Uh Oh... The hissin' Nissan...

[Tunguska_1908]

Hello all my learned colleagues, I hear the onset of yet another issue with the trusty old ZD30.... When I accelerate lightly I can hear a 'hissing' sound, also when I back off the accelerator the sound is more evident. Doesn't seem to be affecting power (such as it has). I have checked all IC hoses etc etc. Could it be a leaking/failed actuator on the turbo? The dawes valve dumping over boost? Something more sinister in the wind perhaps?
Any suggestions or ideas would be greatly appreciated.

Andy
Perth WA

[NP99]

Is it an exhaust leak?

[JonnoDe]

More information would be helpful, what is the boost pressure against? Did this start happening after anything? It does sound like a possible exhaust leak or intercooler leak. I would go over all hose clamps just to be sure as well

[kevin07]

is your egr blocked it could be a split pipe.

[Tunguska_1908]

The EGR is blocked off & the EGR pipe was recently replaced due to being warped. Also replaced the IC with a new one. Hissing sound is coming from the LH (kerb) side of the motor in the region of the turbo. Don't think it's an exhaust leak as there's no 'fluttering' sound.

[Tunguska_1908]

Recently replaced EGR pipe as it was warped and blocked off the EGR & fitted a Dawes valve while I was at it...

[Tunguska_1908]

Boost hovers around 12-16psi, Replaced IC the other day, EGR blocked off & EGR pipe replaced also. Hissing is coming from the turbo side of the motor in that vicinity. Rechecked all hose clamps. I'm stumped...

[P4trol]

Bung missing, eg egt sensor or bung where the sensor would fit?

[threedogs]

If it goes PITOO you may find the exhaust is cracked behind the turbo on the weld.
It could also be a loose or cracked EGR pipe

wouldn't read much into it another member was told he needed a new motor cause the EGR pipe was split, go figure

[mudski]

Do you have a snorkel fitted?

[kevin07]

when the motor is cold start it up with your hand moving around the egr pipe under turbo and get someone to give it a light rev and see iff you can feel any hot air if so make a plate and block that side as well.

[Tunguska_1908]

No snorkel, no. I have noticed between the two halves of the turbo near the base of the actuator there is a small amount of black soot, from what I can see there's no soot on the engine block behind the turbo. It looks as if it is coming from the 'centre' of the turbo. A seal in the exhaust side of the turbo gone? Maybe the gasket where the dump pipe is bolted to the turbo?
Grrrr....

[JonnoDe]

Definitely shouldn't be soot around that area. I agree with Kevin, while cold start it up and feel around the turbo for air/exhaust coming out.

[Tunguska_1908]

Tried your suggestion, couldn't feel any hot air coming from anywhere..... Blahhh totally over it. It's gonna get sold I tell ya. Tired of forking out hundreds of dollars to mechanics to fix $50 gaskets.
I can't do anything with it, don't have the tools or know how. Much easier to sell it and let someone else have the headache...

Just had a long weekend here, was intending to go away for the weekend but couldn't risk the car breaking down in the middle of nowhere, so wasted an entire weekend dicking around with it.

[JonnoDe]

Has this happened after you fitted the Dawes valve? If so I would check all your Hose connections

[P4trol]

Sell it if you want... This is where you either decide to fix, or sell. If you fix, you're either paying someone, or you do it yourself. (sorry to be captain obvious here).

There is a certain amount of diagnosis you can do, which could reduce the overall amount pages to a mechanic. The other option is you divert money going to the mechanic to tools, and educate yourself. We all had to start somewhere.

[mudski]

Remove the air filter and take it for a run and see if the noise changes. This might point you at whether its intake or exhaust.
Also its a long shot and I dont know how you would check, the cat might be blocked... is it lacking power at all from normal?

[Badball]

Mine does the same and has soot under the heat shield. Cause was the 3" exhaust system that didn't have a support bracket off the dump pipe and was too much weight hanging off the 3 studs on the turbo so the dump pipe was leaking off the turbo. Fixed the bracket issue just need to remove the dreaded heat shield to replace the nuts and re-tighten the dump pipe😄