6 replies to this topic

[DavieWeegie]

hi guys,

 

just been out and replaced my oil cooler thermostat, done the job, started her up and let her idle for a bit, took for a 5 mile run and all good, so let it tick over in the drive for a bit to see if the temp fell back down (it didnt phewww) but when I give her a good blast of the accelerator I noticed a noise, like a metallic whoosh almost like a dump valve about 2-3 secs after I let off the throttle pedal.

 

Checked all the hoses and made sure all the clamps are fine, theres no play in the turbo shaft except the bare minimum thats been there in the 5 years I've had the car and its never got any worse.

 

apart from checking all the metal pipes for pin holes anyone got any ideas what it could be?

 

edit: the thing has been overcooling for a while and the idle speed has been raised during this time, obviously the ecu thinking its still a cold engine so upping the idle with more fuel to compensate (ive used a load more fuel lately) could it be the actuator arm or the vanes sooted up due to this overspooling? she doesnt seem to have lost any power that i notice and still reaching around 22 psi normally with around 26-28 psi overboost that i can see on the boost gauge.

Edited by DavieWeegie, 22 January 2021 - 04:22 PM.

[ST56]

Hi

 

My ST started making that noise when the only silencer decided to part company with centre pipe. I believe even the smallest exhaust leak will reduce back pressure and cause this Turbo Twitter.

 

Peter

[DavieWeegie]

Thanks for the reply.

 

I dont think its the exhaust, seems to be coming from turbo area, although its hard to pinpoint exactly. My exhaust is a full stainless powerflow system with stainless decat, although it could be the flexi and coming up from the gap between the bulkhead and turbo i suppose.

 

I used to have a full straight through so I know the sound it makes when you hear the turbo cooo and it doesnt sound like that tbh, more like a metallic sounding whoosh/rasp on spool down, it sounds like a burst hose but none of them are, plus their all 4 ply silicone hoses less than a year old.

[ST56]

Hi

 

Another problem I experienced with my ST was when the rubber boots around the brake rod behind the pedals just disintegrated. This left a hole right through into the engine compartment. Sudden increase in turbo noises had me checking for all sorts of mechanical problems.

 

Sounds as if you have checked for all the obvious leaks, perhaps pop the inlet pipe off and check turbo shaft for play / movement. Perhaps with engine running at a slightly higher temperature it sounds a little different, mine was also running a full SS system with decat that created a lot of noise on overrun.

 

Peter

[nicam49]

What about the hose from the filter box to turbo? If it's an original, they can split under the clamp on the turbo...

[DavieWeegie]

already had that happen and its been replaced by a nice shiny blue silicone one.

 

its deffo coming from the turbo or air filter area, had the wife rev it up hard and still cant really pinpoint it exactly, it sounds like a dump valve, releasing pressure, if it was a hose or pipe id have expected it to be releasing pressure when the turbo is spooling up not spooling down. wierd one.

Edited by DavieWeegie, 23 January 2021 - 12:04 PM.

[PURPLE_2L_LX]

The 6 or 8inch pipe under the engine/gearbox?  Had that pop off on my 2004

car.