BAM dump valve noise change.

Hi Everyone,
My wife said the car made a loud noise (when driving really hard in a low gear) and now the (i think) dump valve noise has changed from a Tisssssh to a sort of spooling noise?
Please excuse my my no tech description but I'm not a turbo guy but pretty good with engines and drive chains in general, I don't even know what a dump valve does hahaha, always had motorcycles or normally aspirated cars.

Any thoughts or help would be gratefully received.

Oh yeah, it doesn't seem to have affected performance and the noise seem to be coming from the passenger side low down.

First off, it should have a recirc valve, if it's got a dump valve, change it. 

Is it a standard valve or a forge item?

Is it a fluttering noise?

Okay here goes, now don't laugh!

I said dump valve because that's what I thought made that noise?

I've no idea if it is standard but guessing not as a friends standard 225 TT does make that noise.

Yeah you could call it a flutter but it wasn't like that when we purchased the car a year ago it made the Tishshshshsh noise that I hear lots of Subaru's make 

VW 1.8t dont have a dump valve, the only way you get an air dump noise is with a cone air filter.

The recirculation valves are plastic and can split, high revs in low gear could cause enough air to do it.

Is the car mapped or modded past the standard 222bhp? If so they can kill them pretty quickly.

Best advice is get hold of a forge 007p valve and ensure the correct colour spring is fitted for the boost its running.

I had to do the same on my VRS when I pushed it from 180bhp to 250bhp

Very short term it wont do any harm if driven sensibly but I'd get it done asap

I

Test your current one holds vacuum. 



I'd personally stick with a genuine Bosch 710, whatever the newest revision is, P rings a bell. 

Roach said

Test your current one holds vacuum. 



I'd personally stick with a genuine Bosch 710, whatever the newest revision is, P rings a bell. 

Unless its running more than standard boost.
The latest ones are still plastic and are still failing just as often

WATERNAIR said

Roach said

Test your current one holds vacuum. 



I'd personally stick with a genuine Bosch 710, whatever the newest revision is, P rings a bell. 

Unless its running more than standard boost.
The latest ones are still plastic and are still failing just as often

We'll agree to disagree.

I ran a 710n on my 280bhp Leon for a couple of years. I've only ever run them on all my 20vt cars.
A friend even uses a standard one on over 300bhp of forged engine. 

Each to his own I suppose. 

Thats impressive actually, maybe its down to the boost delivery difference between the Ko3s and the Ko4?

My Skoda killed the original and a new one within 6 weeks.

I did have an awful power spike on my first map though

Cheers guys, thanks for taking the time to help me out.

I  have no idea what boost it is running but I do know it has be mapped/mod'ed and I was told by the previous owner it was 280+ bhp which I'm happy to believe given it's performance.

One last question (hopefully where will I find the valve located? 
When I though it was a dump valve I did have a recce and couldn't see anything obvious so is it hidden away below the turbo somewhere?

Thanks again guys.
1985 …been i that position a few time 😂 Raced a 250 for a few years with some reasonable success.

I think (could be well off, I'm sure Roach can confirm) if you take the engine cover off it will be at the top of the engine just off to the right.

They are on the main turbo inlet pipe




On mine if you were to go straight up from the Skoda crest its pretty much there

That pic looks like Lydden Hill??
Yeah wasnt a comfy position but at least I was asleep
Beautiful Golf btw

Yeah it's up in the top right corner as said, attached to the intake pipe. 

Here's a pic.



You can just see it under the engine cover, mines shiny because its the polished forge one

If you've up'd your bhp by 50 then you will of raised the turbo pressure as well.
Although the standard valve can take the pressure it isnt designed to,

Its a bit like when I get on my daughters 100kg limit trampoline, it works but its only a matter of time before it goes wrong

Ah, not with the car at the moment but I think I found it the other day but didn't know what is was!
Tee's off of the inlet manifold about 8" from the filter with a approx 15mm pipe. It's a polished affair so guessing non OE.



Got a feeling that is exiting the Lake Esses at Mallory Park, not Lydden Hill, one of the few circuits I haven't raced at, there and Darley Moor.

If it nom oem you should be able to unscrew the top to access the spring, have a look at the condition of it and maybe pull the piston out and regrease it

I'll try after work tomorrow and let you know how I get on 

Took valve apart and all looks good.
You have to listen but you can here the noise in the background on the video.

The fluttering?

Is the valve holding vacuum, is it sticking maybe? Did you re grease it? 

You may have a boost/vac leak somewhere else otherwise… then the valve won't open dude to zero vacuum, then it'll flutter. 

Also, what colour is that spring?

Ill check for a leak then, it's a blue spring.

Is it a forge valve? Is it greased up? Does it hold vacuum?

If so you need to change the spring, I'd say that's too stiff. 

Green is for bog standard car,  yellow for a stage 1 car id say. 

However bill badger, of badger 5 (a legend with tuning these babies) recommended I used a standard green spring when he mapped mine to 270bhp. 

Green and yellow seemed to perform exactly the same.

But as I said at the beginning, I'd be using a 710 standard valve personally.