boost spike on AAZ stuck wastegate?

[ilikevwdiesel]

put a 94 AAZ w/K14 turbo in my latest caddy, stock except for TT exhaust and K&N filter. When I load the engine it pins the boost gauge, backing the setscrew out on the wastegate doesn't help. Thinking I should just crank the screw all the way in and install a bleed valve in the metal line on the turbo. anyone know where to get the parts to do that, or have any other suggestions? I don't want to try and fix the wastegate as it is cause I'd have to pull the turbo off. can I just remove the set screw and spray some PB blaster in there and let it sit overnite? any suggestions would be appreciated.

[rallydiesel]

You need to remove the wastegate. If you're lucky, you can get it to work free with penetrating oil and working it back and forth. Next step is to take the wastegate apart by carefully prying the can apart and taking the valve out and removing the carbon with a scotch pad. Last resort is to get a replacement wastegate. Putting a bleeder on the metal line will reduce intake pressure put you will still be running unnecessarily high exhaust manifold pressure and egt's.

[ilikevwdiesel]

sadness...so remove the turbo from the engine and do it on a bench, right?

[nathan_b]

Try it in car = broken wastegate bolts and curse words

[ilikevwdiesel]

has anyone ever taken the downpipe off and squirted some seafoam or mystery oil in there and freed one up? I don't want to take it off with the engine in the car what a headache.

[rallydiesel]

When I rebuilt my k24, the wastegate was seized so bad that it snapped when I was trying to pull it out. Plus, the bore of the valve itself is far enough away from the exhaust tract that solvent will not reach it. Maybe if you sprayed it into can itself some would trickle past the diaphragm.

[ilikevwdiesel]

You need to remove the wastegate. If you're lucky, you can get it to work free with penetrating oil and working it back and forth. Next step is to take the wastegate apart by carefully prying the can apart and taking the valve out and removing the carbon with a scotch pad. Last resort is to get a replacement wastegate. Putting a bleeder on the metal line will reduce intake pressure put you will still be running unnecessarily high exhaust manifold pressure and egt's.

hey...how can a turbo make boost on the exhaust side? there's nothing to keep the pressure inside the manifold, it leaves the manifold goes thru the turbo fan and out the pipe. besides, how can boost on the exhaust side exceed the level of boost on the intake side? doesn't make sense to me but if someone can explain it I'm reading...

[vanagonturbo]

Combustion creates pressure. Heat from combustion also creates pressure.

[RadoTD]

When you take a hydrocarbon like diesel, it reacts with air and creates tons of heat in increases it's volume significantly. This is what pushes the piston down and actually makes the car go. There's always lots of excess pressure and heat coming out the tail pipe, a turbo uses this pressure and heat to compress the air coming in

[ilikevwdiesel]

you guys aren't hearing me. the exhaust gas leaves the cylinder, goes thru the manifold, thru the exhaust fan and out the pipe. nothing can cause boost to build up inside there, there's nothing restricting it except the fan, if you dump the boost out the cold side it doesn't matter what happens on the hot side it can't build up any more than that. my point is rallydiesel tells me that putting a bleed valve in the line that goes to the wastegate from the cold side housing won't fix my problem because the turbo will still build up pressure on the hot side. I'm saying that's not possible. AmIrite?

[Thezorn]

How much boost are you seeing when It pegs you gauge?

you guys aren't hearing me. the exhaust gas leaves the cylinder, goes thru the manifold, thru the exhaust fan and out the pipe. nothing can cause boost to build up inside there, there's nothing restricting it except the fan, if you dump the boost out the cold side it doesn't matter what happens on the hot side it can't build up any more than that. my point is rallydiesel tells me that putting a bleed valve in the line that goes to the wastegate from the cold side housing won't fix my problem because the turbo will still build up pressure on the hot side. I'm saying that's not possible. AmIrite?

That line is the line that is supposed to tell a working wastegate to open, even if you pull that line off and have an open hole in the compressor side of the intake your car with still build boost just fine, I know this first hand. Personally I would just take the turbo off the car, which isnt as hard as it looks, and pull the wastegate, which is usually harder then It looks. You will have to dismantle the turbo to do this, at least I did. This can be a pain in the ass, but alot of PB Blaster can make this at least 100 times easier. Take your time and do not force the small wastegate bolts out, make sure to soak these in PB Blaster the night before also.
Once you have the wastegate out, all you have to do (All I did) was work the valve up and down, using PB Blaster, then laster oil until it breaks loose and moves with ease. Just to be safe I tried to get a little bit of oil inside the wastegate itself, a bit in the bolt hole from the compressor housing to the wastegate, as much as possible on the valve shank itself, and just for good measure a tiny bit on the bolt that compresses the spring in the cap.

[ilikevwdiesel]

the gauge I have only reads to 20 psi but it can go past that and it does, I'd say I'm hitting 30psi probably.

[Thezorn]

I changed my above post.

the gauge I have only reads to 20 psi but it can go past that and it does, I'd say I'm hitting 30psi probably.

Intercooled?

[ilikevwdiesel]

no intercooler but I have one to install.

[ilikevwdiesel]

How much boost are you seeing when It pegs you gauge?

you guys aren't hearing me. the exhaust gas leaves the cylinder, goes thru the manifold, thru the exhaust fan and out the pipe. nothing can cause boost to build up inside there, there's nothing restricting it except the fan, if you dump the boost out the cold side it doesn't matter what happens on the hot side it can't build up any more than that. my point is rallydiesel tells me that putting a bleed valve in the line that goes to the wastegate from the cold side housing won't fix my problem because the turbo will still build up pressure on the hot side. I'm saying that's not possible. AmIrite?

That line is the line that is supposed to tell a working wastegate to open, even if you pull that line off and have an open hole in the compressor side of the intake your car with still build boost just fine, I know this first hand. Personally I would just take the turbo off the car, which isnt as hard as it looks, and pull the wastegate, which is usually harder then It looks. You will have to dismantle the turbo to do this, at least I did. This can be a pain in the ass, but alot of PB Blaster can make this at least 100 times easier. Take your time and do not force the small wastegate bolts out, make sure to soak these in PB Blaster the night before also.
Once you have the wastegate out, all you have to do (All I did) was work the valve up and down, using PB Blaster, then laster oil until it breaks loose and moves with ease. Just to be safe I tried to get a little bit of oil inside the wastegate itself, a bit in the bolt hole from the compressor housing to the wastegate, as much as possible on the valve shank itself, and just for good measure a tiny bit on the bolt that compresses the spring in the cap.

well maybe I should try loosening one of the bleed line bolts and see how it affects my boost level...