MarkD

Just a reality check... I've read and read threads on this, please tell me if I understand correctly:

- Diverter valve failure can cause underboost problems but not overboost

- Actuator failure will typically cause overboost but not underboost

I am doing some work and have some stuff apart, trying to determine if I need to replace the actuators while I am in there.
Already replacing diverters.
From what I have read I think the above is correct. If not, let me know...

Felix

correct

Depends on the failure mode; if an actuator jams open you'll get virtually no boost from that turbo.

The actuators are quite expensive; IMO make sure you understand the cause of the boost problem before you go throwing money at the car. What are the symptoms and what tests/checks have you done? There is a procedure for checking/adjusting the wastegates in the shop manual using 0.5 bar air pressure to ensure the wastegates are opening the correct amount for that pressure level. Have you done that?

MarkD

Thanks for the confirmation on the diverters.
I haven't put vacuum to the actuators to test operation or adjust yet. I just wanted to be sure I understood the symptoms before I even spent time messing with them.
Based on what you said, they are operating properly. I suppose I should test while I have it apart anyhow, just to be sure.
I am not even certain I have a boost problem... mostly just want to sort things out a bit.

Felix

You can do that till the cows come home and nothing will happen; they need positive pressure.

If it ain't broke don't fix it!

MarkD

ah, ok. Thought they worked on vacuum... wonder why Porsche lists them as "Vacuum unit" in PET then?



When you have had PS fluid leaking all over stuff from a faulty return line with one of those pathetic crimp clamps Porsche used to hold it on I think it is prudent to make sure nothing has been made less than functional. The PO let this go for some time, I think.
I am not doing this because I am bored.

911/Q45

I think that would be defined as broke and needing fixing! PS fluid leaks in the engine compartment are usually due to bad crush washers on the pump connections.

Felix

It's a vacuum, a negative one!

MarkD

Well, I tested the acuators and all is well so they weren't "broke".
PS leak was the low pressure side and a faulty (or just old) crimp-style hose clamp. The source was pretty obvious once I worked my way up. The hose twisted around easily on the nipple... and flow freely when moved. What a mess.
I'd heard those crush washers could be trouble and thought that is what I would find. I was surprised.

I was thinking the same thing.