How To Change Out A Diesel Vaccum Pump On A 2005 Vw Passat 2.0 Ltr

• #1

Hello Listers:

I have a strange problem with my 1996 Passat TDI and I actually don't know where to plow....

I accept very little vacuum reserve in the ability restriction booster..one or two pumps and I'thousand standing on the brakes to stop. In add-on, when I pull the hose off the vacuum pump, there appears to be VERY LITTLE vacuum available - obviously, at idle, I would not expect a LOT of vacuum, but in that location is damn most shut to zip unless I rev the engine to get those vanes spinning.

I replaced the vacuum hose going to the brake booster and I removed the embrace of the vacuum pump to cheque the vanes and the check valve in the cover nipple - all appears OK. The vanes look great and these wet vacuum pumps last FOREVER......I am getting NO check engine lights, and then I presume the engine calculator is happy.

Does anyone know a vacuum spec for this pump at idle? I thought I read it should produce up to 15 inches Hg..could I put a MityVac on the first nipple on the bank check valve associates and go an accurate read there??

Is in that location Any gamble the vacuum pump drive is cleaved/slipping? As I understand, this thing lives in the gasser benefactor location - is it driven past the intermediate shaft and could information technology exist slipping?

I am really at a loss here. I'd capeesh any thoughts.

Happy New Year Everyone!

• #2

It is indeed driven off a gear on the intermediate shaft. I would be very surprised if there is a trouble in that location. Mine looked pristine at 218K miles.

I just looked at the cost for a replacement. Ouch. $116 for a rebuilt + $50 cadre from 1stvwparts.com. 028 145 101AX

I had folks tell me that the oil pumps never go bad on these cars, and my past oil force per unit area problem had to be something else. Wrong. If it turns, it will somewhen wear out.

Final edited: Dec 29, 2006

• #4

The plot thickens.....

I've searched the archives and didn't detect a definite answer to this 1, and so here goes:

I lose ability restriction assist. The first brake awarding is perfect, and and then by the third push I take no power brake assist. I've replaced the vacuum line (that hard plastic piece of junk) and I tested the check valve for proper ioeration..the vac line is good. Then, I put a vacuum gauge on the vac hose from the vacuum pump to the booster. I showtime the motorcar and the brake pedal slowly falls under moderate pes pressure (brake booster passes test). Afterward a few seconds I read 29" Hg vacuum...that'south a LOT of vacuum, so vacuum pump passes the exam. And then, off for a drive....

I press the restriction pedal and everything is ok..no hissing sound inside the motel (brake booster appears OK, no leaks) and vacuum drops to eighteen" Hg and adjacent brake application is a bit harder.....vacuum does not build for a few seconds of running but then returns to 29". If I pump the brakes I am apace downward to Null vacuum and accept NO power brake assist.

So, here's where I am:

- Vac booster appears to exist good, BUT MAYBE I have a hairline fissure in the diaphragm that the vac pump tin overcome so I accept practiced braking in one case the vac pump can suck upwards a vacuum reserve.....OR

- The vac pump has a stuck vane or two so I go good system vacuum 'pressure'..but not enough of it - a loss of vacuum volume. I inspected the internals of the vac pump and everything appears OK (and I accept rebuilt LOTS of vacuum pumps).

- I know the vac booster SHOULD be the well-nigh likely suspect, having a safety diaphragm and all....merely......

Any thoughts?

Thank you everyone for your input.

Regards,

Tracy

• #5

Check the rubber elbow coming off the acme of the pump. The PO of my B4 related similar symptoms and that was the trouble.

Good luck!

• #6

GMCpatrick said:

Check the rubber elbow coming off the pinnacle of the pump. The PO of my B4 related similar symptoms and that was the problem.

Good luck!

Thank you, Patrick. That has been checked; information technology'south new forth with the hose associates....

Right now I'm leaning toward a bad vacuum pump, in that I accept a loss of vacuum Volume. Even though my gut tells me the booster is more likely to fail with a safe diaphragm, I but can't show it.

Anyone else with a proffer??

Tracy

• #7

But pull the hose off the vac pump and stick your finger on it. Information technology's either pulling a vacuum or it isnt. The booster volition maintain a vacuum subsequently the car is shut off. Pull the hose out of the booster and listen for the vacuum whoosh.

• #viii

ninedee_golf_tdi said:

Simply pull the hose off the vac pump and stick your finger on it. It'south either pulling a vacuum or it isnt. The booster volition maintain a vacuum after the motorcar is shut off. Pull the hose out of the booster and mind for the vacuum whoosh.

Howdy Nine-Dee:

I wish information technology was that easy...that's the point of this whole thread. Yeah, I go vacuum....29 inches of vacuum. Trouble is, it appears I don't go ENOUGH vacuum. You brand a good point, though....my symptoms are showing I do non take much vacuum RESERVE, so if I close the car off my vacuum goes away chop-chop also, and I have niggling heave at the brake pedal. I'm thinking I might have a PARTIAL failure of the booster...a small-scale leak I cannot hear only is constantly bleeding off vacuum and the vacuum pump just cannot continue upwardly later on 2 or 3 brake applications ??

Does this brand sense? I thought boosters were similar the vacuum pump you described...either they work or they don't !!

Any thoughts, anyone?

Tracy

Lug_Nut

TDIClub Enthusiast, Pre-Forum Veteran Member

• #9

The symptoms are a volume problem, not a force per unit area trouble. Yous build 29 inches of vacuum, just non quickly enough to go along up with several applications of the brakes.
Vacuum leaks are tough to observe. Pressure leaks are easier, and then pressurize the organization.
Pull the hose afterwards the check valve and use a low force per unit area, high volume air supply (vacuum cleaner outlet, hair dryer on cool) to the booster. Check for air leaking out. It'd have to be a big leak to deplete the vacuum pump's capacity every bit quickly every bit y'all written report, so it should be piece of cake to notice.

• #x

I have not traced all the vacuum plumbing, but what most a possible leak in the vacuum resorvoir or its plumbing?

TW

• #xi

It may be a problem with the restriction booster, they can leak in odd ways, such as only when you printing on them.

Might be useful to put a tee into the vac organisation while yous have the guage in in that location. Let information technology describe a vacuum (29" or whatever) and and so open the tee for a fraction of a sec and and then seal it once again. Then see how long information technology takes to rebuild vacuum. If the vac rebuilds fast with the tee, then it is likely a leak in the brake booster that takes a long time to seal once pressed. If it takes equally long with the tee as with the brakes, then I'd doubtable the pump defective volume capacity

It is not unheard of for the brake booster to fail in a way that causes them to not reseal afterward use. Might want to speak to a place that rebuilds restriction boosters and see if thay have any thoughts. Might be an easy rebuild.

• #13

codeblue said:

Maybe this is simply stupid but...

I don't think anyones mentioned the other vacuum hoses, such as the ones going to the EGR solenoid and going to the cabin recirc flap activator. Those are super long lines of plastic and bits of the frail braided rubber hoses.

If its only a small-scale leak my gauge would be in ane of those lines.

Try getting some small rubber vacuum caps and put them on the two nipples that are correct after the elbow on the principal vacuum line. Cap them off and then try the brakes.

Hello Code:

This is a very VERY expert idea...I was very hesitant to do this since vacuum drives the turbo wastegate through the N75 solenoid and I didn't want to become into an over - or - underboost situation and throwing a code.

BUT - for testing it certain is a good idea !!!!

I'll report back. Cheers for the peachy idea.

Tracy

Lug_Nut

TDIClub Enthusiast, Pre-Forum Veteran Member

• #fourteen

crvsecretary said:

I was very hesitant to do this since vacuum drives the turbo wastegate through the N75 solenoid...

The N75 operates on turbo force per unit area, not vacuum. It is independent of the vacuum system.

Cherry-red heave is blocked, Blue wastegate is open to Black atmosphere to keep wastegate closed.

N75 valve shifts.
Red boost connected to Bluish wastegate. Black atmosphere is blocked. Boost force per unit area pressurizes wastegate chamber and opens wastegate to salvage heave pressure.

• #15

Lug_Nut said:

The N75 operates on turbo pressure, not vacuum. It is independent of the vacuum arrangement.

Cerise boost is blocked, Blue wastegate is open up to Black atmosphere to keep wastegate airtight.

N75 valve shifts.
Ruddy heave connected to Blue wastegate. Black temper is blocked. Boost pressure pressurizes wastegate bedroom and opens wastegate to relieve boost pressure.

Cheers, Lug...and do I ever experience like a fool. When I saw the vacuum routing diagram under the hood I thought ALL the lines were vacuum lines...even the ones to the N75 solenoid. I'm guilty of likewise much looking and not enough knowledge.

I tested the vacuum restriction booster by taking the earlier suggestion to PRESSURIZE the booster...so I took the hose off and put 3 to five PSI into it from my air compressor...and it was air-tight! The only affair that makes any sense is a bad vacuum pump....and I'thousand really astonished since I have rebuilt LOTS of dry and oil-lubricated vacuum pumps and this i looks really good.

One terminal question....is it possible that the intermediate shaft bulldoze is slipping somewhere???? I tried turning the vacuum pump shaft and that is secure to the bulldoze shaft...but...are in that location whatsoever other possibilities?

I'll order upward a vacuum pump in the morning....

Thank you everyone for your thoughts.

Tracy

• #16

The intermediate shaft and gear is one piece, as is the vacuum pump shaft and gear, no slippage possible. You still havent put your finger over meridian of the vacuum pump (or actually hooked a vacuum gauge to i of the several ports) to run across if it's pulling a vacuum ?

• #17

ninedee_golf_tdi said:

The intermediate shaft and gear is one piece, as is the vacuum pump shaft and gear, no slippage possible. Yous all the same havent put your finger over tiptop of the vacuum pump (or really hooked a vacuum gauge to ane of the several ports) to see if it's pulling a vacuum ?

Hello Ninedee:

Yes - earlier in the thread I mentioned I put a gauge on the vacuum nipple going to the cabin recirc door and I was pulling 29" vacuum...Only..later on ii or 3 brake applications that number would drop to 18" and braking assist was marginal at best. It took some fourth dimension for the vacuum to recover to 29"..especially if at idle as if you were braking down a long hill.

The only affair that makes sense is that I have a stuck vane in the pump that is reducing vacuum volume. I'm tempted to pull the cover off a new one and measure the length of the vanes....equally the vanes vesture they get lighter and do not push button out to the body of the vacuum pump every bit readily (easier for them to get stuck in the rotating vane holder). I've seen this a very few times on 'wet' vacuum pumps where the oil is 'glutinous' but admittedly information technology's rare.

However, I reported all the vanes expect great and the length (absent a vane length specification) looks acceptable. I gauge information technology will be a mystery until the pump is changed.

Thanks once again everyone !!

Tracy

• #21

I estimate i will PM CRYS. and hopefully get an answer, I too have been having this problem. My xviii wheeler doesn't take as much foot2pedal pressure to cease as my 97 passat does on the 2nd or tertiary pump in stop in go traffic. My guess is Crys replaced the pump, it fixed the situation and forgot to postal service out of relief the problem was gone.

Nonetheless, I am going to test everything out earlier buying parts.

Dave

• #22

Hi All:

I, too, did not report back to the list subsequently fixing the problem since I was then glad I finally Plant the problem: Pulled autonomously the vac pump and made sure the vanes were of acceptable length (I could not find a spec, so I guessed) and made sure they moved freely. A little parts cleaner in a can sprayed in there made sure everything was OK. Afterwards reassembly, I removed everything and put a vacuum gauge on the line to the vac pump - everything looked good. Then, I took an air line and, under VERY depression pressure, I PRESSURIZED the vac brake booster and started listening for leaks - none found. ( I could not generate enough vacuum with the little handheld vac pump I own, and then, I used pressure). Then, But the vac brake booster was connected - OK. And then, the vac line to the recirc air door was connected....and I found a bad hose connection most the battery area.

After a pocket-sized repair - all is well !!!!

Based on what I plant here: the vac pump can and should last forever. It is an oil-lubricated design and appears to exist very durable. In the futurity I would propose anyone looking for an vacuum problem should await at the pump Concluding. Ever replace the plastic line from the vac pump to the brake booster as a outset step - these go breakable and on our high-mileage cars it'due south not worth the time to take a risk on it.

Final edited: Feb 21, 2009

• #23

I was doing a search for vacuum pump/restriction issues and had the same symptoms. Funny thing is information technology turned out to be the same exact crusade, a vacuum line that runs right in forepart of the battery was disintegrated I think by a combination of battery acid and rust in the nearby area.

I capped it off for at present, but does everyone know where this line goes?

I think my old GTI had a vacuum resevoir that was stored in the fender bicycle well, is that where this goes?

The vacuum diagram in the engine bay does not appear to item out all of the vacuum lines.

• #24

I capped it off for at present, just does anybody know where this line goes?

There are just 2 vacuum solenoids on a TDI Passat:

1. Recirc/fresh air solenoid which is in the fender well, directly adjacent to the battery.
2. EGR.

Tony

• #25

Thanks, that answers my question, it must be the recirc and then.

Source: https://forums.tdiclub.com/index.php?threads/vacuum-pump-gone-bad-how-to-check.162913/

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