Thread: Loud Hissing at High RPM

As far as I know I think its from a bighorn!

Im going to put a balloon on the blowoff valve and take it for a drive tomorrow, see if it makes a nice POP!.

Originally Posted by Davehillbo

As far as I know I think its from a bighorn!

Im going to put a balloon on the blowoff valve and take it for a drive tomorrow, see if it makes a nice POP!.

Rubber gloves make BIGGER pops

Steve

haha it made a nice pop lol. How would i blank it?

First off, get a boost gauge - it is most likely a boost control device where the spring is worn and you don't want to over boost.

But I would un bolt the device and make up a plate to cover the hole it left, and seal it with some silkaflex or something.

But it is most likely an Isuzu part so you may be able to get a replacement that works.

Check to see if all the clamps on the hoses after the turbo are done up tight. I had a similar sympton once on my 300 Tdi. Think it was once after taking the intercooler out to clean it. Forgot to tighten clamp where hose connects to inlet manifold. No effect until turbo boost got up a bit. Then hissing and turbo boost gauge behaving erratically. Remember the standard wastegate setting on 300 Tdi just stops the boost going over 15psi. Under pressure the hose would undoubtedly balloon slightly and importantly, air hiss out the end when hose is not tight enough without clamp done up.

Maybe if all your clamps are tight a similar effect could be caused from a split in a hose that is not readily noticeable unless you could closely observe motor under enough load to produce high boost pressure.

Ok, can anyone direct me as to what boost gauge to get and how to fit it?
Really appreciate the help ive had, most support of a land rover group ive had, over here most people don't have Isuzu conversions.

VDO make good quality ones and you could plumb the pipe fitting into the blanking plate you make up. That way there is no metal filings getting into the intake manifold.

I have the 30PSI gauge listed on this page, with the VDO kit.

VDO: Vision Black Series Gauges: Boost and Turbocharger Gauges - eGauges.com

I went mechanical for simplicity.