Valve beside the intake

[A2TD]

Hey guys, I have an 87 TD and was wondering what the black plastic  valve is beside the intake, it looks alot like a diverter valve you'd see on a 1.8T. It seems to plug into the intake manifold and then plumb back into the intake hose which goes to the turbo. Thanks

[Maarten]

That is the diverter/blowoff valve.. it pops at 0.8bar to protect the engine when the wastegate fails.

Just seal it off with something like this:

http://shop.vwcaddyforum.nl/index.php?cPath=40_106_108

 

[A2TD]

How often do they fail???

[jtanguay]

How often do they fail???

 when not maintained/cleaned properly

[Maarten]

What do you mean by "fail"  stuck open or stuck close?

[jtanguay]

I think he means wastegate.  They don't fail too often, but it does happen.

[A2TD]

No I know where the wastegate is, I was currious how often they stuck open. I tried sealing it off last night, but it didn't solve my barely any boost problem.

[vwmike]

Your barely any boost problem could very well be a barely any fuel problem. Try rotating the LDA pin so you get some smoke out of it and see how the boost response is.

[fspGTD]

The reason why I believe the wastegates fail is that oil vapors in the intake make their way into the wastegate boost connection, and a small amount of boost air and oil gets pushed past the wastegate valve stem (this is by design, to help cool off the wastegate valve.)  But what happens is that over many years, this oil evaporates from turbine section heat, leaving a sticky residue that can in a worst case scenario completely harden from dirty mineral oil and being run along time at high temperatures.

The garrett wastegate is I believe more resistant to sticking, because it has an extra air line in its wastegate can at the bottom that evacuates any oil droplets that make their way into the wastegate can.  This secondary line to evacuate oil droplets from the wastegate can is not part of the KKK wastegate design.

Using synthetic oil would help, as it stays liquid (and slippery) at high temps without evaporating.  Changing oil at recommended intervals would also help slow down residue from accumulating around the wastegate valve stem.  Removing the oil vapors from the air intake by modifying the crankcase ventilation system (installing a filter or venting to atmosphere) would prevent oil from ever getting inside the wastegate in the first place.

But let's face it, 99.9% of these motors have oily air intakes with no crankcase vent filter.  Many have probably been abused at one point in their lives and run without the oil being changed often enough.  The majority of them are probably still run on conventional oil (that's all that the manufacturer recommended back in the 80's right?)  It shouldn't come as a surprise then, that most of these old turbos probably have wastegates sticking to some degree.

[vwmike]

I might point out that at this point it would not be adviseable to switch to synthetic unless you replace all of the seals. It is likely that they would begin leaking and you'd have to replace them anyways.

[vwmike]

That is the diverter/blowoff valve.. it pops at 0.8bar to protect the engine when the wastegate fails.

Just seal it off with something like this:

http://shop.vwcaddyforum.nl/index.php?cPath=40_106_108

 

I just noticed that...it's funny I actually thought about making that a long time ago when I went to remove the pop valve. I was going to use a freeze plug, but I couldn't find one the right size and ended up sticking an expanding plug thing in there for temporary use...which has been more permanent than I would prefer. I'm not sure just how many people would really buy it though.