loud hissing noise at about 70mph and power drop off when going uphill.

Should I buy 4mm bore or 3.5mm, or a selection thereof? I'm talking about the standard woven stuff that seems to connect just about every component under the bonnet.

Thanks

[Rob69]

I doubt you'd hear a vacuum leak, it's more likely to be a leaking boost hose or split intercooler

[3narf]

Thanks.

OK, where is it mounted? Is it likely to be obvious?

A bit more information- it's most noticeable at around 70 on a steady throttle or when putting foot down slightly to maintain speed going uphill; the hissing suddenly stops and the power drops rapidly. As the revs drop the power cuts in again and the hissing noise returns.

Thanks for any info. I'll try have a proper look tomorrow (but I'll still be replacing the vacuum hoses)!

[Crasher]

It is usually the ally pipe to intercooler coupling on the right of the sump, the clip groove area cracks and then it can open up under boost, the worn vacuum hoses would cause an underboost fault code if they were leaking but a boost leak will do the same.

[3narf]

Thanks. I'll have a good look tomorrow.

[3narf]

I doubt you'd hear a vacuum leak, it's more likely to be a leaking boost hose or split intercooler

Well diagnosed; I had the cambelt done in October and the joeys had left the clip off the boost duct where it attaches to the intercooler. I guess the turbo was pressurising the duct and leaking (noise), then MAF or whatever was sensing the pressure drop and telling the turbo to stop its delivery, or something like that.

Anyway, I've got my TDI poke back and hopefully I'll start getting 60+ mpg again. Still going to replace those dodgy vacuum lines though.

Thanks everyone; once more the 4um proved invaluable. It's about time I donated to the running costs.

[Rob69]

Easy fix then !!