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Discussion Starter #1
O.K. so today I go outside thinking hey I am going to try to test the vaccum at the wastegate with the new gauge I bought last week. I take the rubber boot connecting the vac line to the wastegate actuator off, and in the process break the line where it goes into the rubber boot. So I get a new boot, hook it up to the line and to the actuator and go for a ride to make sure everything is still alright. Go out and all is still good, I am attaining the same boost levels as before. So I come back home, pop the hood again and pull the boot off of the actuator and plug my gauge into it using a T with one end of the T plugged, another into the boot with the vac line, and the other end into the gauge line. So I get that all hooked up and to my surprise gauge reads 0. At this time I also realize that at idle the wastegate arm is almost wide open and is not even remotely sucked into the cannister. So at this point I am confused. So I take that setup off again, spray some WD40 and PB Blaster into the vac line going to the actuator, hook the boot back up to the actuator and take off for a ride again. Still no change. So when I get home again, I try hooking the gauge back up and it still reads 0. I also took this opportunity to take off my engine oil cap to see if there is any blowby at all, and again to my surprise there is absolutely no noticable blowby. At this point I am totally confused and decide to give up for the day. It is like 10 F here with a windchill of about -10 so it is pretty cold.
Any thoughts on this? Did I try and test it right?

Thanks, Jacob
 

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Can you move the wastegate lever with the vacuum line plugged in? with it not plugged in?

Is there vacuum on the line?
 

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Discussion Starter #3
At idle I can move the wastegate lever up into the canister, and checking it the way I checked it I was not getting any reading on the gauge. What I don't understand is if there is no vaccum at idle then how can it build up 5psi of boost, shouldn't it just be dead, and not do anything as well as black smoke like crazy. Seems like something weird is going on, like it only builds vaccum under acceleration or something of that nature.

Jacob
 

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Bar (__) of the "T" inserts between the vacuum line and the turbo actuator

Gage goes to the 'handle' of the "T" (|) for 15" on the gage at idle

Or, just connect the gage to the vacuum line.

Gage connected to the vacuum pump reads 25" at idle.
 

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next test the vacuum at the solenoid. If nothing there then your vacuum pump is bad or the line from the vacuum pump is broke. Either way, sounds like its time to make a homemade manual boost controller
 

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Discussion Starter #6
Would it still make boost though. I think I will try testing it at the selenoid maybe tomorrow.

Jacob
 

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You won't make boost w/o vaccuum at the actuator.

Just like GMCTD said, hook your gauge directly to the vac line.

Check at vac pump, should be 25". If yes, try the same line at the solenoid, should be 25". If yes, try the line goin' to turbo actuator. Check it right at the solenoid, should be 15". If yes, try the same line at the turbo actuator, should be 15". Checkin' it this way rules out a bad pump and solenoid as well as bad lines.
 

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Yes when you accelerate it could make boost.

The order of testing. First failure stops the system from working correctly.

At idle..

Check for 25" at pump. If it's low the pump is bad.

Check for 25" at solenoid in line to pump. If it's low the line to the pump is leaking.

Check for 15" on the other side of the solenoid. If it's low the solenoid is not cycling correctly. Check the electrical connections. Check for dtc for wastegate solenoid.

Check the vacuum at the turbo 15". Leak in hose.
 

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Discussion Starter #9
Can all this be done without cutting the lines themselves? If so please explaine more. Anywhere I can get pics of this?

SES light never came on during all of this. I was going to run it without the vac line even plugged into the actuator just to see what would happen but I never got around to doing it.

Jacob
 

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you can make boost without vacuum, about 2-3psi at heavy throttle, nothing that will do you any good though.
 

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Discussion Starter #11
DavidPhillips;1578555; said:
Yes when you accelerate it could make boost.

The order of testing. First failure stops the system from working correctly.

At idle..

Check for 25" at pump. If it's low the pump is bad.

Check for 25" at solenoid in line to pump. If it's low the line to the pump is leaking.

Check for 15" on the other side of the solenoid. If it's low the solenoid is not cycling correctly. Check the electrical connections. Check for dtc for wastegate solenoid.

Check the vacuum at the turbo 15". Leak in hose.
Do you have any more information on doing this. I am a novice at this stuff. Pics would be helpful.

Thanks, Jacob
 

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The plastic line can be pulled out of the pump larger hose, the rubber ends can be pulled off at the solenoid. Not the formed end at the turbo.

If they are brittle they will break.

You could trace this back from the solenoid. Unplug the hose on the solenoid coming from the pump. If it's good there you don't need to check it at the pump.

Pull on the rubber end to unplug it from the solenoid and check it there. If it's bad you will need to get a new vacuum harness if they are cracked up and brittle. If not go ahead and check at the pump.
 

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Discussion Starter #13
DavidPhillips;1578645; said:
The plastic lines can be pulled out except for the formed end at the turbo.
What does this mean?

I know they deffinately might because today when I did this I broke the one going into the boot that hooks to the wastegate arm.
Thanks, Jacob
 

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That one is formed on. The rubber ends can be unplugged at the solenoid.

There is a large hose at the pump. The plastic end can be pulled out.

If these lines are brittle like I think they are they will fall apart when you look at them hard.


Basically try to pull on the rubber, not the plastic. At the pump you don't have much of a choice if you can't get anything at the solenoid.
 

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Discussion Starter #15
I have seen the large one at the pump yes. When you look down it is like the only hose you see around the pump right. It looks like about 1/2" big. When I do this I take off the turbo power cover to gain better access right. What else can I do to make this easier. I also read on here that the little ball in the selenoid can go rust and stick, so I sprayed some WD40 in the vac line going to the wastegate arm, but it didn't seem to do anything. When I unplug the lines from the selenoid is there a place I can spray oil to get at the ball?

Jacob
 

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The plastic pulls out of the large hose on my pump. I replaced the vacuum harness on mine and that end comes with just the plastic. The larger one does not come with it and mine was still good. However the lines were so brittle it broke off at that pump hose.

When you unhook the rubber end from the pump at the solenoid and connect the gauge to that end you will see if the pump and line is good. If it's good don't unhook the line at the pump.


The wastegate arm is free if you can move it by hand.


If you confirm the pump and line is good check at the output of the solenoid. If it's bad there it could be the solenoid.

Not sure about the wd-40. If I were going to keep the vacuum system I would change the lines. I would only change the pump if it's bad, and I would change the solenoid if it's bad.
 

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Discussion Starter #17
Where do you buy replacement line? Can you just be like a 6 foot roll or something and just cut all your pieces to length or does stuff have to be all custom fit and everything.

Jacob
 

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You could make your own. Or you can get it at the dealer. I think I paid $40 something.
 

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Discussion Starter #19
That was from the dealer or buying a roll or whatever?

Thanks, Jacob
 

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Try checking for voltage at the solenoid. The computer gives the ground for the solenoid.
All the rubber plugs should come off for checking vacuum. I usually start at the vacuum pump and work out. Take a good look at the plastic vacuum lines too. With the truck running you must have at least 15" at the waste gate. These solenoids can also get cranky.
 
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