Vacuum pump going out/worn out?

rtz

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Feb 17, 2011
Location
Edmond, OK
TDI
98 Beetle
I put a gauge on it and it reads 5 Hg at idle. If I rev the motor; it shoots up to 20. If I mash the brakes; it's drops back to 5. If I'm driving and rapidly pump the brakes; it depletes the vacuum and I have no vacuum assist and it feels like I have wood brake pads.

I've looked for a new pump. Seen one for sale anywhere? (how much are they at the dealer?)

212k miles.
 

ymz

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May 12, 2003
Location
Between Toronto & Montreal
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2003 Jetta TDI Wagon, 2003 Jetta TDI Wagon
Where are you measuring the vacuum?

Often the clamp that holds the ~1/2 in. (i.d.) hose going to the checkvalve and brake booster loses its seal... Have you tried to stop that area from leaking?

Yuri
 

rtz

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Feb 17, 2011
Location
Edmond, OK
TDI
98 Beetle
I unplugged the hose going to the round vacuum reservoir. I'll check out that clamp tomorrow.
 

ymz

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May 12, 2003
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Between Toronto & Montreal
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2003 Jetta TDI Wagon, 2003 Jetta TDI Wagon
I'd rather you checked the vacuum at the inlet to the N75 valve (but I don't know where that one's found on the New Beetle...) Be sure not to damage the plastic nipple on the N75 when removing the vacuum hose... (be careful - use a thin pick to loosen the hose) The vacuum reservoir is needed to supply a basic level of vacuum... (and I still like that vacuum pump outlet junction for a handy place for a leak... you get two places that can go wrong: the hose clamp, and also the outlet itself, which rotates inside the pump housing, has been known to let air in...)

Yuri
 

DidJettarun

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A5 2005.5 Jetta A4 2003 Jetta
Take a look at the overall condition of the vacuum lines as leaks from worn lines is very common and can easily be repaired by replacing the lines. If you have access to someone with a VCDS cable and software have them check to see if the vacuum driven components are functioning properly to give you an idea where to focus your leak search.

Is the turbo actuator moving...Is the anti shutter valve functioning when you shut off the car. These will also indicate if your pump is generating sufficient vacuum. I will look to see if I can find the vacuum specs and post them

The outlet fitting mentioned above is also a common cause of vacuum leaks...rtv works very well
 
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DanG144

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Aug 2, 2007
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Chapin, South Carolina, USA
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2005 A4 Jetta 5spd
Those vacuum pumps last a very long time.

It is probably, leaking seals at the vacuum pump outlet, and bad hoses.

While measuring vacuum (I do it off the nipple on the large brake booster check valve when checking the pump's health) wiggle, pull, push on the vacuum pump outlet line. See if it doesn't have a sweet spot and go up to a good vacuum. By measuring at the nipple on the brake booster line, you eliminate all the system leak points except the large line, pump outlet, and brake booster itself. You have divorced all the small lines and actuators from the system.

20" is absolute minimum. A healthy leak tight system will have 24" at idle.

As DJR mentions, you may need to replace all of your small vacuum lines.

When testing the health of the system overall, I also measure at the vacuum source line on the N75. If it is good at the brake booster line, but bad at the N75, I isolate one component at a time, putting my gauge in place of the removed component and lines.

If you do use RTV or any other sealant on the vacuum pump outlet make sure that it is warm enough to cure, and you allow enough time for it to cure. 24 hours in summer weather for RTV is normal, since it is a thick layer. You do not want to suck any sealant into your vacuum pump, head, oil pump...
 

Herm TDI

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2002 Golf GLS Malone Stage 3, P+520 nozzles, 11MM Inj pump, Sachs VR6 clutch, Stelth Race Pipe, Immo Deleat, EGR Deleat
As part of the line/ hose inspection one of the first things to inspect is the black plastic hose attached to the brake booster. This hard plastic line often cracks at the fitting (on the brake booster). A leak here will affect all of your vacuum operated components....brakes, turbo, EGR and a few others.

In the photo below check item #21

 
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Kibbs

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Feb 19, 2011
Location
Oakville
TDI
2000 Jetta TDI GL
I am struggling with the same issue. Reading before the check valve is 30" so I think the pump is good. Inlet on the N74 is zero the fresh air intake to the breather box is 5. This does not appear to change even when removing the plug from the booster and covering with my thumb.

Any idea what I should get on the N75 inlet line?
 

Kibbs

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Feb 19, 2011
Location
Oakville
TDI
2000 Jetta TDI GL
Then i think I am looking at a brake booster issue. If I take a reading off the connector on the check valve that will go to the rest of the system i.e. not the booster with the hose connected to the booster I show 5 ". Add to that if I put my foot on the brake while testing the pressure slowly rises to 30"
 

DanG144

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Chapin, South Carolina, USA
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2005 A4 Jetta 5spd
That can be an issue. But more commonly it is the hard nylon hose to the brake booster cracked, or the seal on the vacuum pump outlet port gone bad.

The pump outlet seal can often be sealed with RTV or JB Weld (allow plenty of time at the right temperature to cure.)

If the nylon hose is cracked, you can see that visually.

I would inspect closely for these issues, even though you have some indications that it may be the booster itself.
 

Kibbs

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Oakville
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2000 Jetta TDI GL
Dan

I'll look at the pump port thanks, did not know that could go bad. Putting my thumb over the booster connector the vacuum feels very good, but understand that the vacuum does have to be constant to run the remainder of the system.

The classic test for the booster to pump then hold the brakes then start does seem to work as it should the pedal releases and lowers when started. The leaking sound that many report is not there.

I constantly get a P1556 Charge Pressure Control - Negative adding to the frustration of tracking this down. I can see if plugging the booster end will yield 20" but that is a relatively small space to charge so not the ultimate test. I have some hose and will make my way through the system to replace one evening this week and see if I can get up to Frisco for a few parts booster hose included.

Thanks
 

DanG144

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Chapin, South Carolina, USA
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2005 A4 Jetta 5spd
If you do not have adequate vacuum supply to your N75, then to your vane actuator, you will get that negative deviation code.

I think you are on the right track.

The pump outlet can leak intermittently. Quite often if you wiggle it, and push or pull on it, you can get it to seal. Once it seals it will usually stay sealed until you turn the car off. Then it may or may not seal again after that.

The newer pumps have a solid outlet, not one with a flexible seal. At least the one new replacement pump I have seen did.
 

Kibbs

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Location
Oakville
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2000 Jetta TDI GL
OK so here is my results and an experiment. I replaced a great majority of the hoses, while under the car hooked my mity vac to the actuator and it moves freely, hardly squeeze before it begins moving and appears about 18" to stop.

Next take a reading at the N75 Vac port line measures about 3". Next pull the booster line off and plug the end and take a reading at N75 again 25" + rev the engine and a nice little whistle under the hood so it appears the turbo kicks. A short drive in the parking lot with a couple pops of the throttle and it appears nice and torquey. So I think I have a very badly blown booster I cannot come to any other conclusion.

Now the fix, and where to take it. Doing myself is not in the cards I do not have enough free time, the gear and it is still in the 30's F 0 C in my neck of the woods.

Any other feedback?

Thanks all!
 

PDJetta

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Is it possible the rubber grommet that seals the hard plastic line to the brake booster is bad? You might just want to spend a few dollars and replace it and if that does not work, consider replacing the brake booster.

--Nate
 

Kibbs

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Oakville
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2000 Jetta TDI GL
I would think that would be pretty noticeable while under the hood. I can test the area and see if it is leaking I guess. I also want to look a the other end under the white plastic piece inside the car. There was another post where a suggestion was to spray some white lithium grease there to help with a seal. Will attempt both ends.

This has to be pretty severe as I have next to no vacuum to power the remainder of the system and thus regularly get a P1556 Charge Pressure Control-Negative.

Thanks
 

rtz

Member
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Feb 17, 2011
Location
Edmond, OK
TDI
98 Beetle
The factory crimp bands on the short length of hose that goes from the pump to the valve(on it's way to the booster) were loose enough to allow the hose to spin. Also, the metal tube that sticks out of the vacuum pump can be wiggled and spun around. I've got 20" of vacuum with the new worm drive clamps installed on that short piece of hose. Metal tube is still loose though(normal?).
 

DanG144

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2005 A4 Jetta 5spd
The metal tube being real loose is a sign of a leaking seal.

I usually use JB Kwik Weld if I am in a hurry, or RTV if it can sit for at least 24 hours to seal up that joint. Make sure you have the temperatures for whatever you use to cure properly.

The new ones are solid, the old ones have an elasomeric seal that goes bad.

Just seal it up and I bet your vacuum improves. It usually does.
 

PDJetta

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'04 Jetta GLS TDI Pumpe Duce Platinum Grey w/ Leather
The factory crimp bands on the short length of hose that goes from the pump to the valve(on it's way to the booster) were loose enough to allow the hose to spin. Also, the metal tube that sticks out of the vacuum pump can be wiggled and spun around. I've got 20" of vacuum with the new worm drive clamps installed on that short piece of hose. Metal tube is still loose though(normal?).
That metal tube is crimped into the vacuum pump. Both the tubes on my PD (the tandem pump--fuel feed and vacuum pump in one) and my mother's 2000 Jetta's vacuum pump wiggle and swivel.

Yesterday I replaced the tandem pump (it was leaking fuel) on my '04 and the new pump superceded to a different part number. I noticed that the vacuum nipple for the brake booster line is cast with the pump body and is rigid and does not swivel. This was a Bosch unit from the VW dealer. Maybe the ALH pumps have superceded to to an imroved part without a swivel fitting too. It does appear this could be a vacuum leak source.

--Nate
 

DanG144

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Chapin, South Carolina, USA
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2005 A4 Jetta 5spd
Yes, replacement ALH vacuum pumps also have a solid nipple. The wobbly fitting is a very common place for a very bad vacuum leak.

If you seal it up, then you do not have to buy a new vacuum pump. The pumps very rarely wear out; it is mostly just the outlet fitting that leaks and causes poor performance.
 

PDJetta

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That is good to know. The one on my mother's 2000 Jetta TDI is pretty loose. Time to get the JB Weld out!

--Nate
 

cumminsfromthecold

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Oct 27, 2006
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HumCo
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'84 Toyota 1Z 4WD x-cab
Vacuum pump seal at metal outlet to brake booster, ALH TDI

Throwing the 1556 charge pressure control negative deviation code on a boosted '03 Golf automatic. When I noticed the oversized hose on that outlet and the spinning nipple, I wondered if the whistle under throttle that I'd been hearing was my pressure leak. Thanks for the help, guys. We're going with the JB Weld solution first.
 
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djrhetoric

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MPLS
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80 Rabbit pickup MTDI
Throwing the 1556 charge pressure control negative deviation code on a boosted '03 Golf automatic. When I noticed the oversized hose on that outlet and the spinning nipple, I wondered if the whistle under throttle that I'd been hearing was my pressure leak. Thanks for the help, guys. We're going with the JB Weld solution first.
Did that end up being your issue? I'm having the same whistling under throttle and it's causing some fun boost issues.
 

cumminsfromthecold

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HumCo
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'84 Toyota 1Z 4WD x-cab
TDI leaking vac pump and boost

Djrhetoric, the leaking vacuum pump didn't end up being the issue. There's something going on with the car's new oversized turbo. Something not good, I fear.

Keep rollin' rhetorical coal :cool:
 
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