Engine/Transmission (1994 - 1998) How to Block your wastegate for max press?

[EGILLILAND]

Ref a previous thread of mine:



Low Fueling?



As I begin trouble shooting, it seems to me that if I make my turbo generate max boost... . then if the fueling and EGTs come back as before... then I've found my problem... an air leak.



Ergo... If I pull the line off the TST wastegate elbow and plug the end that leads to the AFC... .



? Will my turbo then generate max boost ?



Just a step in my troubleshooting that would be easier and possibly safer than punching a hole through something soft pink and fleshy with a piece of sewer pipe propelled by compressed air.



Thanks in advance fellas.



Cheers,



Gill

 

[C Schomer]

Just checking for understanding... Make sure you leave the line from the intake manifold to the AFC and plug the wastegate branch. My wastegate tube has been in the attic since I put the 14 cm2 on. I also made sure the wastegate was clean and shut tightly. Make sure all the boost connectors are tight, especially the hot side. Craig

 

[JohnE]

Gil;



Move that pyro probe to pre-turbo. As Forrest menioned in the other thread the ole +300° rule is too weak.



I'm fueled a bit more than you and generate some serious heat. I originally blocked the wastegate, but after a few (OK many) >39 psi runs the head gasket let go.



I added a Turbo-Master and boost is kept down and the EGTs are doing much better.



If you want to check for boost leaks the best way is by plumbing in an air supply and doing a static test. You may find the leak is simply at the CAC boot.



edit

Craig

Auto don't have the boost line plumbed into the AFC as manuals.

 

[EGILLILAND]

Regarding the static test you mention. I've read a couple places where guys actually disconnect the air pipe that leads into the intake and plug it there.



Others have mentioned they (through some technique) discovered actual leaks in o-rings around the grid heater and/or manifold bolts.



Here's my question... it seems to me I need to plug the intake connection, otherwise any air pressure I feed in at the turbo outlet will simply bleed past any open valves in the head... yes? Or can I accomplish a static test and evaluate the "entire" air induction system for leaks by leaving the intake air pipe connected?



Thoughts?



Sorry for veering off... . you lucked out and sounded like you had experience with this.



Cheers,



Gill

 

[radixr]

The only way air will leak past an open valve while you are pressurizing the intake side is if an exhaust valve is also open in the same cylinder (valve overlap). I can't say for sure, but I don't think there is much overlap in the diesel cycle.



I've tested for boost leaks several times, and never experienced leakage through the valves.

 

[JohnE]

The Fernco boot mentioned in the other thread is connected to the turbo intake horn. That applies pressure to the compressor side all through the charge air plumbing (including the intercooler) intake manifold up to the head. Here's the written instruction from someone<blockquote>The tester is as follows: 4"x3" fernco plumbing adapter, reduce the 3" side with 3" to 3/4" threaded pvc bushing, male/male 3/4" x3/4"x 2" nipple, 3/4"x1/2"x1/2" T, pipe pressure gauge to (1) 1/2" side, place supply air nipple in other 1/2" side(grainger has supply valves with 1/8" NPT). Pull the intake hose from the turbo, slip 4" fernco on, and pressurize to 20 psi(Slowly).

This is how I got there. I am sure there is a way eliminate some of the reducers and bushings, but I seem to always need them anyway. The fernco piece costs about $10. 00.

</blockquote>

I'll have to take a photo of my adapter. It is an intake hose off an ISL engine and a $2 regulator from a discount tool show that was in town. Cheap is almost free.



Leaks at the intake horn gasket or bolts happen especially if you have removed the manifold a number of times. A very common leak is where the hoses connect on the charge air cooler. If the cast lines are not ground smooth they will bleed a little pressure.



As far as blocking the turbo wastegate and checking for leaks it is not effective. I had serious leakage through a blown head gasket but never noticed a difference in the boost gauge.

 

[EGILLILAND]

Great info guys... thanks! That's what I needed.