Diverter Valve VAG 1.8T question

PeterT

PeterT

PeterT

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Hi,
One of our cars is a 1998 Golf GTI 1.8T that we have owned since new.
I have just done nearly 600 miles up and around the Lakes this week and noticed that the diverter valve is just starting to chirrup as I back off the throttle. It has done this a couple of times before over the years and I have fitted new OEM valves before.
What does it do and what happens when it goes wrong? Will I be losing power at the moment and does it do any damage if not looked at immediately?
The car will be serviced next month and so I can have it sorted then but am quite happy to do it myself if required.
I have always used the OEM valves as they seem quite cheap in comparison the likes of Forge. You may say that is why they keep on conking out but I have no interest in diverter valve whosh noises.
Thank you for your thoughts,

PeterT
 
The Forge doesn't make silly whooshing noises.

If the standard ones keep failing and you plan to keep the car then its probably worth the extra to replace with a forge.
 
the noise is air being shoved back through the compressor housing the wrong way. bad for the turbo

it could be loosing performance if its closing fully i suppose.

replacements are about £80 innit? i dont think there is much difference between a forge or baileys

a friend of mine put a forge one on here 20vt. it still gets compressor surge afterwards. i think it has the wrong spring
 
Forge 007p's are the way forward. You can get them for around £70 if you look around. Much more reliable, silent operation and look cool to boot
 
I got mine for 70 + 5 delivery from the guy who runs motechperformance.co.uk, don't know if he's still reselling them though
 
Got JKM to source and fit mine and it's been fine every since - 40k on the DV - 83k on the car
 
As said it sounds like compressor surge. I wouldn't worry about it damaging anything. Some old turbo cars dont have any sort of dump valve or recirculator. Only thing it might do is increase fuel usage a bit as it can confuse the air sensor I think.
 
It's not compressor surge, it's compressor stall.

Air in the intake pipes returning to the compressor blades, hitting them and making them slow down.

Sounds cool, won't really do any damage unless you're running huge boost or hoon your car everywhere. Mine's been doing it for about 70% in the last 18 months that I've owned it and *touch wood* the standard turbo is still going strong at 134,000 miles.
 
My mothers A4 TDI has been making compressors stall noises for at least 12 months.

When you come off the throttle with "an" amount of boost, it makes that comp stall noise.
 
I doubt it's compressor stall, 120000rpm to 0rpm would be goodbye turbo, it will be compressor surge or "minor stalls" if you will. Whatever you call it, it's bad for the turbo. Some people claim DV's are only for noise supression...they are wrong. If you think about it, how can it be good the boost backing up through the turbo, sometimes causing the blades to spin in reverse. The boost takes the easiest way out, if it's finding the turbo an easier route than the DV, you probably have something wrong with your DV or wastegate actuator.

It's also proven to cause more lag running without a DV/with a DV not functioning properly. I guess you can get away with it on low boost turbos, but if you're running higher boost/remapped you're in for it
 
Toker said:
I doubt it's compressor stall, 120000rpm to 0rpm would be goodbye turbo, it will be compressor surge or "minor stalls" if you will. Whatever you call it, it's bad for the turbo. Some people claim DV's are only for noise supression...they are wrong. If you think about it, how can it be good the boost backing up through the turbo, sometimes causing the blades to spin in reverse. The boost takes the easiest way out, if it's finding the turbo an easier route than the DV, you probably have something wrong with your DV or wastegate actuator.

It's also proven to cause more lag running without a DV/with a DV not functioning properly. I guess you can get away with it on low boost turbos, but if you're running higher boost/remapped you're in for it
Click to expand...

Q F T, you either have a problem or you have the wrong spring type in you DV etc.
 
This is always where people disagree. AGW it is surge and not stall. I don't see how you are going to be able to stop a turbo spinning at 100000 rpm + just with the pressure built up in the boost pipes and THEN make it reverse as well. I have read it can make a car considerably faster around a track without a dump valve. If you try it, once on boost and you blip the throttle you get next to no lag. But that said this is an average road car. Also depends on compressor design. For example mitsubishi turbos have a good recirculator system in them and would not benefit from anything else.
 
Ditch that Bosch unit, it really is crap!

Yes, they are cheap, but then cheap is cheap!

Get a Forge 007 in there. Also solved a slight hesitation on light throttle on my Cupra. It was deffo a problem with the bosch unit as I tried a brand new one and it was the same. Fitted my forge and it hasn't done it since.

Best thing to do with the bosch unit is to bung it in the boot as a spare for emergencies. Two minute job and will get you home. That's all it's good for.
 
I have a forge007 on my cupra. Has anyone "serviced" their DV? I read somewhere on another forum that it was advisable after a certain amount of mileage
 
The standard Bosch one is fine - If it goes wrong - Just replace it with an original part.

I have a standard bosch in my 1.8T and I'm running 330 BHP - No problems so far ;)
 
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